Perturbative Unitarity Constraints on Gauge Portals

TL;DR

This paper derives upper bounds on the masses of dark matter and associated gauge bosons in gauge portal models using perturbative unitarity, providing constraints relevant for future experiments and model building.

Contribution

It introduces a method to constrain dark matter and mediator masses in gauge portal models based on unitarity, extending previous bounds and guiding experimental searches.

Findings

Upper bound of 9 TeV for dark matter mass with both dark Higgs and gauge bosons involved

Upper bounds of 10 TeV and 16 TeV for dark Higgs and gauge boson masses, respectively

Constraints on dark matter and mediator masses inform future detection efforts.

Abstract

Dark matter that was once in thermal equilibrium with the Standard Model is generally prohibited from obtaining all of its mass from the electroweak phase transition. This implies a new scale of physics and mediator particles to facilitate dark matter annihilation. In this work, we focus on dark matter that annihilates through a generic gauge boson portal. We show how partial wave unitarity places upper bounds on the dark gauge boson, dark Higgs and dark matter masses. Outside of well-defined fine-tuned regions, we find an upper bound of 9 TeV for the dark matter mass when the dark Higgs and dark gauge bosons both facilitate the dark matter annihilations. In this scenario, the upper bound on the dark Higgs and dark gauge boson masses are 10 TeV and 16 TeV, respectively. When only the dark gauge boson facilitates dark matter annihilations, we find an upper bound of 3 TeV and 6 TeV for the dark matter and dark gauge boson, respectively. Overall, using the gauge portal as a template, we describe a method to not only place upper bounds on the dark matter mass but also on the new particles with Standard Model quantum numbers. We briefly discuss the reach of future accelerator, direct and indirect detection experiments for this class of models.