Speaker
Description
There are more particles than antiparticles in our universe. A simple solution to this unexpected asymmetry, known as the baryon asymmetry of our universe (BAU), is leptogenesis, where a heavy right-handed neutrino (RHN) is introduced. Interestingly, the mass of the RHN coincides with the energy scales during inflation. In addition to this outstanding problem, dark matter continues to be elusive in its nature, with the only certainty being that it interacts gravitationally. This provides strong motivation to investigate particle production that occurs through gravitational interactions, commonly referred to as cosmological gravitational particle production (CGPP). During inflation, spacetime expands non-adiabatically, necessarily leading to this particle production mechanism. A simple model that connects the Standard Model (SM) to inflation is one that takes the inflaton to be the SM Higgs field, though it does not require it being the SM Higgs. We investigate the dynamics of a spectator scalar field and we find the the resultant particle spectrum. We find a significant increase in particle production compared to other forms of inflation such as quadratic inflation. The spectrum exhibits new features, including the occupation number $n_k$ scaling like $\xi$, the non-minimal coupling to gravity, and which is peaked on a characteristic wavenumber that also scales with $\xi$. This large particle production enhancement and new scaling with $\xi$ allows us to investigate the parameter space for leptogenesis and DM. In the case of leptogenesis, the spectator field is the heavy RHN that decays asymmetrically into leptons and through non-perturbative effects, produces the BAU. Alternatively, the decay products of this spectator scalar field can comprise the DM of our universe.
| Keyword-1 | inflation |
|---|---|
| Keyword-2 | leptogenesis |
| Keyword-3 | dark matter |