Search for neutrinos from annihilation of captured low-mass dark matter particles in the Sun by Super-Kamiokande

TL;DR

This study used Super-Kamiokande data to search for neutrinos from low-mass dark matter annihilation in the Sun, setting new limits on WIMP-proton cross sections and improving detection sensitivity for light WIMPs.

Contribution

The paper introduces an analysis including neutrino events with interaction vertices in the detector, enhancing sensitivity to light WIMPs compared to previous upward-going muon-only methods.

Findings

No significant excess of neutrinos detected from WIMP annihilation.

Set the best current limits on spin-dependent WIMP-proton cross sections below 200 GeV/c^2.

Ruling out some WIMP candidates with spin-independent coupling in the few-GeV/c^2 range.

Abstract

Super-Kamiokande (SK) can search for weakly interacting massive particles (WIMPs) by detecting neutrinos produced from WIMP annihilations occurring inside the Sun. In this analysis, we include neutrino events with interaction vertices in the detector in addition to upward-going muons produced in the surrounding rock. Compared to the previous result, which used the upward-going muons only, the signal acceptances for light (few-GeV/$c^2$ $\sim$ 200-GeV/$c^2$) WIMPs are significantly increased. We fit 3903 days of SK data to search for the contribution of neutrinos from WIMP annihilation in the Sun. We found no significant excess over expected atmospheric-neutrino background and the result is interpreted in terms of upper limits on WIMP-nucleon elastic scattering cross sections under different assumptions about the annihilation channel. We set the current best limits on the spin-dependent (SD) WIMP-proton cross section for WIMP masses below 200 GeV/$c^2$ (at 10 GeV/$c^2$, 1.49$\times 10^{-39}$ cm$^2$ for $\chi\chi\rightarrow b \bar{b}$ and 1.31$\times 10^{-40}$ cm$^2$ for $\chi\chi\rightarrow\tau^+\tau^-$ annihilation channels), also ruling out some fraction of WIMP candidates with spin-independent (SI) coupling in the few-GeV/$c^2$ mass range.