Observation of the decay Bc+ -> Bs0 pi+

TL;DR

This paper reports the first observation of the decay Bc+ -> Bs0 pi+ using data from the LHCb detector, confirming a rare B meson decay process with high significance.

Contribution

It presents the first experimental observation of a B meson decaying into another B meson through the weak interaction, using multiple decay channels and large collision datasets.

Findings

Decay observed with >5 sigma significance in both channels

Measured ratio of production cross-section times branching fraction

First evidence of B meson decaying into another B meson via weak interaction

Abstract

The result of a search for the decay Bc+ -> Bs0 pi+ is presented, using the Bs0 -> Ds- pi+ and Bs0 -> J/psi Phi channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1 fb-1 taken at a center-of-mass energy of 7 TeV, and 2 fb-1 taken at 8 TeV. The decay Bc+ -> Bs0 pi+ is observed with significance in excess of five standard deviations independently in both decay channels. The measured product of the ratio of cross-sections and branching fraction is sigma(Bc+)/sigma(Bs0) x BR(Bc+ -> Bs0 pi+) = (2.37 \pm 0.31 (stat) \pm 0.11 (syst)^{+0.17}_{-0.13} (tau_Bc)) x 10^-3 in the pseudorapidity range 2 < eta(B) < 5, where the first uncertainty is statistical, the second is systematic and the third is due to the uncertainty on the Bc lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction.