Search for new physics with baryons at BESIII

TL;DR

This paper reports on searches for new physics involving baryons at BESIII, setting the most stringent limits on invisible baryon decays and baryon-number violation, thus probing physics beyond the Standard Model.

Contribution

First search for invisible baryon decays and baryon-number violation at BESIII, providing new stringent limits on these processes.

Findings

No excess observed in the searched channels.

Set upper limits on branching fractions and oscillation probabilities.

Probed new physics beyond the Standard Model.

Abstract

The BESIII experiment at BEPCII provides a clean environment to test baryon-dark sector connections and baryon-number violation. Using $10^{10}$ $J/\psi$ events, searches were performed for $\Sigma^{+}\to p+\text{inv}$, $\Xi^{-}\to\pi^{-}+\text{inv}$, and $\bar{\Lambda}-\Lambda$ oscillations. No excess was observed, yielding $\mathcal{B}(\Sigma^{+}\to p+\text{inv})<3.2\times10^{-5}$, $\mathcal{B}(\Xi^{-}\to\pi^{-}+\text{inv})<(4-7)\times10^{-5}$, and $P(\Lambda)<4.4\times10^{-6}$ (90\% C.L.). These are the most stringent limits on invisible baryon decays and $\Delta B=2$ transitions in strange baryons, probing new physics beyond the Standard Model.