Numerical study of particle production during reheating

Details

Supervisors

Drewes, Marco

Faculty

Faculté des sciences

Degree label

Master [120] en sciences physiques, à finalité approfondie

Abstract

The theory of the Big Bang, first postulated by Georges Lemaître, is the kind of theory that does not leave you indifferent. Together with General Relativity and the current Standard Model (SM) of particle physics, it is able to describe (almost) the entire universe from Big Bang nucleosynthesis (BBN) to the present day, spanning 13.8 billion years. Many experiments have confirmed the predictions of this theory, such as the existence of the Cosmic Microwave Background (CMB). It also predicts the correct abundance of light elements during BBN, explains the large-scale struc- tures, etc. Nevertheless, the theory of the Big Bang is incomplete in the sense that it does not answer some questions in a natural way. This suggests that the radiation- dominated epoch, also called the hot Big Bang, was preceded by a phase of rapid expansion of the universe known as the Cosmic Inflation scenario. While infla- tion as a solution to explain the Big Bang’s problems is largely favored by data, it is still not clear what drove this rapid expansion and how to embed it into a more fundamental theory of nature. Surprisingly, an indirect probe of the connection between inflation and the hot Big Bang can be found by studying the period of transition between them. This epoch is called reheating and describes the production of particles between the in- flation sector and SM. Reheating on its own is a very interesting topic to study, as it sets the initial conditions for the hot Big Bang. It is well known that the process of reheating leaves imprints on CMB observables through its effects on the expansion history. In recent papers, it has been shown that under certain conditions on the value of the coupling g of the inflaton to other fields, we can translate constraints on the duration of reheating to constraints on the coupling. Ultimately, this allows the extraction of information about the microphysics of inflation from CMB obser- vables. This makes reheating a very important subject from the viewpoint of particle physics. In this work, we will try to verify the validity of these conditions, for different interactions, with numerical simulations of the inflation and reheating phases. Simulation will be carried with Cosmolattice, a modern package for numerical simulation of the early universe.