Observation of $B_{c}^{+} \to J/\psi D^{(*)} K^{(*)}$ decays

TL;DR

This paper reports the first observation of certain $B_c^+$ decay modes, measures their branching fractions, and provides the most precise measurement of the $B_c^+$ mass to date using data from the LHCb experiment.

Contribution

First observation of $B_c^+ o J/ o D^{(*)}K^{(*)}$ decays, first evidence for others, and a highly precise $B_c^+$ mass measurement.

Findings

First observation of $B_c^+ o J/ o D^0 K^+$ and $D^{*0} K^+$ decays.

First evidence for $B_c^+ o J/ o D^{*+} K^{*0}$ and $D^+ K^{*0}$ decays.

Most precise $B_c^+$ mass measurement to date.

Abstract

A search for the decays $B_c^+ \to J/\psi D^{(*)0} K^+$ and $B_c^+ \to J/\psi D^{(*)+} K^{*0}$ is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb$^{-1}$. The decays $B_c^+ \to J/\psi D^0 K^+$ and $B_c^+ \to J/\psi D^{*0} K^+$ are observed for the first time, while first evidence is reported for the $B_c^+ \to J/\psi D^{*+} K^{*0}$ and $B_c^+ \to J/\psi D^+ K^{*0}$ decays. The branching fractions of these decays are determined relative to the $B_c^+ \to J/\psi \pi^+$ decay. The $B_c^+$ mass is measured, using the $J/\psi D^0 K^+$ final state, to be $6274.28 \pm 1.40 (stat) \pm 0.32 (syst)$ MeV/$c^2$. This is the most precise single measurement of the $B_c^+$ mass to date.