The traditional approach for WIMP nucleus interaction studies in direct detection experiment is to consider just two types of interactions, the spin independent (SI) and the spin dependent (SD) ones. However, these are not the only types of interactions possible. In recent years, a non-relativistic effective field theory approach has been studied. In this framework, 14 new interaction operators arise. These operators include the SI and SD ones among others. Some of these new operators are momentum dependent and predict a non-exponential event rate as function of energy, in contrast to the traditional expected signals. Moreover, some of these operators predict energy recoils above the upper threshold of the standard analyses done in direct detection experiments. For XENON100, this threshold is 43keV (nuclear recoil).

In this analysis, we extend the upper energy threshold up to ~240 keV. This value is dictated by low statistics in calibration data above it. We divide our signal region into two regimes, low recoil energy, on which we perform the same “standard” analysis done for the SI and SD cases, and high recoil energy, which is the main focus of this work.

Summary of regions of interest, backgrounds, and observed data. ER calibration data, namely 60Co and 232Th data, is shown as light cyan dots. NR calibration data (241AmBe) is shown as light red dots. Dark matter search data is shown as black dots. The red line is the threshold between the low and high energy channels. The lines in blue are the bands. For the low energy channel these are operator and mass dependent, but are shown here for a 50 GeV/c^2 WIMP using the O1 operator. For the high-energy region, the nine analysis bins are presented also in blue lines.

We find that our data is compatible with background expectations. Using a binned profile likelihood, we thus produce 90% CL exclusion limits for both elastic scattering and inelastic WIMP scattering for each operator. Find the preprint of this study on the arxiv.

The XENON100 limits (90% CLS) on isoscalar dimensionless coupling for all elastic scattering EFT operators. The
limits are indicated in solid black. The expected sensitivity is shown in green and yellow (1σ and 2σ respectively). Limits from CDMS-II Si, CDMS-II Ge, and SuperCDMS [30] are presented as blue asterisks, green triangles, and orange rectangles, respectively.