Theoretical update of Bs-(B)over-bars mixing

We update the theory predictions for the mass difference Delta M-s, the width difference Delta Gamma(s) and the CP asymmetry in flavour-specific decays, a(fs)(s), for the B-s-(B) over bar (s) system. In particular we present a new expression for the element Gamma(s)(12) of the decay matrix, which enters the predictions of Delta Gamma(s) and a(fs)(s). To this end we introduce a new operator basis, which reduces the troublesome sizes of the 1/m(b) and alpha(s) corrections and diminishes the hadronic uncertainty in Delta Gamma(s)/Delta M-s considerably. Logarithms of the charm quark mass are summed to all orders. We find Delta Gamma(s)/Delta M-s = (49.7 +/- 9.4) . 10(-4) and Delta Gamma(s) = (f B-s/240MeV)(2)[(0.105 +/- 0.016) B + (0.024 +/- 0.004) (B) over tilde'(S) -0.027 +/- 0.015] ps(-1) in terms of the bag parameters B,(B) over tilde'(S) in the NDR scheme and the decay constant f B-s. The improved result for Gamma(s)(12) also permits the extraction of the CP-violating B-s-B-s mixing phase from a(fs)(s) with better accuracy. We show how the measurements of Delta M-s, Delta Gamma(s), a(fs)(s), A(CP)(mix) (B-s -> J/psi phi) and other observables can be efficiently combined to constrain new physics. Applying our new formulae to data from the DO experiment, we find a 2 sigma deviation of the B-s-(B) over bar (s) mixing phase from its Standard Model value. We also briefly update the theory predictions for the B-d-(B) over bar (d) system and find Delta Gamma(d)/Delta M-d = (52.6(-12.8)(+11.5) ) . 10(-4) and a(fs)(d) = (-4.8(-1.2)(+1.0)) . 10(-4) in the Standard Mode.