Jet substructure probe to freeze-in dark matter in alternative cosmological background

The non-thermally produced freeze-in dark matter is an attractive alternative to look beyond the weakly interacting massive particle (WIMP) paradigm. With the singlet-doublet dark matter model, a simple extension to the standard model (SM), we probe the light dark matter parameter space, assuming feeble couplings between SM particles and the dark matter candidate. We tried to show how non-standard cosmological background affects dark matter production in the early Universe and alters the search strategy at colliders. We found that the prompt decay search using the jet substructure analysis is more effective than the existing displaced vertex searches.