Semileptonic $B_s$ decay measurements at LHCb

Abstract

I discuss the first semileptonic $B_s$ decay measurements performed at LHCb, and the prospects for precise studies of $B_s$ semileptonic decay properties. The analyses covered here are based on data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV. In particular the semileptonic decays $\Bs\to D_s^+ X \munu$ and $\Bs\to D^0K^+ X \munu$ are studied. Two structures are observed in the $D^0{K}^{+}$ mass spectrum at masses consistent with the known $D_{s1}(2536{)}^{+}$ and $D_{s2}^{\ast }(2573{)}^{+}$ mesons. The measured branching fractions relative to the total $\Bs$ semileptonic rate are ${\cal{B}(\Bs\to D_{s2}^{*+} X \munu)}/{\cal{B}(\Bs\to X \munu)}= (3.3\pm 1.0\pm 0.4)%$, and ${\cal{B}(\Bs\to D_{s1}^+ X \munu)}/{\cal{B}(\Bs\to X \munu)}= (5.4\pm 1.2({\rm stat})\pm 0.5({\rm sys}))%$. This is the first observation of the $D_{s2}^{\ast +}$ state in $\Bs$ decays.

Proceedings of CKM2010, the 6th International Workshop on the CKM Unitarity Triangle, University of Warwick, UK, 6-10 September 2010