Fundamental physics in the cosmos: The early, the large and the dark Universe

26 Sept 2017, 13:00 → 29 Sept 2017, 13:20 Europe/Berlin

Main Auditorium (DESY Hamburg)

Julien Lesgourgues

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. More details can be found on the conference homepage, http://th-workshop2017.desy.de

Tuesday 26 September

13:00 → 14:00 Registration

14:00 → 14:10 Welcome

14:00 Welcome

Speaker: TBA

Slides Welcoming_slides_TH2017.pdf

14:10 → 16:10 Plenary Session

Convener: Julien Lesgourgues

14:10 Ultra-light axion dark matter

Speaker: Lam Hui

Slides Hamburg2017_LamHui.pdf

Video http://webcast.desy.de/?p=7742

14:50 Axionic Dark Matter

Speaker: Andreas Ringwald

Slides desy_th_workshop_2017_ar.pdf

Video http://webcast.desy.de/?p=7745

15:30 Dark Matter constraints from astroparticle experiments

Speaker: Francesca Calore

Slides DESYTH_Calore_2017.pdf

Video http://webcast.desy.de/?p=7748

16:10 → 16:40 Coffee break

16:40 → 18:00 Plenary Session

Convener: Geraldine Servant

16:40 Large Scale Structure experiments and consequences for fundamental physics

Speaker: Will Percival

Slides Percival-DESY-26-9-17.pdf

Video http://webcast.desy.de/?p=7751

17:20 PBH as DM

Speaker: Juan Garcia-Bellido

Slides DESY_JGB_26Sep2017_final.pdf

Video http://webcast.desy.de/?p=7754

18:00 → 18:30 Particle Fever - Short, the movie, presented by David Kaplan

Speaker: David Kaplan

Video http://webcast.desy.de/?p=7770

18:30 → 21:00 Reception

Wednesday 27 September

09:00 → 11:00 Plenary Session

Convener: Alexander Westphal

09:10 Relaxing the cosmological constant

Speaker: Paolo Creminelli

Slides creminelli.pdf

Video http://webcast.desy.de/?p=7773

09:50 Cosmological Bounces and Wormholes from Vorticity

Speaker: David Kaplan (U. Johns Hopkins)

Slides Kaplan_-_DESY_Workshop_2017.pdf

Video http://webcast.desy.de/?p=7796

10:30 Light bosons and black hole super radiance

Speaker: Masha Baryakhtar

Slides SR_DESY.pdf

Video http://webcast.desy.de/?p=7800

11:00 → 11:30 Coffee break

11:30 → 13:00 Plenary Session

Convener: Mathias Garny

11:40 Modified Einstein Gravity

Speaker: Tessa Baker

Slides DESY_TBaker.pdf

Video http://webcast.desy.de/?p=7804

12:20 Introduction to Bimetric Theory

Speaker: Angnis Schmidt-May (LMU Munich)

Slides DESY-ASM.pdf

Video http://webcast.desy.de/?p=7808

13:00 → 14:00 Lunch

14:00 → 15:42 Parallel Session: Cosmology & Astroparticle Physics - Dark Matter

Conveners: Nayara Fonseca, Valerie Domcke

14:00 A new halo independent approach for direct dark matter searches

Recent results from N-body simulations point towards the existence of non-virialized structures in the dark matter halo. This weakens the assumptions of the Standard Halo Model and increases the need for ways to analyze results of direct dark matter searches without specifying a halo model. We propose a numerical method that compares an arbitrary number of results from direct detection experiments and neutrino telescopes and quantifies the compatibility of those results in a halo independent way. It takes into account the changing alignment of the earth’s velocity with respect to the sun’s over the course of the year. When applying our numerical method to experimental data, we find that it is important to take into account the impact of the velocity distribution on the interpretation of direct dark matter searches.

Speaker: Mr Andreas Rappelt (Technische Universität München)

Slides DESYTH_Rappelt.pdf

14:17 Measuring mediator masses with low-threshold direct detection experiments

One of the simplest particle physics realizations of self-interacting dark matter is a WIMP interacting with a MeV-scale scalar mediator. While this scenario is already largely excluded for dark matter masses above ~5 GeV by null searches from various direct detection experiments, future low-threshold detectors such as CRESST and CDMS could be sensitive to so far unexplored regions of the parameter space in which the WIMP has a mass of only a few GeV. In this talk I will demonstrate that by combining spectral information from several targets, these future experiments could be able to simultaneously reconstruct both the dark matter and mediator mass, and thereby offer the exciting possibility to probe astrophysical properties of dark matter using direct detection searches.

Speaker: Dr Sebastian Wild (DESY)

Slides Talk_SebastianWild.pdf

14:34 The Sommerfeld Effect at Finite Temperature

The understanding of theoretical uncertainties in the production mechanism of dark matter (DM) particles in the Early Universe has become an important topic from the viewpoint of the percent-level accuracy in the observational determination of the relic abundance. We consider the case where heavy DM self-interacts via t-channel exchange of a light gauge boson, leading to a Sommerfeld-enhanced annihilation rate during the freeze-out. The refinement of the relic abundance prediction including this effect has extensively been studied in the literature and is well understood in the context of the standard computation in vacuum. However, it is conceptionally less known to what extent the hot and dense plasma environment influences the DM gauge-boson exchange during the freeze-out process. We developed a comprehensive ab initio derivation of the Sommerfeld effect at finite temperature in the framework of non-equilibrium quantum field theory. After sketching this novel derivation, I discuss various approximation and solution strategies of this most general result. In certain limits we recover among the standard vacuum case also the equilibrium case, where the finite temperature corrections we obtain are compatible with the results recently derived from linear response theory estimates (see M. Laine et. al. in 2017). I briefly discuss the limitation of the latter approach and finally present phenomenological consequences and the physical origin of the leading finite temperature corrections to the Sommerfeld effect.

Speaker: Mr Tobias Binder (ITP, Goettingen University)

Slides TBINDER_DESY.pdf

14:51 Early Kinetic Decoupling — a case when the standard thermal dark matter relic density calculation fails

Today’s standard formalism to calculate the abundance of thermally produced dark matter particles relies on the underlying assumption that annihilating dark matter particles are in kinetic equilibrium throughout the freeze-out period. I will point out that this assumption does not have to be fulfilled in general and then present two methods on how to generalize the formalism in order to deal with the situation when kinetic decoupling happening so early that it interferes with the chemical decoupling process. One is an approximate method, where two coupled differential equations describe the leading momentum moments of the dark matter distribution, and one is a numerical procedure that enables to solve the Boltzmann equation at the full phase-space level. To illustration the implications, the methods are applied to the renown Scalar Singlet dark matter candidate where it’s shown that even in such a simple model the dark matter abundance predictions can be affected by up to one order of magnitude.

Speaker: Dr Michael Gustafsson (Göttingen University)

Slides DESY.pdf

15:08 Kinetic decoupling of dark matter: how it affects the relic abundance

Kinetic interaction (e.g., elastic scatterings) between dark matter particles and those in the thermal bath does not change the dark matter number, but it may affect the relic density of dark matter. In particular it plays an essential role in determining the relic abundance of strongly interacting massive particles, which may solve issues in the (sub-)galactic structure formation of the conventional cold dark matter model (e.g., weakly interacting massive particles). In this talk we see how the kinetic interaction can be important for the dark matter freeze-out. Proposed portals, which kinetically connect the strongly interacting massive particles to the standard model plasma, are also discussed.

Speaker: Ayuki Kamada (IBS-CTPU)

Slides kamada0927.pdf

15:26 Spectral features from light dark matter decay via gravity portal interactions

One of the key properties of dark matter particles is their longevity. However, even if dark matter is absolutely stable against decay in flat spacetime, as commonly assumed in the literature, the presence of nonminimal couplings to gravity of the dark matter field can spoil this stability in curved spacetime, with potentially remarkable phenomenological implications. More specifically, a scalar dark matter candidate with a mass in the MeV-GeV range, destabilized through a linear coupling to the Ricci scalar, can decay into electron-positron pairs and photons. In this case, observations of the cosmic microwave background by the Planck satellite and of the extragalactic isotropic gamma-ray background by COMPTEL, EGRET and Fermi LAT can be used to constrain the size of the nonminimal coupling parameter.

Speaker: Sebastian Ingenhütt (TU of Munich and MPP, Munich)

Slides DMSDESY.pdf

14:00 → 15:42 Parallel Session: Cosmology & Astroparticle Physics - Neutrinos

Conveners: Bjoern Garbrecht, Kai Schmitz

14:00 Sterile neutrinos with secret interactions

The motivation for new non-standard interactions in the sterile neutrino sector arises from the tension between oscillation experiments and cosmological results. Indeed the former point towards the existence of one (or more) sterile neutrino in the eV mass range, while the latter disfavor additional thermalized light particles with high statistical significance. However a partial thermalization induced by secret interactions can solve this tension, making eV sterile neutrinos fully consistent with big bang nucleosynthesis, cosmic microwave background and large scale structure constraints. In this talk I will present a pseudoscalar model of secret interactions which provides a simple and elegant way of reconciling eV sterile neutrinos with precision cosmology. I will also mention how the hidden interactions can be extended to the dark matter sector and might mitigate the small scale problems of the standard cold dark matter paradigm.

Speaker: Mrs Maria Archidiacono (RWTH Aachen)

Slides DESY_2017_Archidiacono.pdf

14:17 Thermalizing sterile neutrino dark matter

Sterile neutrinos produced through resonant or non-resonant oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. Based on general considerations we find a thermalization mechanism which can increase the yield after resonant and non-resonant production. At the same time, it alleviates the growing tensions with structure formation and X-ray observations and even revives simple non-resonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy- and entropy conservation describes the mechanism well.

