CP-violating phases in neutral meson oscillations

LHCb is one of the four large experiments at the Large Hadron Collider (LHC) at CERN, Geneva, Switzerland and is dedicated to heavy flavour physics. LHCb searches for New Physics (NP) by performing precision measurements of CP-violating parameters. One of the key measurements of LHCb is the extraction of the CP-violating weak phase @f_s. The Standard Model (SM) prediction for this parameter is small: @f_s^S^M=2arg(V_t_bV_t_s^@?V_c_bV_c_s^@?)=-0.0364+/-0.0016 [J. Charles, et al., CKMfitter Group, European Physical Journal C 41 (2005) 1-131, updated results and plots available at: http://ckmfitter.in2p3.fr. arXiv:hep-ph/0406184.]. Possible deviations from this SM prediction may be attributed to NP. The parameter @f_s is measured by performing a time-dependent angular analysis of B_s^0->J/@j@f decays and independently by a time-dependent analysis of B_s^0->J/@j@p@p decays. A simultaneous fit to both decays yields @f_s=-0.002+/-0.083(stat.)+/-0.027(syst.). The fitted values of @f_s and the lifetime difference @D@C_s exhibit a phase ambiguity, which is resolved by performing fits in bins of the K^+K^- invariant mass and looking at the difference in fitted strong phases of P-wave and S-wave contributions. Finally, as a first step towards controlling penguin contributions to b->c(c@?s) transitions such as B_s^0->J/@j@f decays, a branching ratio measurement of B_s^0->J/@jK@?^@?^0 decays is presented. In addition to the @f_s measurement, two other analyses are presented here. Firstly, preliminary results of the LHCb a_s_l^s measurement are presented. The second analysis is the measurement of triple product asymmetries in B_s^0->@f@f decays. The branching ratio measurement of B_s^0->J/@jK@?^@?^0 decays is extracted from a dataset with an integrated luminosity of 0.37 fb^-^1. The results from all other aforementioned analyses are extracted from the full 2011 LHCb data set which has an integrated luminosity of 1.0 fb^-^1.