Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data

Area of Science:

• Experimental particle physics
• Astroparticle physics
• Dark matter searches

Background:

• Direct detection experiments aim to observe dark matter particle interactions.
• Electronic recoil events are a key background and potential signal channel.
• Previous analyses suggested potential modulation signals in dark matter detectors.

Purpose of the Study:

• To search for periodic modulation in electronic recoil event rates within the XENON100 detector.
• To investigate potential dark matter electron interactions as a source of observed modulation.
• To exclude or confirm the DAMA/LIBRA annual modulation signal.

Main Methods:

• Analysis of 4 years of XENON100 data (January 2010 - January 2014).
• Application of a profile likelihood method incorporating detector stability and background models.
• Statistical analysis of event time distributions to quantify periodicity significance.

Main Results:

• A weak modulation signature with a period of 431 days was observed in the low energy region (2.0-5.8 keV) with 1.9σ global significance.
• No other significant modulations were detected.
• The significance of an annual modulation signature decreased to 1.8σ when all data was combined.
• The DAMA/LIBRA annual modulation is excluded as a dark matter electron interaction via axial vector coupling at 5.7σ.

Conclusions:

• The XENON100 data does not support a significant annual modulation signal from dark matter electron interactions.
• The observed weak 431-day periodicity requires further investigation.
• This study places strong constraints on certain dark matter interaction models.