A collider observable QCD axion
  We present a model where the QCD axion is at the TeV scale and visible at a collider via its decays. Conformal dynamics and strong CP considerations account for the axion coupling strongly enough to the standard model to be produced as well as the coincidence between the weak scale and the axion mass. The model predicts additional pseudoscalar color octets whose properties are completely determined by the axion properties rendering the theory testable. 
Savas Dimopoulos, Anson Hook, Junwu Huang, Gustavo Marques-Tavares
hep-ph hep-ex