The focus of the dissertation "Aspects of cosmic acceleration" is the study of possible mechanisms responsible for the late-time accelerated expansion of the universe. It has 5 main chapters. In... Show moreThe focus of the dissertation "Aspects of cosmic acceleration" is the study of possible mechanisms responsible for the late-time accelerated expansion of the universe. It has 5 main chapters. In the first chapter I have given an overview of modern cosmology. Particularly, an introduction to cosmological perturbation theory, and a general overview of the cosmological standard model, as well as an overview to beyond-standard-model scenarios is presented. Chapter two discusses cosmological models based on the so-called alpha-attractor framework. Chapter three is dedicated to the study of constraints imposed by gravitational wave observations on the so-called doubly-coupled massive bimetric gravity theory. Chapter four studies the cosmological stability of the so-called massive mimetic gravity theory. Finally, Chapter five studies the effect of the Symmetron gravity on the so-called splashback radius of dark matter halos. Show less
In the early universe, the dynamics of the Higgs field can give rise to many interesting phenomena. In the first part of this thesis, we study the behavior of the Higgs field during the reheating... Show moreIn the early universe, the dynamics of the Higgs field can give rise to many interesting phenomena. In the first part of this thesis, we study the behavior of the Higgs field during the reheating phase after cosmological inflation. We investigate the stability of the electroweak vacuum when the Higgs field is nonminimally coupled to gravity. We also study reheating in the scenario where the Higgs field itself drives inflation. In the second part, we study the possibility of generating the asymmetry between matter and antimatter during the electroweak phase transition -- the moment when the Higgs field starts to give mass to the other particles of the Standard Model. We show that it is not possible to constrain this process in a model-independent way. We also demonstrate that the predicted value of the baryon asymmetry is enhanced when leptons are included in the computation. Show less
