Out-of-plane QCD radiation in hadronic Z0 production

We present the QCD analysis of the cumulative out-of-event-plane momentumdistribution in the process proton-antiproton into Z0 and a hard jet (eventplane defined by the proton, antiproton and Z0 momenta). Particular attentionis placed on the near-to-planar events for which we derive the all-orderresummed result to next-to-leading accuracy. We consider also the leading powercorrection originating from the fact that, even in hard processes, the resummedQCD coupling runs into the infrared region. We aim at the same level ofaccuracy which, in e+e- annihilation, seems to be sufficient for makingpredictions. Contributions from a ``soft underlying event'' due to beam remnantinteractions are discussed. Experimental data (not yet available) are needed tocast light on the predictive level of standard QCD analysis in hardhadron-hadron collisions. We plot examples of the predicted distribution atTevatron energies. The techniques here developed can be extended to other hardhadron-hadron and hadron-lepton processes.Comment: 36 pages, 3 figures, JHEP class include