Search

If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation – via non-perturbative effects – into an out-of-equilibrium distribution of SM species, which thermalize soon afterwards. If the post-inflationary equation of state of the universe is stiff, w ≃ + 1 , the SM species eventually dominate the total energy budget. This provides a natural origin for the relativistic thermal plasma of SM species, required for the onset of the ‘hot Big Bang’ era. The viability of this scenario requires the inflationary Hubble scale H ⁎ to be lower than the instability scale for Higgs vacuum decay, the Higgs not to generate too large curvature perturbations at cosmological scales, and the SM dominance to occur before Big Bang Nucleosynthesis. We show that successful reheating into the SM can only be obtained in the presence of a non-minimal coupling to gravity ξ ≳ 1 , with a reheating temperature of T RH ≳ O ( 10 10 ) ξ 3 / 2 ( H ⁎ / 10 14 GeV ) 2 GeV . [ABSTRACT FROM AUTHOR]

We study the energy distribution and equation of state of the universe between the end of inflation and the onset of radiation domination (RD), considering observationally consistent single-field inflationary scenarios, with a potential 'flattening' at large field values, and a monomial shape V (ϕ) ∝ | ϕ | p around the origin. As a proxy for (p)reheating, we include a quadratic interaction g 2 ϕ 2 X 2 between the inflaton ϕ and a light scalar 'daughter' field X , with g 2 > 0. We capture the non-perturbative and non-linear nature of the system dynamics with lattice simulations, obtaining that: i) the final energy transferred to X depends only on p , not on g 2 ; i i) the final transfer of energy is always negligible for 2 ≤ p < 4 , and of order ∼ 50 % for p ≥ 4 ; i i i) the system goes at late times to matter-domination for p = 2 , and always to RD for p > 2. In the latter case we calculate the number of e-folds until RD, significantly reducing the uncertainty in the inflationary observables n s and r. [ABSTRACT FROM AUTHOR]