Speaker: Dr Stefan Vogl (Max-Planck-Institut für Kernphysik)

Slides DESY_2017.pdf

14:34 The dark side of neutrinos

The O(1) relationship between the standard model and dark matter relic abundances suggests a connection that is more than just gravitational. If the main portal between the dark and visible sectors is not via charged particles, but rather via neutrinos, then both cosmological phenomenology and search methods here on Earth must be modified. I will discuss the impact of DM-neutrino interactions in the early universe including BBN, CMB and structure formation, as well as on the newly-discovered astrophysical neutrinos seen by the IceCube Neutrino Observatory, and show the great complementarity that exists between these two probes.

Speaker: Mr Aaron Vincent (Imperial College London)

Slides DESY_aaron_neutrinos.pdf

14:51 Cosmological neutrino weighing with the next generation of surveys

Cosmological experiments are exceptionally sensitive to the sum of neutrino masses. Future surveys have the potential to provide a precise measurement of the total neutrino mass, or to establish the neutrino hierarchy. To reliably estimate this, it is crucial to properly account for parameter degeneracies, i.e. how measurements improve or deteriorate with different physical models, such as dynamical dark energy or extra relativistic species. With this in mind, I will present sensitivity forecasts for CMB and LSS surveys, and updated bounds from current data.

Speaker: Mr Thejs Brinckmann (RWTH Aachen)

Slides TB_Neutrinos_Hamburg_270917.pdf

15:08 Improved constraints on lepton asymmetry from the \\ cosmic microwave background

The lepton asymmetry of the Universe is one of the most weakly constrained cosmological parameters. Whereas the baryon asymmetry is tightly constrained to be at the order $\mathcal{O}(10^{-9})$, the lepton asymmetry could be larger by many orders of magnitude. A cosmic lepton asymmetry affects the primordial helium abundance and the expansion rate of the early Universe. Both of these effects have an impact on the anisotropies of the cosmic microwave background. We derive constraints on the neutrino chemical potentials from the Planck 2015 data, assuming equal lepton flavour asymmetries and negligible neutrino masses. Our constraints on the lepton asymmetry are significantly stronger than previous constraints from CMB data analysis and we argue that they are more robust than those from primordial light element abundances. The resulting constraints on the primordial helium and deuterium abundances are consistent with those from direct measurements.

Speaker: Ms Isabel M. Oldengott (Universität Bielefeld)

Slides Oldengott_DESY2017.pdf

15:25 Axions, global symmetries and gravity.

It is commonly believed that no global symmetries can exist in a consistent theory of quantum gravity. This "folk argument" can be put on more solid and quantitative ground by explicitly constructing non-perturbative gravitational instanton solutions. In this talk, I will review such solutions in the case of an axion field minimally coupled to Einstein gravity. I will discuss both theoretical and phenomenological implications, with a special focus on the case of the QCD axion.

Speaker: Dr Alfredo Urbano (CERN)

14:00 → 15:30 Parallel Session: Particle Phenomenology - 1a

Convener: Juergen Reuter

14:00 First SUSY results with GAMBIT

I will give a brief introduction to the public software package GAMBIT (the Global and Modular Beyond-the-Standard-Model Inference Tool) and present the first SUSY results from the BSM science programme currently being pursued with it. We have performed global fit analyses of both GUT-scale and weak-scale parameterisations of the MSSM. Our analyses improve on existing results in terms of the number of observables included, the level of detail in the treatment of these, and the employed scanning techniques.

Speaker: Anders Kvellestad (Nordita)

Slides DESY2017_Kvellestad.pdf

14:17 Precise Higgs mass calculations in supersymmetry

In several supersymmetric (SUSY) models the Higgs mass is predicted to be smaller than the Z boson mass. Therefore, in order for a SUSY model to predict the correct Higgs mass of 125 GeV, large loop corrections are required. Such large loop corrections are achieved in scenarios with large stop masses and/or a large stop mixing. However, the large loop corrections lead to a slow convergence of the perturbation series and therefore to a large truncation error. In this talk I present different approaches to calculate the lightest CP-even Higgs mass in the MSSM and compare their precision. Afterwards, FlexibleEFTHiggs is presented, a general method to resum large logarithmic corrections and at the same time include all non-logarithmic 1-loop terms. FlexibleEFTHiggs therefore provides a precise Higgs mass prediction for both small and large SUSY masses.

Speaker: Dr Alexander Voigt (RWTH Aachen)

Slides talk.pdf

14:34 Sensitivity of the triple Higgs coupling to heavy sterile neutrinos

Massive neutrinos are required to explain the observation of neutrino oscillations. One of the simplest extension of the Standard Model that can successfully generate neutrino masses and mixing is the addition of fermionic gauge singlets or heavy sterile neutrinos. If an approximate lepton number symmetry is present, these sterile neutrinos can have a mass close to the TeV-scale with large Yukawa couplings, leading to a rich phenomenology. In a first study, we showed that they can induce corrections to the triple Higgs coupling as large as 30% in a simplified 3+1 model with Dirac neutrinos. These effects are potentially larger in low-scale seesaw models, as we showed by considering the inverse seesaw. I will discuss how fermionic singlets induce large corrections to the triple Higgs coupling and how they can be used to probe neutrino mass models in a regime otherwise difficult to access.

Speaker: Dr Cedric Weiland (IPPP Durham University)

Slides DESY_workshop_2017.pdf

14:51 Quantifying CP-violation in the 2HDM

The complex two-Higgs doublet model is one of the simplest ways to extend the scalar sector of the Standard Model to include a new source of CP-violation. This can address the matter antimatter asymmetry in the universe through electroweak baryogenesis and can also lead to interesting collider phenomenology. Quantifying the amount of CP-violation, however, remains a surprisingly non-trivial task. Using our parameter scan of the complex 2HDM we present interesting phenomenological consequences of CP-violation. We compare the theoretical Jarlskog-like invariants to experimental observables quantifying the amount of CP-violation. This leads to the conclusion that most of these quantifications are weakly correlated at best, so the derived amount of CP-violation depends strongly on where you are looking for it.

Speaker: Jonas Wittbrodt (DESY)

Slides DTW17_JonasWittbrodt.pdf

15:08 A global view on the Higgs self-coupling

The Higgs self-coupling is notoriously intangible at the LHC. It was recently proposed to probe the trilinear Higgs interaction through its radiative corrections to single-Higgs processes. This approach however requires to disentangle these effects from those associated to deviations of other Higgs-couplings to fermions and gauge bosons. We show that a global fit exploiting only single-Higgs inclusive data suffers from degeneracies that prevent one from extracting robust bounds on each individual coupling. We show how the inclusion of double-Higgs production via gluon fusion, and the use of differential measurements in the associated single-Higgs production channels WH, ZH and ttH, can help to overcome the deficiencies of a global Higgs-couplings fit. In particular, we bound the variations of the Higgs trilinear self-coupling relative to its SM value to the interval [0.1, 2.3] at 68% confidence level at the high-luminosity LHC, and we discuss the robustness of our results against various assumptions on the experimental uncertainties and the underlying new physics dynamics. We also study how to obtain a parametrically enhanced deviation of the Higgs self-couplings and we estimate how large this deviation can be in a self-consistent effective field theory framework.

Speaker: Mr Thibaud Vantalon (IFAE/DESY)

Slides DESY_Trilinear_Vantalon.pdf

14:00 → 15:40 Parallel Session: String & Mathematical Physics

Convener: Valentina Forini

14:00 Are tiny gauge couplings out of the Swampland?

Consistency with quantum gravity and black hole physics puts significant constraints on low-energy effective field theories. In fact, most EFT’s do not satisfy these criteria, and are said to be in the “Swampland”. Most Swampland constraints remain conjectural, supported mainly by a plethora of stringy examples. In this talk I will discuss a rigorous example of a Swampland constraint, in the context of the AdS/CFT correspondence: A bound on the gauge coupling of any U(1) theory coupled to gravity in AdS space. This equivalent to a bound on the two-point coefficient of holographic large N theories. The same logic leads to a logarithmic bound involving the gauge coupling, the cutoff of the effective field theory, the AdS radius, and Planck’s mass.

Speaker: Miguel Montero (Utrecht)

Slides 1._Montero.pdf

14:20 Contraints on the Standard Model from the Weak Gravity Conjecture

It is known that there are AdS vacua obtained from compactifying the Standard Model to 2 or 3 dimensions. However, using the Weak Gravity Conjecture, it has been recently argued by Ooguri and Vafa that non supersymmetric stable AdS vacua are incompatible with quantum gravity. By requiring the absence of these vacua we can put constraints on the SM spectra, obtaining 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 (Utrecht University)

Slides 2._Valenzuela.pdf

14:40 Constrained superfields in string cosmology

I will discuss how a better understanding of non-linearly realized supergravity has led to interesting progress and an improved understanding of dS vacua and inflation in supergravity and string flux compactifications.

