Search for the Decay J/psi -> gamma + invisible

TL;DR

This study searched for invisible decay modes of J/psi into a photon and a weakly interacting neutral particle, setting upper limits on the decay probability due to the absence of a significant signal.

Contribution

First search for J/psi -> gamma + invisible particles using CLEO-c data, establishing upper limits on the decay branching fraction.

Findings

No significant signal observed.

Upper limit on branching fraction at 4.3 x 10^{-6} for m_X=0.

Constraints placed on models predicting invisible J/psi decays.

Abstract

A search for J/psi radiative decay to weakly interacting neutral final states was performed using the CLEO-c detector at CESR. A total of 3.7 x 10^{6} tagged J/psi events was collected at the psi(2S) resonance and used to study the decay J/psi -> gamma+X, where X is a narrow state that is invisible to the detector. No significant signal was observed and upper limits on the branching fraction were set for masses m_X up to 960 MeV/c^2. The upper limit corresponding to m_X=0 is 4.3x 10^{-6} at the 90% confidence level.