Search for T violation and CP violation in the Weak Semileptonic Λ_b⁰ and Λ_c⁺ c Decays with the LHCb Detector

Three discrete symmetries: C,P,T are important in subatomic Physics, their combination (CPT) is considered as the corner stone of investigation in Particle Physics and many other fields. Since C and P are violated, it is important to investigate the direct violation of the T symmetry. This thesis, with all the discussed topics, aims to propose in a direct way a new strategy to test the symmetry of time reversal (T). The Collider LHC gives us the opportunity to do that throughout the enormous production of the beauty baryons. Here, the emphasis will be put on the decay Λ_b⁰ → (Λ_c⁺ → Λπ)(W* → μ^-ν_μ), that is considered as a source of observables that are odd under T symmetry. A special attention is paid to the polarization of Λ_b⁰ and the resonating particles coming from it. First, the theoretical framework concerning the symmetries and their role in physics are presented. Significant progress has been achieved in the development of a kinematic framework from which the angular distributions of the particles involved in the decays are calculated. A detailed study of the reconstruction and selection of the events have been exposed as well as the methodology used to extract the different polarizations from the angular distribution fits. This study is performed using the 2011-2012 data recorded by the LHCb detector during the first run of the LHC. (author)