Abstract
We study models in which the inflaton is coupled to two otherwise decoupled sectors, and the effect of preheating and related processes on their energy densities during the evolution of the universe. Over most of parameter space, preheating is not disrupted by the presence of extra sectors, and even comparatively weakly coupled sectors can get an order 1 fraction of the total energy at this time. If two sectors are both preheated, the high number densities could also lead to inflaton mediated thermalisation. If only one sector is preheated, Bose enhancement of the late time inflaton decays may cause significant deviations from the perturbative prediction for their relative reheat temperatures. Meanwhile, in Non-Oscillatory inflation models resonant effects can result in exponentially large final temperature differences between sectors that have similar couplings to the inflaton. Asymmetric reheating is potentially relevant for a range of beyond the Standard Model physics scenarios. We show that in dark matter freeze-in models, hidden sector temperatures a factor of 10 below that of the visible sector are typically needed for the relic abundance to be set solely by freeze-in dynamics.
Highlights
Some DM models, as well as other motivated beyond the SM scenarios, need significant temperature differences between the visible sector and a dark sector
We show that in dark matter freeze-in models, hidden sector temperatures a factor of 10 below that of the visible sector are typically needed for the relic abundance to be set solely by freeze-in dynamics
The late time relative temperature of two sectors will be close to the perturbative prediction unless inflaton mediated thermalisation is efficient, as noted the early time dynamics might still lead to physically important effects
Summary
In models of freeze-in dark matter [11, 32,33,34,35,36,37,38], prior to freeze-in the abundance of DM is assumed negligible and the DM is generated by a portal operator connecting the hidden and visible sectors. The final relic abundance is controlled only by the DM mass and the portal operator if this is renormalisable (otherwise production is UV sensitive and may depend on the SM reheat temperature). Unless the inflaton has no decays to the dark sector, reheating leads to a population of DM, which we call the primordial component. For freeze-in to set the DM relic density, the primordial component of DM (PDM) should be substantially less than the DM abundance observed today. We consider two example scenarios, depending on if the dark sector has number changing interactions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
