Particle Physics Challenges

Europe/Berlin
Main Auditorium (DESY Hamburg)

Main Auditorium

DESY Hamburg

Description

The annual DESY Theory Workshop is organized by the elementary particle physics community in Germany. The focus is on a topical subject in theoretical particle physics and related fields. This year workshop will have a focus on particle phenomenology. More details can be found on the conference homepage https://th-workshop2018.desy.de

The workshop features:

  • Four half-day plenary sessions of specialized talks by invited speakers.
  • Two half-days of parallel sessions, allowing young researchers to present their work (on Wednesday and Thursday afternoons).
  • The DESY Heinrich-Hertz-Lecture on Physics for public outreach (on Thursday evening).
Participants
  • Abinash Kumar Nayak
  • Ahmed Ali
  • Akanksha Ahuja
  • Alejo Rossia
  • Alessandro Pini
  • Alexander Westphal
  • Alfredo Urbano
  • Ander Retolaza
  • Andrea Caputo
  • Andrea Dei
  • Andreas Pargner
  • Andreas Ringwald
  • Anna Kulesza
  • Anne Ernst
  • Ansgar Denner
  • Astrid Eichhorn
  • Ayan Paul
  • Azaria Coupe
  • Benoit Assi
  • Bikram Sapkota
  • Bradley Kavanagh
  • Brice Bastian
  • Camilo Garcia Cely
  • Carlos Tamarit
  • Caspar Hasner
  • Chao Zhang
  • Chris Ripken
  • Christian Lathe
  • Christoph Borschensky
  • Christophe Grojean
  • Claude Vallee
  • Cristina Guerrero
  • Daniel Dercks
  • Daniel Prins
  • Daniel Schwartländer
  • David Marsh
  • Davide Napoletano
  • Elli Pomoni
  • Enrico Morgante
  • Enrico Olivucci
  • Eric Madge
  • Erwin Tanin
  • Fabio Maltoni
  • Fady Bishara
  • Felix Giese
  • Felix Kahlhoefer
  • Felix Tellander
  • Filip Moortgat
  • Filippo Sala
  • Florian Staub
  • Frank Tackmann
  • Frédéric Dreyer
  • Gauthier Durieux
  • Georg Weiglein
  • George Sterman
  • Georgios Billis
  • Georgios Papathanasiou
  • Geraldine Servant
  • Gherardo Vita
  • Goutam Das
  • Gudrid Moortgat-Pick
  • Gudrun Heinrich
  • Guillermo Ballesteros
  • Hans Kastrup
  • Harold Steinacker
  • Ian Moult
  • Ibrahim Akal
  • Inna Henning
  • Ivan Sobolev
  • Jacobo Lopez Pavon
  • Jakob Moritz
  • Jan Hajer
  • Jan Peter Carstensen
  • Jeff Dror
  • Jian Wang
  • Joachim Kopp
  • Joerg Jaeckel
  • Johannes Brödel
  • Johannes Michel
  • Jonas Mueller
  • Jonas Rademacker
  • Jonas Wittbrodt
  • Jonathan Cornell
  • Jonathan Frazer
  • Jordan BERNIGAUD
  • Josua Faller
  • Juergen Reuter
  • Julia Constanze Herrmann
  • Julia Harz
  • Julien Manshanden
  • Junya Nakamura
  • Kai Schmidt-Hoberg
  • Kai Urban
  • Karapet Mkrtchyan
  • Kyohei Mukaida
  • Kåre Fridell
  • Lais Schunk
  • Liantao Wang
  • Licia Verde
  • Lorenzo Tancredi
  • Luca Mattiello
  • Lukas Mittnacht
  • Mafalda Dias
  • Marc Montull Garcia
  • Marcel Niedermeier
  • Marco Bonetti
  • Marco Hufnagel
  • Markus Diehl
  • Markus Dierigl
  • Markus Ebert
  • Martin Bauer
  • Martin Krauss
  • Martin Schmaltz
  • Matteo Capozi
  • Matthew McCullough
  • Maxim Pospelov
  • Maximilian Ruhdorfer
  • Michael Krämer
  • Michael Matlis
  • Michael Spannowsky
  • Michal Czakon
  • Michelangelo Preti
  • Michele Lucente
  • Mikhail Barabanov
  • Moritz Breitbach
  • Nathaniel Craig
  • Nicola Tamanini
  • Oleh Fedkevych
  • Oleksii Matsedonskyi
  • Oliver Schlotterer
  • Pascal Stienemeier
  • Patrick Foldenauer
  • Paul Frederik Depta
  • Pedro Liendo
  • Peter Niksa
  • Philip Dießner
  • Qin Qin
  • Raghuveer Garani
  • Ranjan Laha
  • Rebecca Leane
  • Reuven Balkin
  • Riccardo Nagar
  • Richard Ruiz
  • Robert Szafron
  • Robin Kopp
  • Rodolfo Panerai
  • Sanjay Bloor
  • Sebastian Hoof
  • Sebastian Jaskiewicz
  • Sebastian Schenk
  • Sebastian Wild
  • Sergey Ketov
  • Severin Lüst
  • Shruti Patel
  • Simon Braß
  • Simone Zoia
  • Song He
  • Stefan Liebler
  • Sven Baumholzer
  • Thomas Bourton
  • Thomas Konstandin
  • Thomas Mannel
  • Tim Stefaniak
  • Troy Figiel
  • Ulla Blumenschein
  • Valerie Domcke
  • Vincent Bettaque
  • Vincent Rothe
  • Volker Schomerus
  • Vsevolod Chestnov
  • Wadim Wormsbecher
  • Wilfried Buchmuller
  • Wojciech Kotlarski
  • Wolfgang Gregor Hollik
  • Yann Gouttenoire
  • Yannick Linke
  • Yiming Zhong
  • Yohei Ema
  • Yoshiyuki Tatsuta
  • Ze Long Liu
  • Zoltan Balazs Laczko
  • Zoltan Nagy
    • 12:45 13:50
      Registration Foyer main Auditorium

      Foyer main Auditorium

      DESY Hamburg

    • 13:50 14:00
      Welcome Main Auditorium

      Main Auditorium

      DESY Hamburg

      • 13:50
        Welcome 10m
        Speaker: Christophe Grojean (DESY)
        Slides
    • 14:00 16:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Michael Kraemer
      • 14:00
        Gravitational waves and particle physics 30m
        Speaker: Alfredo Urbano
        Slides
      • 14:40
        Astroparticles / Cosmology connections 30m
        Speaker: Licia Verde
        Slides
      • 15:20
        Towards BSM model building from asymptotic safety 30m
        Speaker: Astrid Eichhorn
        Slides
    • 16:00 16:30
      Coffee break 30m Main Auditorium

      Main Auditorium

      DESY Hamburg

    • 16:30 17:50
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Christophe Grojean
      • 16:30
        Dark matter: beyond the vanilla case 30m
        Speaker: Kai Schmidt-Hoberg
        Slides
      • 17:10
        News from $\nu$'s: Hot Topics in Neutrino Physics 30m
        Speaker: Joachim Kopp
        Slides
    • 18:30 21:30
      Welcome reception 3h Foyer main Auditorium

      Foyer main Auditorium

      DESY Hamburg

    • 09:00 11:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Anna Kulesza
      • 09:00
        Precision measurements (ATLAS/CMS) 30m
        Speaker: Ulrike Blumenschein
        Slides
      • 09:40
        Multiparticle production and automation 30m
        Speaker: Ansgar Denner
        Slides
        Video recording
      • 10:20
        Top quark physics with high precision 30m
        Speaker: Michal Czakon
        Slides
        Video recording
    • 11:00 11:40
      Coffee break 40m Foyer main Auditorium

      Foyer main Auditorium

      DESY Hamburg

    • 11:40 13:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Gudrun Heinrich
      • 11:40
        Exploring the top-Higgs connection at colliders 30m
        Speaker: Fabio Maltoni
        Slides
        Video recording
      • 12:20
        Higgs physics for the HL-LHC and beyond 30m
        Speaker: Michael Spannowsky
        Slides
    • 13:00 14:00
      Lunch 1h Canteen

      Canteen

      DESY Hamburg

    • 14:00 16:00
      Parallel Session: Cosmo 1: DM (axions & astrophysics) Seminar room 4a (SR 4a)

      Seminar room 4a (SR 4a)

