  The energy spectra of particles produced from dark matter (DM) annihilation
or decay are one of the fundamental ingredients to calculate the predicted
fluxes of cosmic rays and radiation searched for in indirect DM detection. We
revisit the calculation of the source spectra for annihilating and decaying DM
using the Vincia shower algorithm in Pythia to include QED and QCD final state
radiation and diagrams for the Electroweak (EW) corrections with massive
bosons, not present in the default Pythia shower model. We take into account
the spin information of the particles during the entire EW shower and the
off-shell contributions from massive gauge bosons. Furthermore, we perform a
dedicated tuning of the Vincia and Pythia parameters to LEP data on the
production of pions, photons, and hyperons at the $Z$ resonance and discuss the
underlying uncertainties. To enable the use of our results in DM studies, we
provide the tabulated source spectra for the most relevant cosmic messenger
particles, namely antiprotons, positrons, $\gamma$ rays and the three neutrino
flavors, for all the fermionic and bosonic channels and DM masses between 5 GeV
and 100 TeV, on https://github.com/ajueid/CosmiXs.git.
