Photo- and Hadrodisintegration constraints on massive relics decaying into neutrinos

TL;DR

This paper investigates how decaying relic particles into neutrinos affect early Universe light-element abundances, providing new constraints on particle properties through a comprehensive probabilistic analysis of disintegration processes.

Contribution

It introduces a Monte-Carlo inspired probabilistic approach to analyze relic particle decay effects on Big Bang nucleosynthesis, expanding constraints to new mass and lifetime ranges.

Findings

Constraints on relic particle decay are more stringent than previously known.

Late-time disintegration significantly impacts light-element abundances.

New parameter space for relic particle properties is explored.

Abstract

We perform a detailed study of the cosmological constraints on the decay of a relic particle $\phi$ into neutrinos, $\phi \rightarrow \nu \bar{\nu}$, in particular those arising from the observed light-element abundances in the early Universe. We focus on the late-time disintegration of the light elements previously synthesised during BBN. Several processes are relevant, including final-state radiation associated with the decay, as well as subsequent interactions of the injected neutrinos with the thermal background neutrinos or between themselves. All processes generically contribute to the production of electromagnetic and often also hadronic material and may therefore induce late-time photodisintegration and hadrodisintegration reactions, i.e.~the destruction of light elements that have previously been formed during BBN. Here, we examine this scenario with a Monte-Carlo inspired probabilistic approach rather than Boltzmann techniques, taking into account all of these different reactions as well as their interplay. We find the resulting constraints to be very significant, covering a broad range of previously unexplored masses and lifetimes of the relic source particle.