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

Abstract

This thesis is devoted to the study of the B0 → ρ(770)0K∗(892)0 decay mode for which 3 fb−1 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 → (π+π−)(K+π−) decays performed in the two-body invariant mass regions corresponding to 300 < m(π+π−) < 1100 MeV/c2 and 750 < m(K+π−) < 1200 MeV/c2 are documented and the full set of results from the am- plitude analysis is discussed. These correspond to the CP averages and asymmetries for the magnitudes and phase differences of the contributing amplitudes. The results presented in this work 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(ρK*)= 0.164 ± 0.015 ± 0.022 and f ̃0(ωK*) = 0.68 ± 0.17 ± 0.16, and their CP asymmetries, A0ρK∗ = −0.62 ± 0.09 ± 0.09 and A0ωK∗ = −0.13 ± 0.27 ± 0.13, where the first uncertainty is statistical and the second systematic. As a result from this work, the first observation of direct CP violation in amplitude analyses of vector-vector decays was achieved.