      DESY Hamburg

      • 14:00
        Dark Decay of the Neutron 20m
        There is a long-standing discrepancy between the neutron lifetime measured from trapped neutrons versus those decaying in flight. In this talk, I will give an brief description of the experimental status of this puzzle and describe recent proposals to explain it by allowing the neutron to decay into hidden sector particles. In particular, I will focus on a scenario in which the neutron decays into 2 invisible particles: a dark Dirac fermion and an unstable dark photon. This setup can be consistent with all constraints if the fermion is a subdominant component of the dark matter. I will discuss the limits on the model’s parameter space that are derived from the existence of two solar mass neutron stars, direct and indirect dark matter detection, supernova observations, and cosmological considerations.
        Speaker: Jonathan Cornell (University of Cincinnati)
        Slides
      • 14:20
        Tricking Non-Poissonian Template Fitting: Dark Matter Hiding at the Galactic Center? 20m
        The Galactic Center GeV excess is firmly detected. While there is statistical evidence suggesting the excess originates largely from point sources, its interpretation as a signal of annihilating dark matter has not been conclusively ruled out. We examine the degree to which assumptions about the diffuse modeling and source populations could affect non-Poissonian template fitting methods that indicate a point-source origin for the excess. We find a proof-of principle example where a simulated dark matter signal can instead be attributed to point sources by the NPTF, in a simulation including unmodeled sources in the Fermi Bubbles. We confirm this effect is possible in the real Fermi data, finding that an injected dark matter signal is misattributed to point sources.
        Speaker: Dr Rebecca Leane (MIT)
        Slides
      • 14:40
        On Dark Matter Accretion in Neutron Stars 20m
        If Dark Matter (DM) interacts with nucleons and/or electrons it can be trapped in celestial bodies. For a Neutron Star (NS), DM accumulating in the center could form a core which could further gravitationally collapse into a black hole. The requirement that such collapses do not occur gives constraints on the DM mass and interactions. Such phenomena crucially depends on the amount of DM that can accumulate in NS. In this talk, we re-evaluate in detail the maximum amount of DM that could be accumulated in NS by carefully considering the fact that neutrons form a highly degenerate fermi plasma. We find that for asymmetric bosonic DM, for masses below 1 GeV constraints are significantly smaller than previously obtained in the literature.
        Speaker: Dr Raghuveer Garani (Universite Libre De Bruxelles)
        Slides
      • 15:00
        Global Fits of Axion Models 15m
        One of the two possible scenarios for the Peccei-Quinn symmetry is to break before the end of inflation without being restored afterwards. In this case, the axion field is homogeneous across the observable universe and its initial field value is random. A Bayesian analysis of this scenario can quantify the well-known existence of “natural” values for the initial misalignment angle and axion mass. This is particularly interesting when embedded into a consistent, global statistical analysis, including most of the known experimental constraints. We achieve this using the global fitting software GAMBIT. Finally, the predictivity of such a global fit can be improved if cooling anomalies are included.
        Speaker: Mr Sebastian Hoof (Imperial College London)
        Slides
      • 15:15
        Axion Minicluster Power Spectrum and Mass Function 15m
        We present a semi-analytical method to calculate the average axion energy density as well as the power spectrum of density fluctuations when vacuum re-alignment happens after inflation. Furthermore, we develop a modified Press & Schechter approach, suitable to describe the collapse of non-linear density fluctuations during radiation domination. This allows us to make a prediction for the distribution of mass and size of axion miniclusters. The presentation is based on the work published under the arXiv number 1708.04466.
        Speaker: Andreas Pargner (Karlsruhe Insitute of Technology)
        Slides
      • 15:30
        A Proposal to Detect Dark Matter Using Topological Insulators 20m
        Antiferromagnetically doped topological insulators (A-TI) are among the candidates to host dynamical axion fields and axion-polaritons; weakly interacting quasiparticles that are analogous to the dark axion, a long sought after candidate dark matter particle. Here we demonstrate that using the axion quasiparticle and antiferromagnetic fluctuations in A-TI's in conjunction with low-noise methods of detecting THz photons presents a viable route to detect axion dark matter with mass 0.7 to 3.5 meV, a range currently inaccessible to other dark matter detection experiments and proposals.
        Speaker: Dr David Marsh (University of Goettingen)
        Slides
      • 15:50
        Polarized direct detection of dark matter 10m
        Speaker: Kare Fridell
    • 14:00 16:00
      Parallel Session: Cosmo 2: Inflation & Early Universe Seminar room 4b (SR 4b)

      Seminar room 4b (SR 4b)

      DESY Hamburg

      • 14:00
        Primordial black holes from single-field inflation 20m
        I will discuss the formation of primordial black holes from single-field inflation. If time permits, I will also explain why the two-point statistics of primordial black holes is important to estimate their present merger rate
        Speaker: Guillermo Ballesteros (IFT UAM-CSIC)
      • 14:20
        Gauge Field and Fermion Production during Axion Inflation 20m
        A Chern-Simons coupling with a gauge field is common in axion inflation. It is well known that this coupling leads to interesting phenomenology via the resonant production of helical gauge fields; e.g., gravitational wave, magnetogenesis, leptogenesis, etc. In this talk, we extend the previous analysis to the case where chiral fermions are charged under this gauge field which couples with the inflaton via the Chern-Simons coupling. This is the case for instance with the SM gauge group. We discuss how this coupling modifies the phenomenology by the associated production of these chiral fermions.
        Speaker: Dr Kyohei Mukaida (DESY)
        Slides
      • 14:40
        Relaxion Dark Matter 20m
        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)
        Slides
      • 15:00
        Gravitational Waves from Sub-MeV Cosmolocial Phase Transitions 15m
        The next generation of gravitational-wave (GW) observatories will cover a vast array of frequencies, enabling us to probe astronomical and cosmological phenomena in a way complementary to current and future collider experiments. One such phenomenon is a cosmological first-order phase transition (PT) driven by the temperature dependence of the effective potential in the expanding and cooling universe. The transition proceeds by the nucleation of bubbles, which expand and finally collide, thereby sourcing gravitational radiation. In our work we focus on the detection capabilities of pulsar timing arrays (PTAs), which are sensitive to PTs around the keV to MeV scale. Light relics in this mass range can easily come in conflict with cosmological bounds, which I will also discuss. I will further present two toy models featuring first-order transitions, induced at tree-level and at one-loop level respectively.
        Speaker: Mr Moritz Breitbach (Johannes Gutenberg University Mainz)
        Slides
      • 15:15
        Consistent early and late time cosmology from the RG flow of gravity 15m
        The compatibility of cosmological constraints on inflation and the cosmological constant with the asymptotic safety scenario of quantum gravity is discussed. The effective action is taken to be of $f(R)$ form, truncated to second order. The flow generated by the Functional Renormalisation Group Equation is analysed and it is found to allow for trajectories that are compatible with the observational constraints on the parameters of the action, both at early and late cosmological times. In particular, the gravitational effective dynamics generated in the trans-Planckian regime flows to Starobinsky inflation at early times and to standard Einstein Gravity with a cosmological constant at late times. Moreover, the cosmological constant acquires an energy dependence at $10^{−2}$ eV, increasing from its current value of $10^{−66}$ eV$^2$ on Hubble scale to a value of $10^{30}$ eV$^2$ at inflation scale.
        Speaker: Mr Chris Ripken (Radboud University, Nijmegen)
      • 15:30
        Primordial Gravitational Waves and the Swampland 20m
        The swampland conjectures seek to distinguish effective field theories which can be consistently embedded in a theory of quantum gravity from those which can not (and are hence referred to as being in the swampland). We consider two such conjectures, known as the Swampland Distance and de Sitter Conjectures, showing that taken together they place bounds on the amplitude of primordial gravitational waves generated during single field slow-roll inflation. The bounds depend on two parameters which for reasonable estimates restrict the tensor-to-scalar ratio to be within reach of future surveys.
        Speaker: Dr Ander Retolaza (DESY)
        Slides
      • 15:50
        Cosmological aspects of Multifield NMSSM-inspired Higgs Inflation 10m
        Speaker: Michael Matlis
    • 14:00 16:00
      Parallel Session: Pheno 1: BSM I Main Auditorium

