Uploaded January 2024 | Updated September 2026, 2 weeks ago
Speaker: Francesco Costa (University of Göttingen, Germany)
Abstract: FIMP dark matter is produced via the freeze-in mechanism, which implies tiny couplings between the DM and the standard model particles, making DM direct detection and collider searches almost hopeless. Moreover, it is necessary to assume negligible initial abundance which is not generally a physical assumption since gravitational production in the early universe is very efficient. Therefore, we show that one can construct consistent freeze-in models including a matter-dominated epoch that dilutes the initial DM abundance in order to avoid overproduction. This leads reheating to happen “late”. We show that for FIMP at low reheating temperatures (TRs), direct detection plays a fundamental role in constraining the parameter space since the coupling is allowed to be much higher than standard values. We also show that there is a smooth transition betweenthe freeze-in and the freeze-out phases contrary to the standard high TR case.
Speaker: Francesco Costa (University of Göttingen, Germany)
Abstract: FIMP dark matter is produced via the freeze-in mechanism, which implies tiny couplings between the DM and the standard model particles, making DM direct detection and collider searches almost hopeless. Moreover, it is necessary to assume negligible initial abundance which is not generally a physical assumption since gravitational production in the early universe is very efficient. Therefore, we show that one can construct consistent freeze-in models including a matter-dominated epoch that dilutes the initial DM abundance in order to avoid overproduction. This leads reheating to happen “late”. We show that for FIMP at low reheating temperatures (TRs), direct detection plays a fundamental role in constraining the parameter space since the coupling is allowed to be much higher than standard values. We also show that there is a smooth transition betweenthe freeze-in and the freeze-out phases contrary to the standard high TR case.
