Visible effects of invisible Hidden Valley radiation

Assuming there is a new gauge group in a Hidden Valley, and a new type of radiation, can we observe it through its effect on the kinematic distributions of recoiling visible particles? Specifically, what are the collider signatures of radiation in a hidden sector? We address these questions using a generic SU(N)-like Hidden Valley model that we implement in PYTHIA. We find that in both the e(+)e(-) and the LHC cases the kinematic distributions of the visible particles can be significantly affected by the valley radiation. Without a proper understanding of such effects, inferred masses of "communicators" and of invisible particles can be substantially off.