Searches for effects beyond the Standard Model in semileptonic decays of B mesons at LHCb

Stage numéro : Doctorat-1922-LH-01
Laboratoire :Centre de Physique des Particules de Marseille Case 902
 163 avenue de Luminy - 13288 Marseille Cedex 9
Directeur :Cristinel Diaconu - 04.91.82.72.01 - diaconu@cppm.in2p3.fr
Correspondant :William Gillard - 04.91.82.72.67 - gillard@cppm.in2p3.fr
Groupe d'accueil :LHCb
Chef de groupe :Olivier leroy - 04.91.82.76.05 - oleroy@cppm.in2p3.fr
Directeur de thèse :Anton Poluektov - 04.91.82.72.60 - poluektov@cppm.in2p3.fr

Thématique : Physique des particules

The Standard Model of particle physics, the theory that combines all the known fundamental forces of nature apart from gravity, has been so far very successful in describing all the present experimental data in particle physics. However, observations in cosmology, such as existence of Dark Matter or matter-antimatter asymmetry in the Universe, suggest that the Standard Model is not yet complete.

Hints on violation of lepton flavour universality seen in the studies of beauty hadron decays are some of the strongest and most intriguing evidences for the effects of physics beyond the Standard Model. The LHCb experiment at the LHC collider at CERN is dedicated to studies of beauty hadron decays, and the research group at CPPM has been actively involved in these studies.

Currently, LHCb is undergoing a major upgrade, which will allow it in a few years from now collect unprecedented data samples and bring these measurements to a new level of precision.

The candidate will join the LHCb experiment group at CPPM and will play an active role in the programme of analyses using decays of beauty hadrons into the final states with a single tau lepton at LHCb (so-called semileptonic decays which occur due to charged weak current transitions). The aim of these studies is to search for effects beyond the Standard Model in the measurements of lepton flavour universality, angular distributions, and charge-parity (CP) violation in these decays.

During the PhD project, the candidate will develop the procedures to reconstruct the kinematic properties of the decays of beauty mesons into the final states with a tau lepton and a tau neutrino. (S)he will perform the studies of kinematic distributions of the decay products and CP asymmetries in these decays, which may show signs of effects beyond the Standard Model.

In addition to the activities in physics analysis, the candidate will participate in the development of particle identification calibration techniques at LHCb, both with the currently available data and for the ongoing upgrade as a part of our involvement in the LHCb Real-Time Analysis (RTA) project.