Studying QCD modeling of uncertainties in particle spectra from dark-matter annihilation into jets

Abstract

Motivated by various excesses observed by the Fermi-LAT and AMS collaborations, we perform a detailed analysis of QCD uncertainties on particle spectra from dark-matter annihilation (or decay) into jets. When annihilated to SM particles, the final-state annihilation products undergo various complicated processes such as QED and QCD bremsstrahlung, hadronisation, and hadron decays. These processes contain some intrinsic uncertainties which are usually difficult to model and which are neglected in physical analyses. First, we perform several re-tunings of the fragmentation function parameters. Then, we estimate two kinds of uncertainties: {\it (i)} perturbative from QCD showers and {\it (ii)} non-perturbative from hadronisation function. The results are tabulated for a wide range of dark matter masses, $m_\chi \in [10, 10^5]~{\rm GeV}$, and annihilation channels. They can be found on Zenodo: https://doi.org/10.5281/zenodo.3764809