The effect of quark interactions on dark matter kinetic decoupling and the mass of the smallest dark halos

TL;DR

This paper investigates how quark interactions influence dark matter kinetic decoupling, significantly affecting the predicted size of the smallest dark matter halos by connecting particle physics models with astrophysical observations.

Contribution

It demonstrates the importance of including DM-quark interactions in models, showing they can substantially alter the estimated minimum halo mass.

Findings

Adding DM-quark interactions more than doubles the smallest halo mass in MSSM.

Bounds on halo size derived from collider and direct detection data.

Quark interactions are crucial for accurate dark matter small-scale structure predictions.

Abstract

The kinetic decoupling of dark matter (DM) from the primordial plasma sets the size of the first and smallest dark matter halos. Studies of the DM kinetic decoupling have hitherto mostly neglected interactions between the DM and the quarks in the plasma. Here we illustrate their importance using two frameworks: a version of the Minimal Supersymmetric Standard Model (MSSM) and an effective field theory with effective DM-quark interaction operators. We connect particle physics and astrophysics obtaining bounds on the smallest dark matter halo size from collider data and from direct dark matter search experiments. In the MSSM framework, adding DM-quark interactions to DM-lepton interactions more than doubles the smallest dark matter halo mass in a wide range of the supersymmetric parameter space.