Revisiting Big-Bang Nucleosynthesis Constraints on Long-Lived Decaying Particles

TL;DR

This paper revisits constraints on long-lived decaying particles during big-bang nucleosynthesis by updating reaction rates, using recent observational data, and considering new effects like nucleon interconversion and anti-nucleon showers, deriving tighter bounds.

Contribution

It introduces updated reaction rates, incorporates recent observational data, and considers new physical effects to refine constraints on decaying particles during BBN.

Findings

Derived upper bounds on relic abundance of decaying particles.

Placed constraints on reheating temperature after inflation.

Improved limits on unstable gravitino abundance.

Abstract

We study effects of long-lived massive particles, which decay during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundances of light elements. Compared to the previous studies, (i) the reaction rates of the standard BBN reactions are updated, (ii) the most recent observational data of light element abundances and cosmological parameters are used, (iii) the effects of the interconversion of energetic nucleons at the time of inelastic scatterings with background nuclei are considered, and (iv) the effects of the hadronic shower induced by energetic high energy anti-nucleons are included. We compare the theoretical predictions on the primordial abundances of light elements with latest observational constraints, and derive upper bounds on relic abundance of the decaying particle as a function of its lifetime. We also apply our analysis to unstable gravitino, the superpartner of the graviton in supersymmetric theories, and obtain constraints on the reheating temperature after inflation.