We update the theory predictions for the mass difference ∆Ms, the width difference ∆Γs and the CP asymmetry in flavour-specific decays, afss, for the Bs-bar Bs system. In particular we present a new expression for the element Γ12s of the decay matrix, which enters the predictions of ∆Γs and afss. To this end we introduce a new operator basis, which reduces the troublesome sizes of the 1/mb and αs corrections and diminishes the hadronic uncertainty in ∆Γs/∆Ms considerably. Logarithms of the charm quark mass are summed to all orders. We find ∆Γs/∆Ms = (49.7±9.4)bold dot10-4 and ∆Γs = (fBs/240 MeV)2[(0.105±0.016) B + (0.024±0.004) tilde BS' - 0.027±0.015] ps-1 in terms of the bag parameters B, tilde BS' in the NDR scheme and the decay constant fBs. The improved result for Γ12s also permits the extraction of the CP-violating Bs-bar Bs phase from afss with better accuracy. We show how the measurements of ∆Ms, ∆Γs, afss, ACPmix(Bs→J/ψphi) and other observables can be efficiently combined to constrain new physics. Applying our new formulae to data from the DØ experiment, we find a 2σ deviation of the Bs-bar Bs phase from its Standard Model value. We also briefly update the theory predictions for the Bd-bar Bd system and find ∆Γd/∆Md = (52.6+11.5-12.8) bold dot10-4 and afsd = (-4.8+1.0-1.2) bold dot10-4 in the Standard Model.
Journal of High Energy Physics
- Pub Date:
- June 2007
- High Energy Physics - Phenomenology
- 38 pages, 7 figures, revised version to appear in JHEP, comments added. We correct the incorrect use of an experimental input in eq. (93) and Fig. 7. Our conclusions remain unchanged