# Observation of $B_{c}^{+} \rightarrow D^{0} K^{+}$ decays

## TL;DR

This paper reports the first observation of the rare $B_{c}^{+}
ightarrow D^{0} K^{+}$ decay using LHCb data, measuring its branching fraction relative to $B^{+}$ decays with high statistical significance.

## Contribution

The paper presents the first experimental observation of the $B_{c}^{+}
ightarrow D^{0} K^{+}$ decay and measures its branching fraction relative to $B^{+}$ decays.

## Key findings

- Decay observed with 5.1 sigma significance
- Measured relative branching fraction: (9.3^{+2.8}_{-2.5} ext{(stat)} ext{±} 0.6) imes 10^{-7}
- First decay of this type observed for $B_{c}^{+}$ mesons

## Abstract

Using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb$^{-1}$, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV, the $B_{c}^{+} \rightarrow D^{0} K^{+}$ decay is observed with a statistical significance of 5.1 standard deviations. By normalising to $B^{+} \rightarrow \bar{D}^{0} \pi^{+}$ decays, a measurement of the branching fraction multiplied by the production rates for $B_{c}^{+}$ relative to $B^{+}$ mesons in the LHCb acceptance is obtained, $$ R_{D^{0} K} = \frac{f_{c}}{f_{u}}\times\mathcal{B}(B_{c}^{+} \rightarrow D^{0} K^{+}) = (9.3\,^{+2.8}_{-2.5} \pm 0.6) \times 10^{-7}\,, $$ where the first uncertainty is statistical and the second is systematic. This decay is expected to proceed predominantly through weak annihilation and penguin amplitudes, and is the first $B_{c}^{+}$ decay of this nature to be observed.