  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.
