Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T.

Area of Science:

• * Particle Physics
• * Cosmology
• * Astrophysics

Background:

• * The nature of dark matter remains one of the most significant unsolved problems in modern physics.
• * Weakly interacting massive particles (WIMPs) are leading candidates for dark matter.
• * Experimental searches for WIMPs typically involve detecting their rare interactions with ordinary matter.

Purpose of the Study:

• * To present the first experimental results on spin-dependent elastic WIMP-nucleon scattering using the XENON1T detector.
• * To constrain WIMP-nucleon interaction cross-sections, particularly for proton-only and neutron-only scenarios.
• * To probe new parameter space for dark matter theories.

Main Methods:

• * Analysis of the full ton-year exposure data from the XENON1T dark matter search experiment.
• * Application of a profile likelihood ratio analysis to set exclusion limits.
• * Focus on spin-dependent scattering interactions between WIMPs and nucleons.

Main Results:

• * No significant signal excess attributable to WIMP interactions was observed.
• * The study established the most stringent exclusion limits to date on the WIMP-neutron cross-section, reaching a minimum of 6.3×10⁻⁴² cm² at 30 GeV/c² and 90% confidence level.
• * The results were compared with existing constraints from collider searches.

Conclusions:

• * The XENON1T experiment provides the strongest constraints on spin-dependent WIMP-nucleon interactions to date.
• * The findings exclude a significant portion of the parameter space for dark matter models, specifically those involving an isoscalar theory with an axial-vector mediator.
• * The results highlight the ongoing progress in WIMP detection sensitivity and the search for dark matter candidates.