Year: 2015
Type: dissertation
Abstract: Grounded in the increasingly accurate astronomical observations of the past few decades, the study of cosmology has produced a comprehensive account of the history of the universe. This account is contained in the Hot Big Bang cosmological model which describes the expansion of a hot and dense state to become the universe as we observe it today. While the Big Bang model has been extremely successful in being able to account for a wide array of cosmological data, it leaves unexplained the special initial conditions that are required in order to produce the universe we find ourselves in. Such initial conditions are, however, a natural consequence of a period of quasi-exponential expansion of the universe known as inflation. Such a period of expansion can be realized if the universe is dominated by a scalar field - the inflation - which is slowly rolling down the slope of its potential. Inflation also provides a natural mechanism for the production of primordial seeds of structure in the universe through the growth of the quantum fluctuations in the inflaton field to super-horizon scales. Together inflation and the subsequent Big Bang evolution form the back bone of modern cosmology. However, the transition between the inflationary epoch and the thermal state which characterizes the initial conditions of the Big Bang evolution is not well understood. This process - dubbed reheating - involves the decay of the inflaton field into the particles of the Standard Model of particle physics, and may be highly non-trivial, with non-perturbative resonant processes playing a major role. Spectator fields - light scalar fields which are subdominant during inflation - may also play an important role during this epoch. The aim of this thesis is to showcase aspects of non-perturbative decay of scalar fields after inflation, focusing in particular on the role of spectator fields. This includes the modulation of the non-perturbative decay of the inflaton by a spectator field, the non-perturbative decay of a spectator into the Standard Model Higgs, as well as the non-perturbative decay of the Higgs field itself.
Source: Työväentutkimus Vuosikirja
Author: Stanislav Rusak
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2226106486