Search for new physics with baryons at BESIII

Abstract

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

4 pages