Effects of the Gravitino on the Inflationary Universe

TL;DR

This paper investigates the gravitino problem in the early universe, deriving bounds on reheating temperature by improving calculations of gravitino production, photon spectra, and light element evolution.

Contribution

It presents improved methods for calculating gravitino production, photon spectra, and light element evolution, providing more accurate constraints on the reheating temperature.

Findings

Derived upper bounds on reheating temperature.

Enhanced accuracy in gravitino production cross sections.

Numerical solutions for photon spectra and element evolution.

Abstract

Gravitino problem is discussed in detail. We derive an upperbound on the reheating temperature from the constraints of the big-bang nucleosynthesis and the present mass density of the universe. Compared to previous works, we have improve the following three points; (i) the gravitino production cross sections are calculated by taking all the relevant terms in the supergravity lagrangian into account, (ii) high energy photon spectrum is obtained by solving the Boltzmann equations numerically, and (iii) the evolutions of the light elements (D, T, $^3$He, $^4$He) at the temperature lower than $\sim$1MeV are calculated by using modified Kawano's computer code.