Gamma-rays from Dark Showers with Twin Higgs Models

TL;DR

This paper explores a twin Higgs model where dark matter annihilates into a dark shower of twin hadrons, producing gamma rays that could explain the Fermi-LAT galactic center excess while satisfying cosmological and collider constraints.

Contribution

It introduces a hadrosymmetric twin Higgs scenario with detailed simulations of dark showers and gamma-ray spectra, linking dark matter properties to observable signals and collider prospects.

Findings

Dark shower simulations match the galactic center gamma-ray excess.

Parameter space aligns with observed dark matter abundance and minimal fine-tuning.

Additional SM-twin sector mediators are within reach of current or future experiments.

Abstract

We consider a twin WIMP scenario whose twin sector contains a full dark copy of the SM hadrons, where the lightest twin particles are twin pions. By analogy to the standard WIMP paradigm, the dark matter (DM) freezes out through twin electroweak interactions, and annihilates into a dark shower of light twin hadrons. These are either stable or decay predominantly to standard model (SM) photons. We show that this 'hadrosymmetric' scenario can be consistent with all applicable astrophysical, cosmological and collider constraints. In order to decay the twin hadrons before the big-bang nucleosynthesis epoch, an additional portal between the SM and twin sector is required. In most cases we find this additional mediator is within reach of either the LHC or future intensity frontier experiments. Furthermore, we conduct simulations of the dark shower and consequent photon spectra. We find that fits of these spectra to the claimed galactic center gamma-ray excess seen by Fermi-LAT non-trivially coincide with regions of parameter space that both successfully generate the observed DM abundance and exhibit minimal fine-tuning.