Big-Bang Nucleosynthesis and Gravitino

TL;DR

This paper derives updated big-bang nucleosynthesis constraints on gravitino properties, considering recent observational data and improved theoretical modeling of production and bound-state effects, impacting early universe cosmology.

Contribution

It provides new BBN constraints on both unstable and stable gravitinos by incorporating recent data, longitudinal component contributions, and accurate bound-state effect calculations.

Findings

Upper limit on reheating temperature for unstable gravitino

Constraints on properties of Bino, stau, and sneutrino as next-to-lightest supersymmetric particles

Enhanced accuracy in modeling stau bound-state effects

Abstract

We derive big-bang nucleosynthesis (BBN) constraints on both unstable and stable gravitino taking account of recent progresses in theoretical study of the BBN processes as well as observations of primordial light-element abundances. In the case of unstable gravitino, we set the upper limit on the reheating temperature assuming that the primordial gravitinos are mainly produced by the scattering processes of thermal particles. For stable gravitino, we consider Bino, stau and sneutrino as the next-to-the-lightest supersymmetric particle and obtain constraints on their properties. Compared with the previous works, we improved the following points: (i) we use the most recent observational data, (ii) for gravitino production, we include contribution of the longitudinal component, and (iii) for the case with unstable long-lived stau, we estimate the bound-state effect of stau accurately by solving the Boltzmann equation.