Associated Production of Neutrino and Dark Fermion at Future Lepton Colliders

TL;DR

This paper explores the potential of future lepton colliders to detect fermionic dark matter through associated neutrino production, demonstrating that collider sensitivity surpasses current direct detection and astrophysical methods.

Contribution

It introduces the study of associated neutrino and dark fermion production at future $e^+ e^-$ colliders, highlighting the effectiveness of mono-photon and $e^+ e^-$ channels and the impact of beam polarization.

Findings

Collider sensitivity exceeds 1 TeV at CEPC/FCC-ee and ILC.

Sensitivity reaches up to 30 TeV at CLIC.

Collider searches are more sensitive than current direct detection and astrophysical constraints.

Abstract

Fermionic dark matter can be pairly produced and hence searched with missing energy at colliders. We extend such probe to the associated production of a neutrino and a dark sector fermion at the future $e^+ e^-$ colliders such as CEPC, FCC-ee, ILC, and CLIC. Two typical processes, the mono-photon and electron-positron pair productions associated with missing energy, can serve the purpose. While the mono-photon search prevails at CEPC, FCC-ee, and ILC, the $e^+ e^- \met$ channel has more significant contributions at CLIC with much higher collision energy $\sqrt s$. The beam polarizations can help further suppressing the SM backgrounds to enhance the signal significance while differential cross sections can distinguish the Lorentz structure of various effective operators. The combined sensitivity can reach well above $1\tev$ at CEPC/FCC-ee and ILC while it further touches 30\,TeV at CLIC. Comparing with the updated results from the direct detection experiments (XENON1T, PandaX-II, PandaX-4T, LZ, and XENONnT), astrophysical $X/\gamma$-ray observations, and cosmological constraints for the sub-MeV absorption dark matter, the collider searches are actually more sensitive and hence can provide a complementary approach to addressing the dark fermions.