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Register a new userVelocity independent constraints on spin-dependent DM-nucleon interactions from IceCube and PICO
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Adopting the Standard Halo Model (SHM) of an isotropic Maxwellian velocity distribution for dark matter (DM) particles in the Galaxy, the most stringent current constraints on their spin-dependent scattering cross-section with nucleons come from the IceCube neutrino observatory and the PICO-60 C$_3$F$_8$ superheated bubble chamber experiments. The former is sensitive to high energy neutrinos from the self-annihilation of DM particles captured in the Sun, while the latter looks for nuclear recoil events from DM scattering off nucleons. Although slower DM particles are more likely to be captured by the Sun, the faster ones are more likely to be detected by PICO. Recent N-body simulations suggest significant deviations from the SHM for the smooth halo component of the DM, while observations hint at a dominant fraction of the local DM being in substructures. We use the method of Ferrer et al. (2015) to exploit the complementarity between the two approaches and derive conservative constraints on DM-nucleon scattering. Our results constrain $sigma_{mathrm{SD}} lesssim 3 times 10^{-39} mathrm{cm}^2$ (6 $ times 10^{-38} mathrm{cm}^2$) at $gtrsim 90%$ C.L. for a DM particle of mass 1~TeV annihilating into $tau^+ tau^-$ ($bbar{b}$) with a local density of $rho_{mathrm{DM}} = 0.3~mathrm{ GeV/cm}^3$. The constraints scale inversely with $rho_{mathrm{DM}}$ and are independent of the DM velocity distribution.
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We present PandaX-II constraints on candidate WIMP-nucleon effective interactions involving the nucleon or WIMP spin, including, in addition to standard axial spin-dependent (SD) scattering, various couplings among vector and axial currents, magnetic and electric dipole moments, and tensor interactions. The data set corresponding to a total exposure of 54-ton-days is reanalyzed to determine constraints as a function of the WIMP mass and isospin coupling. We obtain WIMP-nucleon cross section bounds of $rm 1.6 times 10^{-41} cm^2$ and $rm 9.0 times 10^{-42} cm^2$ ($90%$ c.l.) for neutron-only SD and tensor coupling, respectively, for a mass $M_mathrm{WIMP} sim {rm 40~GeV}/c^2$. The SD limits are the best currently available for $M_mathrm{WIMP} > {rm 40~GeV}/c^2$. We show that PandaX-II has reached a sensitivity sufficient to probe a variety of other candidate spin-dependent interactions at the weak scale.
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