Rare B decays at LHCb

The 10^12 B hadrons produced yearly at the LHCb interaction region will provide a unique opportunity for studying very rare B decays. Such processes occur via loops in the SM, and hence offer a high sensitivity to new physics through the effect of new particles in additional loops. At LHCb, many rare decay observables will allow either discovering new physics or constraining extensions of the SM. This article describes the LHCb potential on three of them. The first observable is the photon polarization in B_s->phi(K+K-)gamma, which has not been measured yet. The second case considered are the angular distributions in B0->K*(K+pi-)mu+mu-, for which some studies have already been performed at the B factories. The third observable is the branching ratio of Bs->mu+mu-. This extremely rare process is subject to large enhancements in many SUSY models, and it is potentially one of the first observables to be sensitive to new physics at the LHC.