      Main Auditorium

      DESY Hamburg

      • 14:05
        Heavy Neutrinos and Safe Jet Vetoes in Hadron Collisions 20m
        Heavy neutrinos $(N)$ are a common prediction in low-scale neutrino mass models and may be accessible at experiments such as LHC, or its potential successors like the 27 TeV HE-LHC or 100 TeV VLHC. We show how collider searches for such objects employing an usual jet veto scheme can radically improve signal and background separation, and hence greatly improve sensitivity to EW- and TeV-scale heavy $N$. QCD properties of this veto scheme and anticipated sensitivities at future facilities are also presented.
        Speaker: Richard Ruiz (Durham University)
        Slides
      • 14:25
        Walking Technicolor in light of Z' searches at the LHC 17m
        In the post-Higgs era of particle physics there remain many open questions requiring physics Beyond the Standard Model. Minimal Walking Technicolor (WTC) theory provides an alternative to the SM Higgs mechanism of mass generation, where a new strong force with 'walking' (slowly running) coupling breaks electroweak symmetry dynamically. This resolves the hierarchy problem as well as providing a composite Higgs boson that is consistent with observation. The phenomenology of WTC includes two triplets of heavy vector bosons (Z',Z''). We interpret the limits from Run 2 LHC data on neutral Drell-Yan processes in the WTC parameter space, where the Z' and Z'' provide complementary exclusions on WTC. We also evaluate the potential of the LHC to probe the WTC parameter space at future upgraded energy and higher luminosities.
        Speaker: Azaria Coupe (University of Southampton)
        Slides
      • 14:42
        Exploring CPT violation in B-Bbar oscillation. 17m
        CPT is presumed to be one of the fundamental symmetry of nature. Lorentz invariance of the quantum field theories and CPT symmetry are intertwined with each other. With the advent of high precision experimental era, we should test these fundamental symmetries whose violations can have profound impact on our understanding of the physical laws. In this talk, I will talk about observing CPT violations of a non-dynamical origin in $B^0-\bar{B}^0$ mixing.
        Speaker: Abinash Kumar Nayak (IMSc, HBNI, Chennai)
        Slides
      • 14:59
        Five-particle contributions to the inclusive rare $\bar B \to X_{s(d)}\ell^+\ell^-$ decays 20m
        We calculate tree-level contributions to the inclusive rare $\bar B \to X_{s(d)} \, \ell^+\ell^-$ decays. At the partonic level they stem from the five-particle process $b \to s(d) \, q \bar q \, \ell^+\ell^-$, with $q \in \{u,d,s\}$. While for $b \to d$ transitions such five-body final states contribute at the same order in the Wolfenstein expansion compared to the three-body partonic decay, they are CKM suppressed in $b \to s$ decays. In the perturbative expansion, we include all leading-order contributions, as well as partial next-to-leading order QCD and QED effects. In the case of the differential branching ratio, we present all results completely analytically in terms of polylogarithmic functions of at most weight three. We also consider the differential forward-backward asymmetry, where all except one interference could be obtained analytically. From a phenomenological point of view the newly calculated contributions are at the percent level or below. A phenomenological update on $\bar B \to X_{s(d)}\ell^+\ell^-$ results will also be presented.
        Speaker: Qin Qin (University of Siegen)
        Slides
      • 15:19
        Hunting All the Hidden Photons - and more? 17m
        I want to shed some light on the full constraining power of experimental bounds derived for hidden photons by applying them to gauge bosons of a weakly coupled $U(1)_{B-L}$, $U(1)_{L_\mu-L_e}$, $U(1)_{L_e-L_\tau}$ and $U(1)_{L_\mu-L_\tau}$. In contrast to a hidden photon that acquires universal couplings to charged SM particles through kinetic mixing with the photon, several SM particles are uncharged under these gauge groups. Also taking into account loop-induced kinetic mixing the hidden photon bounds are drastically altered for the different gauge groups. As the associated gauge bosons of these anomaly-free groups are well-motivated mediators to a dark sector I further want to discuss some interesting dark matter phenomenology of a light thermal relic charged under the new symmetry.
        Speaker: Patrick Foldenauer (Institut für Theoretische Physik, Heidelberg University)
        Slides
      • 15:36
        B+L violation at colliders and new physics 20m
        Chiral electroweak anomalies predict baryon (B) and lepton (L) violating fermion interactions, which 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. In this article we focus instead on the effect of fermions beyond the Standard-Model (SM) in the polynomial contributions to the rate. It is shown that B + L processes involving the new fermions have a polynomial contribution that can be several orders of magnitude greater than in the SM, for high centre-of-mass energies and light enough masses. We also present calculations that 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)
        Slides
    • 14:00 16:00
      Parallel Session: String 1 Seminar room 1 (SR1)

      Seminar room 1 (SR1)

      DESY Hamburg

      • 14:00
        Scattering Amplitudes from Geometry at Infinity 30m
        Speaker: Song He
        Slides
      • 14:30
        Elliptic polylogarithms for the next generation of Feynman integrals 30m
        Speaker: Johannes Brödel
        Slides
      • 15:00
        Conformal Symmetry and Feynman Integrals 20m
        Speaker: Simone Zoia
        Slides
      • 15:20
        Analytical properties of scattering amplitudes from multiple polylogarithms 15m
        Speaker: Vsevolod Chestnov
        Slides
      • 15:35
        New relations for graviton-matter amplitudes 20m
        Speaker: Wadim Wormsbecher
        Slides
    • 16:00 16:30
      Coffee break 30m Foyer Auditorium and foyer SR 4

      Foyer Auditorium and foyer SR 4

    • 16:30 19:00
      Parallel Session: Cosmo 3: DM (particle physics) Main Auditorium

      Main Auditorium

      DESY Hamburg

      • 16:30
        Higgs enhancement and bound state formation in coannhilation scenarios 20m
        Given the growing constraints on WIMP dark matter, coannihilation scenarios are gaining more and more interest. However, in order to theoretically predict the relic density with a certain precision for a specific model, different effects have to be taken into account. We introduce a so far neglected effect - Higgs enhancement - that significantly alters the prediction of the dark matter abundance. While the importance of long-range interactions mediated by vector bosons is well established, the Higgs is usually thought to transmit contact interactions only. We show however that the Higgs can lead to similarly striking effects. Furthermore, we will demonstrate the significant impact of bound state formation via emission of a gauge boson in coannihilation scenarios featuring non-Abelian long-range interactions. While its impact was previously disregarded in the literature, we will show examples in which the dark matter density prediction would be off by up to 240% when neglecting radiative formation and decay of particle-antiparticle bound states.
        Speaker: Dr Julia Harz (LPTHE / ILP Paris)
        Slides
      • 16:50
        VERY supersymmetric dark sectors 20m
        If supersymmetry exists at any scale, it may be a preserved symmetry in the dark sector enforcing a degeneracy between its lowest lying fermions and bosons. In this talk I explore the plausibility of this scenario, the implications for the early universe, and the corresponding signatures. As I will show this completely changes the thermal history of the dark sector resulting in the sector to undergo "codecay" in the bulk of the parameter space. This results in new phenomenological signatures and presents a new way to discover (potentially high scale) supersymmetry.
        Speaker: Mr Jeff Dror (Lawrence Berkeley National Laboratory)
        Slides
      • 17:10
        Dynamic Freeze-In: Impact of Thermal Masses and Cosmological Phase Transitions on Dark Matter Production 15m
        The cosmological abundance of dark matter can be significantly influenced by the temperature dependence of particle masses and vacuum expectation values. In the paper we illustrate this point in three simple freeze-in models. The first one, which we call kinematically induced freeze-in, is based on the observation that the effective mass of a scalar temporarily becomes very small as the scalar potential undergoes a second order phase transition. This opens dark matter production channels that are otherwise forbidden. The second model we consider, dubbed vev-induced freeze-in, is a fermionic Higgs portal scenario. Its scalar sector is augmented compared to the Standard Model by an additional scalar singlet, S, which couples to dark matter and temporarily acquires a vacuum expectation value (a two-step phase transition or “vev flip-flop”). While $\langle S\rangle \neq 0$, the modified coupling structure in the scalar sector implies that dark matter production is significantly enhanced compared to the $\langle S\rangle = 0$ phases realised at very early times and again today. The third model, which we call mixing-induced freeze-in, is similar in spirit, but here it is the mixing of dark sector fermions, induced by non-zero hSi, that temporarily boosts the dark matter production rate. For all three scenarios, we carefully dissect the evolution of the dark sector in the early Universe. We compute the DM relic abundance as a function of the model parameters, emphasising the importance of thermal corrections and the proper treatment of phase transitions in the calculation.
        Speaker: Mr Lukas Mittnacht (Johannes-Gutenberg University)
        Slides
      • 17:25
        BBN constraints on MeV-scale dark sectors 15m
        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: Mr Marco Hufnagel (DESY Hamburg)
        Slides
      • 17:40
        Consequences of a XENONnT/LZ signal for the LHC and thermal dark matter production 20m
        The discovery of dark matter (DM) at XENONnT or LZ would place constraints on DM particle mass and coupling constants. It is interesting to ask when these constraints can be compatible with thermal production of DM. We address this question within the most general set of renormalizable models that preserve Lorentz and gauge symmetry, and that extend the standard model by one DM candidate of mass $m_{DM}$ and one particle of mass $M_{med}$ mediating DM-quark interactions. We find that for most of the models considered here, O(100) signal events at XENONnT/LZ and the DM thermal production are only compatible for resonant DM annihilations. Furthermore, we develop a method to forecast the outcome of the LHC Run 3 based on the same hypothetical detection of O(100) signal events at XENONnT. Applying our analysis to simulated data, we find that at the end of the LHC Run 3 only two mutually exclusive scenarios would be compatible with the detection of O(100) signal events at XENONnT, depending on the detection or lack of detection of a monojet signal. This would significantly narrow the range of possible dark matter–nucleon interactions. Finally, we want to present an outlook on how this analysis can be extended to inlcude dijet-searches for the mediator particle at the LHC.
        Speaker: Martin B. Krauss (Chalmers University of Technology)
        Slides
      • 18:00
        Is self-interacting dark matter with no light mediator viable? 20m
        Self-interacting dark matter is a well-motivated solution to the core-vs-cusp and the too-big-to-fail problems of the ΛCDM model. In this scenario, a light particle mediating the self-interactions is typically invoked in order to achieve velocity-dependent effects. In this talk, I will argue that a light mediator is not the only possible way to do that. In particular, I will discuss two new ideas: dark matter scenarios with self-heating as well as dark matter resonant scattering.
        Speaker: Dr Camilo Alfredo Garcia Cely (DESY)
        Slides
      • 18:20
        Self-interacting dark matter with a stable vector mediator 20m
        Light vector mediators can naturally induce velocity-dependent dark matter self-interactions while at the same time allowing for the correct dark matter relic abundance via thermal freeze-out. If these mediators subsequently decay into Standard Model states such as electrons or photons however, this is robustly excluded by constraints from the Cosmic Microwave Background. We study to what extent this conclusion can be circumvented if the vector mediator is stable and hence contributes to the dark matter density while annihilating into lighter degrees of freedom. We find viable parts of parameter space which lead to the desired self-interaction cross section of dark matter to address the small-scale problems of the collisionless cold dark matter paradigm while being compatible with bounds from the Cosmic Microwave Background and Big Bang Nucleosynthesis observations.
        Speaker: Dr Sebastian Wild (DESY)
        Slides
      • 18:40
        Cooling self-interacting dark matter halos 20m
        Dark sector models with light or massless mediators naturally introduce elastic and inelastic self-interactions of dark matter. The heat exchange induced by the elastic scattering permits the gravothermal evolution of the halo. Through the evolution, a halo with a cuspy density profile develops a core first but ultimately collapses to a cuspy density profile. We find that a mild inelastic scattering can significantly accelerate this evolution process. Constraints on the inelastic scattering cross section and the dissipated energy per collision can be inferred from the density cores of dwarf galaxies with low baryonic contents.
        Speaker: Yiming Zhong (Boston University)
        Slides
    • 16:30 19:00
      Parallel Session: Pheno 2: Higgs physics + SUSY Seminar room 4a (SR 4a)

