B0 and Mixing: Mass and Width Differences and CP violation

B– mixing involves three physical parameters: the magnitudes of the off-diagonal elements of the mass and decay matrices and their relative phase. These parameters are related to the mass and width differences between the mass eigenstates and to the CP asymmetry in flavour-specific decays, afs. Introducing a new operator basis I present new, more precise theory predictions for the width differences in the and B0 systems: in the Standard Model one finds ΔΓs=0.088±0.17 ps−1 and . Updates of the mass differences ΔMd and ΔMs and of and are also presented. I then discuss how various present and future measurements can be combined to constrain new physics. The extraction of a new CP phase from data on also profits from our new operator basis. Confronting our new formulae with DØ data we find that deviates from zero by 2σ.