TY  - GEN
AV  - public
ID  - heidok28731
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/28731/
Y1  - 2020///
CY  - Heidelberg
TI  - Nonperturbative dynamics in the early universe: from axion-like particles to dark matter and condensates
N2  - Scalar fields play an important role in cosmology. They can be responsible for cosmic inflation in the very early universe, as well as are among well-motivated dark matter (DM) candidates. The aim of this dissertation is to contribute to a better understanding of the dynamics of such fields in the nonperturbative regime.

Motivated by cosmological scenarios, we consider coherent oscillations of a scalar field in potentials that are summed from periodic and monomial terms, which have recently attracted much attention in the context of axion-like particles (ALP). We investigate the resonant amplification of quantum fluctuations, as well as the subsequent nonlinear dynamics after the fragmentation of the field. 

Our studies are extended to the nonthermal production of ALP DM. It is found that the process of fragmentation imprints strong overdensities of DM on small scales, as well as can produce a stochastic gravitational wave background, potentially within reach of future detectors.

Finally, we investigate the role of experiments with ultracold atoms for the quantum simulation of nonperturbative dynamics and describe how, by means of a modulation of the interatomic interaction strength, such Bose gases can go through the characteristic stages of the dynamics of relativistic systems in the early universe.
A1  - Chatrchyan, Aleksandr
ER  -