Measurement of the $B^0 \rightarrow K^{*0}e^+e^-$ branching fraction at low dilepton mass

TL;DR

This paper reports the first measurement of the branching fraction of the decay $B^0 ightarrow K^{*0}e^+e^-$ in the low dilepton mass region using LHCb data, providing important data for testing the Standard Model.

Contribution

It presents the first measurement of the $B^0 ightarrow K^{*0}e^+e^-$ branching fraction in the 30-1000 MeV/c^2 dilepton mass range using LHCb data, with normalization to $B^0 ightarrow J/ heta K^{*0}$.

Findings

Branching fraction measured as (3.1 +0.9 +0.2 -0.8 -0.3 ± 0.2) x 10^{-7}

Results consistent with Standard Model predictions

Provides data for testing flavor-changing neutral currents

Abstract

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.