Mixing and CP Violation in the Bd and Bs Systems at ATLAS

This note includes a measurement of the B decay parameters in the B-s -> J/psi phi channel and a measurement of the B-0 meson proper decay time and decay width using the statistics collected by the ATLAS experiment in Run I of the LHC. The first result presents the measurement of the CP-violating phase phi(s), the decay width Gamma(s) and the width difference between the mass eigenstates Delta Gamma(s). The second result presents the measurement of the width difference Delta Gamma(d), which is extracted from the measurement of the lifetime dependence of B-0 -> J/psi K-S and B-0 -> J/psi K*(0) decays. The obtained results are phi(s) = 0.098 +/- 0.084(stat.) +/- 0.040(syst.) rad. and Delta Gamma(d)/Gamma(d) = (-0.1 +/- 1.1(stat.) +/- 0.9(syst.)) x 10(-2).