Speaker: Timm Wrase (Vienna)

Slides 3._Wrase.pdf

15:00 Anti-brane induced inflation

We develop a new class of supergravity cosmological models where inflation is induced by terms in the Kähler potential which mix a nilpotent superfield S with a chiral sector Φ. As the new terms are non-(anti)holomorphic, and hence cannot be removed by a Kähler transformation, these models are intrinsically Kähler potential driven. Such terms could arise for example due to a backreaction of an anti-D3 brane on the string theory bulk geometry. We show that this mechanism is very general and allows for a unified description of inflation and dark energy, with controllable SUSY breaking at the vacuum. When the internal geometry of the bulk field is hyperbolic, we prove that small perturbative Kähler corrections naturally lead to α-attractor behaviour, with inflationary predictions in excellent agreement with the latest Planck data.

Speaker: Dr Marco Scalisi (KU Leuven)

Slides Scalisi_Hamburg_2017.pdf

15:20 Towards de Sitter from 10D

Using a 10D lift of non-perturbative volume stabilization in type IIB string theory we find that the simplest KKLT vacua cannot be uplifted to de Sitter upon inclusion of SUSY breaking sources like anti-branes. Rather, the uplift is flattened due to stronger back-reaction on the volume modulus than has previously been anticipated such that the resulting vacua are always AdS. We find that this issue can be circumvented in setups such as racetrack stabilization and reveal its physical origin from the 10D perspective.

Speaker: Mr Jakob Moritz (DESY)

Slides 5._Moritz.pdf

15:42 → 16:05 Coffee break

16:05 → 17:45 Parallel Session: Cosmology & Astroparticle Physics - Baryogenesis

Conveners: Marco Drewes, Valerie Domcke

16:05 Testing the low scale seesaw and leptogenesis

Heavy neutrinos with masses below the electroweak scale can simultaneously generate the light neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis. The requirement to explain these phenomena imposes constraints on the mass spectrum of the heavy neutrinos, their flavour mixing pattern and their CP properties. We first combine bounds from different experiments in the past to map the viable parameter regions in which the minimal low scale seesaw model can explain the observed neutrino oscillations, while being consistent with the negative results of past searches for physics beyond the Standard Model. We then study which additional predictions for the properties of the heavy neutrinos can be made based on the requirement to explain the observed baryon asymmetry of the universe. Finally, we comment on the perspectives to find traces of heavy neutrinos in future experimental searches at the LHC, NA62, BELLE II, T2K, SHiP or a future high energy collider, such as ILC, CEPC or FCC-ee. If any heavy neutral leptons are discovered in the future, our results can be used to assess whether these particles are indeed the common origin of the light neutrino masses and the baryon asymmetry of the universe. If the magnitude of their couplings to all Standard Model flavours can be measured individually, and if the Dirac phase in the lepton mixing matrix is determined in neutrino oscillation experiments, then all model parameters can in principle be determined from this data. This makes the low scale seesaw a fully testable model of neutrino masses and baryogenesis.

Speaker: Mr Juraj Klarić (Technical University Munich)

Slides klaric_DESY2017.pdf

16:22 Leptogenesis via Weinberg operator

The simplest description of Majorana neutrino masses is the dimension-5 lepton-number-violating Weinberg operator. It automatically provides out-of-equilibrium dynamics in the early Universe due to the suppression of neutrino masses. Three Sakharov conditions are satisfied if there is a CP-violating phase transition. The latter is strongly motivated by the breaking of some underlying symmetries, such as the B-L symmetry and flavour symmetries. During the phase transition, the coupling of Weinberg operator is time-dependent, and the lepton asymmetry is generated by the interference of Weinberg operator at different times. This mechanism differs from classical leptogenesis as a specific seesaw model, and its UV completion, need not be specified.

Speaker: Dr Ye-Ling Zhou (IPPP Durham)

Slides YLZ_DESY17.pdf

16:39 Electroweak baryogenesis from dimension 6 operators

Effective field theory is an attractive framework to study Electroweak Baryogenesis in a model-independent way. We add a dimension-six operator to the Higgs potential in order to have a strongly first order phase transition, which is necessary for successful baryogenesis. Another necessary ingredient is CP-violation, which can be provided by dimension-six interactions between the Higgs and the top quark. We study two of these operators that are related by the equations of motion. In our study, we compare the parameters that are needed for successful baryogenesis with the experimental constraints and we test the applicability of the effective field theory framework.

Speaker: Ms Jorinde van de Vis (Nikhef)

Slides JvandeVis.pdf

16:56 Magnetic Fields, Baryon Asymmetry and Gravitational Waves from Pseudoscalar Inflation

In models of inflation driven by an axion-like pseudoscalar field, the inflaton, a, may couple to the standard model hypercharge gauge field via a Chern-Simons-type interaction, L ⊃ a F F̃. This coupling results in the explosive production of hypermagnetic fields during inflation, which has two interesting consequences: (1) The primordial hypermagnetic field is maximally helical and, thus, capable of sourcing the generation of nonzero baryon number around the electroweak phase transition (via the chiral anomaly in the standard model). (2) The gauge field production during inflation feeds back into the spectra of primordial perturbations, which leaves an imprint in the stochastic background of gravitational waves (GWs). In this talk, I am going to discuss the correlation between these two phenomena. To this end, I will (a) present an updated study of baryogenesis via hypermagnetic fields after pseudoscalar inflation and (b) describe the corresponding implications for GWs. As it turns out, successful baryogenesis is feasible -- provided the axion couples to the gauge fields with a particular strength. Moreover, in the case of successful baryogenesis, one expects a characteristic peak in the GW spectrum at frequencies in the MHz range.

Speaker: Mr Kai Schmitz

Slides 2017_09_talk_desy_hamburg.pdf

17:13 CP-violation and baryon-asymmetry from varying Yukawas at the weak scale.

Varying Yukawas open new possibilities for electroweak baryogenesis. In this talk I will focus on the CP-violation and the baryon-asymmetry. Starting from first principles, I will derive the general form of the CP-violating semiclassical force and the diffusion equations for models with varying Yukawa couplings. This represents a very general framework to determine the baryon-asymmetry generated in a given model. I will discuss the necessary ingredients for successful baryogenesis and I will apply this framework to different models and discuss the CP-violation and the amount of baryon-asymmetry produced.

Speaker: Mr Sebastian Bruggisser (DESY Theory-Group)

Slides Bruggisser_Baryogenesis.pdf

16:05 → 17:45 Parallel Session: Cosmology & Astroparticle Physics - Dark Matter

Conveners: Bjoern Garbrecht, Enrico Morgante

16:05 Dark matter constraints from antiprotons in the light of AMS-02

I will discuss the implication for dark matter (DM) indirect searches of the recent precise measurements of cosmic-ray (CR) antiprotons from AMS-02 . With respect to previous works we use a new updated CR propagation model consistent with the AMS-02 data. Furthermore, we fit at the same time, in a self-consistent way, both DM and the propagation parameters. We find a significant indication of a DM signal for DM masses near 80 GeV, which, interestingly, is also compatible with the similar excess present in the Galactic center in gamma rays. Possible systematic effects will be also discussed. In terms of DM exclusion limits, we find stringent constraints a factor of 4-5 stronger than limits from gamma-ray observations of dwarf galaxies. ​

Speaker: Dr Alessandro Cuoco (RWTH Aachen TTK)

Slides Hamburg_Desy_Sept2017.pdf

16:22 Searching for WIMPs with charged cosmic rays

I discuss the indirect search for dark matter in the light of the lastest AMS-02 results.

Speaker: Dr Martin Winkler (Nordita Stockholm)

Slides desy.pdf

16:39 Constraining particle dark matter using local galaxy distribution

It has been long discussed that cosmic rays may contain signals of dark matter. In the last couple of years an anomaly of cosmic-ray positrons has drawn a lot of attentions, and recently an excess in cosmic-ray anti-proton has been reported by AMS-02 collaboration. Both excesses may indicate towards decaying or annihilating dark matter with a mass of around 1–10 TeV. In this article we study the gamma rays from dark matter and constraints from cross correlations with distribution of galaxies, particularly in a local volume. We find that gamma rays due to inverse-Compton process have large intensity, and hence they give stringent constraints on dark matter scenarios in the TeV scale mass regime. Taking the recent developments in modeling astrophysical gamma-ray sources as well as comprehensive possibilities of the final state products of dark matter decay or annihilation into account, we show that the parameter regions of decaying dark matter that are suggested to explain the excesses are excluded. We also discuss the constrains on annihilating scenarios.

Speaker: Koji Ishiwata (Kanazawa University)

Slides ishiwata_DESY_1709.pdf

16:56 Testing the CDM paradigm with the CMB

Dark Matter (DM) is a crucial component of the universe and, for calculations of the cosmic microwave background (CMB), is successfully modelled as a pressureless perfect fluid within General Relativity (GR). With data from Planck it becomes possible to test generalisations of this model, searching for DM properties beyond the pressureless perfect fluid and thereby testing the CDM paradigm itself. Although there is no unique way to generalise a pressureless perfect fluid, the Generalised Dark Matter (GDM) model has proven useful in CMB applications. The 3 new parameters of the model describe DM is an imperfect fluid with pressure and shear viscosity. Furthermore we construct a second and more general model, based on the Parametrized Post Friedmann (PPF) parametrization. We present our constraints from Planck data for constant and generally time dependent GDM parameters, finding no evidence for DM properties beyond that of a pressureless perfect fluid. PPF has more freedom than GDM and encompasses more drastic deviations from CDM in which DM effects are a manifestation of modifying GR rather than that of a matter field. Using PPF, we show that in the case of purely modified gravity, where the DM phenomenon is not associated with any degree of freedom, Planck data cannot be fit without fine-tuning.

