Joint cosmology seminar at Tufts:
Tuesday, December 6, 2022, 2:30 pm
574 Boston Ave, Room 310\\
Refreshments at 2:00 outside room 304
Beyond Simple Oscillons: Multi-Field Effects and Excited States
Fabio van Dissel
Oscillons are oscillating, localized configurations in real scalar field theories. They appear in potentials that are shallower than quadratic away from the minimum and can be extremely long-lived. Since plateau models are of great relevance for inflation, oscillons have been shown to form efficiently during preheating in a wide range of such models. Most work on oscillons has focused on single-field dynamics, however, various theories of fundamental physics that go beyond the Standard Model suggest the presence of a multitude of scalar fields in the early Universe. Furthermore, little is known about the dynamics of excited states of single-field oscillons in models that have garnered much attention historically. In this talk, I will describe the work I performed on the dynamics of excited and multi-component oscillons. In particular, I will show how to construct multi-field oscillons in the non-relativistic limit of scalar field theories, and use this formalism to explain the origin of their stability and long lifetimes in a toy model. I will talk about my most recent work in which I show that instabilities in the quantum vacuum can naturally lead to the condensation of multi-field oscillons. This is of special interest in the context of preheating scenarios, but could also find other applications in cosmology. I will comment on strategies for generalizing this work to other models, for example, models with an arbitrary number of fields. Finally, I will talk about excited oscillon states in the Sine-Gordon model, where, surprisingly, excited oscillons could have lifetimes that are comparable to the ground state oscillon.