LHCb Semileptonic Asymmetry

Abstract

A recent LHCb measurement of the CP violating flavour specific asymmetry in $B_s^0$ decays, \asls, is presented. This measurement is based on a data sample corresponding to an integrated luminosity of 1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ $=$ 7 TeV, collected during the 2011 run of the LHC. The result is $\asls = (-0.24 \pm 0.54_{\rm stat} \pm 0.33_{\rm syst})\times 10^{-2}$, which is the most precise measurement of this quantity to date and agrees with the Standard Model prediction.}