Speaker: Dr Michael Kopp (Institute of Physics of the Czech Academy of Sciences)

Slides Kopp_DESY-09-2017-GDM.pdf

17:13 Cosmological attractors and universal predictions

We consider different types of single field inflationary models such as Higgs inflation-types and the attractors models. We discuss their unitarity and renormalizability properties. Once quantum corrections are considered, new physics is demanded. As a matter of fact, to consistently connect the low and high energy regimes of the effective field theories (described in terms of Standard model and inflationary parameters respectively), some threshold corrections are needed. This raises the question: how are the predictions sensitive to the required UV completion? We show under which circumstances the observables predicted by the model are insensitive to the UV completion.

Speaker: Jacopo Fumagalli (Nikhef)

16:05 → 17:45 Parallel Session: Particle Phenomenology - 2a

Convener: Steffen Schumann

16:05 Resummed differential cross sections for top-quark pairs at the LHC

Top quark physics has now entered the precision era with billions of top pairs expected to be produced over the lifetime of the LHC. As such, the need for ever more accurate theory predictions continues to grow. Using a formalism derived from Soft Collienar Effective Theory (SCET), we present predictions for differential cross sections which incorporate the simultaneous resummation of soft and small mass logarithms matched to standard threshold resummation. Building on previous work, results given to NNLO+NNLL$'$ accuracy for the top pair invariant mass and top quark $p_T$ distributions. We will examine the effects the resummation has compared to fixed order as well as assess the impact of the choice of factorisation scale.

Speaker: Mr Darren Scott (IPPP Durham)

Slides DESYTheory2017_darrenscott.pdf

16:22 Parton distributions from high-precision collider data

The latest update in the NNPDF series of PDF determinations, NNPDF3.1, includes a great deal of new experimental information on proton structure determined by collaborations at the LHC and Tevatron. Several of these new datasets provide particular challenges to PDF fitters due to their high-precision nature. We shall discuss the impact upon PDF fits of these new measurements, including W and Z production and asymmetry data, new inclusive jet data and top-quark pair differential measurements. In addition to the expanded dataset, we now extend our analysis to fitting the charm PDF alongside the light quark and gluon distributions. We shall discuss the impact this change has upon LHC phenomenology alongside the differences due to the updated dataset.

Speaker: Nathan Hartland (NIKHEF)

Slides hartland.pdf

16:39 Anomalous gauge couplings in diboson production

Diboson production at the LHC is already setting competitive bounds on anomalous triple gauge couplings (aTGC) for certain types of theories due to the increase in energy. Within the SMEFT, the leading contributions at high energy to this process depend on a combination of aTGC plus other operators. Until now the contribution of these other operators was negligible due to being very constrained by LEP. Recent works have pointed out that a reevaluation of this assumption may be necessary due to the increase in accuracy of the aTGC. In this work we study the impact of these previously neglected operators on the aTGC bounds and find that they may be non-negligible in certain cases. We also make some projections and estimate their impact on future aTGC studies. While doing this, we also notice that a global fit of LEP + Diboson (@LHC) may improve the current constrains on certain vertex corrections (when set only using LEP).

Speaker: Marc Montull (DESY)

Slides montull_aTGC.pdf

16:56 PROBING OF STRONG INTERACTIONS AND HADRON MATTER WITH CHARMONIUM-LIKE STUDIES

The spectroscopy of charmonium-like mesons with masses above the DD\bar threshold has been full of surprises, and their nature remains poorly understood [1]. The currently most compelling theoretical descriptions of the mysterious XYZ mesons attributes them to higher lying charmonium states [2], hybrid structure with a tightly bound diquark [3, 4] or a tetraquark [3, 5] core that strongly couples to S-wave D*D*\bar molecule-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 D*D*\bar component. Until now charmonium-like spectroscopy represents a good testing tool for the theories of strong interactions, including: QCD in both the perturbative and non perturbative regimes, LQCD, potential models and phenomenological models [6 - 8]. The experiments with antiproton-proton annihilation planned at FAIR and proton-proton collisions planned at NICA are well suited for a comprehensive spectroscopy program, in particular, the spectroscopy of charmonium-like exotic states. These states can be produced abundantly in both processes, and their properties can be studied in detail [6 - 8]. This research is of great importance in hadron physics and astrophysics. References [1] S.L. Olsen, Front. Phys. 10, (2015) 101401 [2] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen, Physics of Atomic Nuclei, V.77, N.1, (2014) 126 [3] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen , Physica Scripta, T 166 (2015) 014019 [4] S. Takeuchi, K. Shimizu, M. Takizawa, Prog. Theor. Exp. Phys (2015) 079203 [5] A. Esposito, A. Pilloni, A.D. Polosa, arXiv:1603.07667 [hep-ph] [6] W. Erni et al., arXiv:0903.3905v1 [hep-ex] (2009) 63 [7] N. Brambilla et al., European Physical Journal C 71:1534, (2011) 1 [8] J. Beringer et al., Review of Particle Physic, Physical. Review, D 86, (2012)

Speaker: Dr Barabanov Mikhail (JINR)

Slides Bara_DESY_2017_.pdf

17:13 Entanglement Entropy in a holographic model for the QCD critical point

We study a holographic Einstein-Maxwell-dilaton model, which is adjusted to lattice QCD data for 2+1 flavors and physical quark masses for the equation of state and quark number susceptibility at zero baryo-chemical potential, to explore the resulting phase diagram over the temperature-chemical potential plane. A first-order phase transition sets in at a temperature of about 112 MeV and a baryo-chemical potential of 612 MeV. We estimate the accuracy of the critical point position by considering different low-temperature asymptotics for the second-order quark number susceptibility and characterize the phase transition by analyzing the critical pressure and behavior of isentropes. In addition, we calculate the holographic entanglement entropy for this model and compare its phase diagram to that of the thermodynamic entropy and find a strong agreement in the vicinity of the critical point. Thus, the holographic entanglement entropy qualifies to characterize different phase structures. The scaling behavior near the critical point is analyzed through the calculation of critical exponents.

Speaker: Mr Johannes Knaute (Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf)

Slides Knaute_hQCD_and_Entanglement.pdf

16:05 → 17:45 Parallel Session: String & Mathematical Physics

Convener: Elli Pomoni

16:05 Integrable strings beyond symmetric spaces and AdS/CFT

Strings moving in symmetric spaces are integrable models and can be ``solved'' exactly. Such strings play an important role in furthering our understanding of the AdS/CFT correspondence. In recent years many further integrable string theories were discovered, based on deformations of symmetric space strings. I will give an overview of these integrable models, their interpretation in terms of string theory, and their interpretation in AdS/CFT.

Speaker: Stijn van Tongeren (HU Berlin)

Slides 1._van_Tongeren.pdf

16:25 Trigonometric Quantum Spectral Curve

I will report on the construction of the Quantum Spectral Curve (QSC) for the eta-deformation of the AdS_5 x S^5 superstring. The Quantum Spectral Curve is a very simple set of equations and boundary conditions that describe the spectrum of the deformed string theory. It can be regarded as a trigonometrisation of the QSC that formed the ultimate simplification of the spectral problem of the N=4 super Yang-Mills theory dual to superstring theory on AdS_5 x S^5 through the AdS/CFT correspondence: in contrast to other constructed QSC's, the eta-deformed QSC is real periodic, i.e. defined on a cylinder. This causes the derivation of this QSC to be very different from all previously known cases with regards to its analytic properties. I will discuss this derivation while highlighting the new features of this QSC. In particular, I will touch upon spectral theory for periodic functions and illustrate how one derives the boundary conditions for this QSC.

Speaker: Rob Klabbers (Univ. of Hamburg)

Slides 2._Klabbers.pdf

16:45 Quantum Groups behind the AdS/CFT S-Matrix

Beisert's S-matrix was fixed by centrally extended sl(2|2) symmetry. Here we examine q-deformed centrally extended sl(2|2) and its sl(2) automorphisms for which we obtain the Hopf structure and the universal R-matrix. In addition, we consider this algebra as a contraction limit of the exceptional Lie superalgebra d(2,1,\alpha). This is closely related to 3D kappa-Poincaré for which we find a new free parameter of the Hopf algebra.

Speaker: Reimar Hecht (ETH Zurich)

Slides 3._Hecht.pdf

17:05 Regge limit of scattering amplitudes from an anomalous dimension.

We study massive scattering amplitudes in N=4 super-Yang-Mills in the planar limit, where the mass is generated through a Higgs mechanism. The scattering amplitudes we consider are those of massless gauge bosons interacting through loops of massive W bosons. In such a model it is known that at leading power, both the Regge limit, as well as the soft divergences are controlled by the anomalous dimension of a Wilson loop with a cusp. We show that in the Regge limit the first power suppressed term is governed by a single power law. Furthermore we provide perturbative evidence at two loop accuracy that the exponent of this power law is given by the anomalous dimension of a Wilson loop with a scalar operator inserted at the cusp.

Speaker: Robin Brueser (Univ. Mainz)

Slides 4._Brueser.pdf

17:25 Yangian Symmetry of Fishnet Feynman Graphs

We consider an all-loop conformal Yangian symmetry of four-dimensional fishnet Feynman integrals being built from four-valent vertices which are connected via scalar massless propagators. We will discuss the implications of the Yangian symmetry in terms of differential equations for these graphs and also comment on their relation to observables in an integrable bi-scalar field theory in four dimensions. Finally, we will discuss generalizations to fishnet graphs in three and in six dimensions.

Speaker: Dennis Müller (HU Berlin)

Slides 5._Mueller.pdf

18:00 → 19:00 Hertz Lecture

Convener: Wilfried Buchmuller

18:00 Hertz Lecture - Inflationary Cosmology: Is Our Universe Part of a Multiverse?

