Search for the weak radiative decay $\Lambda_{c}^+\to \Sigma^+\gamma$ at BESIII

TL;DR

This study searched for the weak radiative decay of Lambda_c+ to Sigma+ gamma at BESIII, found no signal, and set an upper limit on its branching fraction consistent with Standard Model predictions.

Contribution

First search for the decay Lambda_c+ to Sigma+ gamma at BESIII, establishing an upper limit on its branching fraction.

Findings

No signal observed above background.

Upper limit on branching fraction set at 4.4×10^{-4}.

Results agree with Standard Model expectations.

Abstract

The Cabibbo-allowed weak radiative decay $\Lambda_{c}^+\to \Sigma^+\gamma$ has been searched for in a sample of $\Lambda_{c}^+\bar{\Lambda}_{c}^-$ pairs produced in $e^+e^-$ annihilations, corresponding to an integrated luminosity of $4.5 \mathrm{fb}^{-1}$ collected with the BESIII detector at center-of-mass energies between 4.60 and 4.70 GeV. No excess of signal above background is observed, and we set an upper limit on the branching fraction of this decay to be ${\mathcal B}(\Lambda_{c}^+\to \Sigma^+\gamma)<4.4\times10^{-4}$ at a confidence level of 90\%, which is in agreement with Standard Model expectations.