Munich Theory Retreat

Feb 22, 2025, 6:00 AM → Feb 26, 2025, 10:00 PM Europe/Berlin

Bad Hofgastein, Austria

Andreas Weiler (TU Munich), Dominik Haslehner (TUM, MPP), Michael Stadlbauer (MPP/TUM)

Sat, February 22

9:00 AM → 12:00 PM Arival and Registration

12:00 PM → 1:00 PM Seminar Talk

3:00 PM → 4:00 PM Minimal EW Baryogenesis with Domain Walls

The Standard Model extended by a real scalar singlet S with an approximate ℤ2 symmetry offers a minimal framework for realizing electroweak baryogenesis (EWBG) during a first-order electroweak phase transition. In this work, we explore a novel mechanism where spontaneous ℤ2 breaking enables EWBG via domain walls separating two distinct phases of the S field. These domain walls feature restored (or weakly broken) EW symmetry in their cores and sweep through space, generating the baryon asymmetry below the temperature of EW symmetry breaking. We identify the key conditions for the existence of EW-symmetric domain wall cores and analyze the dynamics required for wall propagation over sufficient spatial volumes. Additionally, we outline the CP-violating sources necessary for baryogenesis under different regimes of domain wall evolution. The parameter space accommodating this mechanism spans singlet masses from sub-eV to 15 GeV, accompanied by a non-vanishing mixing with the Higgs boson. Unlike the standard realization of EWBG in the minimal singlet-extended SM, which is notoriously difficult to test, our scenario can be probed by a wide range of existing and upcoming experiments, including fifth force searches, rare meson decays, and EDM measurements.

Speaker: Jacopo Azzola (TUM)

RetreatTalk30.pdf

4:00 PM → 5:00 PM Constraining light QCD axions with isolated neutron star cooling

The existence of light QCD axions, whose mass depends on an additional free parameter, can lead to a new ground state of matter, where the sourced axion field reduces the nucleon effective mass.
The presence of the axion field has structural consequences, in particular, it results in a thinner (or even prevents its existence) heat-blanketing envelope, significantly altering the cooling patterns of neutron stars. We exploit the anomalous cooling behavior to constrain previously uncharted regions of the axion parameter space by comparing model predictions with existing data from isolated neutron stars. Notably, this
analysis does not require the light QCD axion to be the dark matter candidate.

Speaker: Kai Bartnick (TUM)

KB_WDandNS_LaboratoriesForNP_BadHofgastein_25.pdf

5:30 PM → 6:00 PM Introduction

6:00 PM → 8:00 PM Dinner

8:00 PM → 10:00 PM Discussion Session

Sun, February 23

7:00 AM → 9:00 AM Breakfast

9:00 AM → 10:00 AM Constraining Higher Spin Particles Using Torsion Balance Experiments and Causality

TBA

Speaker: Elena Kaiser (TUM)

Bad Hofgastein_ Higher Spin Particles.pdf

10:00 AM → 11:00 AM Cosmological archaeology using neutrino isocurvature

I will discuss a more general initial condition for neutrino density isocurvature than previously considered and point out how the new free parameter, the correlation with the matter isocurvature, would allow one to discriminate various cosmological histories in case of detection of isocurvature.

Speaker: Wolfram Ratzinger

11:00 AM → 12:00 PM Minimal Electroweak Baryogenesis: from Elementary to Composite

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Speaker: Oleksii Matsedonskyi (TUM)

12:00 PM → 2:00 PM Lunch

2:00 PM → 6:00 PM Group Activity

6:00 PM → 8:00 PM Dinner

8:00 PM → 10:00 PM Discussion Session

Mon, February 24

7:00 AM → 9:00 AM Breakfast

9:00 AM → 10:00 AM Non-renormalization theorems from conformal-helicity-duality

TBA

Speaker: Michael Stadlbauer (MPP/TUM)

Talk-Gastein-2.pdf

10:00 AM → 11:00 AM Matter matters for axion dark matter matters in matter

In this talk I investigate the implications of matter effects to searches for axion Dark Matter on Earth. The finite momentum of axion Dark Matter is crucial to elucidating the effects of Earth on both the axion Dark Matter field value and its gradient. I find that experiments targeting axion couplings compatible with canonical solutions of the strong CP puzzle are likely not affected by Earth’s matter effects. However, experiments sensitive to lighter axions with stronger couplings can be significantly affected, with a significant part of the parameter space suffering from a reduced axion field value, and therefore decreased experimental sensitivity. In contrast, the spatial gradient of the axion field can be enhanced along Earth’s radial direction, with important implications for ongoing and planned experiments searching for axion Dark Matter.

Speaker: Konstantin Springmann (WIS)

11:00 AM → 12:00 PM Tolerable Inhomogeneities during BBN

In this talk I explain the implications of precision measurement of light abundances in concordance with the Cosmic Microwave Background for different scenarios of BSM physics. I show that they impose strong constraints on any mechanism that generates inhomogeneities in baryons happening at temperatures of the order or below a TeV. This readily rules out some of the proposed mechanisms of baryogenesis in the literature. I briefly discuss the implications for the electroweak baryogenesis, the GW signal from the electroweak phase transition, as well as the PTA measured GW signal, and how they are probed by precision big bang nucleosynthesis. I also discuss the future prospects of improvements in this probe.

Speaker: Stefan Stelzl (TUM Munich)

12:00 PM → 2:00 PM Lunch

2:00 PM → 6:00 PM Group Activity

6:00 PM → 8:00 PM Dinner

8:00 PM → 10:00 PM Discussion Session

Tue, February 25

7:00 AM → 9:00 AM Breakfast

9:00 AM → 10:00 AM Seminar Talk

10:00 AM → 11:00 AM Seminar Talk

11:00 AM → 12:00 PM Seminar Talk

12:00 PM → 2:00 PM Lunch

2:00 PM → 6:00 PM Group Activity

6:00 PM → 8:00 PM Dinner

8:00 PM → 10:00 PM Discussion Session

Wed, February 26

7:00 AM → 9:00 AM Breakfast

9:00 AM → 10:00 AM Seminar Talk

10:00 AM → 11:00 AM Seminar Talk

11:00 AM → 12:00 PM Seminar Talk

12:00 PM → 2:00 PM Lunch

2:00 PM → 5:00 PM Closing