Speaker: Alan Guth

Video http://webcast.desy.de/?p=7196

19:00 → 22:00 Conference dinner

Thursday 28 September

09:00 → 11:00 Plenary Session

Convener: Thomas Schwetz-Mangold

09:10 Cosmology beyond thermal equilibrium

Speaker: Jens Chluba

Slides Chluba_DESY.pdf

Video http://webcast.desy.de/?p=7808

09:50 Planck results and connection with particle physics

Speaker: Julien Lesgourgues

Slides 17.09.28_DESY_Lesgourgues.pdf

Video http://webcast.desy.de/?p=7776

10:30 Future of CMB observations and potential implications for fundamental physics

Speaker: Raphael Flauger

Slides Raphael_Flauger_170927.pdf

Video http://webcast.desy.de/?p=7776

11:05 → 11:40 Coffee break and GROUP PHOTO

11:40 → 13:00 Plenary Session

Convener: Alejandro Ibarra

11:40 Particle cosmology

Speaker: Pasquale Serpico

Slides Hamburg_serpico.pdf

12:20 Light dark sectors

Speaker: Brian Batell

13:00 → 14:00 Lunch

14:00 → 15:42 Parallel Session: Cosmology & Astroparticle Physics - Dark Matter

Conveners: Benedict von Harling, Valerie Domcke

14:00 Dark-Matter Bound States

I will discuss the importance of bound-state formation in the dark matter sector. On the one hand as we have shown in a recent publication, the effect of unstable bound states is crucial for the correct computation of WIMP relic abundances. On the other hand capture photon detection from late time bound state formation will provide a new search method for heavy, multi-TeV dark matter. I will present for the first time, WIMP annihilation spectra containing information about the gauge group structure. Additionally, I will demonstrate that dark matter as a composite state of new heavy fermions is well motivated theoretically and present methods to study the relic abundance and detection signals in the composite models.

Speaker: Dr Juri Smirnov (INFN Firenze)

Slides Smirnov_2017.pdf

14:17 Charged Composite Scalar Dark Matter

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. The global symmetry structure is SO(7)/SO(6), and the DM is charged under an exact U(1) DM ⊂ SO(6) that ensures its stability. Depending on whether the χ shift symmetry is respected or broken by the coupling of the top quark to the strong sector, the DM can be much lighter than the Higgs or have a weak-scale mass. Here we focus primarily on the latter possibility. We introduce the lowest-lying composite resonances and impose calculability of the scalar potential via generalized Weinberg Sum Rules. Compared to previous analyses of pNGB DM, the computation of the relic density is improved by fully accounting for the effects of the fermionic top partners. This plays a crucial role in relaxing the tension with the current DM direct detection constraints. The spectrum of resonances contains exotic top partners charged under the U(1) DM , whose LHC phenomenology is analyzed. We identify a region of parameters with f = 1.4 TeV and 200 GeV < mχ < 400 GeV that satisfies all existing bounds. This DM candidate will be tested by XENON1T in the near future.

Speaker: Mr Maximilian Ruhdorfer (Technische Universität München)

Slides talk_ruhdorfer.pdf

14:34 Search for Secluded Dark Matter with H.E.S.S. and Fermi-LAT Telescopes

Secluded dark matter models feature dark matter annihilations into a metastable mediator which then decays into Standard Model fermions. In this work, we test these models using current data from the Fermi-LAT (6-year observation of dwarf spheroidal galaxies) and the H.E.S.S.~(10-year observation of the Galactic center) instrument. Assuming that the metastable mediator shortly decays into charged leptons we derive constraints on the annihilation cross section {\it vs} dark matter mass. In particular, for decays into taus, we exclude $\sigma v \sim 4 \times 10^{-27} {\rm cm^3/s}$ for dark matter mass of $10$~GeV using Fermi-LAT, and $\sigma v \sim 3 \times 10^{-25} {\rm cm^3/s}$ for $1$TeV dark matter mass with H.E.S.S.. Our findings supersede previous constraints using Fermi-LAT data and constitute the first time limits on secluded dark sectors using H.E.S.S telescope.

Speaker: Clarissa Siqueira (Max Planck Institut für Kernphysik)

Slides search-secluded-dark.pdf

14:51 Axion Dark Matter Miniclusters

If the PQ phase transition happens after inflation, the axion energy density will have density fluctuations of order one. The size of the fluctuations is set by the horizon size at the QCD phase transition. Those fluctuations lead to the formation of gravitationally bound objects called miniclusters. A significant fraction of axion dark matter bound in miniclusters would have severe implication for axion dark matter search experiments. We present a semi-analytic method to calculate the power sepctrum of the axion miniclusters and provide an estimate for the mass function at the time of matter-radiation equality.

Speaker: Thomas Schwetz-Mangold (KIT)

Slides MC-DESY.pdf

15:08 Effective Field Theory phenomenology for an extended Dark Sector

In previous works, effective field theories (EFT) have been used to scan the relevant parameter space for single dark sector particle. We have extended upon that work to include co-annihilation as well as Sommerfeld enhancement. To this end, we have calculated solutions to the Boltzmann equation for the case of a more complex dark sector with arbitrary mass spectrum, interactions and particle spin/parity. We can readily compare the resulting relic density with the measured one to exclude a wide range of possible configurations. Further observational (indirect dark matter searches) and experimental data (direct dark matter searches, collider data) are used to narrow down the relevant parameters which would provide a consistent model. The underlying computations have been programmed in a stand-alone Fortran package which is however designed to interface with other packages.

Speaker: Mr Chao Zhang (IEXP/Univ.Hamburg)

Slides DESY_workshop_ChaoZhang.pdf

15:25 Dark Matter in SO(10) GUT

SO(10) grand unified theories can ensure the stability of new particles in terms of the gauge group structure itself, and in this respect are well suited to motivate and accommodate dark matter (DM) candidates in the form of new stable massive particles. I will give an overview of DM scenarios and related phenomenology within the framework of non-supersymmetric SO(10). In the last part of the talk I will present recent development with SO(10)xU(1), where the abelian part arises from E6 grand unification. This framework offers a rich and varied DM phenomenology.

Speaker: Dr Sofiane Boucenna (KTH Royal Institute of Technology)

Slides SB_DMSO10.pdf

14:00 → 15:42 Parallel Session: Particle Phenomenology 1a

Convener: Kai Schmidt-Hoberg

14:00 Simplified models for dark matter direct detection at one loop

Given the stringent upper limits from direct detection experiments, one possibility is that dark matter scatters with nuclei only at the loop level. In the first part of the talk, I will discuss direct detection signals of simplified models. We impose current limits and analyse how next generation experiments can constrain the dark matter parameter space. In the second part, I analyse the case of a fermion singlet, where neutrino masses can be easily generated at one loop. I will present the results of our study of the phenomenology of the model, including lepton flavour violating processes.

Speaker: Dr Juan Herrero Garcia (University of Adelaide, CoEPP)

Slides Gen_Scot_talk_DESY.pdf

14:17 Belle-II sensitivity for axion-like particles

Light pseudoscalars interacting dominantly with Standard Model gauge bosons (so-called axion-like particles or ALPs) occur frequently in extensions of the Standard Model. There is consequently a great interest in searches for ALPs both at the energy frontier and at the intensity frontier. In my talk I will review these different strategies and present an overview of existing constraints. I will then discuss the potential impact of Belle-II, which can search for both visibly and invisibly decaying ALPs. The latter case allows to explore an interesting class of dark matter models, in which ALPs mediate the interactions between the Standard Model and dark matter.

Speaker: Dr Felix Kahlhoefer (DESY)

Slides DESY_Kahlhoefer.pdf

14:34 A new search for simplified models of dark matter at the LHC

We introduce a new set of simplified models to address the effects of 3-point interactions between the dark matter particle, its dark co-annihilation partner, and the Standard Model degree of freedom, which we take to be the tau lepton. We investigate these effects as well as the discovery potential for dark matter co-annihilation partners at the LHC. A small mass splitting between the dark matter and its partner is preferred by the co-annihilation mechanism and suggests that the co-annihilation partners may be long-lived (stable or meta-stable) at collider scales. It is argued that such long-lived electrically charged particles can be looked for at the LHC in searches of anomalous charged tracks.

Speaker: Alexis Plascencia (Durham University, IPPP)

Slides Plascencia_DESY.pdf

14:51 Higgsino Dark Matter at Collider

The Higgsino is the most promising candidate for the dark matter. The almost pure Higgsino, however, is known to be a very challenging target at the LHC. I will show that improvement of tracking technique of disappearing tracks can significantly increase the sensitivity for the Higgsino. I will also discuss a future 33 TeV collider can probe the 1 TeV Higgsino, which is the most interesting for the thermal relic density.

Speaker: Satoshi Shirai (Kavli IPMU)

Slides Shirai.pdf

15:08 Hunting the dark Higgs

I will discuss a novel signature of dark matter production at the LHC resulting from the emission of an additional Higgs boson in the dark sector. The presence of such a dark Higgs boson is motivated simultaneously by the need to generate the masses of the particles in the dark sector and the possibility to relax constraints from the dark matter relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into Standard Model states via a small mixing with the Standard Model Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. I will present the sensitivities achievable in LHC searches for dark Higgs bosons with already collected data and demonstrate that such searches can probe large regions of parameter space that are inaccessible to conventional mono-jet or di-jet searches.

