Search for K_S K_S in J/psi and psi(2S) decays

TL;DR

This study searches for CP-violating decays J/psi and psi(2S) into K_S K_S, finds no evidence, and sets upper limits on their branching ratios using large data samples from the Beijing Spectrometer.

Contribution

First search for CP-violating J/psi and psi(2S) decays into K_S K_S with large data samples, establishing upper limits on their branching ratios.

Findings

No signal observed for the decays.

Upper limits on branching ratios are set.

Results constrain CP violation in these decays.

Abstract

The CP violating processes J/psi-->K_S K_S and psi(2S)-->K_S K_S are searched for using samples of 58 million J/psi and 14 million psi(2S) events collected with the Beijing Spectrometer at the Beijing Electron Positron Collider. No signal is observed, and upper limits on the decay branching ratios are determined to be BR(J/psi-->K_S K_S) < 1.0x10^{-6} and BR(psi(2S)-->K_S K_S) < 4.6x10^{-6} at the 95% confidence level.