The Warm Dark Matter Doorframe for Light Dark Matter Direct Detection Experiments
Ran Huo, Tao Xu

TL;DR
This paper explores how thermal contact between light dark matter and the visible sector affects structure formation, establishing constraints on dark matter mass from current direct detection experiments and highlighting the implications for future searches.
Contribution
It identifies the interaction responsible for thermal contact in light dark matter and derives detailed bounds on dark matter mass using kinetic decoupling and recasting Lyman-alpha constraints.
Findings
Current bounds require dark matter mass >73 keV
Relaxed bounds allow mass >35 keV for smaller cross sections
Thermal contact imposes a generic 'no go' constraint on light dark matter detection
Abstract
If dark matter has even been in sufficient thermal contact with the visible sector and sufficiently light (), the thermal motion inherited from the visible sector will cause significant free streaming effect which is subject to the structure formation constraint, similar to the benchmark thermal warm dark matter model. Here we identify the interaction responsible for such thermal contact to be the interaction probed by the deep underground dark matter direct detection experiments. With the kinetic decoupling technique on the vs. plot we determine the bound shape in detail, and find that recasting the current Lyman- bound gives a constraint of , and it gets relaxed to for a smaller cross section of with some model dependence. That can…
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Taxonomy
TopicsDark Matter and Cosmic Phenomena · Advanced Thermodynamics and Statistical Mechanics · Scientific Research and Discoveries
