Hazma Meets HERWIG4DM: Precision Gamma-Ray, Neutrino, and Positron Spectra for Light Dark Matter

TL;DR

Hazma 2 is an open-source tool that accurately computes photon, neutrino, and positron spectra from light dark matter annihilation and decay, bridging low and moderate energy regimes for indirect detection analyses.

Contribution

It introduces Hazma 2, combining two advanced codes to extend accurate spectral calculations up to 1.5 GeV for dark matter searches, filling a gap between existing tools.

Findings

Provides example spectra and branching ratios for dark matter models.

Offers observational constraints from gamma-ray data.

Demonstrates improved accuracy over existing codes at certain energy ranges.

Abstract

We present a new open-source package, Hazma 2, that computes accurate spectra relevant for indirect dark matter searches for photon, neutrino, and positron production from vector-mediated dark matter annihilation and for spin-one dark matter decay. The tool bridges across the regimes of validity of two state of the art codes: Hazma 1, which provides an accurate description below hadronic resonances up to center-of-mass energies around 250 MeV, and HERWIG4DM, which is based on vector meson dominance and measured form factors, and accurate well into the few GeV range. The applicability of the combined code extends to approximately 1.5 GeV, above which the number of final state hadrons off of which we individually compute the photon, neutrino, and positron yield grows exceedingly rapidly. We provide example branching ratios, particle spectra and conservative observational constraints from existing gamma-ray data for the well-motivated cases of decaying dark photon dark matter and vector-mediated fermionic dark matter annihilation. Finally, we compare our results to other existing codes at the boundaries of their respective ranges of applicability. Hazma 2 is freely available on GitHub.