Sommerfeld Enhancement from Multiple Mediators

TL;DR

This paper investigates how multiple mediators in a hidden-sector confining model can enhance the Sommerfeld effect, with potential implications for dark matter interactions and observable signals.

Contribution

It demonstrates that a tower of mediators can significantly increase Sommerfeld enhancement, especially in models with a weakly-coupled dual and high conformal symmetry.

Findings

Off-resonant enhancement can increase by ~20% under certain conditions.

Larger enhancements are achievable with lower UV scales due to stronger tower couplings.

Enhancement depends on the structure of the mediator tower and conformal symmetry properties.

Abstract

We study the Sommerfeld enhancement experienced by a scattering object that couples to a tower of mediators. This can occur in, e.g., models of secluded dark matter when the mediator scale is generated naturally by hidden-sector confinement. Specializing to the case of a confining CFT, we show that off-resonant values of the enhancement can be increased by ~ 20% for cases of interest when (i) the (strongly-coupled) CFT admits a weakly-coupled dual description and (ii) the conformal symmetry holds up to the Planck scale. Larger enhancements are possible for lower UV scales due to an increase in the coupling strength of the tower.