LHCb sensitivity to new physics using $B^{0} \to \phi K^{0}_{s}$ decays

We study the LHCb sensitivity to new physics using Bd->phiK0S decays. LHCb can select ~800 untagged Bd->phiK0S after trigger, in one year of data taking. The background over signal ratio is estimated using 10 millions of bb and 1 million of b->phiX decays. It is found below 1.3 at 90%CL. This leads to a statistical uncertainty on sin2beta between 0.27 and 0.41 at 90%CL.