      Seminar room 4a (SR 4a)

      DESY Hamburg

      • 16:30
        NLO Higgs boson pair production in the ElectroWeak Chiral Lagrangian framework 17m
        We will discuss Higgs Boson pair production at full NLO including deviations from the Standard Model arising in an Effective Field Theory framework, the Electro-weak chiral Lagrangian (EWChL). We will briefly review the calculation and then show results for some benchmark points in the BSM parameter space. Subsequently we will discuss how to write the cross section as a function of the 5 anomalous couplings arising in the Higgs sector. We will show iso-countours and 3-D plots based on this parametrization, which illustrate the behaviour of the total and differential cross sections in terms of the anomalous couplings.
        Speaker: Mr Matteo Capozi (MPI)
        Slides
      • 16:47
        Role of the Z polarization in the pp > ZH, H > bb measurement. 20m
        In this talk I show that the Z boson polarization has relevant information to distinguish the signal $pp\to ZH$, $H\to b\bar{b}$ from the dominant irreducible background $Zb\bar{b}$, and can help us to observe the largest Higgs boson branching ratio in this channel.
        Speaker: Junya Nakamura (Universität Tübingen)
        Slides
      • 17:07
        Electroweak Phase Transition in the N2HDM 17m
        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 electroweak phase transition in the Next-to-Two-Higgs Doublet model (N2HDM) where we extended the CP-conserving Two-Higgs-Doublet model with an additional real singlet. The type I and II of the N2HDM are considered where one of the three neutral CP-even Higgs bosons can be the SM-like Higgs boson. After imposing theoretical and experimental constraints, the requirement of the strong phase transition leads to testable implications for the searches at the LHC. We find preferred mass configurations for the non SM-like Higgs bosons and show the implications on the signal rates of the SM-like Higgs boson decay channels. We also use our results to investigate the interplay between a strong phase transition and the size of the trilinear Higgs self-couplings.
        Speaker: Mr Jonas Mueller (ITP-KIT)
        Slides
      • 17:24
        Mixed QCD-electroweak corrections to Higgs gluon fusion 17m
        The study of the Higgs boson properties is one of the main tasks of contemporary high-energy physics. Among Higgs properties, its interaction with gluons is interesting since it can be facilitated by yet unknown elementary particles. One of the major sources of uncertainty in the theoretical description of $ggH$ coupling originates from mixed QCD-electroweak contributions. The NLO QCD corrections to these contributions were evaluated in the approximation where electroweak boson masses were considered to be significantly larger than the mass of the Higgs boson and it is desirable to compute these corrections for physical masses of the gauge bosons and the Higgs boson. I will present a major step towards this goal and describe first the analytic evaluation of NLO mixed QCD-EW three-loop virtual corrections to $gg \to H$, and then their implementation in the evaluation of the total cross section for $gg \to H$ in the soft-gluon approximation for real corrections.
        Speaker: Mr Marco Bonetti (TTP KIT)
        Slides
      • 17:41
        Higgs Inflation and the NMSSM 20m
        In the context of canonical superconformal supergravity, Higgs inflation can be elegantly incorporated with a non-minimal Higgs coupling to supergravity. Such a conformal candidate model can be the Next-to-Minimal Supersymmetric Standard Model. Superconformal breaking induces extra terms in the effective Superpotential at low scales. We study the phenomenology of this model at the electroweak scale and show how the Higgs spectrum differs from the model with minimal coupling and how the branching fractions of the Standard Model-like Higgs boson can be affected by the non-minimal coupling to supergravity.
        Speaker: Dr Wolfgang Gregor Hollik (DESY)
        Slides
      • 18:01
        The prediction of the W boson mass in an R-symmetric SUSY model 20m
        SUSY continues to elude direct searches at Run 2 of the LHC. Hence, indirect probes like electroweak precision observables are relevant to explore the parameter space of a model. The mass of W boson is such an observable where the LHC experiments are on their way improve on the uncertainties of the experimental result. The prediction for $M_W$ has been studied in depth in the MSSM and NMSSM. Here, we show the implementation of an on-shell calculation for $M_W$ in the Minimal R-symmetric Supersymmetric SM (MRSSM) extending previous work. This also includes a comparison of the use of different renormalisation schemes and their respective uncertainties when applying them to the calculation of $M_W$ in a BSM model.
        Speaker: Mr Philip Dießner (DESY)
        Slides
      • 18:21
        Toward a reconstruction of the lightest squark flavour structure 17m
        We investigated different methods for the reconstruction of the lightest up-type squark flavour structure in the framework of the MSSM with non minimal flavour violation.
        Speaker: Mr Jordan BERNIGAUD (LAPTh)
      • 18:38
        The fate of the Littlest Higgs Model with T-parity under 13 TeV LHC Data 20m
        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: Dr Daniel Dercks (University of Hamburg)
        Slides
    • 16:30 19:00
      Parallel Session: Pheno 3: QCD and precision tests Seminar room 4b (SR 4b)

      Seminar room 4b (SR 4b)

