Kinetic Decoupling and Small-Scale Structure in Effective Theories of Dark Matter

TL;DR

This paper uses effective field theory to connect dark matter kinetic decoupling with small-scale structure formation, deriving constraints from multiple experimental probes.

Contribution

It introduces an effective field theory framework to relate dark matter decoupling to observable signals across different detection methods.

Findings

Constraints on kinetic decoupling temperature derived from experiments

Limits on smallest protohalo sizes established

Unified approach linking particle physics and cosmological structure

Abstract

The size of the smallest dark matter collapsed structures, or protohalos, is set by the temperature at which dark matter particles fall out of kinetic equilibrium. The process of kinetic decoupling involves elastic scattering of dark matter off of Standard Model particles in the early universe, and the relevant cross section is thus closely related to the cross section for dark matter scattering off of nuclei (direct detection) but also, via crossing symmetries, for dark matter pair production at colliders and for pair annihilation. In this study, we employ an effective field theoretic approach to calculate constraints on the kinetic decoupling temperature, and thus on the size of the smallest protohalos, from a variety of direct, indirect and collider probes of particle dark matter.