Search for the lepton number violating decay $\Sigma^{-} \to p e^{-} e^{-}$ and the rare inclusive decay $\Sigma^{-} \to \Sigma^{+} X$

TL;DR

This study searches for rare and lepton number violating decays of the Sigma-minus particle using a large J/psi dataset, setting new upper limits on their branching fractions due to no observed signals.

Contribution

First experimental search for the lepton number violating decay $oldsymbol{ ext{Sigma}^{-} o p e^{-} e^{-}}$ and the inclusive decay $oldsymbol{ ext{Sigma}^{-} o ext{Sigma}^{+} X}$, establishing upper limits.

Findings

No signal candidates observed.

Upper limits on branching fractions are $ ext{6.7} imes 10^{-5}$ and $ ext{1.2} imes 10^{-4}$.

Results constrain models predicting these rare decays.

Abstract

Using a data sample of $(1310.6 \pm 7.0) \times 10^{6}$ $J/\psi$ events taken with the BESIII detector at the center-of-mass energy of 3.097 GeV, we search for the first time for the lepton number violating decay $\Sigma^{-} \to p e^{-} e^{-}$ and the rare inclusive decay $\Sigma^{-} \to \Sigma^{+} X$, where $X$ denotes any possible particle combination. The $\Sigma^-$ candidates are tagged in $J/\psi \to \bar{\Sigma}(1385)^+\Sigma^-$ decays. No signal candidates are found, and the upper limits on the branching fractions at the 90\% confidence level are determined to be $\mathcal{B}(\Sigma^{-} \to p e^{-} e^{-}) < 6.7 \times 10^{-5}$ and $\mathcal{B}(\Sigma^{-} \to \Sigma^{+} X) < 1.2 \times 10^{-4}$.