Reheating and post-inflationary production of dark matter

Kaluza-Klein FIMP dark matter in warped extra-dimensions

“…In particular, it has been observed that if the DM is produced during the transition from matter to radiation domination via an interaction rate that scales like γ(T ) ∝ T n , for n > 12 the DM abundance is enhanced by a boost factor proportional to (T max /T rh ) n−12 [66], whereas for n ≤ 12 the difference between the standard UV freeze-in calculation differ only by an O(1) factor from calculations taking into account non-instantaneous reheating. More recently, it has been highlighted that the critical mass dimension of the operator at which the instantaneous decay approximation breaks down depend on the equation of state ω, or equivalently, to the shape of the inflationary potential at the reheating epoch [67][68][69]. Therefore, the exponent of the boost factor becomes (T max /T rh ) n−nc with n c ≡ 6 + 2 3−ω 1+ω , showing a strong dependence on the equation of state [67].…”

Energy-momentum portal to dark matter and emergent gravity

“…Several recent works showed that the naive instantaneous approximation is not valid anymore if one has to deal with highly temperature-dependent production processes. Effects of noninstantaneous reheating were studied in [28], whereas noninstantaneous thermalization in [29] and effects of the inflaton potential in [30]. The effects begin to be important when, if we write the production rate RðTÞ ∝ T nþ6 Λ nþ2 , values of n ≥ 6, which is precisely our case.…”

“…In all these cases, it was shown that due to the high dependence of the scattering rates on the temperature (because of masssuppressed processes), the influence of the early Universe physics is strong, especially during the reheating phase [16,[27][28][29]. Moreover, the (strong) influence of the inflaton equation of state [30] or its decay modes [31] was added to recent studies.…”

Reheating and dark matter production

“…before reheating ends when the Universe becomes dominated by radiation. Note in particular that the temperature at the end of reheating, T reh , is much lower for larger k (Garcia et al 2020b).…”

“…The system of Equations (1)-(3) with rate (7) can be solved in an approximate analytical form for t < t reh , where t reh denotes the time of inflaton-radiation equality (Garcia et al 2020b),…”