Determination of BR(chi_{cJ} --> p \bar{p}) in psi(2S) decays

TL;DR

This study measures the branching fractions of chi_{cJ} decays into proton-antiproton pairs in psi(2S) decays, providing precise experimental results using a large data sample from the Beijing Spectrometer.

Contribution

First precise measurement of BR(chi_{cJ} --> p pbar) in psi(2S) decays with clear signals observed for all three chi_{cJ} states.

Findings

Branching fractions for chi_{c0}, chi_{c1}, chi_{c2} are measured.

Results are consistent with previous measurements and theoretical predictions.

Large data sample improves measurement accuracy.

Abstract

The processes psi(2S) --> gamma chi_{cJ}, chi_{cJ} --> p pbar (J=0,1,2) are studied using a sample of 14X10^6 psi(2S) decays collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider. Very clear chi_{c0}, chi_{c1} and chi_{c2} signals are observed, and the branching fractions BR(chi_{cJ} --> p pbar) (J=0,1,2) are determined to be (27.1^{+4.3}_{-3.9}\pm 4.7)X10^{-5}, (5.7^{+1.7}_{-1.5}\pm0.9)X10^{-5}, and (6.5^{+2.4}_{-2.1}\pm1.0)X10^{-5}, respectively, where the first errors are statistical and the second are systematic.