Observation of the Decay $B_c^{\pm} \to J/\psi \pi^{\pm}$ and Measurement of the $B_c^{\pm}$ Mass

TL;DR

This paper reports the first observation of the $B_c^{ m ext{±}}$ meson decay into $J/ ext{ extbeta}$ and a pion, along with a precise measurement of its mass using data from the Fermilab Tevatron.

Contribution

The study provides the first observation of the $B_c^{ ext{±}}$ decay mode $B_c^{ ext{±}} o J/ ext{ extbeta} ext{ extpi}^{ ext{±}}$ and measures its mass with high significance.

Findings

Observed 108±15 decay candidates with >8σ significance.

Measured $B_c^{ ext{±}}$ mass as 6275.6±2.9 (stat.)±2.5 (syst.) MeV/$c^2$.

Confirmed the decay mode and provided a precise mass measurement.

Abstract

The $B_c^{\pm}$ meson is observed through the decay $B_c^{\pm} \to J/\psi \pi^{\pm}$, in data corresponding to an integrated luminosity of 2.4 fb$^{-1}$ recorded by the CDF II detector at the Fermilab Tevatron. A signal of $108\pm15$ candidates is observed, with a significance that exceeds $8 \sigma$. The mass of the $B_c^{\pm}$ meson is measured to be 6275.6 $\pm$ 2.9 (stat.) $\pm$ 2.5 (syst.) MeV/$c^2$.