Infrared Production of Gravitinos

According to observations, most matter density of our Universe is dark. Efforts have been done to explain this excess, ranging from alternative theories of gravity, to the introduction of new particles and many other exotic suggestions. Nowadays most of the scientific community agrees on the fact that dark matter is at least partially made of a new particle species, underlying the presence of new physics beyond the Standard Model. In this work we present a possible solution to the dark matter dilemma, showing how \textit{gravitino} can be a good particle candidate solving the problem. Exploiting the properties of this particular particle, we show under what assumptions \textit{freeze-in} mechanism could be the appropriate mechanism for gravitino relic density achievement. We focus on the consequences of a non-instantaneous reheating process on the gravitino relic density production, recovering and extending already existing works, showing under what assumptions this process is still able to solve the dark matter problem.