Revisiting XENON100's Constraints (and Signals?) For Low-Mass Dark Matter

TL;DR

This paper reexamines XENON100's constraints on low-mass dark matter, considering uncertainties, and suggests the observed events could be consistent with signals from dark matter particles in the 7-10 GeV range, predicting potential detection by LUX.

Contribution

It introduces a revised analysis of XENON100 data, accounting for uncertainties, and proposes that observed events may be compatible with low-mass dark matter signals, challenging previous constraints.

Findings

XENON100's two nuclear recoil events could originate from low-mass dark matter.

Adjusting scintillation efficiency and signal suppression makes dark matter interpretation plausible.

LUX should observe dark matter signals at a rate of 3-24 events per month.

Abstract

Although observations made with the CoGeNT and CDMS experiments have been interpreted as possible signals of low-mass (~7-10 GeV) dark matter particles, constraints from the XENON100 collaboration appear to be incompatible with this hypothesis, at least at face value. In this paper, we revisit XENON100's constraint on dark matter in this mass range, and consider how various uncertainties and assumptions made might alter this conclusion. We also note that while XENON100's two nuclear recoil candidates each exhibit very low ratios of ionization-to-scintillation signals, making them difficult to attribute to known electronic or neutron backgrounds, they are consistent with originating from dark matter particles in the mass range favored by CoGeNT and CDMS. We argue that with lower, but not implausible, values for the relative scintillation efficiency of liquid xenon (L_eff), and the suppression of the scintillation signal in liquid xenon at XENON100's electric field (S_nr), these two events could consistently arise from dark matter particles with a mass and cross section in the range favored by CoGeNT and CDMS. If this interpretation is correct, we predict that the LUX experiment, with a significantly higher light yield than XENON100, should observe dark matter induced events at an observable rate of ~3-24 per month.