Bound-state formation, dissociation and decays of darkonium with potential non-relativistic Yukawa theory for scalar and pseudoscalar mediators

TL;DR

This paper investigates the formation, dissociation, and decay of darkonium in models with scalar and pseudoscalar mediators using non-relativistic effective field theories, including thermal effects, to understand their impact on dark matter density.

Contribution

It develops a finite-temperature formulation of Yukawa-type dark matter models with scalar and pseudoscalar mediators using NREFTs and pNREFTs, including thermal bound-state rates.

Findings

Bound-state effects can alter dark matter density by up to 35%.

Thermal bound-state formation and dissociation rates are estimated.

The study extends effective field theories to finite temperature for dark matter models.

Abstract

Dark matter models with light mediators featuring sizable interactions among dark particles enjoy an increasing attention in the model building community due to the elegance with which they can potentially explain the scaling relations governing galactic halos and clusters of galaxies. In the present work we continue our study of such models using non-relativistic and potential non-relativistic effective field theories (NREFTs and pNREFTs) and explore the properties of a Yukawa-type model with scalar and pseudoscalar interactions between a low-energetic scalar mediator and heavy dark matter fermions. In particular, we make first steps towards the formulation of such theories at finite temperature by providing the thermal bound-state formation rate and the thermal break-up of bound states from the self-energies of the dark-pair fields, that interact with the thermal environment. We estimate numerically bound-state effects on the dark matter energy density, that provide up to a $35\%$ correction depending on the relative size of the model couplings.