Neutral Hadrons Disappearing into the Darkness

TL;DR

This paper investigates the potential for neutral hadrons to decay invisibly into a dark sector, which could explain anomalies like the neutron lifetime puzzle and offers a new avenue for discovering physics beyond the Standard Model.

Contribution

It introduces a model predicting significant invisible decay rates of neutral hadrons into the dark sector, connecting experimental limits to new physics searches.

Findings

$K_L$ and $B^0$ mesons can decay into dark sector within current experimental bounds.

Neutron decay rates into dark matter could explain the neutron lifetime puzzle.

Invisible decay of neutrons could be just above current experimental limits.

Abstract

We study the invisible decay of neutral hadrons in a representative model of the dark sector. The mesons $K_L$ and $B^0$ decay into the dark sector with branching rates that can be at the current experimental limits. The neutron decays with a rate that could either explain the neutron lifetime puzzle (although only for an extreme choice of the parameters and a fine tuned value of the masses) or be just above the current limit of its invisible decay ($\tau_N^{\rm inv} \ge 10^{29}$ years) if kinematically allowed. These invisible decays of ordinary matter provide a novel and promising window into new physics that should be vigorously pursued.