Effective theory of light Dirac neutrino portal dark matter with observable ΔN_{\rm eff}

2025/02/14 by Borah, Debasish, Mahapatra, Satyabrata, Nanda, Dibyendu +2 · 2 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2502.10318

Abstract

We study the possibility of light Dirac neutrino portal dark matter (DM) in an effective field theory setup. Dirac nature of light neutrino automatically includes its right chiral part ν_R which, in our setup, also acts like a portal between DM and the standard model (SM) particles. Considering a Dirac fermion singlet DM stabilized by an unbroken Z₂ symmetry, we write down all possible dimension-6 effective operators involving DM-ν_R as well as ν_R-SM which conserve Z₂, global lepton number and SM gauge symmetries. DM thermalization also ensures the thermalization of ν_R, leading to enhanced effective relativistic degrees of freedom N_{\rm eff}, within reach of future cosmic microwave background (CMB) experiments. We study the complementarity among DM and CMB related observations for different Lorentz structures of effective operators. We also propose a UV complete gauged \rm B-L symmetric model with Dirac neutrino portal dark matter.

Cited by

• Probing the Phenomenology of Dark Matter from Decoupled Freeze-Out
• Dirac neutrino and dark matter in left-right symmetric models

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