The Ratio of Dimensionless Jet Cross Sections at the Tevatron

Several sources, both experimental and theoretical, subject inclusive jet cross section measurements to large uncertainties. On the experimental side, the energy scale contributes between 10% and 30% uncertainties. On the theoretical side, choice of parton distribution function introduces a 20% variation in the prediction; freedom in renormalization scale provides another uncertainty of up to 30%. The ratio of inclusive jet cross sections reduces the uncertainty from these major sources, permitting a very precise test of next{to{leading order QCD. The preliminary results from D and CDF di er from simple QCD predictions in normalization and di er from each other at small values of jet xT .