The branching fraction of the rate decay $B^0 \rightarrow K^{ *0}e^+e^-$ in the dilepton mass region from 30 to 1000 MeV$/c^2$ 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 $B^0 \rightarrow J/\psi(e^+e^-) K^{ *0}$ is utilized as a normalization channel. The branching fraction $B^0 \rightarrow K^{ *0}e^+e^-$ is measured to be $$ B(B^0 \rightarrow K^{ *0}e^+e^-)^{ 30-1000 MeV/c^2}= (3.1\, ^{ +0.9\mbox{ } +0.2}_{ -0.8\mbox{ }-0.3} \pm 0.2)\times 10^{ -7}, $$ where the first error is statistical, the second is systematic, and the third comes from the uncertainties on the B^0 \rightarrow J/\psi K^{ *0}$ and $J/\psi \rightarrow e^+e^- $ branching fractions.
Categories: hep-ex