# Theorie Palaver

## Programm für das Sommersemester 2020

### Tuesdays, 14:30 Uhr s.t.

##### Institut für PhysikMITP seminar room
 21.04.20 Michele Redi, Florence U. and INFN I will describe the conditions under which the Peccei-Quinn phase transition of the QCD axion is first order. I will then show that in approximately conformal scenarios, both at weak and strong coupling, the PQ phase transition can lead to a gravity wave background that is within the reach of Ligo or future ground based experiments. 14:30 Uhr s.t., at Zoom
 05.05.20 Filippo Sala, CNRS Paris Jussieu Sub-GeV Dark Matter particles upscattered by cosmic rays gain enough kinetic energy to pass the thresholds of large volume detectors on Earth. I will show how public Super-Kamiokande and MiniBooNE data already exclude previously allowed regions of both DM-electron and DM-nucleon interactions. I will then discuss search strategies and prospects at existing and planned neutrino facilities, such as Hyper-K, DUNE, IceCube and KM3NeT. 14:30 Uhr s.t., at Zoom
 19.05.20 Alexander Ochirov, ETH Zurich In view of the recent observations of gravitational-wave signals from black-hole mergers, classical black-hole scattering has received considerable interest due to its relation to the classical bound-state problem of two black holes inspiraling onto each other. In this talk I will discuss the link between classical scattering of spinning black holes and quantum scattering amplitudes for massive spin-s particles. Starting at first post-Minkowskian (PM) order, I will explain how the spin-exponentiated structure of the relevant tree-level amplitude follows from minimal coupling to Einstein's gravity and in the $$s \rightarrow \infty$$ limit generates the black holes' complete series of spin-induced multipoles. The resulting scattering function will be shown to encode in a simple way the known net changes in the black-hole momenta and spins at 1PM order and to all orders in spins. Then I will move on to the new results at 2PM order for the case of aligned black holes' spins and discuss the current state of the art for classical black-hole scattering. 14:30 Uhr s.t., at Zoom
 09.06.20 Elina Fuchs, Chicago U. & Fermilab Complex Yukawa couplings of the Higgs boson have interesting implications for Higgs production and decay rates, EDMs and CP violation for electroweak baryogenesis. I will present if there are viable regions fulfilling all of these three complementary constraints, for real and imaginary dimension-six terms of the tau, muon, top and bottom. After considering each flavor separately, I will show that combinations of several sources allow for cancellations in the EDM and an enhancement of the baryon asymmetry. 15:00 Uhr s.t., at Zoom
 16.06.20 Gustavo Marques Tavares, Johns Hopkins U. In this talk I will discuss the effects of single derivative mixing in massive bosonic fields. In the regime of large mixing this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing the effects of friction due to Hubble expansion. I will discuss how this can change the cosmological evolution of the axion field in the presence of primordial magnetic fields, and show that this increases the axion abundance allowing heavier axions to make up all of dark matter. 14:30 Uhr s.t., at Zoom
 30.06.20 Matheus Hostert, University of Minnesota In light of the recent experimental progress in the study of neutral and charged kaon decays, I will discuss how $K_L$ decays can offer a strong probe of dark sectors, independently from the decays of their charged partner. This is motivated by a recent excess in $K_L \to \pi^0 \nu\overline{\nu}$ reported by the KOTO experiment, which, if confirmed, would indicate the existence of light or new exotic particles. The models I discuss can easily accommodate such signatures, with some examples containing a dark matter candidate. 14:30 Uhr s.t., at Zoom
 07.07.20 Yann Gouttenoire, DESY Cosmic strings (CS) are topological defects formed after spontaneous breaking of a U(1) symmetry. Remarkably, thanks to the scaling regime, CS loops constitute a long-standing source of Gravitational Waves (GW) and produce a flat GW spectrum during radiation domination, spanning many orders of magnitude in frequency. I will discuss reasons to be excited about the possible future detection of GW from CS by the next generation of GW interferometers, in order to bring light on the existence of non-standard cosmology before Big-Bang Nucleosynthesis starts and the related Beyond-Standard-Model physics. I will discuss the possibility to probe superstring theories with moduli scale up to 10^{10} GeV, heavy dark photon with kinetic mixing as low as 10^{-18}, heavy ALPs with masses between 1 GeV and 10^{10} GeV or PBHs below 10^9 grams. 14:30 Uhr s.t., at Zoom
 Koordination: Kontakt: Dr. Enrico Morgante emorgant@uni-mainz.de