Prospects for Finding Sterile Neutrino Dark Matter at KATRIN

TL;DR

This paper explores the conditions under which sterile neutrinos detectable by KATRIN could constitute dark matter, considering production mechanisms, experimental constraints, and new physics scenarios.

Contribution

It analyzes the parameter space for sterile neutrino dark matter detection at KATRIN, including mechanisms to relax X-ray limits and avoid overproduction, and discusses exotic CPT violation effects.

Findings

KATRIN can probe sterile neutrino dark matter under specific conditions.

Production mechanisms can be adjusted to fit experimental constraints.

CPT violation could have observable consequences in sterile neutrino searches.

Abstract

We discuss under what circumstances a signal in upcoming laboratory searches for keV-scale sterile neutrinos would be compatible with those particles being a sizable part or all of dark matter. In the parameter space that will be experimentally accessible by KATRIN/TRISTAN, strong X-ray limits need to be relaxed and dark matter overproduction needs to be avoided. We discuss postponing the dark matter production to lower temperatures, a reduced sterile neutrino contribution to dark matter, and a reduction of the branching ratio in photons and active neutrinos through cancellation with a new physics diagram. Both the Dodelson-Widrow and the Shi-Fuller mechanisms for sterile neutrino dark matter production are considered. As a final exotic example, potential consequences of CPT violation are discussed.