Search for the decays $B_{(s)}^0\to J/\psi\gamma$ at LHCb

TL;DR

This paper reports a search for rare B meson decays into J/psi and gamma using LHCb data, setting new upper limits on their branching fractions and improving previous results.

Contribution

The study provides the most stringent upper limits to date on the branching fractions of $B_{(s)}^0 o J/ ext{gamma}$ decays, surpassing earlier LHCb measurements.

Findings

Upper limit on $ ext{BR}(B_s^0 o J/ ext{gamma})$ is $2.9 imes 10^{-6}$ at 90% CL.

Upper limit on $ ext{BR}(B^0 o J/ ext{gamma})$ is $2.5 imes 10^{-6}$ at 90% CL.

Results improve previous limits by a factor of 2.5 for $B_s^0$ decay.

Abstract

A search for the rare decays $B_{(s)}^0\to J/\psi\gamma$ is performed with proton-proton collision data collected by the LHCb experiment, corresponding to integrated luminosities of $3~\rm{fb}^{-1}$ at centre-of-mass energies of 7 and 8 TeV, and $6~\rm{fb}^{-1}$ at 13 TeV. Assuming no contribution from $B^0\to J/\psi\gamma$ decay, an upper limit is set on the branching fraction $\mathcal{B}(B_{s}^0\to J/\psi\gamma)<2.9\times10^{-6}$ at the 90% confidence level. If instead no contribution from $B_{s}^0\to J/\psi\gamma$ decay is assumed, the limit is $\mathcal{B}(B^0\to J/\psi\gamma)<2.5\times10^{-6}$ at the 90% confidence level. These results supersede the previous LHCb results, with the limit for $B_{s}^0\to J/\psi\gamma$ improved by a factor of 2.5.