Observation of J/psi-->3gamma

Area of Science:

• * Particle Physics
• * High-Energy Physics
• * Quantum Chromodynamics

Background:

• * The J/psi particle is a crucial probe for understanding quantum chromodynamics.
• * Previous studies have explored various J/psi decay modes.
• * The decay J/psi to three photons (3gamma) was theoretically predicted but experimentally unconfirmed.

Purpose of the Study:

• * To report the first experimental observation of the J/psi --> 3gamma decay.
• * To measure the branching fraction of this decay mode.
• * To contribute to the understanding of rare particle decays and fundamental symmetries.

Main Methods:

• * Analysis of J/psi --> 3gamma events collected by the CLEO-c detector.
• * Data acquired from psi(2S) --> pi+pi-J/psi events at the CESR e+e- collider.
• * Statistical analysis to determine signal significance and branching fraction.

Main Results:

• * First observation of the J/psi --> 3gamma decay with a statistical significance of 6 sigma.
• * Measured branching fraction B(J/psi --> 3gamma) = (1.2 +/- 0.3 +/- 0.2) x 10^-5.
• * Statistical and systematic errors were carefully evaluated.

Conclusions:

• * The observation of J/psi --> 3gamma provides direct evidence for this decay mode.
• * The measured branching fraction offers a stringent test for theoretical models.
• * This finding enhances our knowledge of the J/psi particle's properties and rare decays.