Study of Radiative Decays of Psi(2S) Mesons

TL;DR

This study searched for the radiative decay of psi(2S) mesons into gamma eta_c(2S) but did not observe any such decays, setting upper limits on the branching fractions based on extensive data.

Contribution

First comprehensive search for psi(2S) to gamma eta_c(2S) decays with new upper limits established on the branching fractions.

Findings

No psi(2S) to gamma eta_c(2S) decays observed.

Upper limits on branching fractions were set at 90% confidence level.

Data from 25.9 million psi(2S) events were analyzed.

Abstract

We studied the decay psi(2S) to gamma eta_c(2S) with 25.9 million psi(2S) events collected with the CLEO-c detector. No psi(2S) to gamma eta_c(2S) decays were observed in any of the eleven exclusive eta_c(2S) decay modes studied. The product branching fraction upper limits were determined for all modes. The 90% confidence level upper limit of branching fraction of psi(2S) to gamma eta_c (2S) was obtained.