  In an $SU(N_c)$ gauge theory with zero light quark flavours $N_f = 0$, the
only hadronic states that form below the confinement scale are composite gluon
states called glueballs. These minimal confining sectors arise in many Hidden
Valley extensions of the Standard Model, including scenarios that could hold
the solution to the dark matter question and the hierarchy problem.
Quantitative study of dark glueball phenomenology requires an understanding of
pure glue hadronization, which to date is severely lacking. In this work we
show that significant progress can be made by combining a perturbative pure
glue parton shower with a self-consistent and physically motivated
parameterization of the unknown non-perturbative physics, thanks to the modest
hierarchy between the glueball mass and the confinement scale. We make our
simulation code available as the public GlueShower package, the first glueball
generator for Hidden Valley theories, and perform preliminary studies of
several glueball production observables, with theoretical uncertainties that
take the full range of possible hadronization scenarios into account. We hope
this will enable new studies of dark sector phenomenology that were previously
inaccessible.
