Results of a Search for Sub-GeV Dark Matter Using 2013 LUX Data.

Area of Science:

• Particle Physics
• Astrophysics
• Cosmology
• Dark Matter Detection

Background:

• Detecting sub-GeV dark matter (DM) via nuclear recoils in liquid xenon detectors is challenging due to energy transfer below the detection threshold.
• Simultaneous emission of bremsstrahlung photons or Migdal electrons can create detectable electron recoil signatures.
• These signals allow liquid xenon detectors to utilize scintillation and ionization signals for previously invisible nuclear recoil events.

Purpose of the Study:

• To constrain spin-independent dark matter-nucleon scattering for dark matter particles with masses between 0.4-5 GeV/c².
• To extend the reach of liquid xenon detectors to lower dark matter masses.
• To investigate dark matter scattering mediated by four different classes of mediators.

Main Methods:

• Utilized 1.4 x 10⁴ kg-day of exposure data from the 2013 Large Underground Xenon (LUX) experiment.
• Analyzed electron recoil signals, including those from the Migdal effect, to identify dark matter interactions.
• Applied analysis techniques to leverage both scintillation and ionization signals for enhanced sensitivity.

Main Results:

• Established new constraints on spin-independent dark matter-nucleon scattering for dark matter particles in the 0.4-5 GeV/c² mass range.
• Demonstrated the capability of liquid xenon detectors to probe lower dark matter mass regions than previously achieved.
• Provided constraints for four distinct classes of potential dark matter mediators.

Conclusions:

• The Migdal effect provides a viable channel for detecting low-mass dark matter in liquid xenon experiments.
• The LUX experiment's data analysis successfully extended sensitivity to lower dark matter masses.
• This work advances the search for dark matter by enabling liquid xenon detectors to probe previously inaccessible parameter space.