Seeking Alternative Dark Matter Scenarios

Several dark matter (DM) models have been proposed in the broader scientific community; however, the true nature of this elusive particle remains unknown to this day. Many of these models are either excluded by or in tension with the current obser- vational/ experimental results, suggesting that one should look beyond the standard scenarios. This thesis is dedicated to exploring such alternative dark matter scenarios for a different cosmological evolution or particle physics model. The observations strongly suggest that the Primordial Black Holes (PBH) can’t account for all the dark matter we observe today apart from potentially in a very small mass window. The current literature also strongly limits the scenarios with both PBH dark matter and particle dark matter, specifically the s-wave case for the WIMP-like particle dark matter. Here, we consider a different particle physics with a velocity- dependent annihilation cross-section for the particle dark matter and show that the PBHs can still make for a considerable fraction in the case of co-existing PBH dark matter and particle dark matter. We also discuss that a beyond-standard cosmological evolution, such as an early matter-dominated universe, can revive classic models of dark matter interacting with the Standard Model with the Higgs and Z-boson mediator. In a similar context, we highlight the impact of Asymmetric Dark Matter (ADM), where the dark matter relic density is set by dark matter and anti-dark matter asymmetry, identical to the baryons.