First direct detection limits on sub-GeV dark matter from XENON10

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• Dark matter remains undetected, with its properties largely unknown.
• Direct detection experiments typically search for WIMP candidates above GeV masses.
• Light dark matter (MeV-GeV) interactions with electrons are a viable, yet less explored, detection channel.

Purpose of the Study:

• To establish the first direct detection limits for dark matter in the MeV to GeV mass range.
• To constrain the dark matter-electron scattering cross-section using existing experimental data.
• To demonstrate the sensitivity of direct detection experiments to sub-GeV dark matter candidates.

Main Methods:

• Utilized 15 kg·day of data from the XENON10 experiment, collected in 2006.
• Analyzed single- and few-electron events resulting from dark matter-electron scattering.
• Set upper limits on the dark matter-electron scattering cross-section at 90% confidence level.

Main Results:

• Established the strongest direct detection limits for dark matter in the MeV to GeV mass range.
• Achieved a limit of σ(e)<3×10⁻³⁸ cm² at 100 MeV.
• Constrained dark matter masses between 20 MeV and 1 GeV with σ(e)<10⁻³⁷ cm².

Conclusions:

• Direct detection experiments are sensitive to dark matter candidates below the GeV scale.
• The XENON10 data provides a proof of principle for searching light dark matter via electron scattering.
• Future experiments can be optimized to further probe the MeV-GeV dark matter parameter space.