Programm für das Wintersemester 2020/2021
Tuesdays, 14:30 Uhr s.t.
Institut für Physik
live at Zoom
10.11.20  Javier FuentesMartin, JGU Mainz  
In this talk, I will present a model for thirdfamily quarklepton unification at the TeV scale featuring a composite Higgs sector. The model is based on a variant of the PatiSalam model, the socalled 4321 model. The spontaneous symmetry breaking to the SM gauge group is triggered dynamically by a QCDlike confining sector. The same strong dynamics also produces a pseudo NambuGoldstone boson Higgs, connecting the energy scales of both sectors. The model predicts a massive U1 vector leptoquark coupled dominantly to the third generation, recently put forward as a possible solution to the Bmeson anomalies.  
14:30 Uhr s.t., at Zoom  

17.11.20  Ana Peñuelas, JGU Mainz  
We perform a general modelindependent analysis of \(b \to c \tau \bar{\nu}_\tau\) transitions, including measurements of \(\mathcal{R}_D\), \(\mathcal{R}_{D^*}\), their \(q^2\) differential distributions, the longitudinal \(D^*\) polarization \(F_L^{D^*}\), and constraints from the \(B_c \to \tau \bar{\nu}_\tau\) lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective lowenergy Hamiltonian is presented working with a minimal set of assumptions: new physics is present only in the third generation of leptons, there are not light righthanded neutrinos, the electroweak symmetry breaking is linearly realized and the CPconserving limit is taken. The solutions of the fit are interpreted in terms of hypothetical newphysics mediators.
The impact of \(F_L^{D^*}\), measured by Belle last year is studied in detail. The difficulty to accommodate this measurement motivates the relaxation of some of our assumptions so the impact of a nonlinear electroweak symmetry breaking and the addition of light righthanded neutrinos is studied.
From the obtained results we predict selected \(b \to c\tau\bar\nu_\tau\) observables, such as the baryonic transition \(\Lambda_b \to \Lambda_c \tau \bar{\nu}_\tau\), the forwardbackward asymmetries \(\mathcal{A}_\text{FB}^{D^{(*)}}\), the \(\tau\) polarization asymmetries \(\mathcal{P}_\tau^{D^{(*)}}\), the longitudinal \(D^*\) polarization fraction \(F_L^{D^*}\) and several additional differential observables.  
14:30 Uhr s.t., at Zoom  

24.11.20  Davide Racco, Perimeter Institute  
The low frequency part of the gravitational wave spectrum generated by local physics, such as a phase transition, is largely fixed by causality, offering a clean window into the early Universe. Due to the difference between subhorizon and superhorizon physics, it is inevitable that there will be a distinct spectral feature that could allow for the direct measurement of the conformal Hubble rate at which the phase transition occurred.
As an example, freestreaming particles present during the phase transition affect the production of superhorizon modes. This leads to a steeper decrease in the spectrum at low frequencies as compared to the wellknown causal \(k^3\) superhorizon scaling of stochastic gravity waves. If a sizeable fraction of the energy density is in freestreaming particles, they even lead to the appearance of oscillatory features in the spectrum.
If the universe was not radiation dominated when the waves were generated, a similar feature also occurs at the transition between subhorizon to superhorizon causality. These features can be used to show surprising consequences, such as the fact that a period of matter domination following the production of gravity waves actually increases their power spectrum at low frequencies.  
14:30 Uhr s.t., at Zoom  

01.12.20  Saereh Najjari, JGU Mainz  
I will introduce a scenario where both the Higgs and a complex scalar dark matter candidate arise as the pNGB of breaking a global \(SO(7)\) symmetry to \(SO(6)\). In our construction the symmetry partners of the Standard Model topquark are charged under a hidden \(SU(3)_c\) color group. We show how the Large Hadron Collider along with current and next generation dark matter experiments will explore this framework.  
14:30 Uhr s.t., at Zoom  

08.12.20  Aldo Cotrone, Florence U. and INFN  
I will first review the basics of holography and some properties of the SakaiSugimoto model, the topdown holographic theory closest to QCD. Then, in this model I will describe the process of nucleation of bubbles of true vacua in the case of two firstorder transitions: the confinement/deconfinement and chiral symmetry breaking/restoration ones. Finally, using these information, I will present the calculation of the gravitational wave spectra generated in these transitions, when the SakaiSugimoto model is employed as a dark sector. Prospects of detection will be discussed.  
14:30 Uhr s.t., MITP seminar room, at Zoom  

11.12.20  Alexandros Papageorgiou, University of Minnesota  
Motivated by some of the recent swampland conjectures, we study a model of dark energy in which a quintessence axion slowly rolls in a steep potential due to its interactions with a U(1) or an SU(2) gauge field. We compare the differences between the U(1) and SU(2) cases and specify the parameter space for which the model is compatible with observations. We also apply our methodology to studying the transition between a preinflationary era and inflation and note some interesting oscillatory effects in the particle production parameter which could lead to interesting phenomenology. Finally we analyze the potential of the "Warm Dark Energy" model to produce gravitational waves observable by PTA, CMB polarization or spectral distortion experiments and find a negative result.  
15:30 Uhr s.t., MITP seminar room, at Zoom  

19.01.21  Danny van Dyk, TUM, Munich  
I will discuss theory predictions for exclusive b>s ll decays within the SM and beyond, with emphasis on the hadronic matrix elements. There are two categories of these matrix elements: local form factors, and nonlocal contributions arising from e.g. fourquark operators. I will report the status and report recent progress from QCDbased methods on the nonlocal hadronic matrix elements arising from intermediate charm states. A particular focus will be a recent derivation of a dispersive bound on the nonlocal matrix element as discussed in arXiv:2011.09813.  
14:30 Uhr s.t., at Zoom  

zukünftige Termine
26.01.21  Zhengkang (Kevin) Zhang, Caltech  
Matching a UV theory onto a lowenergy EFT can be efficiently accomplished with functional methods. The functional approach is conceptually appealing: all calculations are performed within the UV theory at the matching scale, and no prior determination of an EFT operator basis is required. In this talk, I will present a simple prescription for functional matching up to one loop order, which accommodates any relativistic UV theory that contains generic interactions among scalar, fermion and vector fields. I will also introduce STrEAM (SuperTrace Evaluation Automated for Matching), a Mathematica package that helps streamline the procedure.  
17:30 Uhr s.t., MITP seminar room, at Zoom  

02.02.21  Anders Eller Thomsen, University of Bern  
TBA  
14:30 Uhr s.t., at Zoom  

09.02.21  Riccardo Barbieri, SNS Pisa  
Motivated by the hierarchy problem and by the pattern of quark masses and mixings, I describe a picture of flavour physics that should give rise in a not too distant future to observable deviations from the SM in Higgs compositeness and/or in Bdecays (if LFV confirmed) or perhaps even in supersymmetry, depending on the specific realization.  
14:30 Uhr s.t., MITP seminar room, at Zoom  

16.02.21  Nick Evans, Southampton U.  
TBA  
14:30 Uhr s.t., MITP seminar room, at Zoom  

Koordination:  Kontakt: 
Dr. Enrico Morgante Dr. Javier FuentesMartin  emorgant@unimainz.de jfuentes@unimainz.de 