TPPC weekly seminar (in-person): Swagat Mishra - Towards Preheating after inflation: Inflaton Fragmentation, Oscillon Formation and Decay

Wednesday 6 Nov 2024, 12:30 → 13:45 Europe/London

7.06 (STD)

Title: Towards Preheating after inflation: Inflaton Fragmentation, Oscillon Formation and Decay

 

Abstract: The transition period between the end of inflation and the onset of thermal radiation domination, known as ‘reheating,’ remains a key unresolved issue in cosmology. During the early stages of reheating, the inflaton condensate is expected to decay non-perturbatively via parametric resonance into lighter bosonic fields coupled to the inflaton, a phase referred to as ‘preheating.’ However, when the external couplings of the inflaton are sufficiently weak, the inflaton condensate may undergo fragmentation due to strong self-interactions, leading to the formation of quasi-stable solitonic objects known as ‘oscillons.’ In this seminar, we explore the conditions under which oscillons form during preheating, particularly in the presence of external couplings, within the framework of asymptotically-flat inflationary potentials—a class favored by the latest CMB observations. Using detailed numerical simulations carried out on the public lattice simulation platform CosmoLattice, we map the parameter space that supports the formation of long-lived oscillons. The analysis suggests that reheating could have proceeded through the channel of oscillon decay, along with the usual decay of the oscillating inflaton condensate into the offspring particles.