Collider and CMB complementarity of leptophilic dark matter with light Dirac neutrinos

TL;DR

This paper explores the potential to discover leptophilic dark matter at future lepton colliders and CMB experiments, highlighting the interplay of collider searches, cosmological bounds, and neutrino properties within an effective field theory framework.

Contribution

It introduces a novel EFT approach linking light Dirac neutrinos and leptophilic dark matter, analyzing their combined signatures at colliders and CMB experiments.

Findings

Future lepton colliders can effectively probe leptophilic dark matter via mono-photon searches.

Enhanced $N_{\rm eff}$ from neutrino interactions offers complementary detection prospects.

Cosmological and collider bounds together constrain dark matter properties and neutrino interactions.

Abstract

We study the discovery prospects of leptophilic dark matter (DM) in future lepton colliders by considering the light neutrinos to be of Dirac type. Adopting an effective field theory (EFT) approach, we write down dimension six operators connecting the standard model (SM) fields, light Dirac neutrinos and DM. Considering DM relic to be generated via the thermal freeze-out, we check the discovery prospects at future lepton colliders via mono-photon plus missing energy searches. The right chiral parts of light Dirac neutrinos get thermalised due to their interactions with the bath as well as leptophilic DM, leading to enhanced effective relativistic degrees of freedom $N_{\rm eff}$ within reach of future cosmic microwave background (CMB) experiments. The interplay of existing bounds from cosmological observations related to DM relic and $N_{\rm eff}$, direct and indirect detection of DM, astrophysics and collider observations leave promising discovery prospects at future electron and muon colliders along with complementary signatures at future CMB experiments.