Measurement of the ratio of branching fractions and difference in $CP$ asymmetries of the decays $B^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}$ and $B^{+}\to J/\ddot{I}ˆK^{+}$

Abstract

The ratio of branching fractions and the difference in $CP$ asymmetries of the decays $B^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}$ and $B^{+}\to J/\ddot{I}ˆK^{+}$ are measured using a data sample of $pp$ collisions collected by the LHCb experiment, corresponding to an integrated luminosity of $3~{{\,\mbox{fb}^{-1}}}$ at centre-of-mass energies of 7 and $8\mathrm{Te}\mathrm{V}$. The results are \begin{equation*} {\mathcal{B}(B^+\to J/ψπ^+)\over\mathcal{B}(B^+\to J/ψK^+)}=(3.83\pm0.03\pm0.03)\times10^{-2}\,, \end{equation*} \begin{equation*} \mathcal{A}^{CP}(B^+\to J/ψπ^+)-\mathcal{A}^{CP}(B^+\to J/ψK^+)=(1.82\pm0.86\pm0.14)\times10^{-2}, \end{equation*} where the first uncertainties are statistical and the second are systematic. Combining this result with a recent LHCb measurement of ${\mathcal{A}}^{CP}(B^{+}\to J/\ddot{I}ˆK^{+})$ provides the most precise estimate to date of $CP$ violation in the decay $B^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}$, \begin{equation*} \mathcal{A}^{CP}(B^+\to J/ψπ^+) =(1.91\pm0.89\pm0.16)\times10^{-2}. \end{equation*}

16 pages, 10 figures. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-051.html