Planck 2018 

From the Planck Scale to the Electroweak Scale

from to (Europe/Berlin)
at Bonn
Physikalisches Institut Nussallee 12 53115 Bonn
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  • Monday, May 21, 2018
    • 08:00 - 09:00 Registration
      Location: Zeichensaal (1st floor)
    • 09:00 - 10:00 Review Talk
      Convener: Mr. Herbert Dreiner (Universitaet Bonn)
      • 09:00 Model Building in the LHC Era 1h0'
        I will give my impressions of model building in the LHC era.
        WHAT are the problems for theory, WHERE are the hints for new physics
        and WHEN will we know.
        Speaker: Stuart Raby (The Ohio State University)
        Material: Slides pdf file
    • 10:00 - 10:30 Plenary Session
      Convener: Mr. Herbert Dreiner (Universitaet Bonn)
      • 10:00 Dark matter interactions and large scale structure of the universe 30'
        The cosmological standard model, LCDM, provides a very good overall fit to the precision cosmological data from the CMB, its polarization, baryon acoustic oscillations, measurements of large scale structure, and the current expansion rate of the universe. The most significant tension in the fit is associated with two quantities: the current expansion rate, H_0, and the amplitude of the matter power spectrum at the scale of galaxy clusters, sigma_8. I explain the physics behind this tension and present models with dark matter interactions which can remove it. I also show how future measurements of the shape of the matter power spectrum from weak lensing can be used to differentiate between models.
        Speaker: Martin Schmaltz (Boston University)
        Material: Slides pdf file
    • 10:30 - 11:00 Coffee Break ( Foyer )
    • 11:00 - 12:30 Plenary Session
      Convener: Prof. Howard Haber (Santa Cruz Institute for Particle Physics)
      • 11:00 ALP-driven magnetogenesis and photon-ALP-dark photon oscillations 30'
        String theory suggests the existence of multiple axion-like particles (ALPs) as well as hidden sector gauge bosons. Some of those ALPs and hidden U(1) gauge bosons (dark photons) might be light enough to result in interesting astrophysical and/or cosmological consequences. As an example of such possibility, we examine ALP-driven late time magnetogenesis generating the cosmic magnetic field via the generation of dark photon field. We also study the photon-ALP-dark photon oscillations in the presence of background dark photon field, and examine if such oscillations can explain the recently noticed gamma-ray spectral modulations of some galactic pulsars and supernova remnants.
        Speaker: Kiwoon Choi (CTPU/IBS)
        Material: Slides pdf file
      • 11:30 Solving the Hierarchy Problem Discretely 30'
        We present a new mechanism for making a scalar parametrically 
        lighter than the UV cutoff utilizing non-linearly realized discrete 
        symmetries. The cancelations occur due to a discrete symmetry that is 
        realized as a shift symmetry on the scalar and as an exchange symmetry 
        on the particles with which the scalar interacts.
        Speaker: Anson Hook (University of Maryland)
        Material: Slides pdf file
      • 12:00 An Update on the LHC Monojet Excess 30'
        While the LHC has done an excellent job of looking for new physics in all the expected places using simplified models, so far much less attention has been paid to model-independent, data-driven approaches. I will review a recently proposed method of "rectangular aggregations" that can find potentially interesting excesses in existing LHC searches without relying on simplified models. As a proof of concept, I will show how the method uncovers some highly statistically significant (and previously overlooked) discrepancies in the low-pT regions of ATLAS and CMS monojet searches. I will describe a simplified model that fits the monojet excess well, and discuss its implications. I will also discuss various issues with the background estimation and the control regions which may provide a SM explanation for this discrepancy. Regardless of whether this discrepancy is due to new physics or missing SM effects, there are interesting things going on in the monojet channel, and more generally, in the overlooked bulk of the LHC data.
        Speaker: David Shih (Rutgers University)
        Material: Slides pdf file
    • 12:30 - 14:30 Lunch Break ( Foyer, Bonn )
    • 14:30 - 16:00 Plenary Session
      Convener: Marek Olechowski
      • 14:30 Order-4 CP symmetry: flavor, dark matter, and beyond 30'
        I will describe recent results on phenomenological consequences of imposing an exotic CP-symmetry of order 4 in multi-Higgs models. Despite minimality of the assumptions, such models have well shaped scalar and flavor sectors and lead to rich phenomenology to be tested in experiments and astroparticle observations.
        Speaker: Dr. Igor Ivanov (CFTP, Instituto Superior Tecnico)
        Material: Slides pdf file
      • 15:00 Improved theoretical constraints on BSM models 30'
        BSM models must be confronted with a series of experimental and
        theoretical constraints. On the theoretical side, it is standard to
        check the tree-level vacuum stability, the tree-level perturbative
        unitarity constraints in the limit of large scattering energies, and
        the cut-off scale using one-loop running with tree-level matching. I
        will discuss that these constraints can get crucial corrections: (i)
        loop corrections to the vacuum stability can re-open parameter
        regions, (ii) 2 to 2 scattering at small energies can lead to much
        stronger constraints, and (iii) reliable results for the  high-scale
        behaviour of a theory are sometimes just obtained by combining
        two-loop running and matching. In addition, the check of the
        perturbative behaviour of the theory can become important. Examples
        for SM extensions with singlets, doublets and triplets are given.
        Speaker: Dr. Florian Staub (KIT)
        Material: Slides pdf file
      • 15:30 Composite Dark Matter 30'
        We consider a composite model where both the Higgs and a complex scalar χ, which is the dark matter (DM) candidate, arise as light pseudo Nambu-Goldstone bosons (pNGBs) from a strongly coupled sector with TeV scale confinement. 
        Speaker: Andreas Weiler (TUM)
    • 16:00 - 16:30 Coffee Break ( Foyer )
    • 16:30 - 17:00 Plenary Session
      Convener: Dr. Thomas Flacke (IBS CTPU)
      • 16:30 Theories of Flavour from the Planck scale to the Electroweak Scale 20'
        In this talk we discuss various Theories of Flavour from the Planck scale to the
        Electroweak Scale, ranging from SUSY GUTs with Flavour Symmetry (with or without extra
        dimensions) to Flavourful Z' Models at the Electroweak scale capable of accounting for
        Speaker: Steve King (University of Southampton)
        Material: Slides pdf file
    • 18:00 - 20:00 Welcome
      Location: Foyer Wegelerstr. 10
  • Tuesday, May 22, 2018
    • 08:00 - 09:00 Registration
      Location: Zeichensaal (1st floor)
    • 09:00 - 10:00 Review Talk
      Convener: Manuel Drees (Bonn University)
      • 09:00 Status and perspectives of BSM searches at the LHC 1h0'
        With the LHC Run II coming to an end and the LHC experiments already preparing for HL-LHC, this talk will review the current status of BSM searches, with particular emphasis on new analysis techniques developed in the recent past and possible implications for the LHC Run III and the long term.
        Speaker: Maurizio Pierini (CERN)
        Material: Slides pdf file
    • 10:00 - 10:30 Plenary Session
      Convener: Manuel Drees (Bonn University)
      • 10:00 Higgs coupling measurements and their implications on new physics 30'
        With increasingly precise measurements of Higgs boson interactions, we start to set tighter limits on Standard Model extensions. First, I will review the impact of existing and ongoing Higgs coupling measurements on how they constrain such extensions. In the second part of the presentation, I will focus on one of the most important couplings of the scalar sector, the Higgs self-coupling. Given theoretical constraints on the Higgs self-coupling, the capacity of future colliders will be assessed in measuring deviations from Standard Model predictions.
        Speaker: Michael Spannowsky (Durham University)
        Material: Slides pdf file
    • 10:30 - 11:00 Coffee Break ( Foyer )
    • 11:00 - 12:30 Plenary Session
      Convener: Prof. Margarete Mühlleitner (KIT)
      • 11:00 LHC Recasting Tools and Applications 30'
        Speaker: Dr. Jong Soo Kim (University of the Witwatersrand, NITheP, MITP)
        Material: Slides pdf file
      • 11:30 Natural SUSY from the landscape 30'
        I review how natural SUSY may emerge from the string landscape and present probability distributions for Higgs and sparticle masses
        Speaker: Prof. Howard Baer Baer (University of Oklahoma)
        Material: Slides pdf file
      • 12:00 Searches for long-lived particles at the LHC: closing the gaps in BSM signature coverage 30'
        Speaker: Dr. Nishita Desai (LUPM, Montpellier)
        Material: Slides pdf file
    • 12:30 - 14:00 Lunch Break
    • 14:00 - 15:00 Parallel Session Higgs and Flavor Model Building
      Location: Lecture Hall 1, PI
      • 14:00 Mass Degeneracies in Extended Higgs Sectors 20'
        Mechanisms that yield mass degeneracies in extended Higgs sectors with multiple Higgs doublets are examined. Some puzzling features of a recent 3HDM constructed by Ivanov and Silav are considered that appear to be connected to the mass degeneracies of their model.
        Speaker: Prof. Howard Haber (Santa Cruz Institute for Particle Physics)
        Material: Slides pdf file
      • 14:20 Muon anomalous magnetic moment in the presence of CP-violation 20'
        I will talk about popular scalar extensions of the Standard Model, namely the singlet extension, the 2-Higgs doublet model (2HDM) and its extension by a singlet scalar. I will focus on the contributions of the added scalars to the anomalous magnetic moment of the muon, and the electric dipole moment of the electron in these models.
        Speaker: Dr. Venus Keus (University of Helsinki)
        Material: Slides pdf file
      • 14:40 Third Family Quark-Lepton Unification at the TeV Scale 20'
        We construct a model of quark-lepton unification at the TeV scale based on an SU(4) gauge symmetry, while still having acceptable neutrino masses and enough suppression in flavor changing neutral currents. An approximate U(2) flavor symmetry is an artifact of family-dependent gauge charges leading to a natural realization of the CKM mixing matrix. The model predicts sizeable violation of PMNS unitarity as well as a gauge vector leptoquark U1 = (3,1,2/3) which can be produced at the LHC -- both effects within the reach of future measurements. In addition, recently reported experimental anomalies in semi-leptonic B-meson decays, both in charged b->cτν and neutral b->sμμ currents, can be accommodated.
        Speaker: Dr. Benjamin Stefanek (Johannes Gutenberg Universität Mainz)
        Material: Slides pdf file
    • 14:00 - 15:00 Parallel Session on Experimental Searches
      Location: bctp, Seminar Room 1
      • 14:00 IceCube bounds on sterile neutrinos above 10 eV 20'
        We study the capabilities of IceCube to search for sterile neutrinos with masses above 10 eV by analyzing its νμ disappearance atmospheric neutrino sample. We find that IceCube is not only sensitive to the mixing of sterile neutrinos to muon neutrinos, but also to the more elusive mixing with tau neutrinos through matter effects. The currently released 1-year data shows a mild (around 2σ) preference for non-zero sterile mixing, which overlaps with the favoured region for the sterile neutrino interpretation of the ANITA upward shower. Although the null results from CHORUS and NOMAD on νμ to ντ oscillations in vacuum disfavour the hint from the IceCube 1-year data, the relevant oscillation channel and underlying physics are different. At the 99% C.L. an upper bound is obtained instead that improves over the present Super-Kamiokande and DeepCore constraints in some parts of the parameter space. We also investigate the physics reach of the roughly 8 years of data that is already on tape as well as a forecast of 20 years data to probe the present hint or improve upon current constraints.
        Speaker: Julia Gehrlein (IFT-UAM)
        Material: Slides pdf file
      • 14:20 Axion Production and Detection using Superconducting RF cavities 20'
        We propose a ``Light Shining Through Walls"-type experiment to search for axions with high-$Q$ superconducting RF cavities. Our setup uses a gapped toroid to confine a static magnetic field, with production and detection cavities positioned in regions of vanishing external field. We argue that the confining toroid does not significantly screen the axion-induced signal for frequencies of order the inverse toroid size. This allows both cavities to be superconducting with quality factors $Q \sim 10^{10}$, thus significantly improving the sensitivity of the experiment. Such a search has the potential to probe axion-photon coupling $\sim 2 \times 10^{-11} ~\GeV^{-1}$, comparable to the future ALPS II.
