Freeze-in at stronger coupling

TL;DR

This paper investigates freeze-in dark matter production at the electroweak scale, highlighting how stronger couplings and lower reheating temperatures influence detectability and relic abundance.

Contribution

It analyzes the impact of reheating temperature and coupling strength on freeze-in dark matter production, providing new insights into experimental constraints.

Findings

Strong couplings are necessary for relic density at low reheating temperatures.

Current direct detection experiments already constrain significant parameter space.

Future experiments will probe lower couplings and higher reheating temperatures.

Abstract

Predictivity of many non-thermal dark matter (DM) models is marred by the gravitational production background. This problem is ameliorated in models with lower reheating temperature $T_R$, which allows for dilution of gravitationally produced relics. We study the freeze-in dark matter production mechanism in the thermal bath with the electroweak scale temperature. The process is Boltzmann-suppressed if the dark matter mass is above $T_R$. In this case, the coupling to the thermal bath has to be significant to account for the observed dark matter relic density. As a result, the direct DM detection experiments already probe such freeze-in models, excluding significant parts of parameter space. The forthcoming experiments will explore this framework further, extending to lower couplings and higher reheating temperatures.