Speaker: Michael Duerr (DESY)

Slides talk_Duerr.pdf

15:25 Direct Detection of Ultralight Dark Matter

Ultralight bosonic particle is one of the dark matter and called fuzzy dark matter. Its astrophysical properties are interesting and have been recently studied. On the other hand, the detection method is less discussed. We propose a new method to detect them using the motions of heavenly bodies. (This is a work in progress)

Speaker: Mr Hajime Fukuda (Kavli IPMU)

Slides presentation.pdf

14:00 → 15:42 Parallel Session: Strings & Mathematical Physics

Convener: Miguel Montero

14:00 No smooth beginning for spacetime

I will discuss a fundamental obstruction to any theory of the beginning of the universe, formulated as a semiclassical path integral. Hartle and Hawking’s no boundary proposal and Vilenkin’s tunneling proposal are examples of such theories. Each may be formulated as the quantum amplitude for obtaining a final 3-geometry by integrating over 4-geometries. The result is obtained using a new mathematical tool - Picard-Lefschetz theory - for defining the semiclassical path integral for gravity. The Lorentzian path integral for quantum cosmology with a positive cosmological constant is meaningful in this approach, but the Euclidean version is not. Framed in this way, the resulting framework and predictions are unique. Unfortunately, the outcome is that primordial tensor (gravitational wave) fluctuations are unsuppressed. One can prove a general theorem to this effect, in a wide class of theories.

Speaker: Jean - Luc Lehners (AEI Golm)

Slides 1._Lehners.pdf

14:20 Quantum Transitions through Cosmological Singularities

We study quantum mechanical tunneling using complex solutions of the classical field equations. Simple visualization techniques allow us to unify and generalize previous treatments, and straightforwardly show the connection to the standard approach using Euclidean instanton solutions. Applying these techniques to quantum cosmology we describe transitions between classical patches of the configuration space on which the universe's quantum state is defined. In particular we calculate the quantum transition, in the saddle point approximation connecting asymptotically classical, inflating as well as ekpyrotic histories. This supplies probabilities for how a classical history on one side transitions and branches into a range of classical histories on the opposite side. We find a small quantum probability to bounce even when the classical extrapolation of the incoming history is singular.

Speaker: Sebastian Bramberger (MPI-AEI Golm)

Slides 2._Bramberger.pdf

14:40 How general is holography? Flat space limit and soft hairs in higher spin gravity

It is still an open question how general holographic dualities are, and what they possibly tell us about quantum gravity in asymptotically flat spacetimes. In this talk I will focus on a concrete example of an holographic duality involving higher spin gravity. In particular, I report on recent progress within three-dimensional higher spin gravity concerning the flat space limit and the soft hair proposal therein. I present a new set of boundary conditions for higher spin gravity, inspired by a recent “soft Heisenberg hair"-proposal for General Relativity. The asymptotic symmetry algebra consists of set of affine u(1) current algebras. Its associated canonical charges generate higher spin soft hair. The generators of the three-dimensional higher spin version of the Bondi-Metzner-Sachs algebra arise from composite operators of the affine u(1) currents through a twisted Sugawara-like construction.

Speaker: Martin Ammon (Univ. of Jena)

Slides 3._Ammon.pdf

15:00 Algebraic properties of the monopole formula

In this talk, I will discuss how the two geometric notions "fan" and "monoid" can be very fruitful for the understanding of the Coulomb branch Hilbert series (the monopole formula) for 3d N=4 gauge theories. After a brief reminder of the monopole formula, I will introduce the matter fan and reorganise the monopole formula accordingly. I then discuss the resulting algebraic properties and their implications.

Speaker: Marcus Sperling (Univ. Vienna)

Slides 4._Sperling.pdf

15:20 BMS4 at spatial infinity

A few years ago Strominger argued that the BMS4 algebra, usually defined at null infinity, should be regarded as a true symmetry of gravitational evolution of asymptotically flat space-times. This implies the existence of an infinite tower of conserved quantities and brings new insight to various problems like gravitational scattering or black-holes evaporation. In this talk, I will show how BMS4 algebra arises as a symmetry at spatial infinity and prove the associated conservation laws conjectured by Strominger

Speaker: Cedric Troessaert (MPI-AEI Golm)

Slides 5._Troessaert.pdf

14:00 → 15:42 Parallel Sessions: Cosmology & Astroparticle Physics - Inflation

Conveners: Bjoern Garbrecht, Sebastien Clesse

14:00 CMB constraints on the inflaton couplings in $\alpha$-attractor models

We show that the parameter space of single field models of inflation contains viable regions in which the inflaton couplings to radiation can be determined from the properties of CMB temperature fluctuations, in particular the spectral index. This may be the only way to measure these fundamental microphysical parameters, which shaped the universe by setting the initial temperature of the hot big bang and contain important information about the embedding of a given model of inflation into a more fundamental theory of physics. We apply the method to $\alpha$-attractor models in which the inflaton couples to other scalars or fermions.

Speaker: Dr Marco Drewes (Université catholique de Louvain)

Slides Drewes_DESY2017.pdf

14:17 Stochastic Methods for Inflation Model Building

Incorporating stochastic methods into the model building process can significantly improve our understanding of how to reliably compute predictions. In addition, as high energy physics models of inflation continue to improve, it is expected that they will become increasingly complex. This again makes the use of stochastic methods an appealing option, as they present a wealth of new tools for gaining analytic control. At the heart of both of these perspectives is the idea that we can take advantage of universal behaviour that emerges when a system becomes sufficiently complex.

Speaker: Dr Jonathan Frazer (DESY)

Slides DESY_-_Fundamental_Physics_in_the_Cosmos_-_stochastic_methods_for_inflation_model_building.pdf

14:34 Universal predictions from inflation

An ultraviolet-complete description of inflation may not be simple. Indeed, our best paradigm for physics at high energies seems to point towards a low-energy effective potentials with a large number of degrees of freedom. Cosmological data however shows a very simple primordial distribution of matter. I will discuss how complex inflation can give rise to universal simple predictions by analysing two distinct scenarios — one with random manyfield potential and one with poles in the kinetic terms.

Speaker: Mafalda Dias (DESY)

Slides DESY_theory_workshop.pdf

14:51 Electroweak Vacuum Stability During and After Inflation

Currently favoured values of the Standard Model parameters show that the model can be consistently extended all the way up to the Planck scale. The only required new physics at high energies being inflation. However, those values also indicate that at high energies the SM potential might have another, much deeper negative minimum. We show, that apparent negative states do not exclude high energy inflation. The compulsory Higgs-inflaton interactions can stabilise the vacuum. And even if the same interactions tend to destabilise it via the resonant Higgs production after inflation, we show that there is a large parameter space where this can be avoided.

Speaker: Dr Mindaugas Karčiauskas (University of Jyväskylä)

Slides Karciauskas-DESY.pdf

15:08 Higgs Dynamics During And After Inflation

Current measurements of the Higgs boson and top quark mass favor metastability of the electroweak vacuum in the Standard Model. This raises some questions when we consider the evolution of our universe: how the Higgs ended up in such an energetically disfavored state? Why it remained there during inflation? These problems can be addressed by assuming that the Higgs couples directly to the inflaton and/or interacts non-minimally with gravity. In this talk I will review the effects of these interactions on the dynamics of the Higgs field during the inflationary period and the subsequent period of particle production, namely reheating. I will show that there exists a favorable range of parameters that allows to explain why the Higgs remained in the electroweak vacuum during the evolution of the universe.

Speaker: Marco Zatta (University of Helsinki)

Slides zatta_desy.pdf

15:25 Extranatural Inflation and CMB observations

The success of a given inflationary model crucially depends upon two features: its predictions for observables such as those of the Cosmic Microwave background (CMB) and its insensitivity to the unknown ultraviolet (UV) physics such as quantum gravitational effects. Extranatural inflation is a well motivated scenario which is insensitive to UV physics by construction. In this five dimensional model, the fifth dimension is compactified on a circle and the zero mode of the fifth component of a bulk U(1) gauge field acts as the inflaton. In this talk, I will present simple variations of the minimal extranatural inflation model which help in improving its CMB predictions while retaining its numerous merits. As will be presented, it is possible to obtain CMB predictions identical to those of e.g. Starobinsky model of inflation and show that this can be done in the most minimal way by having two additional light fermionic species in the bulk, with the same U(1) charges. I would then present the constraints that CMB observations impose on the parameters of the model. Finally, I would comment on the connections of this to the Weak Gravity Conjecture.

Speaker: Dr Gaurav Goswami (Ahmedabad University)

15:42 → 16:05 Coffee break

16:05 → 18:05 Parallel Session: Cosmology & Astroparticle Physics - PBH

Conveners: Bjoern Garbrecht, Juan Garcia-Bellido

16:05 Can Primordial Black Holes be the Dark Matter?

Since the detection by Advanced LIGO/VIRO of gravitational waves emitted by black holes with masses beyond most expectations, primordial black holes (PBH) have seen a revival of interest as a possible Dark Matter candidate, supported by the coincidence between inferred merging rates by LIGO and the expected rates for PBH abundances comparable to the Dark Matter. I will review the recent and less recent observations that constrain or support the existence of Primordial Black Holes in the mass range [1-100] Msun, as well as the future observational perspectives.