        Speaker: Vijay Narayan (UC Berkeley)
        Material: Slides pdf file
    • 14:00 - 15:00 Parallel Session on Collider Searches
      Location: Big Lecture Hall, Mathematics
      • 14:00 Heavy Neutral Leptons at the LHC 20'
        Heavy neutral leptons or massive sterile neutrinos are present in many well-motivated beyond the Standard Model theories, sometimes being accesible at present colliders. Our aim is to discuss the potential of the LHC to produce and discover this kind of new particles when their masses are in the GeV range. Moreover, and depending on their masses and couplings, they can be long-lived and lead to signatures with displaced vertices, or decay promptly within the detector.
        Speaker: Dr. Xabier Marcano (LPT Orsay)
        Material: Slides pdf file
      • 14:20 Heavy neutral fermions at the high-luminosity LHC 20'
        Long-lived light particles (LLLPs) appear in many extensions of the standard model. LLLPs are usually motivated by the observed small neutrino masses, by dark matter or both. Typical examples for fermionic LLLPs (a.k.a. heavy neutral fermions, HNFs) are sterile neutrinos or the lightest neutralino in R-parity violating supersymmetry. The high luminosity LHC is expected to deliver up to 3/ab of data. Searches for LLLPs in dedicated experiments at the LHC could then probe the parameter space of LLLP models with unprecedented sensitivity. Here, we compare the prospects of several recent experimental proposals, FASER, CODEX-b and MATHUSLA, to search for HNFs and discuss their relative merits.
        Speaker: Simon Zeren Wang (bctp, Bonn University)
        Material: Slides pdf file
      • 14:40 B+L violation at colliders and new physics 20'
        Chiral electroweak anomalies predict fermion interactions that violate baryon (B) and lepton number (L), and can be dressed with large numbers of Higgs and gauge bosons. The estimation of the total B+L violating rate from an initial two-particle state --potentially observable at colliders-- has been the subject of an intense discussion, mainly centered on the resummation of boson emission, which is believed to contribute to the cross-section with an exponential function of the energy, yet with an exponent (the "holy-grail" function) which is not fully known in the energy range of interest. Focusing instead on the effect of fermions beyond the Standard-Model (SM) in the polynomial contributions to the rate, it is shown that the latter can be enhanced by several orders of magnitude with respect to the SM result, for high centre-of-mass energies and light enough masses. Further calculations hint at a simple dependence of the holy grail function on the heavy fermion masses. Thus, if anomalous B+L violating interactions are ever detected at high-energy colliders, they could be associated with new physics.
        Speaker: Carlos Tamarit (Technische Universität München)
        Material: Slides pdf file
    • 14:00 - 15:00 Parallel Session on Inflation
      Location: Small Lecture Hall, Mathematics
      • 14:00 Hill-climbing inflation and gravitational reheating 20'
        I will present a model of a hill-climbing inflation based on a scalar-tensor theory. I will show how the reheating can be generated by gravitational particle production and I will present the consequences of the gravitational reheating on the thermal history of the Universe and primordial gravitational waves.
        Speaker: Dr. Michal Artymowski (Jagiellonian University)
        Material: Slides pdf file
      • 14:40 Electroweak Phenomenology of Higgs Inflation in the NMSSM 20'
        We study the phenomenology of a Next-to-Minimal Supersymmmetric Standard Model (NMSSM) that can achieve early universe inflation. The Higgs sector of such a model clearly differs from the usual NMSSM and can provide a smoking gun of inflation at low energies.
        Speaker: Dr. Wolfgang Gregor Hollik (DESY)
        Material: Slides pdf file
    • 15:00 - 15:30 Coffee Break ( Foyer )
    • 15:30 - 16:30 Parallel Session on Higgs Vacuum and RGE
      Location: bctp, Seminar Room 1
      • 15:30 Higgs domain walls in the Standard Model and its extensions 20'
        The study of the renormalization group improved effective potential of the Standard Model has revealed existence of a local maximum at field strengths of the order of 10^10 GeV. If the Standard Model is valid for very high energy scales, then the possibility of the production of cosmological domain walls in the early Universe occurs. We investigated dynamics of networks of domain walls using lattice simulations. We studied domain walls in the extensions of the Standard Model using the formalism of the Effective Field Theory. The energy spectrum of gravitational waves emitted from Higgs domain walls was determined.
        Speaker: Tomasz Krajewski (University of Warsaw)
        Material: Slides pdf file
      • 15:50 NLO Matching Conditions in Extended Higgs Sectors 20'
        The absence of new physics in current LHC searches leads to increasing interest in a variety of non-minimal extensions of the Standard Model (SM). Also the scale of new physics in widely studied models is pushed to higher energies. Automation tools such as SARAH allow for comprehensive studies of a wider class of models beyond the Standard Model (SM). Not only the tree-level values but also NLO and NNLO corrections to mass spectra can be studied within a reasonable amount of time. However, large mass gaps can lead to problematic large logarithms increasing the uncertainty in fixed order calculations. The use of effective field theories (EFTs) is a common tool to resum these large logs. Thus, precise matching conditions between EFTs and UV complete -or intermediate- theories are needed. After a brief introduction into the running and matching procedures applied by SARAH/SPheno I will discuss various aspects important for a generic matching of scalar sectors at NLO. The connection of systematic cancellations of infrared divergences and contributions from mixed loops containing heavy and light fields in matching conditions is shown. Example cases for EFT Higgs mass calculations within heavy SUSY are presented as well.
        Speaker: Martin Gabelmann (Karlsruhe Institute of Technology)
        Material: Slides pdf file
      • 16:10 Regularization without a renormalization scale 20'
        I will describe a version of the dimensional regularization of a classically scale invariant theory, motivated by the requirement to preserve scale invariance at the level of loop corrections. The theory is embedded in a nonrenormalizable Lagrangian, where both the dimensionful regulator \mu and suppression scale of higher-dimensional interactions are interpreted as a vev of a new dynamical scalar field that mixes with the Higgs. The method is applied to an SM-like theory, where the electroweak symmetry and the scale symmetry are broken spontaneously together. The shape of the scalar effective potential and interpretation of the high energy Higgs vacuum are modified. Based on: arXiv:1608.05336, arXiv:1612.09120.
        Speaker: Pawel Olszewski (University of Warsaw)
        Material: Slides pdf file
    • 15:30 - 16:30 Parallel Session on Composite Higgs
      Location: Lecture Hall 1, PI
      • 15:30 Partially composite Goldstone Higgs 20'
        Recently there has been revival of interest in partially composite Higgs models, where electroweak symmetry breaking is dynamically induced, and the Higgs boson is a mixture of a composite and an elementary state. While the Goldstone nature of the composite sector explains the lightness of the Higgs, the elementary scalars provide an UV completion for the SM fermion mass generation via traditional Yukawa interactions. However, in this type of models, requiring vacuum stability up to the compositeness scale already imposes relevant constraints. We study the interplay of the these constraints and the LHC results, and we find that in the minimal realisation, a small part of parameter space around the classically conformal limit is stable up to the Planck scale, but this same region is however already disfavored by LHC data. We also consider minimal extensions to alleviate these constraints. Based on PRD 96 (2017) 095012 and JHEP 1810 (2018) 051.
        Speaker: Dr. Tommi Alanne (MPIK Heidelberg)
        Material: Slides pdf file
      • 15:50 Asymptotically Free Supersymmetric Twin Higgs 20'
        Twin Higgs (TH) models explain the absence of new colored particles responsible for natural electroweak symmetry breaking. All known ultraviolet completions of TH models require some non-perturbative dynamics below the Planck scale. A new type of supersymmetric Twin Higgs model is presented in which the TH mechanism is introduced by a new asymptotically free gauge symmetry. The model features natural electroweak symmetry breaking for squarks and gluino heavier than 2 TeV even if supersymmetry breaking is mediated around the Planck scale, and has interesting flavor phenomenology including the top quark decay into the Higgs and the up quark which may be discovered at the LHC. The talk will be primarly based on arXiv:1707.09071 and arXiv:1711.11040.
        Speaker: Marcin Badziak (University of Warsaw)
        Material: Slides pdf file
      • 16:10 Composite resonances of fundamental Composite Higgs models 20'
        Composite Higgs models are among the most promising alternatives to solve the hierarchy problem and provide a dynamical mechanism to break the electroweak symmetry. In this talk I will discuss some predictions of specific UV realizations of such scenario. I will analyze in particular the phenomenology of vector and scalar states in a SU(4)/Sp(4) symmetry breaking pattern, using lattice results as well as unitarity and analyticity arguments to constrain the parameters of the theory. I will also discuss the phenomenology of vector and scalar states of a SU(4) gauge theory with symmetry breaking SU(5)/SO(5) and their interplay with a top partner responsible for the top mass via the partial compositeness mechanism, which is also present in the theory. The talk will be based on arXiv:1605.01363, arXiv:1705.02787 and ongoing work.
        Speaker: Dr. Diogo Buarque Franzosi (II Physics Institute, Goettingen U.)
        Material: Slides pdf file
    • 15:30 - 16:30 Parallel Session on Collider Searches
      Location: Big Lecture Hall, Mathematics
      • 15:30 Searching for new physics in vector boson scattering at the LHC 20'
        The electroweak symmetry breaking (EWSB) sector still keeps some mysteries under the sleeve. Questions such as what is the dynamical origin of EWSB, what is the true nature of the Higgs boson or are the properties of this particle the ones predicted in the SM remain unanswered. The LHC is our tool to unveil these mysteries and vector boson scattering (VBS) is the perfect window to access them. In this work we perform a model independent analysis of the phenomenology of VBS at the LHC and give predictions for the sensitivity to possible new physics scenarios in the EWSB sector.
        Speaker: Claudia Garcia-Garcia (IFT-UAM/CSIC)
        Material: Slides pdf file
      • 15:50 Top, Electroweak & Higgs sector processes in the Standard Model EFT at NLO in QCD 20'
        The Standard Model Effective Field Theory (SMEFT) provides a consistent formalism to parametrise the effects of heavy new physics appearing as deviations from SM expectations. One of the key goals of the LHC legacy will be to cover this parameter space as much as possible and contribute to a global fit of the EFT parameter space and, hopefully, provide hints on the nature of physics beyond the SM. To this end, precise predictions for all observables of interest in the SMEFT are required, both at fixed order and for Monte Carlo event generators interfaced with parton showers. I will present recent developments towards a first model implementation of operators in the leading Minimal Flavor Violation assumption, showcasing some results at next-to-leading order in QCD for single top production on its own and in association with a Higgs or Z boson at the LHC. The issue of EFT validity will be discussed alongside some LHC sensitivity studies and future prospects for the High Luminosity run.
        Speaker: Ken Mimasu (Université catholique de Louvain)
        Material: Slides pdf file
      • 16:10 Consistent Searches for SMEFT Effects in Non-Resonant Dijet Events 20'
        We investigate the bounds which can be placed on generic new-physics contributions to dijet production at the LHC using the framework of the Standard Model Effective Field Theory, deriving the first consistently-treated EFT bounds from non-resonant high-energy data. In order to reach consistent, model-independent EFT conclusions, it is necessary truncate the EFT effects consistently at the first non-trivial order in the expansion in inverse powers of the new-physics scale and to include the possibility of multiple operators simultaneously contributing to the observables, neither of which has been done in previous searches of this nature. Furthermore, it is important to give consistent error estimates for the theoretical predictions of the signal model, particularly in the region of phase space where the probed energy is approaching the cutoff scale of the EFT. There are two linear combinations of operators which contribute to dijet production in the SMEFT with distinct angular behavior; we identify those linear combinations and determine the ability of LHC searches to constrain them simultaneously.
