Observation of $B^+_c \rightarrow J/\psi D_s^+$ and $B^+_c \rightarrow J/\psi D_s^{*+}$ decays

TL;DR

This paper reports the first observation of specific Bc+ meson decays into J/psi and D_s+ or D_s*+ with high statistical significance, measuring branching ratios and the Bc+ mass using LHCb data.

Contribution

First experimental observation of Bc+ decays to J/psi D_s+ and J/psi D_s*+ with precise measurements of branching ratios and meson mass.

Findings

Branching ratio of Bc+ to J/psi D_s+ measured as 2.90 ± 0.57 ± 0.24

Branching ratio of Bc+ to J/psi D_s*+ relative to D_s+ is 2.37 ± 0.56 ± 0.10

Mass of Bc+ meson measured as 6276.28 ± 1.44 (stat) ± 0.36 (syst) MeV/c^2

Abstract

The decays $B^+_c \rightarrow J/\psi D_s^+$ and $B^+_c \rightarrow J/\psi D_s^{*+}$ are observed for the first time using a dataset, corresponding to an integrated luminosity of 3$fb^{-1}$, collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies of $\sqrt{s}$=7 and 8 TeV. The statistical significance for both signals is in excess of 9 standard deviations. The following ratios of branching fractions are measured to be $BR(B^+_c \rightarrow J/\psi D_s^+)/BR(B^+_c \rightarrow J/\psi \pi+) = 2.90 \pm 0.57 \pm 0.24$, $BR(B^+_c \rightarrow J/\psi D_s^{*+}) / BR (B^+_c \rightarrow J/\psi D_s^+) = 2.37 \pm 0.56 \pm 0.10$, where the first uncertainties are statistical and the second systematic. The mass of the \Bc meson is measured to be $m_{B^+_c} = 6276.28 \pm 1.44 (stat) \pm 0.36(syst) MeV/c^2$, using the $B^+_c \rightarrow J/\psi D_s^+$ decay mode.