Abstract
Cosmic Microwave Background (CMB) observations are used to constrain reheating to Standard Model (SM) particles after a period of inflation. As a light spectator field, the SM Higgs boson acquires large field values from its quantum fluctuations during inflation, gives masses to SM particles that vary from one Hubble patch to another, and thereby produces large density fluctuations. We consider both perturbative and resonant decay of the inflaton to SM particles. For the case of perturbative decay from coherent oscillations of the inflaton after high scale inflation, we find strong constraints on the reheat temperature for the inflaton decay into heavy SM particles. For the case of resonant particle production (preheating) to (Higgsed) SM gauge bosons, we find temperature fluctuations larger than observed in the CMB for a range of gauge coupling that includes those found in the SM and conclude that such preheating cannot be the main source of reheating the Universe after inflation.
Highlights
Inflation [1,2,3] is a period of accelerated expansion that occurred in the very early epoch of our Universe
For the case of resonant particle production to (Higgsed) standard model (SM) gauge bosons, we find temperature fluctuations larger than observed in the cosmic microwave background for a range of gauge coupling that includes those found in the SM and conclude that such preheating cannot be the main source of reheating the Universe after inflation
Density perturbations are created that later source cosmic microwave background (CMB) fluctuations as well as potentially seed large scale structure
Summary
Inflation [1,2,3] is a period of accelerated expansion that occurred in the very early epoch of our Universe. If the light spectators are associated with the decay of the inflaton field in each Hubble patch, their stochastic dynamics can cause spatial fluctuations in the reheat temperature and large density perturbations. We show constraints on the parameters (inflaton decay rate to SM fermions when masses are negligible, Yukawa coupling of SM decay products with the SM Higgs boson, and self-coupling of the Higgs during inflation) obtained by requiring that the amplitude of temperature fluctuations do not exceed CMB observations. For the case of resonant preheating to SM Higgsed gauge bosons, our main results can be seen in Fig. 10; one can see that for all reasonable parameter choices the density fluctuations (shown in terms of the Bardeen potential) are too large
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