        Speaker: Stefan Alte (JGU Mainz)
        Material: Slides pdf file
    • 15:30 - 16:30 Parallel Session on Light Hidden Sector
      Location: Small Lecture Hall, Mathematics
      • 15:30 Probing Light Hidden Sectors with Pulsar Timing Arrays 20'
        In this talk I will present the projected sensitivities of upcoming pulsar timing arrays (PTAs) to gravitational waves produced by first-order phase transitions. In contrast to ground- or space-based detectors these experiments are sensitive to phase transitions that occur around keV to MeV energy scales. Consequently, they are excellent probes of many types of light new physics contributing to non-standard cosmology. As an example, I will focus on a sequestered dark-photon model paying particular attention to the complementarity between standard cosmological probes and gravitational wave signals in PTAs.
        Speaker: Toby Opferkuch (JGU Mainz)
        Material: Slides pdf file
      • 15:50 Constraining Ultralight Scalars with Neutron Star Superradiance 20'
        We demonstrate that rotational superradiance can be efficient in millisecond pulsars. Measurements from the two fastest known pulsars PSR J1748-2446ad and PSR B1937+21 can place bounds on bosons with masses below 10^-11 eV. The bounds are maximally good at masses corresponding to the rotation rate of the star, where scalar interactions that mediate forces ∼ 10^7 times weaker than gravity are ruled out, exceeding existing fifth force constraints by 4 orders of magnitude. For certain neutron star equations of state, these measurements also constrain the QCD axion with decay constant around ∼ 10^19 GeV, ruling out axions with masses between 5*10^-13 and 3*10^-12 eV. The observed absence of pulsars above ∼ 700 Hz despite the ability of the neutron star equation of state to support frequencies as high as ∼ 1500 Hz could be due to the superradiant damping of the stellar rotation as a result of its coupling to a new particle of mass ∼ 1500-3000 Hz with Yukawa couplings to nucleons. Although similar bounds have been placed by black hole superradiance, we note these bounds are strong functions of the (difficult to measure) black hole rotation rate, and thus the present bounds benefit from the extreme reliability of pulsar period measurements.
        Speaker: Paul Riggins (University of California at Berkeley)
        Material: Slides pdf file
      • 16:10 The Higgs decay into two photons in the Standard Model Effective Field theory 20'
        Assuming that new physics effects are parametrized by the Standard-Model Effective Field Theory (SMEFT) written in a complete basis of up to dimension-6 operators, 
        we calculate the CP-conserving one-loop amplitude for the decay h->gamma+gamma in general R_xi-gauges.
        We use this gauge invariant amplitude and recent LHC data to check upon sensitivity to various Wilson coefficients entering from a more complete theory at the matching energy scale.
        We present a closed expression for the ratio \mathcal{R}_{h->gamma+gamma}, of the Beyond the SM versus the SM contributions as appeared in LHC h->gamma+gamma searches.
        With mild assumptions, we point out a set of possibilities for a field theory content at higher energies which may generate sizeable corrections in h->gamma+gamma amplitude.
        Speaker: Dr. Athanasios Dedes (University of Ioannina)
        Material: Slides pdf file
  • Wednesday, May 23, 2018
    • 08:00 - 09:00 Registration
      Location: Zeichensaal (1st floor)
    • 09:00 - 10:00 Review Talk
      Convener: Kiwoon Choi (CTPU/IBS)
      • 09:00 Flavour anomalies: phenomenology and BSM interpretations 1h0' ( Big Lecture Hall, Mathematics )
        Several observables in flavour physics deviate from their Standard-Model
        (SM) expectation. The most prominent ones are related to the decay $b\to
        s \mu^+ \mu^-$, with a combined statistical significance well above 4
        standard deviations. Similarly, branching fractions of $b \to c \tau
        \nu$ decays and the direct CP asymmetry in $K\to \pi \pi$ decays exceed
        the SM expectation. I'll discuss theoretical interpretations of these
        anomalies and highlight which future measurements will help to confirm
        or refute these anomalies and clarify the underlying theory.
        Speaker: Prof. Ulrich Nierste (Karlsruhe Institute of Technology)
        Material: Slides pdf file
    • 10:00 - 10:30 Plenary Session
      Convener: Kiwoon Choi (CTPU/IBS)
      • 10:00 New physics in b->c cbar s transitions 30'
        b->c cbar s transitions proceed at the tree-level in the weak interactions
        in the Standard Model, and for this reason are typically ignored in the search for
        new physics. I will show that, in fact, even small BSM contributions can give
        observables effects in B-meson lifetime observables, CP-violation measurements,
        as well as rare and radiative decays. This can provide useful constraints on or
        possible signatures of new physics, and may even play a role in some of the
        anomalies seen in rare semileptonic B-decay.
        Speaker: Sebastian Jaeger (University of Sussex)
        Material: Slides pdf file
    • 10:30 - 11:00 Coffee Break ( Foyer )
    • 11:00 - 12:30 Plenary Session
      Convener: Michal Malinsky
      • 11:00 Deviations in Flavor Physics and Their Implications 30'
        Several intriguing deviations from Standard Model expectations have been observed in flavor-violating processes in the last few years, most notably hints for violation of lepton flavor universality, both in neutral-current B meson decays involving light leptons and in charged-current B meson decays involving tau leptons. I will give an overview of the status of these deviations and discuss possible interpretations within and beyond the Standard Model.
        Speaker: Dr. David Straub (TUM)
        Material: Slides pdf file
      • 11:30 Status of eV-scale Sterile Neutrinos 30'
        I review the experimental indications in favor of short-baseline
        neutrino oscillations
        and I discuss their interpretation in the framework of 3+1 neutrino
        mixing with a
        sterile neutrino at the eV scale. I show that the recent results of
        the NEOS and DANSS
        reactor neutrino experiments give a new model-independent indication in favor of
        short-baseline electron antineutrino disappearance, confirming the
        reactor and Gallium
        anomalies. On the other hand, the recent result of the MINOS+
        experiment disfavors the
        LSND anomaly. I also discuss the interpretation of the Daya Bay fuel
        evolution data.
        Speaker: Dr. Carlo Giunti (INFN)
        Material: Slides pdf file
      • 12:00 Clockwork Inspired Models For Ultra-Light Scalars 30'
        Speaker: Stefan Pokorski (University of Warsaw)
        Material: Slides pdf file
    • 12:30 - 14:00 Lunch Break
    • 14:00 - 15:40 Parallel Session on Collider Searches
      Location: Big Lecture Hall, Mathematics
      • 14:00 Novel measurements of anomalous triple gauge couplings for the LHC 20'
        A very important and promizing direction of reasearch is finding better ways of testing Standard Model and New Physics using Effective Field Theory approach and exploiting precision measurements. In this framework, Electroweak Triple Gauge Couplings play a special role, particularly within diboson production processes. However, there is often a cancellation in the inclusive measurements of the formally leading contribution to the interference between the SM amplitude and the contribution of irrelevant operators in the EFT. In this talk (based on JHEP10 (2017) 027) I will show that this suppression can be overcome by considering various differential distributions, that significantly improve the sensitivity to BSM effects and the accuracy in their measurements.
        Speaker: Elena Venturini (SISSA)
        Material: Slides pdf file
      • 14:20 Flavour Physics meets Heavy Higgs Searches 20'
        We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searches for new heavy Higgs bosons. We propose novel LHC searches that could be performed in the coming years to unravel the existence of these new Higgs bosons.
        Speaker: Dr. Ayan Paul (DESY)
        Material: Slides pdf file
      • 14:40 The CP-Violating 2HDM in Light of a Strong First Order Electroweak Phase Transition and Implications for Higgs Pair Production 20'
        The generation of the observed matter-antimatter asymmetry in the universe through baryogenesis cannot be explained in the Standard Model. We therefore investigate the possibility of a strong first order phase transition in the CP-Violating 2-Higgs-Doublet Model (C2HDM) after imposing theoretical and experimental constraints. We study the type I and II C2HDM where one of the neutral Higgs bosons can be the Standard Model-like Higgs boson. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC. We find additional preferred mass hierarchies compared to those of the CP-conserving 2HDM. We also use our results to investigate the interplay between a strong phase transition and the size of the trilinear Higgs self-couplings.
        Speaker: Prof. Margarete Mühlleitner (KIT)
        Material: Slides pdf file
      • 15:00 Collider phenomenology of Hidden Valley mediators of spin 0 or 1/2 with semivisible jets 20'
        Many models of Beyond the Standard Model physics contain particles that are charged under both Standard Model and Hidden Valley gauge groups, yet very little effort has been put into establishing their experimental signatures. We provide a general overview of the collider phenomenology of spin 0 or 1/2 mediators with non-trivial gauge numbers under both the Standard Model and a single new confining group. Due to the possibility of many unconventional signatures, the focus is on direct production with semivisible jets. For the mediators to be able to decay, a global U(1) symmetry must be broken. This is best done by introducing a set of operators explicitly violating this symmetry. We find that there is only a finite number of such renormalizable operators and that the phenomenology can be classified into five distinct categories. We show that large regions of the parameter space are already excluded, while others are unconstrained by current search strategies. We also discuss how searches could be modified to better probe these unconstrained regions by exploiting special properties of semivisible jets.
        Speaker: Hugues Beauchesne (University of Sao Paulo)
        Material: Slides pdf file
      • 15:20 Diboson Interference Resurrection at LHC via subjets 20'
        In the absence of new particles at the LHC, the effective field theory framework is appropriated to look for small deviations from the Standard Model (SM). In this case, the leading effect is encoded on the interference term between the SM and dimension-6 operators. However, at the high energy limit due to helicity selection rules, this term, for some operators, is suppressed which leads to an obstacle to probe new physics. In this work, we exploit the resurrection of this suppressed interference term unfolding the angular distribution in the diboson production. The unfolding is performed using jet substructure techniques, allowing us to build an observable sensible to the energy growth for those operators.
        Speaker: Rafael Aoude (JGU, Mainz)
        Material: Slides pdf file
    • 14:00 - 15:40 Parallel Session on Neutrinos and Baryogenesis
      Location: Lecture Hall 1, PI
      • 14:00 Leptogenesis from small lepton number violation 20'
        A compelling mechanism for leptogenesis consists into CP-violating oscillations of mass-degenerate pairs of sterile neutrinos with masses lying at the GeV scale. This kind of setup finds a natural embedding in models like the Inverse See-Saw, where the mass degeneracy of these neutrino pairs is associated to a small violation of the lepton number. We present the resulst of a systematic study based on the numerical solution of suitable Boltzmann equation. Interestingly, Inverse See-Saw models can provide also a solution to the Dark Matter puzzle. We will then discuss the impact, on Dark Matter phenomenology, of the requirement of successful generation of the baryon asymmetry of the Universe.
        Speaker: Dr. Giorgio Arcadi (MPIfK, Heidelberg)
        Material: Slides pdf file
      • 14:20 Low-Scale Leptogenesis in Extended Neutrino Mass Models 20'
        Standard thermal leptogenesis in the type-I seesaw model requires very heavy right-handed neutrinos (RHNs). This diminishes the prospects of directly testing this scenario in experiments and, thus, motivates efforts to construct models that generate the baryon asymmetry of the Universe at a lower RHN mass scale. In this talk, I will discuss two such alternative scenarios: First, I will revisit Ernest Ma's scotogenic model of radiative neutrino masses and present an analysis of "scotogenic leptogenesis for pedestrians". Then, I will turn to a singlet-extended version of the type-I seesaw model that introduces additional sources of CP violation as well as novel RHN decay channels. In both cases, successful leptogenesis can be achieved for a RHN mass scale of 10 TeV (or lower) and without any approximate degeneracy in the RHN mass spectrum. The two scenarios discussed in this talk therefore present viable and attractive alternatives to the well studied case of resonant leptogenesis. This talk is based on work in collaboration with Tommi Alanne, Thomas Hugle, and Moritz Platscher at MPIK Heidelberg.
