Measurement of the branching fraction and CP asymmetry in B+→J/ψρ+ decays

Abstract

The branching fraction and direct CP$$C!P$$ asymmetry of the decay B+→J/ψρ+$${{{B} ^+}} !\rightarrow {{J /\psi }} {{\rho } ^+} $$ 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 3fb-1$$,\text{ fb }^{-1}$$. The following results are obtained: B(B+→J/ψρ+)=(3.81-0.24+0.25±0.35)×10-5,ACP(B+→J/ψρ+)=-0.045-0.057+0.056±0.008,$$\begin{aligned} \mathcal {B}({{B} ^+} !\rightarrow {{J /\psi }} {{\rho } ^+} )&= (3.81^{+0.25}{-0.24} \pm 0.35) \times 10^{-5},\ \mathcal {A}^{{C!P}} ({{B} ^+} !\rightarrow {{J /\psi }} {{\rho } ^+} )&= -0.045^{+0.056}{-0.057} \pm 0.008, \end{aligned}$$where the first uncertainties are statistical and the second systematic. Both measurements are the most precise to date.