Study of the rare $B^0_d \to K^{*0}(K^+ \pi^-) \mu^+\mu^-$ decay with the LHCb detector

The status of the study of the rare decay B0_d -> K*0 mu+mu-, with K*0 -> K+pi-, or its charged conjugate state, using the LHCb detector is presented. This decay is very sensitive to deviations from Standard Model physics through Forward-Backward and CP asymmetries, among other observables. In one year of LHCb data taking we expect to collect about 4400 of these events with a B/S ratio below 2. This allows the determination of the branching ratio and of the possible CP asymmetry of the branching ratio with a precision of a few percent. The evaluation of the sensitivity of the other observables needs a better understanding of the backgrounds and their distributions. Therefore, more statistics of background simulations is needed. However I find good resolutions for the measurement of the relevant quantities.