Enhanced preheating after multi-field inflation: on the importance of being special

Abstract

Abstract. We discuss preheating after multi-field inflation in the presence of several preheat matter fields that become light in the vicinity of (but not at) the inflatons' VEV, at distinct extra-species-points (ESP); this setup is motivated by inflationary models that include particle production during inflation, e.g. trapped inflation, grazing ESP encounters or modulated trapping, among others. While de-phasing of inflatons tends to suppress parametric resonance, we find two new effects leading to efficient preheating: particle production during the first in-fall (efficient if many preheat matter fields are present) and a subsequent (narrow) resonance phase (efficient if an ESP happens to be at one of several distinct distances from the inflatons' VEV). Particles produced during the first in-fall are comprised of many species with low occupation number, while the latter are made up of a few species with high occupation number.We provide analytic descriptions of both phases in the absence of back-reaction, which we test numerically. We further perform lattice simulations to investigate the effects of backreaction. We find resonances to be robust and the most likely cause of inflaton decay in multi-field trapped inflation if ESP distributions are dense.

Features and new physical scales in primordial observables: Theory and observation

“…An interesting generalization has also been considered in [149][150][151][152] xli , where motivated by string theoretic considerations, the effects of traversing multiple intervals in field space where massless fields appear along (or nearby) the inflaton trajectory was considered. In the limiting case where these regions appear frequently (while satisfying (79) throughout), a limiting velocity results for the inflaton due to continual particle production as inflation progresses.…”

From wires to cosmology

“…12 Armed with the FP equation, we can study the statistics of the produced particles as a function of time. 12 FP equations have also been used to describe the evolution of fluctuations in stochastic inflation [54][55][56]. In that case, the stochasticity in the equations of motion for long-wavelength fluctuations arises due to short-wavelength quantum fluctuations.…”

“…The occupation number after a time τ will be a stochastic quantity. By considering how the system responds to 'adding' a differential time interval δτ (and averaging over the randomness it contains), we can derive a Fokker-Planck (FP) equation for the evolution of the probability density, P (n k ; τ ) 12. Armed with the FP equation, we can study the statistics of the produced particles as a function of time.12 FP equations have also been used to describe the evolution of fluctuations in stochastic inflation[54][55][56].…”

Shape of the inflaton potential and the efficiency of the universe heating

“…A new mechanism of enhanced preheating after multifield inflation has been found in the recent paper [19], due to the presence of extra produced species which became light in the course of the multifield inflaton evolution.…”