title: Spin-Dependent Weakly-Interacting-Massive-Particle-Nucleon Cross Section Limits from First Data of PandaX-II Experiment.
abstract: New constraints are presented on the spin-dependent weakly-interacting-massive-particle- (WIMP-)nucleon interaction from the PandaX-II experiment, using a data set corresponding to a total exposure of 3.3×10^{4}  kg day. Assuming a standard axial-vector spin-dependent WIMP interaction with ^{129}Xe and ^{131}Xe nuclei, the most stringent upper limits on WIMP-neutron cross sections for WIMPs with masses above 10  GeV/c^{2} are set in all dark matter direct detection experiments. The minimum upper limit of 4.1×10^{-41}  cm^{2} at 90% confidence level is obtained for a WIMP mass of 40  GeV/c^{2}. This represents more than a factor of 2 improvement on the best available limits at this and higher masses. These improved cross-section limits provide more stringent constraints on the effective WIMP-proton and WIMP-neutron couplings.
authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: School of Physics, Peking University, Beijing 100871, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800 Shanghai, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.|Center of High Energy Physics, Peking University, Beijing 100871, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.|Center of High Energy Physics, Peking University, Beijing 100871, China.|Department of Physics, University of Maryland, College Park, Maryland 20742, USA.|T. D. Lee Institute, Shanghai 200240, China.
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authors.affiliation: School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800 Shanghai, China.
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authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800 Shanghai, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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authors.affiliation: Center of High Energy Physics, Peking University, Beijing 100871, China.|Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.
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authors.affiliation: INPAC and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai Laboratory for Particle Physics and Cosmology, Shanghai 200240, China.|Department of Physics, Tsinghua University, Beijing 100084, China.
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