Search for the lepton-flavor-violating decays B(s)0→e(±)µ(∓) and B0→e(±)µ(∓).

ABSTRACT

A search for the lepton-flavor-violating decays B(s)0→e(±)µ(∓) and B0→e(±)µ(∓) is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb(-1) of pp collisions at √s=7 TeV, collected by the LHCb experiment. The observed number of B(s)0→e(±)µ(∓) and B0→e(±)µ(∓) candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(B(s)0→e(±)µ(∓))<1.1(1.4)×10(-8) and B(B0→e(±)µ(∓))<2.8(3.7)×10(-9) at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, M(LQ)(B(s)0→e(±)µ(∓))>101 TeV/c(2) and M(LQ)(B0→e(±)µ(∓))>126 TeV/c(2) at 95% C.L., and are a factor of 2 higher than the previous bounds.