Rate observables for cosmology and heavy ion collision experiments

Gregory Scott Jackson
2020
The early universe is perhaps the best conceivable multi-particle system in nature, for which the degrees of freedom are those of the Standard Model. This elementary particle plasma traced a path through its phase diagram, while evolving, that was largely determined by the underlying symmetries of the theory. Another trajectory, through the same phase diagram, is followed in a central collision between two heavy nuclei at high energies. Fortunately, theoretical methods developed and tested for
more » ... ped and tested for heavy ion collision experiments are also proving useful in cosmology, and vice versa . We demonstrate this by giving context to (and summarising) the work in Refs. [1] [2] [3] [4] [5] . Important properties can be studied through the 'eyes' of different probes that escape a thermal medium. In this thesis we consider three: Photons, neutrinos and gravitational waves. Each of these signals is a forensic tool for one or another facet of the Standard Model at finite temperature. Among the dynamical observables, interaction rates for hot gauge theories are conceptually interesting in their own right because they are sensitive to many scales in the problem. It is therefore crucial to evaluate the predictive power of perturbative approximations, either by examining higher-order terms or by comparing them with non-perturbative information.
doi:10.24442/boristheses.2185 fatcat:ve2qzrtr6nfzzmkbe3kjuiztkm