Beyond the Veil: Charting WIMP Territories at the Neutrino Floor

TL;DR

This paper develops theoretical benchmarks for WIMP dark matter detection near the neutrino background, exploring various production mechanisms and cosmological scenarios to guide future experimental efforts.

Contribution

It provides a comprehensive theoretical framework for WIMP detection at the neutrino floor, including new insights into suppressed cross-sections and non-standard cosmologies.

Findings

Identification of parameter regions with suppressed detection cross-sections

Demonstration of freeze-in scenarios producing detectable FIMPs

Impact of early universe cosmology on relic density and detection prospects

Abstract

We establish comprehensive theoretical benchmarks for Weakly Interacting Massive Particles (WIMPs) accessible to ultimate direct detection experiments, focusing on the challenging parameter space between current experimental limits and the irreducible neutrino background. We systematically examine both thermal freeze-out and freeze-in production mechanisms across a range of simplified dark matter models, including s-channel scalar and vector portals, t-channel mediator scenarios, and electroweakly interacting multiplets. For thermal relics, we identify parameter regions where suppressed direct detection cross-sections naturally arise through momentum-dependent interactions and blind-spot configurations, while maintaining the correct relic abundance. We extensively investigate freeze-in scenarios, demonstrating how feebly interacting massive particles (FIMPs) in portal models can populate experimentally accessible parameter space despite their ultra-weak couplings. Additionally, we explore how non-standard cosmological histories including early matter domination and fast-expanding Universe scenarios can dramatically alter the relationship between relic density and detection prospects, opening new avenues for discovery. Our analysis provides a roadmap for next-generation experiments approaching the neutrino floor, highlighting complementary detection strategies and identifying the most promising theoretical targets for ultimate sensitivity dark matter searches. These benchmarks establish the theoretical foundation for the final push toward comprehensive coverage of well-motivated WIMP parameter space.