Search for Event Rate Modulation in XENON100 Electronic Recoil Data

TL;DR

This study searched for periodic variations in electronic recoil event rates in XENON100 data to identify potential dark matter signals, but found no significant modulation consistent with dark matter interpretations.

Contribution

It provides the first detailed search for periodic event rate modulation in XENON100 data, setting constraints on dark matter models with annual modulation signatures.

Findings

No statistically significant periodic modulation detected.

The observed local significance for annual modulation is 2.8 sigma.

Dark matter interpretation of DAMA/LIBRA signal is excluded at 4.8 sigma.

Abstract

We have searched for periodic variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an un-binned profile likelihood analysis to identify any periodicity up to 500 days. We find a global significance of less than 1 sigma for all periods suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8 sigma, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of WIMPs to electrons is excluded at 4.8 sigma.