      DESY Hamburg

      • 16:30
        Analytic Resummation for multi-differential cross sections at the LHC 15m
        We present work on analytically resummed predictions for two classes of multi-differential observables at the LHC, namely (1) the simultaneous measurement of the transverse momentum of a Drell-Yan pair with event shapes like beam thrust and (2) 0-jet cross sections with realistic jet selection criteria that are relaxed beyond a certain jet rapidity cut. Common to both observables is their intricate all-order structure in the soft-collinear limit. This structure is reflected in the multi-scale extensions of Soft-Collinear Effective Theory (SCET) which we employ to achieve their resummation. Generic features that arise in both calculations include the presence of multi-differential soft and collinear matrix elements and their refactorization in kinematic limits. These features make the resummation more challenging than the single-differential case or the well-known joint resummation with threshold effects (where the threshold limit simplifies the calculation). We also discuss technical challenges such as ensuring that integrals of the double spectrum recover the resummed single-differential result. We will close by presenting resummed predictions for the double-differential Drell-Yan spectrum at NNLL and for 0-jet cross sections with a jet rapidity cut at NLL$'$.
        Speaker: Mr Johannes Michel (DESY)
        Slides
      • 16:45
        Soft factorization in multi-parton scattering 15m
        Multi-parton interactions in proton-proton scattering are processes in which two or more pairs of partons undergo a hard interaction. In order to rigorously describe multi-parton scattering in perturbative QCD, one needs to prove a factorization theorem that allows one to separate the hard interactions from the collinear and soft ones, in a similar way as has already been done for single-parton scattering. We introduce the strategy applied in the proof of the decoupling of soft gluons from the collinear sub-processes, which is based on a recursive application of Ward identities, and give a sketch of the procedure leading to the final formula.
        Speaker: Mr Riccardo Nagar (DESY)
        Slides
      • 17:00
        Next to Leading Power Corrections: Resummation and Improving Fixed Order Subtractions 18m
        In this talk I will present some recent developments in the computation of LHC observables at next to leading power in SCET. I will explain why the analytical computation of power corrections are important for fixed order calculations via subtraction methods and show the first all order resummation of logarithms at subleading power for an event shape.
        Speaker: Mr Gherardo Vita (MIT)
        Slides
      • 17:18
        s-channel Single Top Quark Production and Decay at NNLO in QCD 18m
        We report on a fully differential next-to-next-to-leading order (NNLO) calculation of s-channel single top (anti-)quark production with a semi-leptonic decay at the LHC, neglecting the color correlation between the light and heavy quark lines and in the narrow width approximation. The NNLO corrections can increase the cross section by about 10% in the low transverse momentum region of the top quark and reduce scale variation uncertainty. In order to compare with experimental results without unfolding procedures, we also present theoretical predictions with fiducial cuts, including total cross sections and distributions of observables used in the experimental multivariate analysis. The NNLO corrections are found to be about -8% for fiducial cross sections.
        Speaker: Dr Ze Long Liu (Johannes Gutenberg University Mainz)
        Slides
      • 17:36
        Associated production of a top quark pair with a W or Z boson at the LHC at NNLL+NLO 15m
        The measurements of associated production of a vector boson with a top-antitop quark pair provide an important test for the Standard Model at the LHC. These are not only key processes to measure the top quark properties but also are very relevant in searches for new physics, both as being directly sensitive to it and as providing an important background. While NNLO calculations for this particular type of 2 to 3 processes are currently out of reach, a class of corrections beyond NLO can be taken into account with the help of resummation methods. In this talk we consider an application of soft gluon resummation in Mellin space to these processes at hadron colliders and discuss numerical predictions at NNLL matched to NLO precision for the LHC.
        Speaker: Mr Daniel Schwartländer (Institut für theoretische Physik, Universität Münster)
        Slides
      • 17:51
        Precise tests of the Standard Model with QED bound states. 18m
        Measurements of lepton magnetic moments provide important tests of the Standard Model and may lead to an indirect discovery of new physics. In my talk, I will discuss bound electron g-factor and recent progress in the computation of the higher order corrections to the magnetic moment of an electron in hydrogen-like ions. I demonstrate a modern effective field theory approach to bound state QED and show how the state-of-the-art experiments, combined with precise theoretical predictions, lead to the most accurate determination of the fundamental constants. I will present prospects for future improvements and discuss the connection with the free electron and muon anomaly.
        Speaker: Dr Robert Szafron (Technical University of Munich)
        Slides
      • 18:09
        Resummed PT spectrum for Drell-Yan including massive bottom quark effect 18m
        We study the resummed transverse momentum spectrum for Drell-Yan production including the bottom mass effect. The pt-distribution of DY or Z boson is very important observable at the LHC, particularly to the ratio of W boson and Z boson spectrum to precisely measure of the W boson mass. The presence of an extra mass scale namely the bottom mass along with the Hard scale and the pt-scale makes it very difficult to study within QCD. The three different mass scales give rise to several mass hierarchies leading to large logarithms which needs to be resummed at all orders to get a meaningful result. Moreover the different regions have to be properly matched to get a smooth distribution avoiding double counting or gaps. For these kind of problem, effective theories show a better grasp onto the problem. Using SCET based factorisation we resum these large logarithms in a systematic way upto NNLLp accuray. We discuss different theoretical issues namely order counting, rapidity divergences etc. We identify two different kind of contributions namely the primary effect where bottom quark initiates the hard process and the secondary effect where bottom quark contributes through loop. Both these contributions are included into our calculation. Finally we present properly matched pt-distribution which will be useful at the LHC to the measurement of Z boson and W boson properties.
        Speaker: Dr Goutam Das (DESY)
        Slides
      • 18:27
        Quasi Transverse Momentum Dependent PDFs from Lattice QCD 18m
        Transverse-momentum dependent PDFs (TMDPDFs) are an important ingredient for high-precision measurements of transverse momentum distributions, e.g. of the Higgs boson, and an interesting probe of the proton structure itself. So far, they have only been poorly extracted from measurement. Recently, much progress has been made in calculating PDFs from lattice QCD using the so-called quasi PDF approach. I will briefly review quasi PDFs and discuss the construction of quasi TMDPDFs and to what extent they can be used to directly calculate TMDPDFs with Lattice QCD. In particular, complications arising from combining soft and collinear matrix elements are pointed out and possible solutions are suggested.
        Speaker: Markus Ebert (MIT)
        Slides
      • 18:45
        Resummation at next-to-leading power 15m
        In the last few years, the resummation of large logarithmic contributions up to next-to-next-to-next-to-leading logarithm has been performed for a number of observables within Soft Collinear Effective Theory (SCET). This formalism has been successful at improving theoretical predictions for several important observables in collider physics. One of the first examples is threshold resummation in Drell-Yan production and more recently N-jettiness. In this talk, the framework for threshold resummation in Drell-Yan production at subleading power within the position space SCET formalism will be demonstrated. I will present the general factorisation formula and explain the contributing ingredients focusing on the power suppressed effects and new features which enter the factorisation at next-to-leading power. I will also discuss the resummation of power suppressed logarithms.
        Speaker: Mr Sebastian Jaskiewicz (Technische Universität München)
        Slides
    • 16:30 19:00
      Parallel Session: String 2 Seminar room 1 (SR 1)

      Seminar room 1 (SR 1)

      DESY Hamburg

      • 16:30
        Mellin Amplitudes for Fermionic Correlators 20m
        Speaker: Josua Faller
        Slides
      • 16:50
        Interactions of arbitrary spin gauge fields and special dimensions 20m
        Speaker: Karapet Mkrtchyan
        Slides
      • 17:10
        Intersecting branes, Higgs sector, and chirality from N = 4 SYM with soft SUSY breaking 30m
        Speaker: Harold Steinacker
        Slides
      • 17:40
        Twist fields and moduli space of D-branes 20m
        Speaker: Luca Mattiello
        Slides
      • 18:00
        Global tensor-matter transitions in F-theory 20m
        Speaker: Markus Dierigl
        Slides
      • 18:20
        Strongly deformed N=4 SYM in the double scaling limit as an integrable CFT 20m
        Speaker: Michelangelo Preti
        Slides
      • 18:40
        Integrability in N = 1 gauge theories 20m
        Speaker: Jan-Peter Carstensen
        Slides
    • 09:00 11:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Gudrid Moorgat-Pick
      • 09:00
        Direct searches for new physics at the LHC (ATLAS/CMS) 30m
        Speaker: Filip Moortgat
        Slides
      • 09:40
        New solutions to hierarchy problems 30m
        Speaker: Nathaniel Craig
        Slides
        Video recording
      • 10:20
        The $\sigma_8$ and $H_0$ problems and BSM of Cosmology 30m
        Speaker: Martin Schmaltz
        Slides
        Video recording
    • 11:00 11:40
      Coffee break 40m Foyer main Auditorium

