Search for invisible decays of the $\Lambda$ baryon

TL;DR

This paper reports the first search for invisible decays of the $ ext{Lambda}$ baryon using $J/\psi$ decay data, setting an upper limit on the branching fraction to constrain dark sector models.

Contribution

It is the first experimental search for invisible baryon decays, providing new constraints relevant to dark matter and baryon asymmetry theories.

Findings

No signals for invisible $ ext{Lambda}$ decays were observed.

An upper limit of $7.4 imes 10^{-5}$ on the branching fraction was established.

This search constrains models involving dark sectors and baryon asymmetry.

Abstract

A search for invisible decays of the $\Lambda$ baryon is carried out in the process $J/\psi\to\Lambda\bar{\Lambda}$ based on $(1.0087\pm0.0044)\times10^{10}$ $J/\psi$ events collected with the BESIII detector located at the BEPCII storage ring. No signals are found for the invisible decays of $\Lambda$ baryon, and the upper limit of the branching fraction is determined to be $7.4 \times 10^{-5}$ at the 90% confidence level. This is the first search for invisible decays of baryons; such searches will play an important role in constraining dark sector models related to the baryon asymmetry.