Reconstructing WIMP Properties in Direct Detection Experiments Including Galactic Dark Matter Distribution Uncertainties

TL;DR

This paper introduces a method to accurately determine WIMP properties in direct detection experiments by accounting for uncertainties in the Milky Way's dark matter distribution, improving reliability of results.

Contribution

The authors develop a novel approach that marginalizes over Milky Way dark matter uncertainties, enabling unbiased WIMP property reconstruction in future large-scale detectors.

Findings

Local dark matter density constrained to ~20% accuracy

Bias in WIMP cross section can be corrected by marginalizing over MW potential parameters

Method applicable to various detector technologies and halo models

Abstract

We present a new method for determining Weakly Interacting Massive Particle (WIMP) properties in future tonne scale direct detection experiments which accounts for uncertainties in the Milky Way (MW) smooth dark matter distribution. Using synthetic data on the kinematics of MW halo stars matching present samples from the Sloan Digital Sky Survey, complemented by local escape velocity constraints, we demonstrate that the local dark matter density can be constrained to approximately 20% accuracy. For low mass WIMPs, we find that a factor of two error in the assumed local dark matter density leads to a severely biased reconstruction of the WIMP spin-independent cross section that is incorrect at the 15-sigma level. We show that this bias may be overcome by marginalizing over parameters that describe the MW potential, and use this formalism to project the accuracy attainable on WIMP properties in future 1 tonne Xenon detectors. Our method can be readily applied to different detector technologies and extended to more detailed MW halo models.