      Foyer main Auditorium

      DESY Hamburg

    • 11:40 13:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Frank Tackmann
      • 11:40
        QCD at high precision for the LHC 30m
        Speaker: Lorenzo Tancredi
        Slides
        Video recording
      • 12:20
        Jet substructure and machine learning 30m
        Speaker: Ian Moult
        Slides
        Video recording
    • 13:00 14:00
      Lunch 1h Canteen

      Canteen

      DESY Hamburg

    • 14:00 15:45
      Parallel Session: Cosmo 4: PBH and GW Seminar room 4a (SR 4a)

      Seminar room 4a (SR 4a)

      DESY Hamburg

      • 14:00
        Gravitational wave cosmology with LISA 20m
        In this talk I will present the current status of cosmological forecasts for the Laser Interferometric Space Antenna (LISA). I will show that LISA will constitute a unique cosmological probe able to measure the expansion of the universe from low redshifts (z=0.01) up to very large redshifts (z=10). This is made possible by the use of different gravitational wave sources as standard sirens: stellar origin black hole binaries (low redshift), extreme mass ratio inspirals (intermediate redshift) and massive black hole binaries (high redshift). I will discuss the methodologies used to obtain cosmological constraints and present the latest cosmological forecasts based on state of the art simulated catalogues of gravitational wave sources.
        Speaker: Dr Nicola Tamanini (Max Planck Institute for Gravitational Physics (AEI))
        Slides
      • 14:20
        Cuckoo's Eggs in Neutron Stars: Can LIGO Hear Chirps from the Dark Sector? 20m
        We explore in detail the possibility that gravitational wave signals from binary inspirals are affected by a new force that couples only to dark matter particles. We discuss the impact of both the new force acting between the binary partners as well as radiation of the force carrier. We identify numerous constraints on any such scenario, ultimately concluding that observable effects on the dynamics of binary inspirals due to such a force are not possible if the dark matter is accrued during ordinary stellar evolution. Constraints arise from the requirement that the astronomical body be able to collect and bind at small enough radius an adequate number of dark matter particles, from the requirement that the particles thus collected remain bound to neutron stars in the presence of another neutron star, and from the requirement that the theory allows old neutron stars to exist and retain their charge. Thus, we show that any deviation from the predictions of general relativity observed in binary inspirals must be due either to the material properties of the inspiraling objects themselves, such as a tidal deformability, to a true fifth force coupled to baryons, or to a non-standard production mechanism for the dark matter cores of neutron stars. Viable scenarios of the latter type include production of dark matter in exotic neutron decays, or the formation of compact dark matter objects in the early Universe that later seed star formation or are captured by stars.
        Speaker: Dr Ranjan Laha (Johannes Gutenberg University Mainz)
        Slides
      • 14:40
        Leptophilic dark matter from gauged lepton number: Phenomenology and gravitational wave signatures 15m
        In this work, we consider a model in which the SM is extended by a lepton number gauge group $U(1)_\ell$. The arising gauge anomalies are canceled by adding two sets of SM vector-like leptons. We further add a scalar field that spontaneously breaks $U(1)_\ell$. 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: Mr Eric Madge (Johannes Gutenberg University Mainz)
        Slides
      • 14:55
        Gravitational Wave Constraints on Clustered Primordial Black Hole Dark Matter 15m
        Primordial black holes (PBHs) are a well-motivated candidate for dark matter that regained research interest after the first detections of gravitational waves by LIGO. PBHs can form binaries in the early universe. Due to the production process of PBHs, e.g. by large and rare density perturbations, clustering of PBHs can become important. This is used in the literature to avoid current exclusion limits. However, we point out that once the clustering is high enough such that the merger time for typical PBH binaries is sufficiently less than the age of the universe, multiple successive mergers, i.e. merging of binaries consisting of previously merged PBHs, can occur and gain importance. This has been neglected up to now. We present a simple cascading model taking into account this effect and show that it enhances existing constraints due to the observed binary black hole merger rate, the stochastic gravitational wave background, the effective number of additional neutrino species, and the conversion of PBHs as dark matter to gravitational waves as dark radiation.
        Speaker: Mr Paul Frederik Depta (DESY)
        Slides
      • 15:10
        Gravitational waves produced by compressible MHD turbulence from cosmological phase transitions 15m
        We discuss the gravitational wave spectrum produced by magneto-hydrodynamic turbulence in a first order phase transitions. In particular, we discuss the impact of the rate of turbulent decorrelation on the spectrum of gravitational waves and how this can impact future constraints on cosmological first order phase transitions. Additionally, we discuss how "sound-wave" driven turbulence can transform into vortically driven turbulence in the presence of magnetic fields, some inital vorticity or due to a non-barotropic flow. This leads to important changes of an initially sound-wave driven gravitational wave spectrum at later times in the evolution affecting both the amplitude and the shape of the spectrum.
        Speaker: Peter Niksa (Uni HH II. Institut für Theoretische Physik)
        Slides
      • 15:25
        Black Holes' Dark Dress: The impact of local Dark Matter halos on the mergers of primordial black hole binaries 20m
        The observation of gravitational waves from binary black hole mergers has renewed interest in the possibility of primordial black holes (PBHs) that are around 10 to 100 times more massive than the Sun. Such PBHs may form large numbers of binaries before matter-radiation equality and, if these binaries survive until today, they may contribute to the merger rate observable by LIGO and Virgo. However, if PBHs are a sub-dominant fraction of the Dark Matter (DM), they will be dressed in local DM halos which may disrupt the binaries through dynamical friction. I will present the results of N-body simulations and analytic estimates, studying the impact of this 'dark dress'. While the size and shape of PBH binaries is dramatically altered by local DM halos, there is a surprisingly subtle effect on the rate of mergers expected today. Limits on the merger rate observed by LIGO-Virgo may be translated into bounds on the fraction of DM in the form of PBHs. I will argue that our calculations place such bounds on a more solid footing, constraining the fraction of DM in the form of 10-300 solar mass PBHs to be around $10^{-3}$ or less. The techniques I present also pave the way for future studies of DM halos around astrophysical black holes and their impact on gravitational wave signals.
        Speaker: Dr Bradley Kavanagh (GRAPPA, University of Amsterdam)
        Slides
    • 14:00 15:34
      Parallel Session: Pheno 4: Ions and other topics Main Auditorium

