Flavor anomalies in semileptonic b-> c ell nu transition: a detailed study in the Covariant Confined Quark Model

Il 21 Novembre 2019, alle 16 in aula multimediale, il dr. Chien-Thang Tran, dell' Universita di Napoli Federico II e INFN Sezione di Napoli, terra' il seminario:  "Flavor anomalies in semileptonic b -> c ell nu transition: a detailed study in the Covariant Confined Quark Model"ABSTRACT:In the Standard Model (SM), the three charged lepton generations($\ell=e,\mu,\tau$) together with their neutral and massless neutrinosinteract with the weak gauge bosons universally. This fundamental featureof the SM is called lepton flavor universality (LFU). Recent measurementsof semileptonic decays of $B$ mesons have shown some deviations from LFU.If the observed anomalies would be confirmed in the future experiments,they will open a new window in the search for New Physics (NP) beyond the SM.There are many theoretical studies in which different scenarios for theimplementation of NP are considered: some extend the SM by introducing newparticles and new interactions; other adopt a model-independent approach byadding a set of NP operators to the effective Hamiltonian describing the$b\to c\ell\nu$ transition. In the second approach, the NP contributions areeffectively encoded in the new Wilson coefficients which are determined byfitting available experimental data. Once these coefficients are obtained,one can analyze the effects of the NP operators on the physical observables.Such analysis can help to probe NP in future experiments. In recent years,my colleagues and I have obtained several interesting results following thisapproach. In this talk, I will share with you some of these interesting findings.It is also important to note that in the study of these decays, one has totake good care of nonperturbative effects in the corresponding hadronic$H_b\to H_c$ transitions, which most often are evaluated using methods ofheavy quark effective theory. In our studies, we used instead the CovariantConfined Quark Model, which previously developed by ourselves, for hadroniccalculations. Therefore, I will also briefly discuss our model in the talk.