Search for Cosmic-ray Boosted Sub-GeV Dark Matter using Recoil Protons at Super-Kamiokande

TL;DR

This study searches for cosmic-ray boosted sub-GeV dark matter via proton recoils at Super-Kamiokande, setting new limits on dark matter interactions and being the first to use directional hadron detection for such a search.

Contribution

It introduces the first experimental search for boosted dark matter with hadrons using directional information and provides the most stringent limits on the interaction cross-section in the specified mass range.

Findings

No excess proton recoils observed above background.

Set the most stringent limits on dark matter-nucleon cross-section.

Excluded cross-sections between 10^{-33} and 10^{-27} cm^2 for 10 MeV/c^2 to 1 GeV/c^2 mass.

Abstract

We report a search for cosmic-ray boosted dark matter with protons using the 0.37 megaton$\times$years data collected at Super-Kamiokande experiment during the 1996-2018 period (SKI-IV phase). We searched for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross-section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross-section between $10^{-33}\text{ cm}^{2}$ and $10^{-27}\text{ cm}^{2}$ for dark matter mass from 10 MeV/$c^2$ to 1 GeV/$c^2$.