Hidden MeV-Scale Dark Matter in Neutrino Detectors

TL;DR

This paper investigates the potential for neutrino detectors to directly detect light MeV-scale dark matter through specific interactions, identifying a viable operator and estimating the detector sensitivity to new physics scales up to 100 TeV.

Contribution

It provides a model-independent analysis of dark matter interactions in neutrino detectors, identifying a promising operator and estimating experimental reach for new physics scales.

Findings

One operator enables detectable interactions for dark matter mass below the pion mass.

Super-Kamiokande can probe new physics scales up to approximately 100 TeV.

Existing astrophysical constraints are reviewed and considered in the analysis.

Abstract

The possibility of direct detection of light fermionic dark matter in neutrino detectors is explored from a model-independent standpoint. We consider all operators of dimension six or lower which can contribute to the interaction $\bar{f} p \to e^+ n$, where $f$ is a dark Majorana or Dirac fermion. Constraints on these operators are then obtained from the $f$ lifetime and its decays which produce visible $\gamma$ rays or electrons. We find one operator which would allow $\bar{f} p \to e^+ n$ at interesting rates in neutrino detectors, as long as $m_f \lesssim m_{\pi}$. The existing constraints on light dark matter from relic density arguments, supernova cooling rates, and big-bang nucleosynthesis are then reviewed. We calculate the cross-section for $\bar{f} p \to e^+ n$ in neutrino detectors implied by this operator, and find that Super-K can probe the new physics scale $\Lambda$ for this interaction up to ${\cal O}(100 {TeV})$