      Main Auditorium

      DESY Hamburg

      • 14:00
        The Heavy Metal Path to New Physics 20m
        We explore the potential to test weakly coupled New Physics in heavy ion collisions. We find that the data from heavy ion collisions at the HL-LHC can yield constraints that are only an order of magnitude weaker than those expected from proton-proton collisions for generic parameter choices in well-motivated New Physics scenarios, and that they may even achieve the same sensitivity in some corners in the parameter space.
        Speaker: Jan Hajer
        Slides
      • 14:20
        Four-jet and three-jet plus gamma DPS production in pp and pA collisions at the LHC 17m
        In spite of the recent progress in both theoretical and experimental studies many aspects of $\textit{multiple parton interactions}$ (MPI) still require a detail investigation. In particular, $\textit{double parton scattering}$ (DPS) processes can play a dominant role for some specific kinematic regions of multi-jet production, especially in $\textit{proton-nucleus}$ (pA) collisions where the total DPS cross section is approximately $\sim$3A times bigger as the corresponding total DPS cross section in $\textit{proton-proton}$ (pp) collisions. In this talk I will discuss the DPS in the four-jet and three-jet plus gamma production processes in pp and pA collisions. Specifically the impact of parton shower effects on predictions for DPS sensitive observables, the role of nuclear effects and the dependence of the DPS cross sections on different kinematical cuts and phenomenological assumptions.
        Speaker: Mr Oleh Fedkevych (Institute of Theoretical Physics, Münster)
        Slides
      • 14:37
        Probing of XYZ meson structure with near threshold pp and pA collisions 20m
        The spectroscopy of charmonium-like mesons with masses above the 2mD open charm threshold has been full of surprises and remains poorly understood [1]. The currently most compelling theoretical descriptions of the mysterious XYZ mesons attribute them to hybrid structure with a tightly bound cc\bar diquark [2] or cq(cq')\bar tetraquark [3 - 5] core that strongly couples to S-wave DD\bar molecular-like structures. In this picture, the production of a XYZ particle in high energy hadron collisions and its decays into light hadron plus charmonum final states proceed via the core component of the meson, while decays to pairs of open charmed mesons proceed via the DD\bar component. These ideas have been applied with some success to the X(3872) [2], where a detailed calculation finds a cc\bar core component that is only above 5% of the time with the DD\bar component (mostly D^0D^0\bar) accounting for the rest. In this picture, the X(3872) is compose of three rather disparate components: a small charmonium-like cc\bar core with r_rms < 1 fm, a larger D^+D^- component with r_rms = ħ/\sqrt(2µ+B+) ≈ 1.5 fm and a dominant component D^0D^0\bar with a huge, r_rms = ħ/\sqrt(2µ0B0)> 9 fm spatial extent. Here µ+(µ0) and B+(B0) denote the reduced mass for the D^+D^- (D^0D^0\bar) system and the relevant binding energy |mD + mD - MX(3872)| (B+ = 8.2 MeV, B0 < 0.3 MeV). The different amplitudes and spatial distributions of the D^+D^- and D^0D^0\bar components ensure that the X(3872) is not an isospin eigenstate. Instead it is mostly I = 0, but has a significant (~ 25 %) I = 1 component. In the hybrid scheme, an X(3872) is produced in high energy pA collisions via its compact (r_rms < 1 fm) charmonium-like structure and this rapidity mixes in a time (t ~ ħ/δM) into a huge and fragile, mostly D^0D^0\bar, molecular-like structure. δM is the difference between the X(3872) mass and that of the nearest cc\bar mass pole core state, which we take to be that of the χ_c1(2P) pure charmonium state which is expected to lie about 20 ~ 30 MeV above M_X(3872) [6, 7]. In this case, the mixing time, cτ_mix 5 ~ 10 fm, is much shorter than the lifetime of X(3872) which is cτ_X(3872) > 150 fm [8]. The experiments with proton-proton (pp) and proton-nuclear (pA) collisions with momentum up to 26 Gev/c and luminosity up to 10^32 cm^-2s^-1 are well suited to test this picture for the X(3872) and, possibly, other XYZ mesons. In near threshold production experiments in the √SpN ≈ 8 GeV energy range, X(3872) mesons can be produced with typical kinetic energies of a few hundred MeV (i.e. with γβ ≈ 0.3). In the case of X(3872), its decay length will be greater than 50 fm while the distance scale for the cc\bar → D^0D^0*\bar transition would be 2 ~ 3 fm. Since the survival probability of an r_rms ~ 9 fm “molecular” inside nuclear matter should be very small, X(3872) meson production on a nuclear target with r_rms ~ 5 fm or more (A ~ 60 or larger) should be strongly quenched. Thus, if the hybrid picture is correct, the atomic number dependence of X(3872) production at fixed √SpN should have a dramatically different behavior than that of the ψ', which is long lived compact charmonium state. The current experimental status of XYZ mesons together with hidden charm tetraquark candidates and present simulations what we might expect from A-dependence of X(3872) mesons in pp and pA collisions are summarized. References [1] S. Olsen, Front. Phys. 10 101401 (2015) [2] S. Takeuchi, K. Shimizu, M. Takizawa, Progr. Theor. Exp. Phys. 2015, 079203 (2015) [3] A. Esposito, A. Pilloni, A.D. Poloza, arXiv:1603.07667[hep-ph] [4] M.Y.Barabanov, A.S.Vodopyanov, S.L.Olsen, A.I.Zinchenko, Phys. Atom. Nuc. 79, 1, 126 (2016) [5] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen, Phys. Scripta 166 014019 (2015) [6] N. Isgur, Phys. Rev. D 32, 189 (1985) [7] K. Olive et al. (PDG), Chin. Phys. C 38, 090001 (2014) [8] The width of X(3872) is experimentally constrained to be Г X(3872) < 1.2 (90% CL) in S.-K. Choi et al (Belle Collaboration), Phys. Rev. D 84, 052004 (2011)
        Speaker: Prof. Mikhail Barabanov (JINR)
      • 14:57
        The Lund Jet Plane 20m
        Lund diagrams, a representation of the phase space within jets, have long been used in discussing parton showers and resummations. We point out here that they can also serve as a powerful tool for experimentally characterising the radiation pattern within jets. We briefly comment on some of their analytical properties and highlight their scope for constraining Monte Carlo simulations. We then examine the use of the Lund plane for boosted electroweak boson tagging. When used as an input to deep-learning methods it yields high performance. Furthermore, much of that performance can be reproduced by using the Lund plane as an input to simpler log-likelihood type discriminators. This suggests a potential for unique insight and experimental validation of the features being used by machine-learning approaches. In the context of our discussion, we also highlight the importance of accounting for detector effects when considering the performance of machine-learning approaches.
        Speaker: Mr Frederic Dreyer (Oxford)
        Slides
      • 15:17
        Combining WHIZARD and Pythia 8 17m
        `WHIZARD` is a multi-purpose event generator for hadron and lepton colliders. Support for lepton beam spectra (`CIRCE1` and `CIRCE2`), polarization, initial-state radiated photons and the equivalent-photon approximation make `WHIZARD` suitable for lepton-collider physics simulations. We have added support for `Pythia 8` on an event-per-event basis, enabling the transformation from the hard process to fully showered and hadronized events while accounting for resonances and spin correlations. We compare simulated data using the new interface to results from the standard `PYTHIA6` interface and to available $\mathrm{e}^{+}\mathrm{e}^{-}$ data.
        Speaker: Simon Braß (Theoretial Particle Physics - University Siegen)
        Slides
    • 14:00 15:30
      Parallel Session: String 3 Seminar room 1 (SR 1)

      Seminar room 1 (SR 1)

      DESY Hamburg

      • 14:00
        Inversion formula for Defects I: Defect Channel 20m
        Speaker: Pedro Liendo
        Slides
      • 14:20
        Inversion formula for Defects II: Bulk Channel 15m
        Speaker: Yannick Linke
        Slides
      • 14:35
        4d N = 3 indices via discrete gauging 20m
        Speaker: Alessandro Pini
        Slides
      • 14:55
        Deconstructing Little Strings with N = 1 Gauge Theories on Ellipsoids 20m
        Speaker: Rodolfo Panerai
        Slides
      • 15:15
        Instanton counting for Class S_k 15m
        Speaker: Thomas Bourton
        Slides
    • 15:30 16:00
      Coffee break 30m Foyer Main Auditorium

      Foyer Main Auditorium

    • 15:35 16:00
      Coffee break 25m Foyer Main Auditorium

      Foyer Main Auditorium

    • 15:45 16:15
      Coffee Break 30m Foyer SR4

      Foyer SR4

    • 16:00 17:30
      Parallel Session: Pheno 5: BSM II (Dark Matter and Neutrinos) Main Auditorium

      Main Auditorium

      DESY Hamburg

      • 16:00
        Energetic $\gamma$-rays from TeV scale dark matter\\[0.1cm] annihilation resummed 17m
        The annihilation cross section of TeV scale dark matter particles $\chi^0$ with electroweak charges into photons is affected by large quantum corrections due to Sudakov logarithms and the Sommerfeld effect. We calculate the semi-inclusive photon energy spectrum in $\chi^0\chi^0\to \gamma+X$ in the vicinity of the maximal photon energy $E_\gamma = m_\chi$ with NLL' accuracy in an all-order summation of the electroweak perturbative expansion adopting the pure wino model. This results in the most precise theoretical prediction of the annihilation rate for $\gamma$-ray telescopes with photon energy resolution of parametric order $m_W^2/m_\chi$ for photons with TeV energies.
        Speaker: Mr Caspar Hasner (Technical University Munich)
        Slides
      • 16:17
        Constraining MSSM Benchmark Scenarios through Vacuum Stability 17m
        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 study the impact of these constraints on the newly proposed benchmark scenarios for the MSSM.
        Speaker: Jonas Wittbrodt (DESY)
        Slides
      • 16:34
        Dark matter pair-production in the MSSM and simplified dark matter models at the LHC 20m
        Dark matter (DM) makes up around 25% of the matter-energy content of our universe today. However, no evidence for a DM particle has been found so far. Supersymmetry adds an ideal candidate, a Weakly Interacting Massive Particle. To avoid its large parameter space with many parameters being unrelated to DM, such as in the Minimal Supersymmetric Standard Model (MSSM), simplified DM models (SDMMs) offer a way to describe only the DM phenomenology while other effects from new particles are neglected. If the DM particle is light enough, it can be produced at particle colliders to study its properties in a controlled way. Thus, for experimental searches to be as efficient as possible, a proper description of these models is required. In my talk, I will present a comparison of DM pair-production at the LHC in the MSSM and SDMMs with s- and t-channel mediators. The comparison involves a scan over the MSSM parameter space, where the differences of the total cross sections and typical kinematical distributions between the different models are studied. All calculations are done at NLO QCD accuracy and the results for the distributions include parton showering in the POWHEG formalism.
        Speaker: Dr Christoph Borschensky (Eberhard Karls Universität Tübingen)
        Slides
      • 16:54
        High Multiplicity Amplitudes and Anharmonic Oscillators 18m
        Calculations of multiparticle scattering amplitudes in scalar field theories at high multiplicities exhibit an extremely rapid growth with increasing number of final state particles. This either indicates an end of perturbative behaviour, or possibly even a breakdown of the theory itself. With the discovery of a scalar Higgs boson this has also turned into a problem of the Standard Model. To shed some light on this question we consider the quantum mechanical analogue of the scattering amplitude for multiparticle production in scalar quantum field theory, which corresponds to transitions in the anharmonic oscillator. For potentials both with and without degenerate vacua we show that the amplitude can be written as an exponential. This allows us to study its behaviour at large excitation number where tree-level perturbation theory violates unitarity constraints. We finally discuss possible generalisations to a broader class of quantum mechanical potentials governed by non-perturbative effects.
        Speaker: Sebastian Schenk (Heidelberg University)
        Slides
      • 17:12
        Composite pNGB Dark Matter 15m
        Non-minimal composite Higgs (CH) models, with additional Goldstone bosons (GB) beside the Higgs, do not only present a solution to the hierarchy problem but could also shed light on the dark matter (DM) puzzle. A realization of this scenario was presented in (arXiv:1707.07685): The symmmetry breaking structure is $SO(7)/SO(6)$ and the DM is a complex GB, stabilized by an exact $U(1)_{\rm DM}$. The couplings of the top quark break explicitly both the Higgs and the DM shift symmetries, linking the DM and Higgs potentials and predicting direct detection signals of the size currently tested by XENON1T. In this talk we shortly review the main results of (arXiv:1707.07685) and present a new class of CH models, where the main breaking of the DM shift symmetry comes either from the light quarks or from the gauging of the stabilizing $U(1)_{\rm DM}$ symmetry. This naturally explains the null results of direct detection experiments, while featuring an interesting complementary phenomenology.
        Speaker: Mr Maximilian Ruhdorfer (Technical University of Munich)
        Slides
    • 16:00 17:30
      Parallel Session: String 4 Seminar room 1 (SR 1)

