First observation of a baryonic $B_c^{+}$ decay

Abstract

A baryonic decay of the $B_c^{+}$ meson, $B_c^{+}\to J/\ddot{I}ˆp\overline{p}\ddot{I}{€}^{+}$, is observed for the first time, with a significance of $7.3$ standard deviations, in $pp$ collision data collected with the LHCb detector and corresponding to an integrated luminosity of $3.0$ fb${}^{-1}$ taken at center-of-mass energies of $7$ and $8$ $\mathrm{TeV}$. With the $B_c^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}$ decay as normalization channel, the ratio of branching fractions is measured to be \begin{equation*} \frac{\mathcal{B}(B_c^+\to J/ψp\overline{p}π^+)}{\mathcal{B}(B_c^+\to J/ψπ^+)} = 0.143^{\,+\,0.039}_{\,-\,0.034}\,(\mathrm{stat})\pm0.013\,(\mathrm{syst}). \end{equation*} The mass of the $B_c^{+}$ meson is determined as $M(B_c^{+})=6274.0\pm 1.8(\mathrm{stat})\pm 0.4(\mathrm{syst})\mathrm{MeV}/c^2$, using the $B_c^{+}\to J/\ddot{I}ˆp\overline{p}\ddot{I}{€}^{+}$ channel.

20 pages, 2 figures