Speaker
Description
We propose a light Dirac neutrino portal dark matter (DM) scenario by minimally extending the particle content of the standard model (SM) with three right handed neutrinos ($\nu_R$), a Dirac fermion DM candidate ($\psi$) and a complex scalar ($\phi$), all of which are singlets under the SM gauge group. An additional $Z_4$ symmetry has been introduced for the stability of DM candidate $\psi$ and also ensuring the Dirac nature of light neutrinos at the same time. Depending upon the strength of couplings involving these particles, one can have either thermal or non-thermal production of DM. Since the same interaction produces DM as well as relativistic $\nu_R$ leading to enhanced effective relativistic degrees of freedom $N_{\rm eff}$, the DM parameter space gets tightly constrained by Planck 2018 data. The next generation CMB experiments like CMB-S4, SPT-3G etc. will have the required sensitivities to probe most of the parameter space of this minimal scenario, which other experiments like direct detection are not much sensitive to.