      Seminar room 1 (SR 1)

      DESY Hamburg

      • 16:00
        A Non-Unitary Surprise 20m
        Speaker: Zoltan Laczko
        Slides
      • 16:20
        Non-perturbative dualities between 6d circular quiver gauge theories 20m
        Speaker: Brice Bastian
        Slides
      • 16:40
        Integrable spin chain for stringy Wess-Zumino-Witten models 20m
        Speaker: Andrea Dei
        Slides
      • 17:00
        N = 2 AdS_4 backgrounds of massive type IIA 20m
        Speaker: Daniel Prins
        Slides
    • 16:15 17:45
      Parallel Session: Cosmo 5: Leptogenesis Seminar room 4a (SR 4a)

      Seminar room 4a (SR 4a)

      DESY Hamburg

      • 16:15
        Low-scale leptogenesis with 3 right-handed neutrinos 20m
        We provide the first systematic study of the low-scale leptogenesis scenario in the minimal Standard Model extended with 3 right-handed neutrinos having masses at the GeV scale. We highlight and discuss the differences between the 2- and the 3-right-handed neutrino cases, the major qualitative distinction being the possibility, in the latter scenario, of probing part of the parameter space at the LHC. Moreover, 3-right-handed neutrinos allow for the generation of a CP-asymmetry already in the oscillating sterile sector, without the need of relying on flavour asymmetric washout. We quantitatively study the differences between the parameter space of solutions in the two scenarios, highlighting the viability of the models and their testability in current and future experiments, as well as the different impact of the identified solutions in neutrino observables, as for instance in the neutrinoless double beta decay expected rate.
        Speaker: Dr Michele Lucente (CP3 - UCLouvain)
        Slides
      • 16:35
        Leptogenesis and light DM in the Scotogenic Model 15m
        This talk is based on [arXiv:1806.06864][1]. We will present an extension of the Standard Model, including three right-handed neutrinos $N_i$ and a new Higgs doublet $\Sigma$, all charged under a exact $Z_2$ parity symmetry. This framework is also known as the "Scotogenic model". We will discuss how one can realize the SM neutrino masses + mixing angles and also generate the observed DM density and the baryon asymmetry of the universe (BAU) in this model framework. The DM is suppossed to be a keV right-handed neutrino which is mainly produced via a freeze-in mechanism given by decays of the new scalars. The BAU is generated via Leptogenesis, which relies on two CP violating mechanisms: 1) Oscillations among the RH neutrinos 2) Heavy scalar decays $\Sigma \to N L$ Combining everything, we found a quite constraint parameter region which places an upper bound on the allowed DM mass of $\mathcal{O} (20)\,\mathrm{keV}$ at most. [1]: https://arxiv.org/abs/1806.06864 "arXiv:1806.06864"
        Speaker: Mr Sven Baumholzer (Johannes Gutenberg-Universitaet Mainz)
        Slides
      • 16:50
        Testable scenarios for leptogenesis 20m
        The simplest extension of the SM that can account for neutrino masses consists in the addition of 2 right-handed neutrinos to the SM field content. In addition to the generation of the light neutrino mass and mixing pattern measured in neutrino oscillations, the low scale realization of the model provides an explanation for the matter-antimatter asymmetry of the Universe via ARS leptogenesis, with right-handed neutrino masses in the range [0.1-100] GeV. The heavy states can thus be produced and searched for in neutrinoless double beta decay searches, beam dump experiments, as SHiP or DUNE, and collider experiments as FCC-ee. I will show that for O(GeV) scale right-handed neutrinos, future experimental data can provide sufficient information to predict the matter asymmetry of the universe. Furthermore, the flavor structure of the minimal model is extremely constrained and shows a very interesting correlation with the PMNS CP-phases which opens a new window for leptonic CP violation.
        Speaker: Jacobo Lopez Pavon (CERN)
      • 17:10
        Low-scale leptogenesis and dark matter 15m
        I will discuss extension of the ARS mechanism which can explain dark matter
        Speaker: Mr Andrea Caputo (University of Valencia and IFIC)
        Slides
      • 17:25
        Thermal DM beyond 100 TeV and Cosmic Rays 15m
        Constraining thermal DM above 100 TeV using Indirect Detection experiments is generally accepted to be either irrelevant or technically challenging. Irrelevant, because the unitarity of the S-matrix implies an upper bound on the thermal DM mass of order 100 TeV. Technically challenging, because the electroweak radiative corrections become non-perturbative above 100 TeV. We consider the class of models in which thermal DM annihilates into lighter mediators, themselves decaying into SM particles. In these models, not only the entropy dilution which results from the mediator decay can evade the unitarity bound on the DM mass but also the scaled-down electroweak radiative corrections allow to reliably compute the energy spectra of the SM final states. Considering for definiteness a model of dark U(1) DM, we compute the Indirect Detection constraints coming from various high-energy telescopes observing gamma-rays, neutrinos and charged cosmic-rays, taking into account the full Sommerfeld effects with a finite mediator mass.
        Speaker: Yann Gouttenoire (DESY)
    • 18:00 19:00
      Hertz Lecture Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Markus Diehl
      • 18:00
        Imaging Fundamental Processes: Thought, experiment and the accessible universe 1h
        Speaker: George Sterman
        Slides
        Video recording
    • 19:20 22:20
      Conference dinner 3h DESY Canteen

      DESY Canteen

    • 09:00 11:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Joerg Jaeckel
      • 09:00
        Recent results from heavy flavour physics 30m
        Speaker: Jonas Rademacker
        Slides
        video recording
      • 09:40
        Searching for New Physics with Flavour Observables 30m
        Speaker: Thomas Mannel
        Slides
        Video recording
      • 10:20
        Future of Physics Beyond Colliders at CERN 30m
        Speaker: Claude Vallée
        Slides
        Video recording
    • 11:00 11:40
      Coffee break 40m Foyer main Auditorium

      Foyer main Auditorium

      DESY Hamburg

    • 11:40 13:00
      Plenary Session Main Auditorium

      Main Auditorium

      DESY Hamburg

      Convener: Georg Weiglein
      • 11:40
        Non-collider BSM 30m
        Speaker: Maxim Pospelov
        Slides
        Video recording
      • 12:20
        Future facilities 30m
        Speaker: Matthew McCullough (CERN)
        Slides
        Video recording
    • 13:00 13:10
      Closing Main Auditorium

      Main Auditorium

      DESY Hamburg

      • 13:00
        Closing 10m