The Bs -> Ds pi and Bs -> Ds K selections

The decay channels Bs->Dspi and Bs->DsK will be used to extract the physics parameters $\Delta m_s$, $\Delta\Gamma_s$ and $\gamma + \phi_s$. Simulation studies based on Monte Carlo samples produced in 2004 and 2005 show that a total of 140k Bs->Dspi and 6.2k Bs->DsK events are expected to be triggered, reconstructed and selected in $2fb^{-1}$ of data ($10^7s$ of data taking at a luminosity of $2\times 10^{32}\unit{cm^{-2}s^{-1}}$). The combinatorial background-over-signal ratio originating from inclusive bb events is expected to be $B/S < 0.05~\at~90\%$ CL~for Bs->Dspi whereas, for Bs->DsK, the limit is $B/S < 0.18~\at~90\%$~CL.