Theorie Palaver

Programm für das Sommersemester 2023

Tuesdays, 14:00 Uhr s.t.

Institut für Physik

Lorentz room (Staudingerweg 7, 5th floor)
18.04.23Anna Socha, Warsaw U.
According to the standard model of cosmology, the Universe at its very beginning underwent a phase of rapid expansion, followed by a reheating period. During this epoch, the energy density, initially accumulated in the coherent oscillations of the inflaton field, was injected into the visible sector, eventually setting the initial conditions for the hot Big Bang. In this talk, I will discuss perturbative production of the Standard Model (SM) particles adopting a non-standard post-inflationary scenario with a generic equation-of-state parameter \(\bar{w}\). To specify the inflaton dynamics, I will employ the \(\alpha\)-attractor T-model of inflation, such that \(\phi\) has a monomial potential \(V(\phi) \propto \phi^{2n}\) about the minimum. Moreover, I will explore the Higgs boson-induced reheating, assuming that it is achieved through a cubic inflaton-Higgs coupling \(\phi |\mathcal{H}|^2\). In the presence of such interaction, the Higgs field acquires a \(\phi\)-dependent mass which generates a vacuum expectation value that oscillates in time and breaks the electroweak gauge symmetry. Interestingly, the non-zero Higgs mass leads to a time-dependent inflaton decay rate and generates a phase-space suppression of the reheating efficiency. This, in turn, has non-trivial consequences for the reheating dynamics, modifying the evolution of the SM radiation energy density or the duration of the reheating phase. Furthermore, the implications of the non-standard reheating for the dark sector will be discussed, exemplified by the UV freeze-in dark matter model.
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

25.04.23Fabrizio Rompineve, CERN
A population of relativistic QCD axions can be produced in the early Universe, via scatterings with Standard Model particles. This can be searched for in cosmological datasets, which therefore provide the opportunity to discover/constrain the QCD axion, independently of astrophysical and/or laboratory probes. In this talk, after reviewing the subject, I present an improved calculation of the relic abundance of such “hot” axions from scatterings with pions below the QCD crossover, as well as the resulting upper bound on the QCD axion mass. I then discuss the exciting outlook of upcoming cosmological surveys, which may probe otherwise unexplored regions of the QCD axion parameter space. I highlight the need of a non-perturbative calculation of axion production rates throughout the QCD crossover, to fully exploit the reach of such datasets.
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

02.05.23Jose Zurita, IFIC Valencia
In the last years there has been a renewed interest in the particle physics theoretical and experimental communities on the study of exotic (non-standard) signatures at colliders, including Long-Lived Particles (LLPs). In this talk I will first give a brief overview of the theoretical motivations for long-lived particles. Later I will illustrate the impact of LLPs in the current LHC physics programme, including new LHC detectors specifically hunting for LLPs (MoEDAL, FASER, SND@LHC), detector proposals under consideration (MATHUSLA, ANUBIS, FPF) and relevant upgrades to the ATLAS, CMS and LHCb experiments. Finally, I will present snapshots of novel signatures and the implications of LLP searches in the context of neutrino, axion, dark matter and Higgs physics.
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

16.05.23Anne Spiering, Bohr Inst
The direct integration of Feynman integrals can be a daunting task, in particular for increasing numbers of loops and external particles. The “symbol bootstrap” has proven to be a powerful tool in the calculation of certain polylogarithmic Feynman integrals and scattering amplitudes that bypasses this direct integration. In this approach one first writes an ansatz for the symbol of the integral and then fixes its degrees of freedom by imposing known mathematical and physical properties of the final result. In this talk I will discuss a generalisation of this approach to an elliptic case: the 12-point two-loop double-box integral. The bootstrapping ansatz is obtained from an elliptic generalisation of the so-called Schubert problem, and after imposing a sufficient number of constraints on this ansatz, we obtain a compact one-line formula for the (2,2)-coproduct of the double-box integral.
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

23.05.23Felipe Llanes Estrada, Madrid U.
The Electroweak Symmetry Breaking Sector of the Standard Model is an active field where new physics is sought. In the absence of new higher-energy particles at colliders, Effective Field Theories in terms of the Standard Model particles (longitudinal gauge and Higgs bosons) seem a natural tool. New physics could then manifest itself as new forces modifying the couplings of those particles. Should such new forces be found, they could be used to confront (falsify?) the popular SMEFT: as it is not the most general possible EFT, we have managed to produce correlations among the parameters of the embedding HEFT that can be tested if that new physics is describable by SMEFT. We have also extended HEFT via the Inverse Amplitude Method to be able to address resonances in the electroweak sector directly from the low-energy particles and eventual BSM couplings, thus maintaining agnosticism about the nature of the eventual new physics, and I will discuss the systematic uncertainties of the unitarization procedure. Based on various works, e.g. https://inspirehep.net/literature/2120028 https://inspirehep.net/literature/2154526 https://inspirehep.net/literature/1826204 https://inspirehep.net/literature/1345172 https://inspirehep.net/literature/1310013
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

30.05.23Christian Ecker, Frankfurt U.
According to the inflationary theory of cosmology, most elementary particles in the current universe were created during a period of reheating after inflation. In this talk I will show how to self-consistently couple the Einstein-inflaton equations to a strongly coupled quantum field theory (QFT) that is described by holography. I will then use a specific example to demonstrate that this setup leads to an inflating universe, a reheating phase and finally a universe dominated by the QFT in thermal equilibrium. This talk is based on arXiv:2302.06618.
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

aktuell

06.06.23Bibhushan Shakya, DESY

The Tachyonic Higgs and the Inflationary Universe 

The Standard Model Higgs becomes tachyonic at high energy scales according to current measurements. This unstable regime of the Higgs potential can be realized in the early Universe during high scale inflation, potentially with catastrophic consequences. In this talk, we will discuss a crucial inherent feature of such configurations that has so far remained ignored: Higgs particle production out of vacuum induced by the rapidly evolving Higgs field, which gets exponentially enhanced due to the tachyonic instability. We will discuss various theoretical and observational implications of this effect.
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

zukünftige Termine
13.06.23Thomas Thiemann, Erlangen Nürnberg
TBA
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

20.06.23Thomas Becher, Bern
TBA
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

04.07.23Pouria Mazloumi, MPP Munich
TBA
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

25.07.23Tin Sulejmanpasic, Durham U.
TBA
14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Koordination: Kontakt:

Dr. Anke Biekötter

Dr. Philipp Böer

biekoetter@uni-mainz.de

pboeer@uni-mainz.de