The Strong Force meets the Dark Sector: a robust estimate of QCD uncertainties for anti-matter dark matter searches

TL;DR

This paper quantifies QCD uncertainties in antimatter spectra from dark-matter annihilation, significantly impacting the interpretation of indirect detection signals and providing tools for more accurate dark-matter parameter estimation.

Contribution

It presents a comprehensive analysis of QCD uncertainties using Pythia 8 variations, offering a conservative estimate and practical tools for dark-matter indirect detection studies.

Findings

QCD uncertainties can cause up to 40 GeV variation in dark-matter mass estimates.

Uncertainties can lead to about 10% variation in annihilation cross section.

Provided tabulated spectra and code for incorporating QCD uncertainties in dark-matter analyses.

Abstract

In dark-matter annihilation channels to hadronic final states, stable particles -- such as positrons, photons, antiprotons, and antineutrinos -- are produced via complex sequences of phenomena including QED/QCD radiation, hadronisation, and hadron decays. These processes are normally modelled by Monte Carlo event generators whose limited accuracy imply intrinsic QCD uncertainties on the predictions for indirect-detection experiments like Fermi-LAT, Pamela, IceCube or AMS-02. In this article, we perform a complete analysis of QCD uncertainties in antimatter spectra from dark-matter annihilation, based on parametric variations of the Pythia 8 event generator. After performing several retunings of light-quark fragmentation functions, we define a set of variations that span a conservative estimate of the QCD uncertainties. We estimate the effects on antimatter spectra for various annihilation channels and final-state particle species, and discuss their impact on fitted values for the dark-matter mass and thermally-averaged annihilation cross section. We find dramatic impacts which can go up to $\mathcal{O}(40)$ GeV for uncertainties on the dark-matter mass and up to $\mathcal{O}(10\%)$ for the annihilation cross section. We provide the spectra in tabulated form including QCD uncertainties and code snippets to perform fast dark-matter fits, in this https://github.com/ajueid/qcd-dm.github.io.git repository.