Evidence for psi' decays into gamma pi^0 and gamma eta

TL;DR

This study reports the first observation of psi' decays into gamma pi^0 and gamma eta, measuring their branching fractions and providing new insights into charmonium radiative decay processes.

Contribution

First observation of psi' decays into gamma pi^0 and gamma eta with measured branching fractions using BESIII data.

Findings

First detection of psi'->gamma pi^0 and psi'->gamma eta decays.

Branching fractions measured as (1.58±0.40±0.13)×10^{-6} and (1.38±0.48±0.09)×10^{-6}.

Branching fraction for psi'->gamma eta' is (126±3±8)×10^{-6}.

Abstract

The decays psi'->gamma pi^0, gamma eta and gamma eta' are studied using data collected with the BESIII detector at the BEPCII e^+e^- collider. Processes psi'->gamma pi^0 and psi'->gamma eta are observed for the first time with signal significances of 4.6 sigma and 4.3 sigma, respectively. The branching fractions are determined to be: B(psi'->gamma pi^0)=(1.58+-0.40+-0.13)x10^{-6}, B(psi'->gamma eta)=(1.38+-0.48+-0.09)x10^{-6}, and B(psi'->gamma eta')=(126+-3+-8) x 10^{-6}, where the first errors are statistical and the second ones systematic.