CP violation studies and test of CPT symmetry in three-body charmless B decays

This thesis describes two analyses performed on charmless three-body B decays. The first study concerns the measurement of the inclusive CP violation in four decays channels: B± ! K+K±K−, B± ! _+K±_−, B± ! K+_±K− and B± ! _+_±_− using Run II (2015-2016) LHCb dataset, which corresponds to an integrated luminosity of 0.328 fb−1 in 2015, 1.665 fb−1 in 2016 recorded at centre-of-mass energy of 13 TeV. Also, a qualitative study was performed in the phase-space of these four decay channels, with the combination of the Run I and Run II data samples. The second analysis describes the measurement of the lifetime difference between B+ and B− in B± ! K+K±K− and B± ! K+_±K− decays. It exploits the Run I (2011-2012) LHCb dataset, corresponding to an integrated luminosity of 1.0 fb−1 in 2011 and 2.0 fb−1 in 2012 at centre-of-mass energy of 7 TeV and 8 TeV, respectively. Apart from the analysis side, this thesis also presents quality assurance tests developed to monitor the performance of some components of the new LHCb tracking detector, the SciFi tracker.