Search for the Lepton-Number-Violating Decay $\Xi^- \to p \mu^- \mu^-$

TL;DR

This paper reports a highly sensitive search for a rare lepton-number-violating decay of the Xi- hyperon, setting a new upper limit on its branching ratio that surpasses previous results by four orders of magnitude.

Contribution

The study provides the most stringent experimental limit to date on the lepton-number-violating decay $ ext{Xi}^- o p ext{mu}^- ext{mu}^-$, significantly improving previous bounds.

Findings

Upper limit on branching ratio: < 4.0×10^{-8} at 90% confidence

Used a large sample of approximately 10^9 Xi- hyperons

Improved previous experimental limits by four orders of magnitude

Abstract

A sensitive search for the lepton-number-violating decay $\Xi^-\to p \mu^-\mu^-$ has been performed using a sample of $\sim10^9$ $\Xi^-$ hyperons produced in 800 GeV/$c$ $p$-Cu collisions. We obtain $\mathcal{B}(\Xi^-\to p \mu^-\mu^-)< 4.0\times 10^{-8}$ at 90% confidence, improving on the best previous limit by four orders of magnitude.