Dark Matter Results From 54-Ton-Day Exposure of PandaX-II Experiment

TL;DR

This paper reports a new search for WIMPs using PandaX-II data, setting the most stringent upper limits on WIMP-nucleon cross sections for masses above 100 GeV/c², with improved background reduction and exposure.

Contribution

It presents the latest results from PandaX-II with increased exposure and reduced background, providing the most stringent constraints on WIMP interactions for certain mass ranges.

Findings

No excess events observed above background.

Set new upper limits on WIMP-nucleon cross section.

Achieved the lowest exclusion at 8.6×10⁻⁴⁷ cm² for 40 GeV/c² WIMPs.

Abstract

We report a new search of weakly interacting massive particles (WIMPs) using the combined low background data sets in 2016 and 2017 from the PandaX-II experiment in China. The latest data set contains a new exposure of 77.1 live day, with the background reduced to a level of 0.8$\times10^{-3}$ evt/kg/day, improved by a factor of 2.5 in comparison to the previous run in 2016. No excess events were found above the expected background. With a total exposure of 5.4$\times10^4$ kg day, the most stringent upper limit on spin-independent WIMP-nucleon cross section was set for a WIMP with mass larger than 100 GeV/c$^2$, with the lowest exclusion at 8.6$\times10^{-47}$ cm$^2$ at 40 GeV/c$^2$.