# Search for the rare decay $B^{+} \rightarrow {\mu}^{+}{\mu}^{-}{\mu}^{+}{\nu}_{{\mu}}$

## TL;DR

This paper reports a search for a rare B+ meson decay involving three muons and a neutrino, using LHCb data, resulting in setting an upper limit on its branching fraction due to no significant signal detection.

## Contribution

First search for the $B^{+}
ightarrow \mu^{+}\mu^{-}\mu^{+}
u_{\mu}$ decay using LHCb data, establishing an upper limit on its branching fraction.

## Key findings

- No significant excess observed over background.
- Upper limit on branching fraction set at $1.6 imes 10^{-8}$.
- Analysis in the specified kinematic region.

## Abstract

A search for the rare leptonic decay $B^{+} \rightarrow {\mu}^{+}{\mu}^{-}{\mu}^{+}{\nu}_{{\mu}}$ is performed using proton-proton collision data corresponding to an integrated luminosity of $4.7$ fb$^{-1}$ collected by the LHCb experiment. The search is carried out in the region where the lowest of the two ${\mu}^{+}{\mu}^{-}$ mass combinations is below $980$MeV/c$^{2}$. The data are consistent with the background-only hypothesis and an upper limit of $1.6 \times 10^{-8}$ at 95% confidence level is set on the branching fraction in the stated kinematic region.