Description
Observations of the cosmic microwave background (CMB) lend strong evidence for the paradigm of cosmic inflation, but the specific form of the inflaton potential remains unknown. Under certain conditions, the oscillating inflaton condensate filling the Universe after inflation can fragment and form interesting non-linear structures known as oscillons. These long-lived soliton-like field configurations can dominate the Universe for several e-folds of expansion, leading to an early matter-dominated phase preceding the standard radiation era.
In this talk, I will show how the rapid decay of the oscillons leads to an enhanced production of induced gravitational waves (GWs), whose energy density can saturate the observational bound on the effective number of relativistic species. We leverage this bound to constrain the inflaton mass, cubic, and quartic self-coupling in generic models that admit oscillon formation, providing novel and complementary constraints in regions of parameter space that are inaccessible with CMB observations alone.
