On the Simulation of Hidden Parton Showers in the Conformal Window

Abstract

We consider confining Hidden Valley/Dark Sector theories containing many dark quark flavors. These theories are in the ``conformal window'': they reach an infrared fixed point when their quarks are massless, and have unfamiliar confinement when the quark masses are non-zero but small. Their jets of hidden hadrons may be quite different from those familiar from QCD, but their details cannot currently be simulated even qualitatively. This is partly due to the use of approximations to the two-loop running coupling in existing event generators' parton showers, which are not broadly applicable across the conformal window. We argue that the exact two-loop running coupling, and a corresponding Sudakov factor employing that coupling, must be implemented in simulation packages in order to allow phenomenological studies of these theories.