Selection of the Decay Bd -> K*O mu+ mu- at LHCb

The selection for the "Bd -> K*0 mu+ mu-" decay is presented. We expect the events to be triggered and selected with an efficiency of 1.11 +/- 0.03%, with a background to signal ratio of 0.5 +/- 0.2. For an integrated luminosity of 2 fb-1, this will yield 7200 (+2200 -1900) signal events. The background has been studied using an inclusive bb-bar sample and a number of specific samples and is dominated by "Bd -> K+ pi- mu+ mu-" events. The expected background from this source is 1700 events per 2 fb-1. However, for the analysis of the forward-backward-asymmetry, these events can be treated as signal, under certain conditions. The remaining background is expected to be dominated by 1050 "b -> mu-, b -> mu+" events per 2 fb-1. With respect to previous estimates this represents an increase in the signal yield by a factor of 1.6, with an improved background-to-signal ratio.