Study of CP Symmetry Violation in the Charmonium-K*(892) Channel By a Complete Time Dependent Angular Analysis (BaBar Experiment)

This thesis presents the full-angular time-dependent analysis of the vector-vector channel Bd0 → J/ψ(KS0π0)*0. After a review of the CP violation in the B meson system, the phenomenology of the charmonium-K*(892) channels is exposed. The method for the measurement of the transversity amplitudes of the B → J/ψK*(892), based on a pseudo-likelihood method, is then exposed. The results from a 81.9 fb-1 of collected data by the BABAR detector at the Υ(4S) resonance peak are |A0|2 = 0.565 ± 0.011 ± 0.004, |A#parallel#|2 = 0.206 ± 0.016 ± 0.007, |A#perpendicular#|2 = 0.228 ± 0.016 ± 0.007, (delta)#parallel# = -2.766 ± 0.105 ± 0.040 and (delta)#perpendicular# = 2.935 ± 0.067 ± 0.040. Note that ((delta)#parallel#, (delta)#perpendicular#) → (-(delta)#parallel#, π - (delta)#perpendicular#) is also a solution. The strong phases (delta)#parallel# and (delta)#perpendicular# are at ∼> 3σ from ±π, signing the presence of final state interactions and the breakdown of the factorization hypothesis. The forward-backward analysis of the Kπ mass spectrum revealed the presence of a coherent S-wave interfering with the K*(892). It is the first evidence of this wave in the Kπ system coming from a B meson. The particularity of the Bd0 → J/ψ(KS0π0)*0 channel is to have a time-dependent but also an angular distribution which allows to measure sin 2β but also cos2β. The results from an unbinned maximum likelihood fit are sin 2β = -0.10 ± 0.57 ± 0.14 and cos 2β = 3.32-0.96+0.76 ± 0.27 with the transversity amplitudes fixed to the values given above. The other solution for the strong phases flips the sign of cos 2β. Theoretical considerations based on the s-quark helicity conservation favor the choice of the strong phases given above, leading to a positive sign for cos 2β. The sign of cos 2β is the one predicted by the Standard Model