        Speaker: Dr. Kai Schmitz (MPIK Heidelberg)
        Material: Slides pdf file
      • 14:40 Strong thermal SO(10)-inspired leptogenesis in the light of recent results from long-baseline neutrino experiments 20'
        We confront recent experimental results on neutrino mixing parameters with the requirements from strong thermal $SO(10)$-inspired leptogenesis. There is a nice agreement with latest global analyses supporting $\sin\delta < 0$ and normal ordering at $ \sim 95\%$ C.L. On the other hand, the more stringent experimental lower bound on the atmospheric mixing angle starts to corner this paradigm. Prompted and encouraged by this rapid experimental advance, we obtain a precise determination of the allowed region in the plane $\delta$ versus $\theta_{23}$. Though most of the solutions are found outside the $95\%$ C.L. experimental region, there is still a big allowed fraction that does not require a too fine-tuned choice of the Majorana phases so that the neutrinoless double beta decay effective neutrino mass allowed range is still $m_{ee}\simeq [10,30]\,{\rm meV}$. We also show how the constraints depend on some parameters such as the initial pre-existing $B-L$ asymmetry and the intermediate neutrino Dirac mass.
        Speaker: Dr. Marco Chianese (University of Southampton)
        Material: Slides pdf file
      • 15:00 Predictions for RH Neutrinos from the Littlest Seesaw and Leptogenesis 20'
        The Littlest Seesaw model based on two right-handed neutrinos with constrained Yukawa couplings provides a highly predictive description of neutrino masses and PMNS mixing parameters. If realised at high energies there will be renormalisation group corrections to the low energy predictions, which depend on the right-handed neutrino masses. We perform a chi squared analysis to determine the right-handed neutrino masses from a four-parameter fit to the low energy neutrino parameters, also eventually taking into account leptogenesis.
        Speaker: Sam Rowley (University of Southampton)
        Material: Slides pdf file
      • 15:20 Pendulum Leptogenesis 20'
        We propose a new non-thermal Leptogenesis mechanism that takes
        place during the reheating epoch, and utilizes the Ratchet mechanism. The
        interplay between the oscillation of the inflaton during reheating and a
        scalar lepton leads to a dynamical system that emulates the well-known
        forced pendulum. This is found to produce driven motion in the phase of the
        scalar lepton which leads to the generation of a non-zero lepton number
        density that is later redistributed to baryon number via sphaleron
        processes. This model successfully reproduces the observed baryon
        asymmetry, while simultaneously providing an origin for neutrino masses via
        the seesaw mechanism.
        Speaker: Neil Barrie (Kavli IPMU)
        Material: Slides pdf file
    • 14:00 - 15:40 Parallel Session on Axion-DM
      Location: Small Lecture Hall, Mathematics
      • 14:00 QCD axion dark matter from parametric resonance 20'
        The QCD axion is a good dark matter candidate. The observed dark matter abundance can arise from misalignment or defect mechanisms, which generically require an axion decay constant fa ~ O(10^11) GeV (or higher). We introduce a new cosmological origin for axion dark matter, parametric resonance from oscillations of the Peccei-Quinn symmetry breaking field, that requires fa ~ (10^8 − 10^11) GeV. The axions may be warm enough to give deviations from cold dark matter in Large Scale Structure.
        Speaker: Dr. Keisuke Harigaya (UC Berkeley)
        Material: Slides pdf file
      • 14:20 Axion strings and dark matter 20'
        The axion solution to the strong CP problem also provides a natural dark matter candidate. If the PQ symmetry has ever been restored after inflation, topological defects of the axion field would have formed and produced relic axions, whose abundance is in principle calculable. Using numerical simulations I will present a detailed study of the evolution of axion strings and the resulting spectrum of axion produced. The features found are important for a correct estimate of the total DM abundance. Work to appear in collaboration with A.Azatov, E.Hardy and G.Villadoro
        Speaker: Marco Gorghetto (SISSA)
        Material: Slides pdf file
      • 14:40 Axions in a highly protected gauge symmetry model 20'
        I will present QCD axion or cosmological Goldstone bosons, such as ultra-light dark matter or quintessence, in a model with global symmetry highly protected by gauge symmetries. The global symmetry is accidental, obtained from an abelian quiver with scalar bifundamental fields. The Goldstone boson mass may receive explicit breaking contributions, but these are already much suppressed for a few quiver sites if the gauge charges of the scalars are appropriately chosen. The model can be obtained by latticizing an abelian 5d gauge theory on the linear dilaton background.
        Speaker: Quentin Bonnefoy (Centre de Physique Théorique, Ecole Polytechnique)
        Material: Slides pdf file
      • 15:00 Colour Unified Dynamical Axion 20'
        A massless quark solution to the Strong CP problem is implemented with an extra confining gauge group that is unified with the SM QCD group in a CUT (Colour Unified Theory). A novel contribution to the axion mass (due to the small-size instantons at the CUT breaking scale) renders the dynamical axion heavy. This allows to protect the PQ symmetry from semi-classical gravitational effects that could spoil the solution to the strong CP problem.
        Speaker: Pablo Quílez Lasanta (UAM/CSIC)
        Material: Slides pdf file
      • 15:20 Accidental Peccei-Quinn symmetry in a model of flavour 20'
        In Peccei-Quinn (PQ) solutions to the strong CP problem, a global $U(1)_{PQ}$ symmetry is typically added by hand. However, $U(1)_{PQ}$ need not be exact: it may arise from discrete symmetry, provided the PQ solution is protected to sufficient order. We present a rather complete model, based on Pati-Salam unification and $A_4$, wherein such discrete symmetries are the very same symmetries that govern quark and lepton flavour. The QCD axion itself resides within $A_4$ triplet flavons, which dictate fermion Yukawa structures; axion and flavour scales are firmly linked. Potentially viable avenues for testing the model include: (1) model fitting to quark and lepton mixing, (2) flavour-violating meson and lepton decays, (3) dark matter.
        Speaker: Fredrik Björkeroth (INFN-LNF)
        Material: Slides pdf file
    • 14:00 - 15:20 Parallel Session Formal
      • 14:00 The SO(10) F-theory Landscape and Tensor-Matter Transitions 20'
        We systematically construct all torically resolved SO(10) theories theories with possible additional (discrete) Abelian gauge symmetries. We show that most of these models are connected via higgsing or superconformal matter transitions involving small E8 instantons. Motivated by this observations, we classify superconformal matter transitions in 6d SUGRA theories with Abelian and non-Abelian gauge groups. From consistency under gauge and gravity anomaly cancellation follow strong constraints on the involved matter representations and charges involved in the transition.
        Speaker: Dr. Paul-Konstantin Oehlmann (Virginia Tech)
        Material: Slides pdf file
      • 14:20 Yukawa couplings from D-branes on non-factorisable tori 20'
        The classical part of Yukawa couplings from D6-branes is computed by summing over worldsheet instantons. On non-factorisable tori the worldsheet instantons obey selection rules, which depend on the underlying lattice of the torus. Quantum corrections to the couplings are obtained by T-dualizing the setup and computing the overlapping wavefunctions of three chiral matter fields.
        Speaker: Mr. Christoph Liyanage (Bethe Center for Theoretical Physics)
        Material: Slides pdf file
      • 14:40 Anomaly Cancellation in Effective Supergravity Theories from the Heterotic String: Two Simple Examples 20'
        We use Pauli-Villars regularization to evaluate the conformal and chiral anomalies in the effective field theories from Z3 and Z7 compactifications of the heterotic string without Wilson lines. We show that parameters for Pauli-Villars chiral multiplets can be chosen in such a way that the anomaly is universal in the sense that its coefficient depends only on a single holomorphic function of the three diagonal moduli. It is therefore possible to cancel the anomaly by a generalization of the four-dimensional Green-Schwarz mechanism. In particular we are able to reproduce the results of a string calculation of the four-dimensional chiral anomaly for these two models.
        Speaker: Jacob Leedom (University of California, Berkeley)
        Material: Slides pdf file
      • 15:00 AdS-phobia, the WGC, the Standard Model and Supersymmetry 20'
        It has been recently argued that the presence of any non-SUSY AdS stable vacua implies that a theory can not be consistently coupled to gravity (Ooguri-Vafa conjecture). In particular, this can be applied to the SM and its compactifications to 3 or 2 dimensions to obtain predictions on low energy physics. We will review some implications from these compactifications in general and present in detail the results from the compactification on $T^ 2/Z_4$. We find that the SM is not robust against the appearance of AdS vacua in 2D and hence would be by itself inconsistent with quantum gravity. On the contrary, if the SM is embedded at some scale into a SUSY version like the MSSM, the AdS vacua present in the non-SUSY case disappear or become unstable, pointing towards a preference for the SUSY extensions of the SM coming from the WGC. Moreover, in a $T^ 2/Z_4$ in which the orbifold action is embedded into a B-L symmetry the bounds on neutrino masses and the cosmological constant found in previous works can be recovered, suggesting that the MSSM should be extended with a $U(1)_{B-L}$ gauge group. Finally, in another families of vacua the spectrum of SUSY particles can be further constrained.
        Speaker: Alvaro Herraez (UAM-CSIC)
        Material: Slides pdf file
    • 15:40 - 16:10 Coffee Break ( Foyer )
    • 16:10 - 17:50 Parallel Session on Collider Searches
      Location: Big Lecture Hall, Mathematics
      • 16:10 The fate of the Littlest Higgs Model with T-parity under 13 TeV LHC Data 20'
        We scrutinize the allowed parameter space of Little Higgs models with the concrete symmetry of T-parity by providing comprehensive LHC analyses of all relevant production channels of heavy vectors, top partners, heavy quarks and heavy leptons and all phenomenologically relevant decay channels. Constraints on the model will be derived from the signatures of jets and missing energy or leptons and missing energy by using the collider phenomenology tool CheckMATE which exploits all available LHC BSM searches at center-of-mass energies of 8 and 13 TeV. Besides the symmetric case, we also study the case of T-parity violation.
        Speaker: Mr. Daniel Dercks (University of Hamburg)
        Material: Slides pdf file
      • 16:30 Higgs data does not rule out a sequential fourth generation 20'
        Contrary to common perception, we show that the current Higgs data does not eliminate the possibility of a sequential fourth generation that get their masses through the same Higgs mechanism as the first three generations. The inability to fix the sign of the bottom-quark Yukawa coupling from the available data plays a crucial role in accommodating a chiral fourth generation which is consistent with the bounds on the Higgs signal strengths. We show that effects of such a fourth generation can remain completely hidden not only in the production of the Higgs boson through gluon fusion but also to its subsequent decay to γγ and Zγ. This, however, is feasible only if the scalar sector of the standard model is extended. We also provide a practical example illustrating how our general prescription can be embedded in a realistic model.
        Speaker: Ipsita Saha (INFN, Roma 1)
        Material: Slides pdf file
      • 16:50 Higgs decays into SM particles in the NMSSM 20'
        The decays of neutral Higgs bosons into Standard Model fermions and gauge-bosons in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) are investigated at the full one-loop order with some higher-order QCD corrections. We take mixing effects for the external Higgs particles consistently into account. In the beginning, some formal aspects of our approach are discussed, before we compare our results to the predictions of existing public tools. Especially the decays of heavy Higgs-doublet states into gauge bosons are dominated by higher-order corrections; popular tree-level approximations fail. Finally, our framework is employed to investigate the properties of a light singlet-dominated state with a mass close to 95 GeV. We find scenarios which can interpret the fluctuations reported by LEP in the bb searches, and by CMS in the diphoton searches as true signals.
