Branching Fraction and CP Asymmetry of the Decays B+ → K0S π+ and B+ → K0S K+

An analysis of B+ → K0S π+ and B+ → K0S K+ decays is performed with the LHCb experiment. The pp collision data used correspond to integrated luminosities of 1 fb^−1 and 2 fb^−1 collected at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, respectively. The ratio of branching fractions and the direct CP asymmetries are measured to be B(B+ → K0S K+)/B(B+ → K0S π+) = 0.064 ± 0.009(stat.) ± 0.004(syst.), ACP(B+ → K0S π+) = −0.022 ± 0.025(stat.) ± 0.010(syst.) and ACP(B+ → K0S K+) = −0.21 ± 0.14(stat.) ± 0.01(syst.). The data sample taken at √s = 7 TeV is used to search for Bc+ → K0S K+ decays and results in the upper limit (f_c ⋅ B(Bc+ → K0S K+)) / (f_u ⋅ B(B+ → K0S π+)) < 5.8 x 10^−2 at 90% confidence level, where f_c and f_u denote the hadronisation fractions of a anti-b quark into a Bc+ or a B+ meson, respectively.