Model-Independent Determination of the WIMP Mass from Direct Dark Matter Detection Data

TL;DR

This paper introduces a model-independent method to determine the WIMP mass from direct detection data, avoiding assumptions about WIMP density, velocity distribution, or cross section, requiring signals from at least two different detectors.

Contribution

It presents a novel approach for estimating WIMP mass that is independent of many unknown astrophysical and particle physics parameters, using data from multiple detectors.

Findings

Can determine WIMP mass with ~35% error using 100 events for 50 GeV WIMPs.

Method's accuracy decreases if WIMP mass exceeds the heaviest target nucleus.

Requires signals from at least two detectors with different target nuclei.

Abstract

Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. We develop a model-independent method for determining the mass $m_\chi$ of the WIMP by using data (i.e., measured recoil energies) of direct detection experiments. Our method is independent of the as yet unknown WIMP density near the Earth, of the form of the WIMP velocity distribution, as well as of the WIMP-nucleus cross section. However, it requires positive signals from at least two detectors with different target nuclei. In a background-free environment, $m_\chi \sim 50$ GeV could in principle be determined with an error of $\sim 35%$ with only $2 \times 50$ events; in practice upper and lower limits on the recoil energy of signal events, imposed to reduce backgrounds, can increase the error. The method also loses precision if $m_\chi$ significantly exceeds the mass of the heaviest target nucleus used.