Measurement of the charge asymmetry in B±→φK± and search for B±→φπ± decays

Abstract

The CP-violating charge asymmetry in B± →φK± decays is measured in a sample of pp collisions at 7 TeV centre-of-mass energy, corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment. The result is ACP(B± →φK± ) = 0.022 ± 0.021 ± 0.009, where the first uncertainty is statistical and the second systematic. In addition, a search for the B± →φπ± decay mode is performed, using the B± →φK± decay rate for normalization. An upper limit on the branching fraction B(B± → φπ± ) < 1.5×10−7 is set at 90% confidence level.