Limits on Spin-Dependent WIMP-Nucleon Cross Sections from 225 Live Days of XENON100 Data

We present new experimental constraints on the elastic, spin-dependent WIMP-nucleon cross section using recent data from the XENON100 experiment, operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 224.6 live $\mathrm{\text{days}}\times 34\mathrm{kg}$ of exposure acquired during 2011 and 2012 revealed no excess signal due to axial-vector WIMP interactions with ${}^{129}\mathrm{Xe}$ and ${}^{131}\mathrm{Xe}$ nuclei. This leads to the most stringent upper limits on WIMP-neutron cross sections for WIMP masses above $6\mathrm{GeV}/c^2$, with a minimum cross section of $3.5\times {10}^{-40}{\mathrm{cm}}^2$ at a WIMP mass of $45\mathrm{GeV}/c^2$, at 90% confidence level.

Figure 1

Structure functions for ${}^{129}\mathrm{Xe}$ (top) and ${}^{131}\mathrm{Xe}$ (bottom) for the case of neutron (plain) and proton (dashed) couplings, as a function of recoil energy using the calculations of Ressell and Dean [14], Toivanen et al. [16], and Menendez et al. [9]. The difference is most significant in the case of the proton coupling for the Toivanen et al. results.

Figure 2

XENON100 90% C.L. upper limits on the WIMP SD cross section on neutrons (top) and protons (bottom) using Menendez et al. [9]. The $1\sigma$ ($2\sigma$) uncertainty on the expected sensitivity of this run is show as a green (yellow) band. Also shown are results from XENON10 [24] (using Ressel and Dean [14]), CDMS [25, 26], ZEPLIN-III [21, 27] (using Toivanen et al. [16] and Ressel and Dean [14] for the neutron and proton case, respectively), PICASSO [28], COUPP [29], SIMPLE [30], KIMS [31], IceCube [32] in the hard ($W^{+}$ $W^{-}$, ${\tau }^{+}$ ${\tau }^{-}$ for WIMP masses $<80.4\mathrm{GeV}/c^2$), and soft ($b\overline{b}$) annihilation channels.

Figure 3

The ratio of upper limits calculated with the Ressell and Dean [14] and the Toivanen et al. [16] results for the structure functions to the ones obtained using Menendez et al. [9] for the case of neutron (top) and proton (bottom) couplings, along with the theoretical uncertainty band due to chiral two-body currents [9].