Numerical updates of lifetimes and mixing parameters of B mesons

Abstract

We update the Standard-Model predictions for several quantities related to $B_s-{\bar{B}}_s$ and $B_d-{\bar{B}}_d$ mixing. The mass and width differences in the $B_s$ system read $\Delta M_s^{\mathrm{SM}}=(17.3\pm 2.6)p{s}^{-1}$ and $\Delta {\Gamma }_s^{\mathrm{SM}}=(0.087\pm 0.021)p{s}^{-1}$, respectively. The CP asymmetries in flavour-specific decays are $a_{\mathrm{fs}}^{s,\mathrm{SM}}=(1.9\pm 0.3)\cdot 10^{-5}$ and $a_{\mathrm{fs}}^{d,\mathrm{SM}}=-(4.1\pm 0.6)\cdot 10^{-4}$. We further critically discuss the sensitivity of $\Delta {\Gamma }_d$ to new physics and the uncertainties in the relation between $\Delta {\Gamma }_s$ and the branching fraction of $B_s\to D_s^{(\ast )}{}^{+}{D}_s^{(\ast )}{}^{-}$. Then we present a numerical update of the average width ${\Gamma }_s$ in the $B_s$ system and correlate ${\Gamma }_s$ with the $B^{+}$-$B_d$ lifetime ratio. Finally we summarise the key results of our recent global analysis with the CKMfitter collaboration addressing new physics in $B-\bar{B}$-mixing. In an appropriately defined scenario parametrising new physics in $B-\bar{B}$-mixing by two complex parameters ${\Delta }_d$ and ${\Delta }_s$ the Standard-Model point {${\Delta }_d={\Delta }_s=1$} is disfavoured by 3.6 standard deviations.

Comments: Proceedings of the CKM workshop 2010 in Warwick