Determining Ratios of WIMP-Nucleon Cross Sections from Direct Dark Matter Detection Data

TL;DR

This paper introduces methods to determine ratios of WIMP-nucleon cross sections from direct detection data without prior assumptions on WIMP mass or halo properties, using measured recoil energies and event counts.

Contribution

It presents novel techniques for extracting WIMP-nucleon cross section ratios considering both spin-independent and spin-dependent interactions without prior knowledge of WIMP mass or halo distribution.

Findings

Methods can determine cross section ratios from minimal data

No assumptions needed about WIMP mass or local halo properties

Applicable with exponential recoil spectrum shape

Abstract

Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. So far the usual procedure for constraining the WIMP-nucleon cross sections in direct Dark Matter detection experiments have been to fit the predicted event rate based on some model(s) of the Galactic halo and of WIMPs to experimental data. One has to assume whether the spin-independent (SI) or the spin-dependent (SD) WIMP-nucleus interaction dominates, and results of such data analyses are also expressed as functions of the as yet unknown WIMP mass. In this article, I introduce methods for extracting information on the WIMP-nucleon cross sections by considering a general combination of the SI and SD interactions. Neither prior knowledge about the local density and the velocity distribution of halo WIMPs nor about their mass is needed. Assuming that an exponential-like shape of the recoil spectrum is confirmed from experimental data, the required information are only the measured recoil energies (in low energy ranges) and the number of events in the first energy bin from two or more experiments.