Speaker
Description
The identity of neutrinos, Dirac or Majorara, is an essential yet unsolved puzzle of nature. By assuming that neutrinos are Dirac particles, we propose a light Dirac neutrino portal dark matter scenario which is based on the possible correlation between the relic right-handed neutrinos and present dark matter abundance. We studied the connection between dark matter and the light right-handed neutrinos produced both thermally and non-thermally and showed that the observables like $\Delta{N_{\rm eff}}$ and free-streaming length of dark matter can put tight constraints on the available parameter space. For example, in the case of non-thermal dark matter, such constraints can rule out DM mass all the way up to $\mathcal{O}$(100 keV). This can be a possible way to probe the dark matter parameter space even when the direct detection cross-section is suppressed or forbidden in the theory.