Speaker: Mr Sebastian Clesse (RWTH Aachen)

Slides CLESSE_DESY_TH_WORKSHOP_lowres.pdf

16:22 Primordial black hole constraints for extended mass functions

I will discuss the cosmological and astrophysical constraints on the fraction of the dark matter in primordial black holes (PBHs). First, I will describe a general method for extracting constraints for extended PBH mass functions from those for monochromatic ones, demonstrating that the constraints become more stringent in the extended case than the monochromatic one [1]. Then, I will discuss the production of PBH binaries and the projected constraints on PBH abundance from non-detection of the resulting stochastic gravitational wave background [2]. [1] B. Carr, M. Raidal, T. Tenkanen, V. Vaskonen and H. Veermäe, arXiv:1705.05567. [2] M. Raidal, V. Vaskonen and H. Veermäe, arXiv:1707.01480.

Speaker: Dr Ville Vaskonen (NICPB)

Slides talk.pdf

16:39 Loop effects in QED in the presence of a Schwarzschild black hole

Black holes can manifest themselves in local electromagnetic phenomena. This appears to be a consequence of the formation of the event horizon. In this talk, we shall discuss several local imprints of black holes in the far-from- and near-horizon region.

Speaker: Dr Viacheslav Emelyanov (Karlsruhe Institute of Technology, Institute of Theoretical Physics)

Slides Loop_effects_in_QED_with_BHs-Hamburg.pdf

16:56 Primordial black holes from inflaton and spectator field perturbations in a matter-dominated era

We study production of primordial black holes (PBH) during an early matter-dominated phase. As a source of perturbations, we consider either the inflaton field with a running spectral index or a spectator field that has a blue spectrum and thus provides a significant contribution to the PBH production at small scales. First, we identify the region of the parameter space where a significant fraction of the observed dark matter can be produced, taking into account all current PBH constraints. Then, we present constraints on the amplitude and spectral index of the spectator field as a function of the reheating temperature. We also derive constraints on the running of the inflaton spectral index, which are comparable to those from the Planck satellite for a scenario where the spectator field is absent.

Speaker: Dr Tommi Tenkanen (Queen Mary University of London)

Slides Tommi_Tenkanen_DESY17.pdf

17:13 Probing inflationary primordial black holes for the LIGO gravitational wave events

Primordial black holes (PBHs) are one of the candidates to explain the gravitational wave (GW) signals observed by the LIGO detectors. Among several phenomena in the early Universe, cosmic inflation is a major example to generate PBHs. In this case, the primordial curvature perturbation should be large enough to generate a sizable amount of PBHs, and thus we have several other probes to test this scenario. We point out that the current pulsar timing array (PTA) experiments already put severe constraints on GWs generated via the second-order effects, and that the observation of the cosmic microwave background (CMB) offers tight bounds on its small-scale distortions, such as mu-distortion. In particular, for simple inflation models, it is found that the scalar power spectrum should have a sharp peak at k ~ 10^6 Mpc^-1 to fulfill the required abundance of PBHs while evading constraints from the PTA experiments and the mu-distortion.

Speaker: Dr Kyohei Mukaida (Kavli IPMU)

Slides pbh.pdf

17:30 Primordial Black Holes and Gravitational waves from Axion Inflation

In my talk I discuss the phenomenology of models in which a pseudoscalar inflaton is coupled to some abelian gauge fields. The coupling between the inflaton and the gauge fields induces an instability in the theory which gives rise to a wide range of potentially observable signatures. In particular, I focus on the possibility of generating chiral gravitational waves in the range of direct gravitational wave detectors and primordial black holes which can account for a part (or all) of the dark matter observed in the Universe. The results of this analysis can be used to extract information on the microphysics of inflation.

Speaker: Dr Mauro Pieroni (Instituto de Fisica Teorica)

Slides Slides.pdf

17:48 Primordial Black-Holes from Critical Higgs Inflation

The question of the origin of the dark matter (DM) remains as one of the most fundamental mysteries of modern physics. LIGO detections may be the first observations of a large population of primordial black-holes (PBHs) that could constitute today the dominant component of the DM. These PBHs arise naturally in models of Critical Higgs Inflation (CHI), where there is a peak in the spectrum associated to the near-critical value of the running of both the Higgs self-coupling and its non-minimal coupling to gravity. The CMB spectrum at large scales of this model is in agreement with Planck-2015 data, with a relatively large tensor-to-scalar ratio that may be detected soon with B-mode polarization experiments. Moreover, it predicts a broad lognormal PBH mass distribution that is consistent with the present constraints on PBH. The stochastic background of gravitational waves coming from the unresolved black-hole-binary mergings could be detected by LISA or PTA. The PBH-CHI scenario opens a new portal to test fundamental physics above the LHC scale.

Speaker: Jose María Ezquiaga (Instituto de Física Teórica UAM-CSIC)

Slides DESY17_Ezquiaga.pdf

16:05 → 18:05 Parallel Session: Particle Phenomenology 1b

Convener: Daniel Dercks

16:05 B-physics anomalies

Several deviations from Standard Model expectations have been observed in decays of B mesons in recent years, including hints for violation of lepton flavour universality in b->c and b->s transitions and deviations in branching ratios and angular observables in exclusive semileptonic rare decays. While these "anomalies" could be explained by a combination of statistical fluctuations in some observables and underestimated hardonic uncertainties in others, they can also be consistently explained in terms of physics beyond the Standard Model. This talk will discuss the status of these deviations and possible new physics models explaining them.

Speaker: Dr David Straub (TUM)

16:22 Low scale neutrino mass models from High scale

Neutrino masses generated by physics around the weak-scale offer the advantage of testability, however from the model-building viewpoint they appear to be ad-hoc. I will present two classes of models which predict a radiative seesaw formula for neutrino masses and the presence of weakly interacting stable dark matter from (non-supersymmetric) SO(10) Grand Unified Theories. The model achieves precision unification and offers experimental tests.

Speaker: Dr Sofiane Boucenna (KTH Royal Institute of Technology)

16:39 The ALP miracle: unified inflaton and dark matter

We propose a scenario where both inflation and dark matter are described by a single axion-like particle (ALP) in a unified manner. In a class of the minimal axion hilltop inflation, the effective masses at the maximum and minimum of the potential have equal magnitude but opposite sign, so that the ALP inflaton is light both during inflation and in the true vacuum. After inflation, most of the ALPs decay and evaporate into plasma through a coupling to photons, and the remaining ones become dark matter. We find that the observed CMB and matter power spectrum as well as the dark matter abundance point to an ALP of mass mφ = O(0.01)-O(0.1)eV and the axion-photon coupling gφγγ = O(10^{−11})GeV^{−1}: the ALP miracle. The suggested parameter region is within the reach of the next generation axion helioscope, IAXO, and high-intensity laser experiments in the future. Furthermore, thermalized ALPs contribute to hot dark matter and its abundance is given in terms of the effective number of extra neutrino species, ∆Neff ≃ 0.03, which can be tested by the future CMB and BAO observations.

Speaker: Dr Wen Yin (IHEP in Chinese Academy of Sciences)

Slides DESY_WEN_YIN5.key DESY_WEN_YIN5.pdf

16:56 Realizing the relaxion mechanism with particle production

In this talk I will analyze realizations of the relaxion mechanism in which quantum excitations of an auxiliary field slow down the relaxion and fix the Higgs vev at the electro-weak scale.

Speaker: Enrico Morgante (DESY)

17:13 Warped Relaxion

The relaxion idea is a new alternative to justify the smallness of the Higgs mass. In this framework, the effective Higgs mass is scanned by a scalar field (the relaxion) starting at some large value which slowly decreases during inflation. We propose a UV completion for this mechanism in the context of warped extra dimension scenarios. In our construction, the warp factor can naturally explain the large hierarchy between the decay constants in the relaxion potential.

Speaker: Nayara Fonseca (DESY)

17:30 The Dark Sequential Z' portal: Collider and Direct Detection Experiments

We revisit the status of a Majorana fermion as a dark matter candidate, when a sequential Z' gauge boson dictates the dark matter phenomenology. Direct dark matter detection signatures rise from dark matter-nucleus scatterings at bubble chamber and liquid xenon detectors, and from the flux of neutrinos from the Sun measured by the IceCube experiment, which is governed by the spin-dependent dark matter-nucleus scattering. On the collider side, LHC searches for dilepton and mono-jet + missing energy signals play an important role. The relic density and perturbativity requirements are also addressed. By exploiting the dark matter complementarity we outline the region of parameter space where one can successfully have a Majorana dark matter particle in light of current and planned experimental sensitivities.

Speaker: Mr Miguel Campos (Max-Planck-Institut für Kernphysik)

Slides DarkSequential_Campos_Final.pdf

16:05 → 18:05 Parallel Session: String & Mathematical Physics

Convener: Valentina Forini

16:05 A complexity/fidelity susceptibility g-theorem for AdS3/BCFT2

I use a recently proposed holographic Kondo model as a well-understood example of AdS/boundary CFT (BCFT) duality and show explicitly that in this model the bulk volume decreases along the RG flow. I then obtain a proof that this volume loss is indeed a generic feature of AdS/BCFT models of the type proposed by Takayanagi in 2011. According to recent proposals holographically relating bulk volume to such quantities as complexity or fidelity susceptibility in the dual field theory, this suggests the existence of a complexity or fidelity susceptibility analogue of the Affleck-Ludwig g-theorem, which famously states the decrease of boundary entropy along the RG flow of a BCFT.

Speaker: Mario Flory (MPI Munich & Jagellonian Univ.)

