Search for the Light WIMP Captured in the Sun Using Contained Events in Super-Kamiokande

Super-Kamiokande can search for dark matter by detecting neutrinos and muons which are produced by WIMP pair annihilations occur inside the Sun. The huge gravity and hydrogen-rich composition of the Sun combined with high sensitivity of Super-Kamiokande for low energy(few GeV) neutrinos allow us good sensitivity to light(few GeV to few 10 GeV) WIMP dark matter, especially for spin-dependent coupling case. In this analysis, we increased signal acceptance by using fully-contained and partially-contained neutrino events added to up-going muons in Super-Kamiokande. We also used minimum c 2 method to use energy, direction and flavor informations. We fitted Super-Kamiokande I-IV data to find the allowed contribution of WIMP-induced neutrino events added to large back-ground of atmospheric neutrino events. As a result, we found no signal observed and the null result was interpreted as upper limit on the spin-dependent (SD) WIMP-proton elastic scattering cross-section for cc! b¯ and cc! t + t WIMP annihilation channels. We set current best limit for WIMP mass below 100 GeV.