Search for the C-parity violating process J/psi->gamma gamma via psi(2S)->pi+pi- J/psi

TL;DR

This study searches for C-parity violation in J/psi decays to two photons, setting a new upper limit on the branching ratio that is significantly more restrictive than previous measurements.

Contribution

The paper provides the most stringent upper limit to date on the branching ratio of J/psi decaying into two photons, improving sensitivity by a factor of 20.

Findings

Upper limit on B(J/psi->gamma gamma) < 2.2×10^{-5} at 90% C.L.

No evidence of C-parity violation observed.

Enhanced experimental constraints on C-parity violating processes.

Abstract

Using 14.0\times 10^6 \psi(2S) events collected with the BES-II detector, the C-parity violating process J/psi->gamma gamma via psi(2S)->pi+pi- J/psi is studied. We determine a new upper limit for the J/psi->gamma gamma branching ratio of B(J/psi->gamma gamma)<2.2\times 10^{-5} at the 90% C.L., which is about 20 times lower than the previous measurement.