Upcoming Seminars

Date/Place Feb. 9 (Fri.) (Informal) 13:00-14:00 / H711
Name Cheng-Wei Chiang (NTU)
Title Georgi-Machacek Model beyond tree level
Abstract We calculate 1-loop radiative corrections to the hZZ and hWW couplings in models with next-to-simplest Higgs sectors satisfying the electroweak ρ parameter equal to 1 at tree level: the real Higgs singlet model, the two-Higgs doublet models, and the Georgi?Machacek model. Under theoretical and current experimental constraints, the three models have different correlations between the deviations in the hZZ and hWW couplings from the standard model predictions. In particular, we find for each model predictions with no overlap with the other two models. We also update with some preliminary results of hff and hhh couplings at one loop.

 

Date/Place Feb. 20 (Tues.) (Informal) 15:30-16:30 / H711
Name Yuta Hamada (U. of Wisconsin, KEK)
Title An infinite set of soft theorems in gauge/gravity theories as Ward-Takahashi identities
Abstract We show that the soft photon, gluon and graviton theorems can be understood as the Ward- Takahashi identities of large gauge transformation, i.e., diffeomorphism that does not fall off at spatial infinity. We found infinitely many new identities which constrain the higher order soft behavior of the gauge bosons and gravitons in scattering amplitudes of gauge and gravity theories.

 

Date/Place Feb. 21 (Wed.) (Informal) 15:00-16:00 / H711
Name Chiara Arina (UC Louvain)
Title Comprehensive studies of dark matter simplified models
Abstract Studies of dark matter lie at the interface of collider physics, astrophysics and cosmology. Constraining models featuring dark matter candidates entails the capability to provide accurate predictions for large sets of observables and compare them to a wide spectrum of data. In this talk, I will present a new framework which, starting from a model lagrangian, allows one to consistently and systematically make predictions, as well as to confront those predictions with a multitude of experimental results. This numerical tool is provided by MadDM v.3.0, a plugin of the known MadGraph platform, which will be soon publicly available. As example applications, I will show the global analyses performed for simplified dark matter models. I will focus particularly on the case of a scalar/pseudoscalar mediator coupling to quark and a fermionic dark sector. I will show the complementarity of relic density, direct/indirect detection and collider searches in constraining the multi-dimensional model parameter space, and efficiently identify regions where individual approaches to dark matter detection provide the most stringent bounds. I will also show how this is achievable with the latest version of MadDM.

 

Date/Place Feb. 21 (Wed.) (Informal) 16:15-17:15 / H711
Name Sacha Davidson (Lyon)
Title Spin dependent mu-e conversion
Abstract Charged Lepton Flavour Violation is New Physics that must occur, because neutrinos have masses and mixing angles. In many cases, it can be parametrised at low energy by contact interactions. I focus on the process of mu->e conversion in nuclei, because its experimental sensitivity should improve by 4-6 orders of magnitude in coming years. The nuclear physics of this process is similar to WIMP scattering: previous calculations of mu-e conversion focused on the (coherent, A^2 enhanced) spin-independent contribution; I will introduce the spin-dependent process, which depends on different operator coefficients, and explore the prospects for distinguishing coefficients (or models) by using different targets.

 

Date/Place March 1st (Thu.) (Informal) 15:30-16:30 / H711
Name Shimada Kengo (EPFL)
Title Cosmological implications of quantum scale invariance
Abstract We study cosmology in scale invariant models with renormalization prescription preserving the scale invariance even at quantum level. Such models are known to be non-renormalizable and hence interpreted as effective field theory. The associated cut-off scale is evaluated and we argue that it can be high enough to justify the usual perturbative computation of effective potential. However the resultant potential is still scale invariant with some non-polynomial corrections. We apply it to a realistic model including the standard model fields and discuss how it impacts on the thermal history.

 

Past Seminars