Slides 1._Flory.pdf

16:25 Holographic lattice field theories

Recent developments in tensor network models (which are, roughly speaking, quantum circuits designed to produce analogues of the ground state in a conformal field theory) have led to speculation that such networks provide a natural discretization of the AdS/CFT correspondence. This raises many questions: just to begin, is there any sort of lattice field theory model underlying this connection? And how much of the usual AdS/CFT dictionary really makes sense in a discrete setting? I'll give a brief overview of some recent work that proposes a setting in which such questions can perhaps be addressed: a discrete spacetime whose bulk isometries nevertheless match its boundary conformal symmetries. Many of the first steps in the AdS/CFT dictionary carry over without much alteration to lattice field theories in this background, and one can even consider natural analogues of BTZ black hole geometries.

Speaker: Ingmar Saberi (Univ. Heidelberg)

Slides 2._Saberi.pdf

16:45 Circuit complexity in QFT

Motivated by recent studies of holographic complexity, we examine the question of circuit complexity in quantum field theory. We provide a quantum circuit model for the preparation of Gaussian states, in particular the ground state, in a free scalar field theory for general dimensions. Applying the geometric approach of Nielsen to this quantum circuit model, the complexity of the state becomes the length of the shortest geodesic in the space of circuits. We compare the complexity of the ground state of the free scalar field to the analogous results from holographic complexity, and find some surprising similarities.

Speaker: Ro Jefferson (AEI Golm)

Slides 3._Jefferson.pdf

17:05 Gaugino Condensation and Holomorphic BF Theory

Pure N = 1 supersymmetric gauge theory with a simple gauge group G is widely believed to have k massive vacua, where k is the dual Coxeter number of the Lie algebra corresponding to G. The vacua are distinguished by the phase of the gaugino condensate. The appearance of the dual Coxeter number is a hint of the role of affine Lie algebras. A holomorphic twist of pure N = 1 gauge theory is known to be equivalent to holomorphic BF theory. It is natural to wonder if the perturbative physics of holomorphic BF theory has any relation to the non-perturbative dynamics of the full physical theory. We study the classical spectrum of local observables in holomorphic BF theory and find that an index cons! tructed out of the local operators can be expressed in terms of the orbits of an affine Weyl group corresponding to G. The index can also be expressed as quotients of Dedekind's eta-function and in the case of E_8 it is intricately connected with Monstrous Moonshine.

Speaker: Richard Eager (Univ. Heidelberg)

Slides 4._Eager.pdf

17:25 The toric SO(10) F-theory landscape (part I)

We will discuss a full classification of toric F-theory models with gauge group SO(10) in six dimensions and a subclass of models that might lead to interesting phenomenological applications within 6d flux compactifications.

Speaker: Markus Dierigl (DESY)

Slides 5._Dierigl.pdf

17:45 The toric SO(10) F-theory landscape (part II)

We present a full classification of SO(10) theories that can be represented as a toric hypersurface. These models generically exhibit additional Abelian, non-Abelian and discrete symmetries that can be used for phenomenological applications. We compute all charges and 6D multiplicities as well as anomaly coefficients base independently. These theories have a rich structure, such as non-Kodaira Fibers in codimension three as well as connections via higgsings and superconformal matter transitions.

Speaker: Paul Oehlmann (DESY)

Slides 6._Oehlmann.pdf

16:05 → 18:05 Parallel Sessions: Cosmology & Astroparticle Physics - Inflation + Gws

Conveners: Chiara Caprini, Valerie Domcke

16:05 Quantum corrections to conformally coupled scalars

I will discuss quantum corrections during inflation in general. And in particular, I will talk about our recent work on the one loop order corrections  of gravitons to scalar mode functions which is conformally coupled to gravity.

Speaker: Ms SİBEL BORAN (Istanbul Technical University)

Slides sibelboran_DESY_cosmo_workshop_17.pdf

16:22 Constraining warm inflation from the Planck data

The dissipative mechanism in warm inflation scenario can provide the inflating universe with a warm exit to the radiation dominated era rather than a supercooled exit to a reheating phase. In this work, we constrain the model parameters for warm inflation from Planck 2015 data. In addition, the reheating era can be optimized by varying the number of $e$-folds of inflation. Best fit values for the model parameters are estimated with and without the contribution to fluctuation from thermal excitations.

Speaker: Ms Sukannya Bhattacharya (Saha Institute of Nuclear Physics)

Slides desy_2809_sukannya.pdf

16:39 Dealing with axion monodromy and other oscillating inflationary models

Despite the increasingly more precise constraints on the amplitude and tilt of the primordial power spectrum, the shape of the inflaton potential is still largely unconstrained. This allows for potentials with oscillating contributions, such as the string theory motivated axion monodromy inflation. However, dealing with these models is computationally expensive, and as such analytical approximations are generally used. In this talk I will discuss the first fully numerical treatment of axion monodromy inflation using the Boltzmann code CLASS, emphasising the noticeable differences with the analytical methods, as well as presenting the most recent constraints for this model obtained with the Planck data.

Speaker: Ms Deanna C. Hooper (RWTH Aachen, TTK Institute)

Slides desy_0917.pdf

16:56 Testing Modified Gravity with Merging Neutron Stars

The recent first direct detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) has marked the dawn of a new era for probing the theory of general relativity (GR) as well as possible modifications of it. To test gravity at extreme conditions, current and future gravitational wave detectors are targeted to explore merging binary systems of black holes and/or neutron stars. Motivated by this, we study the final stages of evolution of a neutron star binary system and investigate how modifications of GR can effect the emitted gravitational wave signal. Already for the simplest $f(R)$ theory of modified gravity, $R^2$ gravity, we find characteristic features in the gravitational wave signal that make it clearly distinguishable from the one in GR and that should be detectable with LIGO.

Speaker: Dr Laura Sagunski (York University / Perimeter Institute)

Slides Talk_DESYTheoryWorkshop_2017.pdf

17:13 Damping of gravitational waves by matter

We develop a unified description via the Boltzmann equation, of damping of gravitational waves by matter incorporating collisions. We identify two physically distinct damping mechanisms -- collisional and Landau damping. Maximal collisional damping of a gravitational wave, independent of the details of the matter collisions is significant only when its wavelength is comparable to the size of the horizon. Thus damping by intergalactic or interstellar matter for all but primordial gravitational radiation can be neglected. Although collisions in matter lead to a shear viscosity, they also act to erase anisotropic stresses, thus suppressing the damping of gravitational waves. Damping of primordial gravitational waves remains possible. We generalize Weinberg's calculation of gravitational wave damping, now including collisions and particles of finite mass and interpret the collisionless limit in terms of Landau damping. We comment on the possible processing of primordial gravitational waves during matter domination in scenarios of ultra-light dark matter.

Speaker: Dr Subodh Patil (Niels Bohr Institute)

Slides Damping_of_gravitational_waves_by_matter.pdf

17:30 Effects of equation of state in the Standard Model on the primordial gravitational wave spectrum

The existence of relic gravitational waves (GWs) is one of the most important predictions of inflationary models, and the knowledge about their detailed spectrum will become indispensable in future direct detection experiments. In this work, we investigate thermodynamic properties of high temperature plasma composed of elementary particles of the Standard Model, and identify how such properties affect the spectrum of primordial GWs. The evolution of the equation of state of radiations with interacting particles is estimated based on the latest results of perturbative and non-perturbative calculations, and the effective degrees of freedom for the energy density and the entropy density as a function of temperature are obtained. After obtaining the effective degrees of freedom, we numerically compute the spectrum of GWs by taking account of the evolution of the Standard Model equation of state. It is shown that the spectrum of GWs at high frequencies is corrected due to the effect of particle interactions, and that such corrections are relevant to future high sensitivity experiments.

Speaker: Ken'ichi Saikawa (DESY)

Slides DESYworkshop2017.pdf

17:47 Gravitational Wave Oscillations in Bigravity

With the first detection of a gravitational wave signal in September 2015 by the LIGO collaboration, a new era in physics has begun. Gravitational wave astronomy allows us to probe the contents and properties of our Universe in a completely new manner, accessing so far inaccessible scales and phenomena. In this talk I will present one such phenomenon, dubbed gravitational wave oscillations, which, in full analogy to neutrino oscillations, arises in theories of multi-metric gravity, where the matter and propagation bases do not coincide. It is illustrated how the presence of more than one tensor field modifies the wave form observed in a detector on the Earth and how this can be used to put constraints on the parameter space of the model.

Speaker: Mr Moritz Platscher (Max-Planck-Institut fuer Kernphysik)

Slides Platscher_DESY_2017.pdf

Friday 29 September

09:00 → 11:00 Plenary Session

Convener: Bruce Allen

09:00 Current experimental limits on gravity waves

Speaker: Nelson Christensen

Slides DESY_NC_2017.pdf

Video http://webcast.desy.de/?p=7826

09:40 Astrophysical sources of GWs and future prospects for their detection

Speaker: Ilya Mandel

Slides Mandel-GWsources20170929.pdf

Video http://webcast.desy.de/?p=7826

10:20 EFT approach to gravitational radiation by astrophysical sources

Speaker: Rafael Porto

Slides RPorto_DESY.pdf

Video http://webcast.desy.de/?p=7834

11:00 → 11:30 Coffee break

11:30 → 12:40 Plenary Session

Conveners: Alexander Westphal, Geraldine Servant, Julien Lesgourgues

11:30 Cosmology with the LISA interferometer

Speaker: Chiara Caprini (APC Paris)

Slides caprini_DESY_2017.pdf

Video http://webcast.desy.de/?p=7837

12:05 News ideas on inflation

Speaker: Arthur Hebecker

Slides Hebecker_DESY_2017.pdf

Video http://webcast.desy.de/?p=7824