Equation of state and beginning of thermalization after preheating
Abstract
We study the outofequilibrium nonlinear dynamics of fields after postinflationary preheating. During preheating, the energy in the homogeneous inflaton is exponentially rapidly transfered into highly occupied outofequilibrium inhomogeneous modes, which subsequently evolve towards equilibrium. The infrared modes excited during preheating evolve towards a saturated distribution long before thermalization completes. We compute the equation of state during and immediately after preheating. It rapidly evolves towards radiation domination long before the actual thermal equilibrium is established. The exact time of this transition is a nonmonotonic function of the coupling between the inflaton and the decay products, and it varies only very weakly (around 10^{35} s) as this coupling changes over several orders of magnitude. This result is applied to refine the relation between the number of efoldings N and the physical wavelength of perturbations generated during inflation. We also discuss the implications for the theory of modulated perturbations from preheating. We finally argue that many questions of the thermal history of the universe should be addressed in terms of prethermalization, illustrating this point with a calculation of perturbative production of gravitinos immediately after chaotic inflation. We also highlight the effects of threelegs inflaton interactions on the dynamics of preheating and thermalization in an expanding universe.
 Publication:

Physical Review D
 Pub Date:
 January 2006
 DOI:
 10.1103/PhysRevD.73.023501
 arXiv:
 arXiv:hepph/0507096
 Bibcode:
 2006PhRvD..73b3501P
 Keywords:

 98.80.Cq;
 11.10.z;
 Particletheory and fieldtheory models of the early Universe;
 Field theory;
 High Energy Physics  Phenomenology;
 Astrophysics;
 High Energy Physics  Theory
 EPrint:
 15 pages, 13 figures