Search for the lepton number violating process $\Xi^- \rightarrow \Sigma^+ e^- e^- +c.c.$

TL;DR

This study searches for a rare lepton number violating decay of the Xi- baryon using a large dataset from BESIII, finding no evidence and setting an upper limit on its branching fraction.

Contribution

First search for the lepton number violating decay $ ext{Xi}^- ightarrow ext{Sigma}^+ e^- e^-$ with a large dataset, establishing an upper limit on its branching fraction.

Findings

No significant signal observed.

Upper limit on branching fraction set at $2.0 imes 10^{-5}$.

Large dataset of over 10 billion $J/\psi$ events used.

Abstract

We present a search for the lepton number violating decay $\Xi^-\rightarrow\Sigma^+e^-e^- +c.c.$ with $(10087\pm44)\times10^6$ $J/\psi$ events collected by the BESIII detector at the BEPCII collider. Employing a blind analysis strategy, no significant signal is observed above the expected background yield. The upper limit on the branching fraction is determined to be ${\rm Br}(\Xi^-\rightarrow\Sigma^+e^-e^-+c.c.)< 2.0\times10^{-5}$ at the $90\%$ confidence level.