Prospects for CP violation in B0s → J/ψφ from first LHCb data

Summary. — The determination of the CP-violating phase in B0s → J/ψφ decays is one of the key goals of the LHCb experiment. Its value is predicted to be very small in the Standard Model but can be significantly enhanced in many models of New Physics. The steps towards a precise determination of this phase with a flavour-tagged, time-dependent angular analysis of the decay B0s → J/ψφ are reviewed and first studies performed with data collected in 2010 at LHC in pp collisions at 7 TeV center-of-mass energy are presented for the first time. In particular, we report the first LHCb measurements of lifetime in the channels B+ → J/ψK+, B0 → J/ψK∗0, B0 → J/ψK0S, B0s → J/ψφ, Λb → J/ψΛ; the polarization amplitudes in B0 → J/ψK∗0 and B0s → J/ψφ; the width and mass differences of the B0s mass eigenstates, ∆Γs and ∆ms. The data sample used corresponds to an integrated luminosity of 36 pb −1