# Flavor-changing hyperon decays with light invisible bosons

## TL;DR

This paper investigates hyperon decays involving missing energy carried by light invisible bosons, highlighting potential large decay rates detectable by current experiments, and explores how these signals could indicate new physics beyond the standard model.

## Contribution

It provides a model-independent analysis of hyperon decays with invisible bosons, identifying conditions under which these decays could be significantly enhanced and detectable, especially with parity-odd couplings.

## Key findings

- Hyperon decay rates can be large with parity-odd couplings.
- Certain mass ranges weaken kaon decay constraints.
- Hyperon decays could serve as unique probes of new physics.

## Abstract

We consider the strangeness-changing decays of hyperons into another baryon and missing energy which is carried away by a pair of invisible spinless bosons. Pursuing a model-independent approach and taking into account constraints from the kaon sector, we find that these hyperon modes can have large rates, especially if the bosons have parity-odd effective couplings to light quarks. In that case the rates could attain values which are well within the expected reach of the currently running BESIII experiment. Since the branching fractions of hyperon decays with missing energy are tiny in the standard model, observing them at ongoing or upcoming facilities would likely be indicative of new physics. In addition, we show that the kaon restrictions may be weakened or absent if the bosons have nonnegligible mass. Specifically, if the bosons interact with the quarks solely via an axial-vector current, in the mass region from about 115 to 175 MeV the constraints from rare kaon decays no longer apply and a couple of the hyperon modes become the only direct probes of such interactions. We also make comparisons with the previously explored new-physics scenario where the invisible particles are spin-1/2 fermions.