# Measurement of the branching fraction and $C\!P$ asymmetry in $B^{+}\rightarrow J/\psi \rho^{+}$ decays

## TL;DR

This paper reports the most precise measurements to date of the branching fraction and direct $C ext{P}$ asymmetry in the decay $B^{+}
ightarrow J/
ho^{+}$ using LHCb data at 7 and 8 TeV.

## Contribution

It provides the first highly precise measurements of the branching fraction and $C ext{P}$ asymmetry for this decay mode, improving previous results.

## Key findings

- Branching fraction measured as (3.81 +0.25/-0.24) x 10^{-5}.
- $C ext{P}$ asymmetry measured as -0.045 ± 0.056/0.057 (stat) ± 0.008 (syst).
- Results are the most precise to date.

## Abstract

The branching fraction and direct $C\!P$ asymmetry of the decay $B^{+}\rightarrow J/\psi \rho^{+}$ are measured using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to a total integrated luminosity of 3$\mbox{fb}^{-1}$. The following results are obtained: \begin{align} \mathcal{B}(B^{+}\rightarrow J/\psi \rho^{+}) &= (3.81 ^{+0.25}_{-0.24} \pm 0.35) \times 10^{-5}, \nonumber \\ \mathcal{A}^{C\!P} (B^{+}\rightarrow J/\psi \rho^{+}) &= -0.045^{+0.056}_{-0.057} \pm 0.008, \nonumber \end{align} where the first uncertainties are statistical and the second systematic. Both measurements are the most precise to date.