Formula omitted] and [formula omitted] Mixing: Mass and Width Differences and CP violation

Abstract

B– 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 B s 0 and B 0 systems: in the Standard Model one finds Δ Γ s = 0.088 ± 0.17 ps −1 and Δ Γ d = ( 26.7 −6.5 +5.8 ) ⋅ 10 −4 ps −1 . Updates of the mass differences Δ M d and Δ M s and of a fs d and a fs s 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 ϕ s Δ from data on a fs s also profits from our new operator basis. Confronting our new formulae with DO data we find that sin ϕ s Δ deviates from zero by 2σ.