Search for Light Dark Matter in Low-Energy Ionization Signals from XENONnT

Area of Science:

• Particle Physics
• Astrophysics
• Cosmology

Background:

• The nature of dark matter remains one of the most significant unsolved problems in physics.
• Direct detection experiments aim to observe the faint signals produced by dark matter particles interacting with ordinary matter.
• The XENONnT experiment is a leading dark matter direct detection facility.

Purpose of the Study:

• To conduct a blinded search for dark matter using single- and few-electron signals in the XENONnT detector.
• To derive 90% confidence upper limits on dark matter-electron interactions for various theoretical models.
• To set new stringent limits on specific dark matter candidates, such as axionlike particles and dark photons.

Main Methods:

• Utilized data from the first science run of the XENONnT experiment.
• Employed a novel, physics model-dependent detector response framework for signal analysis.
• Performed a blinded analysis to mitigate potential biases.
• Considered both standard halo model and solar up-scattered dark matter scenarios.
• Investigated heavy and light mediator models for dark matter-electron interactions.

Main Results:

• Derived 90% confidence upper limits on dark matter-electron scattering cross-sections.
• Set stringent new limits on dark matter-electron scattering via a heavy mediator in the mass range of 10-20 MeV/c².
• Established new limits on the electron absorption of axionlike particles and dark photons for dark matter particle masses below 0.03 keV/c².

Conclusions:

• The XENONnT experiment has provided significant constraints on dark matter-electron interactions.
• The results exclude certain parameter spaces for light and heavy dark matter candidates.
• This study demonstrates the power of novel analysis techniques in direct detection experiments.