        Speaker: Dr. Sebastian Paßehr (LPTHE)
        Material: Slides pdf file
      • 17:10 Common exotic decays of top partners 20'
        Many Standard Model extensions that address the hierarchy problem contain Dirac-fermion partners of the top quark, which are typically expected around the TeV scale. Searches for these vector-like quarks mostly focus on their decay into electroweak gauge bosons or Higgs plus a standard model quark. In this talk, backed by models of composite Higgs, we propose a set of simplified scenarios that include more exotic decay channels, which modify the search strategies and affect the bounds. Analysing several classes of underlying models, we show that exotic decays are the norm and commonly appear with large rates. All of these models contain light new scalars that couple to top partners with charge 5/3, 2/3, and −1/3. We identify the contributing particle content and novel top partner decays that occur most commonly, provide effective Lagrangians, benchmarks, and a brief discussion of phenomenological bounds and newly occurring final states.
        Speaker: Dr. Thomas Flacke (IBS CTPU)
      • 17:30 Problems with unstable particles in high energy processes 20'
        3 topics appeared in the description of processes with unstable particles. 1. Plane wave formalism is insufficient for some realistic problems. The wave packets formalism become necessary. Illustration:The t--channel singularity in small angle scattering. 2. Perturbation series become invalid like in the case of infrared divergence in QED, but in more strong form. Illustration: The s--channel singularity near the threshold. 3. Theory with unstable fundamental particles don't allow conditions for construction of perturbation diagrammatic expansion. Signature: Gauge dependence in the description of observable processes in higher orders
        Speaker: Prof. Ilya Ginzburg (Sobolev Institute of Mathematics)
    • 16:10 - 17:50 Parallel Session on Astro-DM I
      Location: Lecture Hall 1, PI
      • 16:10 White Dwarfs as DM Detectors 20'
        Dark matter that is capable of sufficiently heating a local region in a white dwarf will trigger runaway fusion and ignite a type 1a supernova. We consider dark matter (DM) candidates that heat through the production of high-energy standard model (SM) particles, and show that such particles will efficiently thermalize the white dwarf medium and ignite supernovae. Based on the existence of long-lived white dwarfs and the observed supernovae rate, we put new constraints on ultra-heavy DM candidates $m_\chi \gtrsim 10^{16}~\text{GeV}$ which produce SM particles through annihilation, decay, and DM-SM scattering in the stellar medium. As a concrete example, we rule out supersymmetric Q-ball DM in parameter space complementary to terrestrial bounds. We put further constraints on DM that is captured by white dwarfs, considering the formation and self-gravitational collapse of a DM core. For asymmetric DM, such a core may form a black hole that ignites a supernovae via Hawking radiation, and for ``almost asymmetric'' DM with non-zero but sufficiently small annihilation cross section, the core may ignite the star via a burst of annihilation during gravitational collapse. This constrains much lighter candidates, $m_\chi \gtrsim 10^{7}~\text{GeV}$. It is also intriguing that the DM-induced ignition discussed in this work provide an alternative mechanism of triggering supernovae from sub-Chandrasekhar mass progenitors.
        Speaker: Ryan Janish (University of California, Berkeley)
        Material: Slides pdf file
      • 16:30 BBN constraints on MeV-scale dark sectors: Sterile decays 20'
        We study constraints from Big Bang Nucleosynthesis on inert particles in a dark sector which contribute to the Hubble rate and therefore change the predictions of the primordial nuclear abundances. We pay special attention to the case of MeV-scale particles decaying into dark radiation, which are neither fully relativistic nor non-relativistic during all temperatures relevant to Big Bang Nucleosynthesis. As an application we discuss the implications of our general results for models of self-interacting dark matter with light mediators.
        Speaker: Marco Hufnagel (DESY Hamburg)
        Material: Slides pdf file
      • 16:50 Boltzmann equation for relativistic species and Hot Dark Matter 20'
        The latest Planck CMB data seem to strongly constrain the Hot Dark Matter scenarios, although they stay in tension with direct Hubble constant measurements. One can expect that in near future the experimental uncertainly for the effective number of neutrino species N_{eff} will shrink vastly. Therefore, in order to estimate the allowed parameter space of models predicting a Hot Dark Matter component, it is crucial to calculate its relic density with high accuracy. In my talk I will exploit the Boltzmann equation in the form suitable for relativistic species in Weinberg’s Higgs portal model. I will also discuss how in similar scenarios different statistics of incoming/outgoing particles my influence the results. Work in collaboration with prof. Marek Olechowski.
        Speaker: Paweł Szczerbiak (University of Warsaw)
        Material: Slides pdf file
      • 17:10 Dark Matter Production in an Early Matter Dominated Era 20'
        We investigate dark matter (DM) production in an early matter dominated era where a heavy long-lived particle decays to radiation and DM. In addition to DM annihilation into and thermal DM production from radiation, we include direct DM production from the decay of the long-lived particle.
        Speaker: Mr. Fazlollah Hajkarim (BCTP, University of Bonn)
        Material: Slides pdf file
      • 17:30 Hunting light dark sectors in sub-GeV dark matter scenarios 20'
        Minimal scenarios with light (sub-GeV) dark matter are usually accompanied by a correspondingly light "dark sector". We will show that the presence of the latter usually leads to strong bounds from cosmology and bright detection prospects at fixed target experiments and colliders.
        Speaker: Mr. Luc Darmé (LPTHE)
        Material: Slides pdf file
    • 16:10 - 17:30 Parallel Session on Flavor and EFTs
      Location: bctp, Seminar Room 1
      • 16:10 An EFT approach to lepton anomalies 20'
        Beside neutrino masses, an assortment of precision observables probe new physics in the lepton sector. Experimental anomalies include a 3.5-sigma discrepancy in the anomalous magnetic moment of the muon and a 4-sigma indication of lepton universality violation in B-meson semi-leptonic decays. Effective field theory is a useful framework for studying observables sensitive to multi-TeV scales in a model-independent way. Using this approach, I discuss the interplay between different lepton observables, including possibilities of relating several of them simultaneously. I also comment on the links between EFT and specific UV completions.
        Speaker: Rupert Coy (Laboratoire Charles Coulomb, CNRS)
        Material: Slides pdf file
      • 16:30 Future DUNE constraints on EFT 20'
        In the near future, fundamental interactions at high-energy scales may be most efficiently studied via precision measurements at low energies. In this talk I will discuss the possible impact of the DUNE neutrino experiment on constraining the SM Effective Field Theory. The unprecedented neutrino flux offers an opportunity to greatly improve the current limits via precision measurements of the trident production and neutrino scattering off electrons and nuclei in the DUNE near detector. We quantify the DUNE sensitivity to dimension-6 operators in the SMEFT Lagrangian, and find that in some cases operators suppressed by an O(30) TeV scale can be probed. We also compare the DUNE reach to that of future experiments involving atomic parity violation and polarization asymmetry in electron scattering, which are sensitive to an overlapping set of SMEFT parameters.
        Speaker: Giovanni Grilli di Cortona (University of Sao Paulo)
        Material: Slides pdf file
      • 16:50 SO(3) family symmetry, the axion and the flavor puzzle 20'
        The understanding of flavor and the strong CP problem could be closely related. Motivated by the idea of Comprehensive Unification of elementary particle forces and families, we propose a minimal SO(3) flavor extension of the of the Standard Model which accounts for the observed fermion mass hierarchies, and provides a dynamical understanding of quark mixing and CP violation.
        Speaker: Mario Reig (Instituto de Física Corpuscular (IFIC))
        Material: Slides pdf file
      • 17:10 Froggatt-Nielsen mechanism in a model with 331-gauge group 20'
        The models with the gauge group $SU(3)_c\times SU(3)_L\times U(1)_X$ (331-models) have
        been advocated to explain why there are three fermion generations in Nature. As such they
        provide partial understanding of the flavour sector. The hierarchy of fermion masses in
        the Standard Model is another puzzle which remains without compelling explanation. In this
        talk I present a model that incorporates Froggatt-Nielsen mechanism into a 331-model in
        order to explain both fundamental problems. It turns out that no new additional scalar
        representations are needed to take care of this. The 331-models thus naturally include
        explanations to both the number of fermion generations and their mass hierarchy. This talk
        is based on arXiv:1706.09463[hep-ph].
        Speaker: Niko Koivunen (University of Helsinki)
        Material: Slides pdf file
    • 16:10 - 17:30 Parallel Session on Relaxion/Light bosons
      • 16:10 Cosmological Higgs relaxation without inflation 20'
        The relaxion models propose a new idea to explain the smallness of the Higgs mass. They rely on the scanning of the Higgs mass parameter by a new field, the relaxion, and a back-reaction mechanism that is triggered when Higgs vacuum expectation value has reached the size of the electroweak scale, making the relaxion evolution cease. In the usual relaxion model the scanning happens during an inflationary period. Here we explore the cosmological consequences if the relaxation happens independently of inflation. In this scenario, the stopping mechanism is provided by particle production friction. The parameter space is very different from the usual relaxion scenarios; for instance, the relaxion mass can be as high as O(100) TeV.
        Speaker: Nayara Fonseca (DESY)
      • 16:30 Relaxion Dark Matter 20'
        I discuss a scenario in which the relaxion field, whose evolution in the early universe is responsible for the smallness of EW scale compared to the cutoff of the theory, also constitutes the Dark Matter of the Universe.
        Speaker: Enrico Morgante (DESY)
      • 16:50 Backreaction in the dynamical relaxation 20'
        Dynamical relaxation in an interesting framework in which the scale of new physics is pushed far beyond the observable range without abandoning the principles of naturalness. A low value of the electroweak scale originates from a dynamical selection process that comes from an interaction between the Higgs boson and an axion-like particle (a relaxion). During the relaxation, the relaxion rolls down a potential hill scanning a range of Higgs masses in the process. Usually, it is assumed that this roll-down has no effects beyond a varying mass of the Higgs. In this talk, I will discuss a possibility of non-negligible side-effects of the relaxation and how their inclusion may spoil the mechanism, especially if additional dimensions are involved.
        Speaker: Adam Markiewicz (University of Warsaw)
        Material: Slides pdf file
      • 17:10 Generalized Clockwork Theory 20'
        I show how generating hierarchy via the clockwork mechanism can be generalized in various directions including nonabelian global groups, supergravity and Susy breaking.
        Speaker: Dr. Ido Ben-Dayan (Ariel University)
        Material: Slides pdf file
  • Thursday, May 24, 2018
    • 08:00 - 09:00 Registration
      Location: Zeichensaal (1st floor)
    • 09:00 - 10:00 Review Talk
      Convener: Stefan Foerste
      • 09:00 Big Data and Machine Learning in String Phenomenology: An Overview 1h0'
        Recently, machine learning techniques have entered the field of string phenomenology, for example, in order to identify promising string models in the vast landscape of string theory vacua. We review different approaches and techniques, like 'Autoencoders', 'Reinforcement Learning' and 'Generative Adversarial Networks' and apply them to several physical questions.
        Speaker: Mr. Patrick Vaudrevange (TU München)
        Material: Slides link
    • 10:00 - 10:30 Plenary Session
      Convener: Stefan Foerste
      • 10:00 Quantum Gravity constraints on Particle Physics and Cosmology 30'
        Consistency with quantum gravity can have significant consequences on low energy physics. Interestingly, it seems that not every effective field theory can be consistently coupled to quantum gravity unless it satifies some additional consistency constraints. Recently substantial effort has been dedicated to determine these constraints in terms of black-hole physics and string theory. Some proposals, dubbed Quantum Gravity Conjectures, would imply thattheories with small gauge couplings or parametrically large scalar field variations are inconsistent with quantum gravity. This can have important phenomenological implications for Beyond Standard Model proposals and Inflationary Cosmology models. Furthermore, when applying one of this conjectures to compactifications of the Standard Model, we obtain a lower bound for the cosmological constant in terms of the neutrino masses. This can also be translated into an upper bound for the EW scale around the TeV range, bringing a new perspective into the issue of the EW hierarchy.
