Collider Bounds on Pseudoscalars Coupling to Gauge Bosons
  We bound the coupling of pseudo-scalar particles to Tr G^G_{QCD} using (the lack of) monojet plus missing E_T events at the Tevatron, and estimate the bounds obtainable from LHC. In addition, we revisit the bounds on the coupling to F^F_{EM} from e^+e^- collider events with single photon and missing E_T final states. This is especially interesting in light of the recent experimental results from the PVLAS collaboration, which we believe can be tested by data which will be available in the near future. 
Matthew Kleban and Raul Rabadan