Timelike dipole-antenna showers with massive fermions

Abstract

We present a complete formalism for final-state (timelike) dipole-antenna showers including fermion masses, but neglecting polarization and finite-width effects. We make several comparisons of tree-level expansions of this shower algorithm to fixed-order matrix elements for hadronic $Z$ decays, up to and including $Z\ensuremath{\rightarrow}6$ partons, to which the algorithm can be consistently matched over all of phase space. We also compare to analytical resummations at the next-to-leading logarithmic (NLL) level. The shower algorithm has been implemented in the publicly available VINCIA plug-in to the PYTHIA 8 event generator, which enables us to compare to experimental data at the fully hadronized level. We therefore also include comparisons to selected observables in $b$-tagged $Z$ decays.