Study of the B0→ρ(770)0K*(892)0 decay with an amplitude analysis of B0→(π+π−)(K+π−) decays

Resumen

This thesis is devoted to the study of the B0->rho(770)0K*(892)0 decay mode for which 3 1/fb of proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV were analysed. The details of an amplitude analysis of B0->(pi+pi-) (K+pi-) decays performed in the two-body invariant mass regions corresponding to 300 < m(pi+pi-)<1100 MeV/c^2 and 750 < m(K+pi-)<1200 MeV/c^2 are documented and its results are discussed. Particular emphasis is placed in the measurements of the CP averages and asymmetries for the magnitudes and phase differences of the contributing amplitudes. The presented results correspond to the first measurements of most of these observables. In particular, the CP-averaged longitudinal polarisation fractions of the vector-vector modes are found to be f^0_{rho K*} = 0.164 +/- 0.015 +/- 0.022 and f^0_{omega K*} = 0.68 +/- 0.17 +/- 0.16, and their CP asymmetries, A^0_{rho K*} = -0.62 +/- 0.09 +/- 0.09 and A^0_{omega K*} = -0.13 +/- 0.27 +/- 0.13, where the first uncertainty is statistical and the second systematic. Consequently, the first observation of direct CP violation in amplitude analyses of vector-vector decays is reported.