        Speaker: Ms. Irene Valenzuela (IFT UAM/CSIC)
        Material: Slides pdf file
    • 10:30 - 11:00 Coffee Break ( Foyer )
    • 11:00 - 12:30 Plenary Session
      Convener: Stuart Raby
      • 11:00 Light states in the distance: evidence for a Quantum Gravity Conjecture 30'
        It has been conjectured that in theories consistent with quantum 
        gravity infinite distances in field space coincide with an infinite tower of states 
        becoming massless exponentially fast. In this talk I present non-trivial evidence
        for this conjecture from the study of Type IIB string theory on Calabi-Yau threefolds. 
        I will also comment on the observation that the behavior of the metric and gauge 
        coupling function near infinite distance points can be recovered by integrating out the BPS states. 
        This suggests that theses properties might be emergent. 
        Speaker: Dr. Thomas Grimm (Utrecht University & Max Planck Institute for Physics)
        Material: Slides pdf file
      • 11:30 Pole N-flation 30'
        A second order pole in the scalar kinetic term can lead to a class of inflation models with universal predictions referred to as pole inflation or α-attractors. While this kinetic structure is ubiquitous in supergravity effective field theories, realising a consistent UV complete model in e.g. string theory is a non-trivial task. For one, one expects quantum corrections arising in the vicinity of the pole which may spoil the typical attractor dynamics. As a conservative estimate of the range of validity of supergravity models of pole inflation we employ the weak gravity conjecture (WGC). We find that this constrains the accessible part of the inflationary plateau by limiting the decay constant of the axion partner. For the original single complex field models, the WGC does not even allow the inflaton to reach the inflationary plateau region. We propose addressing these problems by evoking the assistance of N scalar fields from the open string moduli. This improves radiative control by reducing the required range of each individual field. Furthermore, it relaxes the WGC bound allowing to inflate on the plateau, although remaining at finite distance from the pole. Finally, we outline steps towards an embedding of pole N-flation in type IIB string theory on fibred Calabi-Yau manifolds.
        Speaker: Alexander Westphal (DESY)
        Material: Slides pdf file
      • 12:00 From stringy vacua with particle physics spectrum to the effective action - exemplified by a non-factorisable orientifold - 30'
        For most string vacua, only the chiral matter spectrum can be computed in terms of topological data of the compact extra dimensions, while already the vector-like spectrum remains elusive. If the compact extra dimensions consist of (orbifolds of) tori, however, the string quantisation can be explicitly performed and thus not only the full tower of massless and massive matter states can be computed but also exact results on the effective action beyond the leading SUGRA approximation can be derived.  In particular, the one-loop corrections to the gauge couplings generically depend on the moduli of the compact extra dimensions, challenging the separation of gravity and QFT sectors at tree-level. In this talk, I will demonstrate these features in terms of a Pati-Salam model constructed on D-branes in a non-factorisable orientifold background.
        Speaker: Prof. Gabriele Honecker (Johannes-Gutenberg-Universität Mainz)
        Material: Slides pdf file
    • 12:30 - 14:00 Lunch Break
    • 14:00 - 15:40 Parallel Session on DM
      Location: Big Lecture Hall, Mathematics
      • 14:00 Dark matter direct detection at one loop 20'
        The strong direct detection limits indicate that dark matter may not directly couple to quarks and consequently direct detection only occur at loop level. We study direct detection in the prototype example of an electroweak singlet dark matter fermion coupled to an extended dark sector composed of a new fermion and a new scalar. We also discuss the cases if either the new fermion or scalar is a SM particle. The results can be applied to many different scenarios. We specifically discuss its application to a radiative neutrino mass model.
        Speaker: Michael Schmidt
        Material: Slides pdf file
      • 14:20 Dark matter direct detection with pseudoscalar mediators 20'
        Due to its highly suppressed cross section (fermionic) dark matter interacting with the Standard Model via pseudoscalar mediators is expected to be essentially unobservable in direct detection experiments. We consider both a simplified model and a more realistic model based on an extended two Higgs doublet model and compute the leading one-loop contribution to the effective dark matter- nucleon interaction. This higher order correction dominates the scattering rate completely and can naturally, i.e. for couplings of order one, lead to a direct detection cross section in the vicinity of the neutrino floor. Taking the observed relic density and constraints from low-energy observables into account we analyze the direct detection prospects in detail and find regions of parameter space that are within reach of upcoming direct detection experiments such as XENONnT, LZ, and DARWIN.
        Speaker: Stefan Vogl
        Material: Slides pdf file
      • 14:40 Self-interacting dark matter with a stable vector mediator 20'
        Self-interactions of dark matter induced by a MeV-scale vector mediator $Z_\text{D}$ can naturally cure some shortcomings of the standard cold dark matter paradigm at small scales. However, if the vector particle decays into Standard Model states, such a scenario is robustly excluded by constraints from energy injection during CMB. We study to what extent this conclusion can be circumvented if $Z_\text{D}$ is stable and annihilates into lighter degrees of freedom, such that it contributes itself to the observed amount of dark matter in the Universe. Indeed, we find viable parts of the parameter space which lead to the desired self-interaction cross section while being compatible with all relevant bounds from CMB and BBN observations.
        Speaker: Mr. Sebastian Wild (TU München)
        Material: Slides pdf file
      • 15:00 Residual annihilations of asymmetric DM 20'
        Dark matter coupled to light mediators has been invoked to resolve the putative discrepancies between collisionless cold DM and galactic structure observations. However, $\gamma$-ray searches and the CMB strongly constrain such scenarios. To ease the tension, we consider asymmetric DM. We show that, contrary to the common lore, detectable annihilations occur even for large asymmetries, and derive bounds from the CMB, $\gamma$-ray, neutrino and antiproton searches. We then identify the viable space for self-interacting DM. Direct detection does not exclude this scenario, but provides a way to test it.
        Speaker: Dr. Iason Baldes (DESY)
        Material: Slides pdf file
      • 15:20 Dark Matter from the Top 20'
        We study simplified models of top-flavoured dark matter in the framework of Dark Minimal Flavour Violation. In this setup the coupling of the dark matter flavour triplet to SM quark triplets constitutes the only new source of flavour and CP violation. The parameter space of the model is restricted by LHC searches with missing energy final states, by neutral meson mixing data, by the observed dark matter relic abundance, and by the absence of signal in direct detection experiments. We consider all of these constraints in turn, studying their implications for the allowed parameter space. Especially interesting is the combination of all constraints, reveling a non-trivial interplay. Large parts of the parameter space are excluded, most significantly in light of future bounds from upcoming experiments.
        Speaker: Simon Kast
        Material: Slides pdf file
    • 14:00 - 15:40 Parallel Session on Neutrino Mass Models
      Location: Lecture Hall 1, PI
      • 14:00 Neutrino masses from Planck-scale lepton number breaking 20'
        We consider an extension of the Standard Model by right-handed neutrinos and we argue that, under plausible assumptions, a neutrino mass of O(0.1) eV is naturally generated by the breaking of the lepton number at the Planck scale, possibly by gravitational effects, without the necessity of introducing new mass scales in the model. Some implications of this framework are also briefly discussed.
        Speaker: Dr. Takashi Toma (Technische Universität München)
        Material: Slides pdf file
      • 14:20 Dirac Neutrinos and its Many Surprising Connections 20'
        More than eighty years after they were first proposed, neutrinos still remain an enigma. Although they are an integral part of Standard Model but still we know very little about them. In particular, the Dirac or Majorana nature of neutrinos is still unclear with no clear indication of their nature. However, for a long time, theoretical particle physicists believed that neutrinos must be Majorana in nature and several elegant mass generation mechanisms have been proposed for Majorana neutrinos. In this talk, I will discuss the multitude of ways in which naturally small Dirac neutrino masses can be generated. I will also discuss the various interesting and sometimes surprising connections between Dirac nature of neutrinos and Dark Matter stability, proton decay etc.
        Speaker: Rahul Srivastava
        Material: Slides pdf file
      • 14:40 Seesaw roadmap to neutrino masses 20'
        We describe the many pathways to generate Majorana and Dirac neutrino mass through generalized dimension-5 operators a la Weinberg. The presence of new scalars beyond the Standard Model Higgs doublet implies new possible field contractions, which are required in the case of Dirac neutrinos. We also notice that, in the Dirac neutrino case, the extra symmetries needed to ensure the Dirac nature of neutrinos can also be made responsible for stability of dark matter.
        Speaker: Salvador Centelles Chuliá
        Material: Slides pdf file
      • 15:00 WIMP dark matter in a Two-loop Dirac neutrino mass mechanism 20'
        Despite great efforts over several decades, neutrinoless double beta decay has not yet been detected and neutrinos could be Dirac particles. In this talk we present a “scotogenic” mechanism relating small neutrino mass and cosmological dark matter. Neutrinos are Dirac fermions with masses arising only in two-loop order through the sector responsible for dark matter. A global spontaneously broken U(1) symmetry leads to a physical Diracon that induces invisible Higgs decays which add up to the Higgs to dark matter mode. This enhances sensitivities to spin-independent WIMP dark matter search below mh/2 .
        Material: Slides pdf file
      • 15:20 Deviations of exact neutrino textures using radiative neutrino masses 20'
        The Weinberg operator allows for the construction of radiative Majorana neutrino masses. In this letter, it will be shown that it is possible to construct a one-loop diagram that will be the principal component of the neutrino mass matrix and that will have an exact mixing matrix with θ13=0. The addition of a two-loop diagram, which is naturally suppressed, allows the creation of the correct perturbations that will give a neutrino mixing matrix with entries inside experimental constrains, including the possibility of large CP Dirac phases.
        Speaker: Daniel Wegman
        Material: Slides pdf file
    • 14:00 - 15:40 Parallel Session on Unified Models
      Location: Small Lecture Hall, Mathematics
      • 14:00 Axion Predicitons in SO(10)xU(1) GUT models 20'
        Non-supersymmetric Grand Unified SO(10) × U(1)PQ models have all the ingredients to solve several fundamental problems of particle physics and cosmology — neutrino masses and mixing, baryogenesis, the non-observation of strong CP violation, dark matter, inflation — in one stroke. The axion — the pseudo Nambu-Goldstone boson arising from the spontaneous breaking of the U(1)PQ Peccei-Quinn symmetry — is the prime dark matter candidate in this setup. We determine the axion mass and the low energy couplings of the axion to the Standard Model particles, in terms of the relevant gauge symmetry breaking scales. We work out the constraints imposed on the latter by gauge coupling unification. We discuss the cosmological and phenomenological implications.
        Speaker: Anne Ernst (Desy)
        Material: Slides pdf file
      • 14:20 Witten's loop in the flipped SU(5) revisited 20'
        The flipped SU(5) unification represents one of the rare cases in which the Witten's loop mechanism for the radiative RH neutrino mass generation may be implemented in a potentially realistic manner. It was shown recently that, in a large part of the parameter space, the tight flavour structure of the minimal model of this kind yields relatively strong constraints on the principal smoking-gun observables of this setting, namely, the partial proton decay widths with electrons and muons in the final state. We shall present a new study of the absolute size of the Witten's effect in the minimal flipped SU(5) scenario and comment on its impact on the relevant physics.
        Speaker: Michal Malinsky
        Material: Slides pdf file
      • 14:40 Planck-scale induced uncertainties in proton lifetime estimates and flavour structure of GUTs 20'
        Grand Unified Theories predict the proton to be unstable and if a particular model is considered, the partial proton decay widths can be calculated. Most often, however, a renormalizable setting is considered and the effective operators possibly describing the physics at the Planck scale are not taken into account. It is well known that one of such effective operators involving the unification gauge field strength tensor may shift the position of the unification scale and, hence, cause a considerable error in the proton lifetime estimates. On the other hand, we are studying the Planck-suppressed operators which contribute to the flavour structure of the theory and have an impact on the determination of the individual partial proton decay widths.
