Dark matter search results from the commissioning run of PandaX-II

We present the results of a search for weakly interacting massive particles (WIMPs) from the commissioning run of the PandaX-II experiment located at the China Jinping Underground Laboratory. A WIMP search data set with an exposure of 306 ×19.1 kg -day was taken, while its dominant <mml:mmultiscripts>Kr 85 </mml:mmultiscripts> background was used as the electron recoil calibration. No WIMP candidates are identified, and a 90% upper limit is set on the spin-independent elastic WIMP-nucleon cross section with a lowest excluded cross section of 2.97 ×10^-45 cm² at a WIMP mass of 44.7 GeV /c² .