A Bayesian view of the current status of dark matter direct searches

TL;DR

This paper applies Bayesian methods to current dark matter direct detection data, accounting for systematic and astrophysical uncertainties, revealing that previous exclusion claims may be less constraining and that experimental compatibility is challenging.

Contribution

It introduces a Bayesian framework for analyzing dark matter search data, incorporating uncertainties and assessing experimental compatibility in a novel, systematic way.

Findings

Uncertainties in Xenon100 scintillation efficiency weaken exclusion limits.

Astrophysical uncertainties do not easily reconcile DAMA and CoGeNT regions.

High sodium quenching factor for DAMA is favored for compatibility.

Abstract

Bayesian statistical methods offer a simple and consistent framework for incorporating uncertainties into a multi-parameter inference problem. In this work we apply these methods to a selection of current direct dark matter searches. We consider the simplest scenario of spin-independent elastic WIMP scattering, and infer the WIMP mass and cross-section from the experimental data with the essential systematic uncertainties folded into the analysis. We find that when uncertainties in the scintillation efficiency of Xenon100 have been accounted for, the resulting exclusion limit is not sufficiently constraining to rule out the CoGeNT preferred parameter region, contrary to previous claims. In the same vein, we also investigate the impact of astrophysical uncertainties on the preferred WIMP parameters. We find that within the class of smooth and isotropic WIMP velocity distributions, it is difficult to reconcile the DAMA and the CoGeNT preferred regions by tweaking the astrophysics parameters alone. If we demand compatibility between these experiments, then the inference process naturally concludes that a high value for the sodium quenching factor for DAMA is preferred.