Next-to-leading order QCD predictions for Z , γ + 3 -jet distributions at the Tevatron

Using BlackHat in conjunction with SHERPA, we have computed next-to-leading order QCD predictions for a variety of distributions in Z, {gamma}{sup {asterisk}}+ 1, 2, 3-jet production at the Tevatron, where the Z boson or off-shell photon decays into an electron-positron pair. We find good agreement between the NLO results for jet {sub pT} distributions and measurements by CDF and D0. We also present jetproduction ratios, or probabilities of finding one additional jet. As a function of vector-boson {sub pT} , the ratios have distinctive features which we describe in terms of a simple model capturing leading logarithms and phase-space and parton-distribution-function suppression.