psi(2S) Radiative Decay Measurements

TL;DR

This paper reports measurements of branching fractions for various radiative decay modes of the psi(2S) particle using a large data sample collected with the BESII detector, providing new experimental data on these decay processes.

Contribution

First comprehensive set of branching fraction measurements for psi(2S) radiative decays into multiple hadronic final states with invariant mass below 2.9 GeV/c^2.

Findings

Branching fractions or upper limits for numerous decay channels reported.

Data enhances understanding of psi(2S) decay mechanisms.

Provides experimental input for testing QCD models.

Abstract

Using a sample of 14 million $\psip$ events collected with the BESII detector, branching fractions or upper limits on the branching fractions of $\psip$ decays into $\gamma\ppb$, $\gamma 2(\pip\pim)$, $\gamma \kskp$, $\gamma \kap\kam\pip\pim$, $\gamma\kstarz\kam\pip+c.c.$, $\gamma \kstarz \kstarzb$, $\gamma\pip\pim\ppb$, $\gamma2(\kap\kam)$, $\gamma3(\pip\pim)$ and $\gamma2(\pip\pim)\kap\kam$ with hadron invariant mass less than 2.9$\gev/c^2$ are reported. We also report branching fractions of $\psip$ decays into $\gamma\ppb\piz$, $\ppb\piz\piz$, $2(\pip\pim)\piz$, $\omega\pp$, $\omega f_2(1270)$, $b_1^\pm\pi^\mp$, $\piz\kskp$, $K^\pm\rho^\mp\ks$, $\piz2(\pip\pim)\kap\kam$ and $\gamma\piz2(\pip\pim)\kap\kam$.