Measurement of the B 0 → K ∗0 e + e - branching fraction at low dilepton mass

Abstract

The branching fraction of the rare decay B0→ K∗0 e +e− in the dilepton mass region from 30 to 1000 MeV/c2 has been measured by the LHCb experiment, using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, at a centre-of-mass energy of 7 TeV. The decay mode B0 → J/ψ(e+e−)K∗0 is utilized as a normalization channel. The branching fraction B(B0 → K∗0e+e−) is measured to beB(B 0→ K∗0 e+e−)30−1000 MeV/c2= (3.1+0.9 +0.2−0.8 −0.3 ± 0.2) × 10−7 , where the first error is statistical, the second is systematic, and the third comes from the uncertainties on the B0→ J/ψ K∗0 and J/ψ → e+e− branching fractions.