        Speaker: Helena Kolesova
        Material: Slides pdf file
      • 15:00 SO(10) inspired Z′ models at the LHC 20'
        We study Z′ models arising from SO(10)SO(10), focussing in particular on the gauge group of SU(3)C×SU(2)L×U(1)R×U(1)B−L, broken at the TeV scale to the Standard Model gauge group. This gauge group is well motivated from SO(10) breaking and allows neutrino mass via the linear seesaw mechanism. Assuming supersymmetry, we consider single step gauge unification to predict the gauge couplings, then consider the detection and characterisation prospects of the resulting Z′ at the LHC by studying its possible decay modes into di-leptons, including the expected forward-backward asymmetry, as well as into Higgs bosons, also comparing these predictions to other related Z′ scenarios such as the well studied U(1)B−L and U(1)χ models.
        Speaker: Mr. Simon King (University of Southampton)
        Material: Slides pdf file
      • 15:20 Pseudo-Goldstone scalars in the minimal SO(10) Higgs model 20'
        The minimal renormalizable SO(10) Higgs model in which the unified symmetry is broken down by the adjoint representation is known to suffer from tachyonic instabilities along all potentially realistic symmetry-breaking chains. Few years ago, this issue has been identified as a mere relic of the tree level calculations and the radiative corrections to the masses of the pair of the “most dangerous” pseudo-Goldstone scalars in the model’s spectrum have been computed. Remarkably enough, it turns out that - in its minimal potentially realistic renormalizable realization - there is third pseudo-Goldstone scalar (a full SM singlet) suffering from the same disease that, until recently, happened to escape the community’s attention. In this talk we will provide a short account of the calculation of the one-loop correction to its mass and comment briefly on the prospects of an implementation of this scheme within a fully realistic grand unified scenario.
        Speaker: Katerina Jarkovska
        Material: Slides pdf file
    • 14:00 - 15:20 Parallel Session on Gravity and Quantum Effects
      • 14:00 An asymptotically safe link between the Planck scale and the eletroweak scale 20'
        I will discuss the asymptotic-safety paradigm as a framework for model of quantum gravity and matter at and beyond the Planck scale. I will highlight indications for the theoretical viability of this scenario and discuss how in this setting, Planck-scale physics could lead to testable consequences at the electroweak scale. In particular, the asymptotic-safety paradigm could have a higher predictive power than the Standard Model, and thus the values of free parameters of the Standard Model, such as, e.g., the values of gauge couplings, the Higgs mass, as well as Yukawa couplings, could be fixed uniquely by demanding asymptotic safety at the Planck scale.
        Speaker: Astrid Eichhorn
        Material: Slides pdf file
      • 14:20 The status of Horava gravity 20'
        Horava gravity is a proposal for a non-relativistic UV completion of General Relativity, which has been proven to be renormalizable and (in 2+1 dimensions) asymptotically free while propagating non-trivial degrees of freedom. We review the current status of the theory as a plausible proposal for a description of quantum gravity and describe the main challenges for its success.
        Speaker: Mario Herrero Valea
        Material: Slides pdf file
      • 14:40 Quark masses from Planck-scale physics 20'
        Asymptotic safety provides a framework for a UV-complete model of quantum gravity and matter. Within this framework, Renormalization Group flows allow to connect Planck-scale physics to the electroweak scale. I will present indications that asymptotically safe quantum gravity uniquely determines the top Yukawa coupling, resulting in a “retrodiction” of the top-quark mass close to its experimental value. Taking into account the non-trivial role of the U(1) hypercharge in the asymptotically safe setting, could moreover generate a mass difference between charged quarks and ''retrodict'' the bottom-quark mass.
        Speaker: Aaron Held
        Material: Slides pdf file
    • 15:40 - 16:10 Coffee Break ( Foyer )
    • 16:10 - 17:30 Parallel Session on DM at Colliders
      Location: Big Lecture Hall, Mathematics
      • 16:10 Effective Field Theory for the LHC and Dark Matter 20'
        In this talk, I will discuss the EFT approach to LHC physics and Dark Matter searches regarding its validity and prospects to gain information on the underlying UV physics. In particular in the first case, correlations will be pointed out that allow to directly access the mass of new particles beyond collider reach, while in the second case, a new effective description will be presented that allows to consistently combine results from direct-detection experiments and LHC searches for missing energy.
        Speaker: Dr. Florian Goertz (MPIK)
        Material: Slides pdf file
      • 16:30 Minimal Dark Matter at Collider 20'
        A massive particle charged under the electroweak gauge symmetry is one of the best candidate of the dark matter and called "Minimal dark matter." In this talk, I will discuss new strategies for such a dark matter hunting at collider, using precision measurements of the standard processes.
        Speaker: Satoshi Shirai (Kavli IPMU)
        Material: Slides pdf file
      • 16:50 Top-philic dark matter within and beyond the WIMP paradigm 20'
        We present a comprehensive analysis of top-philic Majorana dark matter that interacts via a colored t-channel mediator. Despite the simplicity of the model - introducing three parameters only - it provides an extremely rich phenomenology allowing to accommodate the relic density for a large range of coupling strengths spanning over six orders of magnitude. This model features all 'exceptional' mechanisms for dark matter freeze-out, including the recently discovered conversion-driven freeze-out mode, with interesting signatures of long-lived colored particles at colliders. We constrain the cosmologically allowed parameter space with current experimental limits from direct, indirect and collider searches, with special emphasis on light dark matter below the top mass. In particular, we explore the interplay between limits from Xenon1T, Fermi-LAT and AMS-02 as well as limits from stop, monojet and Higgs invisible decay searches at the LHC. We find that several blind spots for light dark matter evade current constraints. The region in parameter space where the relic density is set by the mechanism of conversion-driven freeze-out can be conclusively tested by R-hadron searches at the LHC with 300 fb−1.
        Speaker: Dr. Jan Heisig (RWTH Aachen University)
        Material: Slides pdf file
      • 17:10 Interplay between collider and dark matter searches in composite Higgs models 20'
        Many composite Higgs models predict the existence of vector-like quarks with masses outside the reach of the LHC, e.g. mQ > 2 TeV, in particular if these models contain a dark matter candidate. In such models the mass of the new resonances is bounded from above to satisfy the constraint from the observed relic density. We therefore develop new strategies to search for vector-like quarks at a future 100 TeV collider and evaluate what masses and interactions can be probed. We find that masses as large as ∼6.4 (∼9) TeV can be tested if the fermionic resonances decay into Standard Model (dark matter) particles. We also discuss the complementarity of dark matter searches, showing that most of the parameter space can be closed. On balance, this study motivates further the consideration of a higher-energy hadron collider for a next generation of facilities
        Speaker: Dr. Mikael Chala (DESY)
        Material: Slides pdf file
    • 16:10 - 17:30 Parallel Session on Astro-DM II
      Location: Lecture Hall 1, PI
      • 16:10 Lessons from the DAMPE data 20'
        The cosmic ray electron + positron flux measured recently by the DAMPE experiment up to 5 TeV has gained great attention. So far, the interpretations focuss on the spectral softening around 0.9 TeV and on a small fluctuation of one data point at 1.4 TeV. We want to point at three additional features that can be found in the data by separating the primary and the seconary compontent of the cosmic rays and discuss their implications.
        Speaker: Ms. Annika Reinert (BCTP, PI der Universität Bonn)
        Material: Slides pdf file
      • 16:30 Radiation Injection as a Solution to the EDGES 21 cm Anomaly 20'
        The recently claimed anomaly in the measurement of the 21 cm hydrogen absorption signal by EDGES at redshift z = 17, if cosmological, requires the existence of new physics. The possible attempts to resolve the anomaly rely on either (i) cooling the hydrogen gas via new dark matter-hydrogen interactions or (ii) modifying the soft photon background beyond the standard CMB (suggested by the ARCADE 2 excess as well). We argue that solutions belonging to the first class are generally in tension with cosmological dark matter probes once simple dark sector models are considered. Therefore, we propose soft photon emission by light dark matter as a natural solution to the 21 cm anomaly. We find that the signal singles out a photophilic dark matter candidate characterised by an enhanced collective decay mechanism, such as axion mini-clusters.
        Speaker: Kristjan Kannike
        Material: Slides pdf file
      • 16:50 Leptophilic dark matter from gauged lepton number: Phenomenology and gravitational wave signatures 20'
        In this work, we consider a model in which the SM is extended by a lepton number gauge group $U(1)_L$. The arising gauge anomalies are canceled by adding two sets of SM vector-like leptons. We further add a scalar field that spontaneously breaks $U(1)_L$. A residual global symmetry ensures the stability of the lightest additional lepton, thus providing a dark matter candidate. We investigate current and future constraints on the model from collider searches as well as dark matter experiments. We further study the lepton number breaking phase transition, particularly focusing on its potential to generate a stochastic gravitational wave background accessible to GW interferometry as a complementary way to probe the model.
        Speaker: Eric Madge
        Material: Slides pdf file
      • 17:10 The inflaton portal to PeV-EeV Dark Matter 20'
        In this talk I will present a new paradigm for dark matter production in which the dark constituent of our Universe is in contact with the visible bath exclusively through the inflationary sector. I will show that experimental constraints on the inflationary energy scale and the dark matter relic density can be balanced by the use of a very minimal set up and that such a construction allows to constrain both inflation physics and dark matter phenomenology by various cosmological considerations. I will show that such a model can be therefore very predictive and lead to a dark matter mass range of order O(10-1000) PeV which could be probed by various experimental collaborations, depending on the interactions considered.
        Speaker: Dr. Lucien Heurtier (University of Arizona)
        Material: Slides pdf file
    • 16:10 - 17:30 Parallel Session on EW Vacuum Stability
      Location: Small Lecture Hall, Mathematics
      • 16:10 Decay Rate of Electroweak Vacuum in the Standard Model and Beyond 20'
        We perform a precise calculation of the decay rate of the electroweak vacuum in the standard model as well as in models beyond the standard model. We use a recently developed technique to calculate the decay rate of a false vacuum, which provides a gauge invariant calculation of the decay rate at the one-loop level. We give a prescription to take into account the zero modes in association with translational, dilatational, and gauge symmetries. We calculate the decay rate per unit volume, γ, by using an analytic formula. The decay rate of the electroweak vacuum in the standard model is estimated to be log γ × Gyr Gpc^3 = −582. We also provide errors to γ due to the uncertainties of the Higgs mass, the top quark mass, the strong coupling constant and the choice of the renormalization scale. The analytic formula of the decay rate, as well as its fitting formula given in this paper, is also applicable to models that exhibit a classical scale invariance at a high energy scale. As an example, we consider extra fermions that couple to the standard model Higgs boson, and discuss their effects on the decay rate of the electroweak vacuum.
        Speaker: So Chigusa
        Material: Slides pdf file
      • 16:30 Constraining BSM Scalar Sectors through Vacuum Stability 20'
        Since the LHC has not provided us with any hints towards new physics, it is ever more interesting to constrain BSM theories from purely theoretical considerations. Requiring that the electroweak vacuum in any BSM model is at least metastable, can lead to stringent constraints on the parameter space of the model. Many popular extensions of the SM, such as supersymmetry, feature greatly extended scalar sectors. In the resulting high dimensional scalar potential, vacuum decay can happen in many different field directions. Constraints from vacuum decay thus rely on finding all minima of multidimensional scalar potentials which is a nontrivial task even at tree-level. We present results on the vacuum stability in supersymmetric models from a new code aiming to provide an efficient and reliable check of vacuum stability for use in BSM parameter scans.
        Speaker: Mr. Jonas Wittbrodt (DESY)
        Material: Slides pdf file
      • 16:50 RG improvement of multi-field potentials 20'
        In this talk a new method or renormalisation-group (RG) improvement of effective potentials in models with extended scalar sector is presented. With the use of this method, the RG improved potential can be expressed as the tree-level potential evaluated at a suitably chosen field-dependent scale. This follows from solving the RG equation for the effective potential with a suitably chosen boundary condition. In this talk I introduce the method, discuss its advantages (e.g. possibility to compute vacuum expectation values of the scalar fields which are substantially less scale dependent than the ones following from perturbative one-loop potential), applications (e.g. study of stability of the potential beyond tree level which is impossible without RG improvement) and shortcomings. The presentation is based on JHEP 1803 (2018) 014.
        Speaker: Bogumila Swiezewska
        Material: Slides pdf file
      • 17:10 Electroweak vacuum stability from extended Higgs portal dark matter and type-I seesaw 20'
        We investigate the electroweak vacuum stability in presence of a scalar dark matter and neutrino mass model through type-I seesaw. The minimal Higgs portal dark matter framework is extended here with another scalar singlet field carrying non-zero vacuum expectation value. Our results reveal that inclusion of this extra scalar not only helps in achieving absolute vacuum stability (even with large neutrino Yukawa coupling) of the electroweak vacuum upto Planck scale, but also opens up the low mass window for a scalar dark matter (< 500 GeV) which otherwise was excluded from recent XENON 1T data.
        Speaker: Dr. ARUNANSU SIL (IIT Guwahati)
        Material: Slides pdf file
    • 16:10 - 17:30 Parallel Session on SUSY and Naturalness
      Location: bctp, Seminar Room 1
      • 16:10 Electroweak symmetry breaking by a neutral sector: Dynamical relaxation of the little 20'
        We propose a new dynamical relaxation mechanism based on a singlet extension of the MSSM.
        In this scenario, a small enough soft mass of the MSSM singlet is responsible for the
        electroweak symmetry breaking and the Higgs VEV of order 100 GeV, whereas the effects of a
        large soft mass parameter of the Higgs boson, −m_{hu}^2 are dynamically compensated by an
        MSSM singlet field. The smallness of the Higgs VEV can be protected by a hierarchy between
        the gravity and gauge mediated SUSY breaking scales and the smallness of the relevant
        Yukawa couplings. Since its VEV is adjusted by the VEV of the Higgs of order 100 GeV, the
        Z boson mass can remain light even if the stop mass is heavier than 10 or 20 TeV. A focus
        point of the singlet's soft mass parameter emerges around the stop decoupling scale, and
        so the various fine-tuning measures can be reduced to order 10.
        Speaker: Bumseok Kyae (Pusan National University)
        Material: Slides pdf file
      • 16:30 Exploring Non-Holomorphic Soft Terms in the Framework of Gauge Mediated Supersymmetry Breaking 20'
        It is known that in the absence of a gauge singlet field, a specific class of supersymmetry (SUSY) breaking non-holomorphic (NH) terms can be soft breaking in nature so that they may be considered along with the Minimal Supersymmetric Standard Model (MSSM) and beyond. There have been studies related to these terms in minimal supergravity based models. Consideration of an F-type SUSY breaking scenario in the hidden sector with two chiral superfields however showed Planck scale suppression of such terms. In an unbiased point of view for the sources of SUSY breaking, the NH terms in a phenomenological MSSM (pMSSM) type of analysis showed a possibility of a large SUSY contribution to muon g−2, a reasonable amount of corrections to the Higgs boson mass and a drastic reduction of the electroweak fine-tuning for a higgsino dominated neutralino in some regions of parameter space. We investigate here the effects of the NH terms in a low scale SUSY breaking scenario. In our analysis with minimal gauge mediated supersymmetry breaking (mGMSB) we probe how far the results can be compared with the previous pMSSM plus NH terms based study. We particularly analyze the Higgs, stop and the electroweakino sectors focusing on a higgsino dominated neutralino and chargino, a feature typically different from what appears in mGMSB. The effect of a limited degree of RG evolutions and vanishing of the trilinear coupling terms at the messenger scale can be overcome by choosing a non-minimal GMSB scenario, such as one with a matter-messenger interaction.
        Speaker: Samadrita Mukherjee
        Material: Slides pdf file
      • 16:50 A role of SUSY before/around Planck 20'
        Considering NLSUSY-structure of space-time just inspired by nonlinear representation of SUSY(NLSUSY) and performing the ordinary geometric arguments of Einstein general relativity(GR) principle, we obtain NLSUSY invariant Einstein-Hilbert-type general relativity action(nonlinear supersymmetric general relativity (NLSUSYGR)) equipped with the cosmological term of the robust SUSY breaking encoded in space-time itself. NLSUSYGR would collapse spontaneously(Big Collapse) to ordinary Riemann space-time(Einstein gravity) and Nambu-Goldstone fermion(matter) for [superGL(4,R)/GL(4,R)]. We show in the simple model that SM and probably SUGRA as well can emerge in the true vacuum of NLSUSYGR as the effective theory composed of NG fermion, which bridge naturally the cosmology and the low energy particle physics and gives new insights into unsolved problems of cosmology and SM, which may explain naturally mysterious relations among them, e.g. the space-time dimension four, the dark energy density≃( neutrino mass)4 , the three-generations structure of quarks and leptons, the magnitude of the gauge coupling constant, etc. [Ref.] K. Shima, Plenary talk(lecture) at Conference on Cosmology, Gravitational Waves and Particles}, 6-10, January, 2017, NTU, Singapore.. Proceeding of CCGWP, ed. Harald Fritzsch, (World Scientific, Singapore, 2017), 301.
        Speaker: Prof. Kazunari Shima (Saitama Institute of Technology)
        Material: Slides pdf file
      • 17:10 Bayesian Analysis and Naturalness in (Next-to-)Minimal SUSY Models 20'
        One of the key motivations for supersymmetric (SUSY) models is their ability to naturally stabilize the electroweak scale and so address the hierarchy problem. However, in the Minimal Supersymmetric Standard Model (MSSM) accommodating a 125 GeV Higgs boson appears to once again require a degree of fine-tuning. This has fueled interest in non-minimal SUSY models, such as the Next-to-MSSM (NMSSM), that raise the Higgs mass at tree-level, and so are claimed to be more natural. Such a comparison, when made on the basis of traditional fine-tuning measures, is somewhat futile, since the result heavily depends on the chosen definition of fine-tuning. We instead advocate for an approach in which the plausibility that a given model reproduces the electroweak scale is quantified using Bayesian statistics. We contrast popular fine-tuning measures with naturalness priors, which automatically arise in this approach, in the constrained MSSM and a semi-constrained NMSSM. We find that results obtained using naturalness priors agree qualitatively with traditional measures, while having a well-defined probabilistic interpretation. Our comparison shows that naturalness can be rigorously grounded in Bayesian statistics, and that naturalness priors provide valuable insight into the hierarchy problem.
        Speaker: Dylan Harries
        Material: Slides pdf file
    • 18:30 - 22:00 Conference Dinner
      Location: Kleine Beethoven-Halle
  • Friday, May 25, 2018
    • 08:00 - 09:00 Registration
      Location: Zeichensaal (1st floor)
    • 09:00 - 10:00 Review Talk
      Convener: Athanasios Dedes
      • 09:00 Looking beyond WIMP Dark Matter 1h0'
        I review theories of dark matter and their detection
        Speaker: Kathryn Zurek
    • 10:00 - 10:30 Plenary Session
      Convener: Athanasios Dedes
      • 10:00 Gravitational waves from first order phase transitions 30'
         I will discuss phase transitions at the TeV scale, in particular the electroweak one (in extensions of the standard model). I will review the current status of how gravitational waves are generated during the phase transition, and show how the resulting gravitational wave signal can be computed from key properties of the transition. Finally, I will discuss detection prospects at future interferometers, such as LISA.
        Speaker: Stephan Huber
        Material: Slides pdf file
    • 10:30 - 11:00 Coffee Break ( Foyer )
    • 11:00 - 12:30 Plenary Session
      Convener: Prof. Hans Peter Nilles (Univ. Bonn)
      • 11:00 Signatures of particle production during inflation 30'
        We will discuss several phenomenological signatures that can result from particle production during inflation, with a paricular attentions ot models of axion inflation. The signatures include large non-gaussianity and sourced gravitational waves at CMB scales, primordial black holes, and gravitational waves at interferometer scales
        Speaker: Marco Peloso
        Material: Slides pdf file
      • 11:30 Dark Matter Searches with Charged Cosmic Rays 30'
        Weakly Interacting Massive Particles (WIMPs) have been the target of 
        cosmic ray experiments for decades. AMS-02 is the first experiment which can 
        realistically probe WIMP annihilation signals in the antiproton channel. Due to 
        the tiny experimental errors, uncertainties in the astrophysical background 
        have become the most limiting factor for the dark matter detection. I will use 
        the combination of antiproton, boron to carbon and positron data in order to 
        systematically reduce uncertainties related to the propagation of charged 
        cosmic rays. In addition, I will use a wide collection of accelerator data to 
        improve the calculation of the astrophysical antiproton source term. Finally, I 
        will present a spectral search for dark annihilation in the AMS-02 antiproton 
        data. I will also comment on prospects of dark matter detection with 
        Speaker: Dr. Martin Winkler (Bonn University)
        Material: Slides pdf file
      • 12:00 New signals from dark sectors 30'
        The astrophysical evidence for dark matter suggests that the standard model should be supplemented by a dark sector, containing a particle dark matter candidate. In my talk I will give give an overview of new experimental signatures of non-minimal dark sectors with new interactions, in particular: emerging jets from QCD-like dark sectors at colliders, flavour violating signatures of dark pions in fixed target experiments, and gravitational wave signatures from phase transitions in the dark sector.
        Speaker: Pedro Schwaller
        Material: Slides pdf file
    • 12:30 - 14:00 Lunch Break
    • 14:00 - 16:00 Plenary Session
      Convener: Stefan Pokorski
      • 14:00 Saxion/Higgs Inflation and Axion Dark Matter 30'
        The saxion - the modulus of the Peccei-Quinn scalar - or a mixture 
        of it with the modulus of the Higgs - represents a viable 
        inflaton candidate, if one takes into account the possible non-minimal coupling 
        of the PQ scalar to gravity. Remarkably, reheating in saxion/Higgs inflation inevitably
        restores the PQ symmetry and results therefore in a lower bound on the axion 
        mass around 30 micro-eV. Otherwise, the amount of axion dark matter exceeds
        the observed amount of cold dark matter. This cosmological scenario
        can be decisively tested by the next generation of CMB and axion experiments, 
        such as CMB-S4, MADMAX, and IAXO. 
        Speaker: Andreas Ringwald (DESY)
        Material: Slides pdf file
      • 14:30 Recent Progress in sub-GeV Dark Matter Direct Detection 30'
        Speaker: Tien-Tien Yu
        Material: Slides pdf file
      • 15:00 Novel decay and scattering signatures of light dark matter 30'
        I will discuss experimental and observational signatures of dark matter with mass at and very well below the MeV scale. The first signature regards dark matter decay into dark radiation states. I will comment on the experimental detectability of dark radiation, and further show that 21 cm astronomy becomes a probe of very light dark radiation; an explanation of the EDGES result is offered. The second signature regards dark matter scattering on nuclei and electrons in direct detection experiments. I will show how smaller but irreducible signal components can be tapped to dramatically extend the low-mass reach of existing searches.
        Speaker: Josef Pradler
        Material: Slides pdf file
      • 15:30 Physics Potential of the LHC Upgrades 30'
        The luminosity upgrade of the LHC (HL-LHC) is being actively pursued with the targeted integrated luminosity of 3 ab-1 by the year of 2037. There has been increasing interest to upgrade the energy of the LHC (HE-LHC) to about a c.m. energy of 27 TeV by doubling the magnetic field in the same tunnel, which is part of the effort of the European Strategy of Particle Physics led by CERN. I present a few well-motivated case studies to demonstrate the physics potential of the HE-LHC, in comparison with the HL-LHC expectations. 
        Speaker: Tao Han (Univ. of Pittsburgh)
        Material: Slides pdf file