Ratio of W+N jets to Z0/γ*+N jets versus N as a precision test of the standard model

We suggest replacing measurements of the individual cross sections for the production of W+N jets and Z+N jets in searches for new high-energy phenomena at hadron colliders by the precision measurement of the ratios (W+0 jet)/(Z+0 jet), (W+1 jet)/(Z+1 jet), (W+2 jets)/(Z+2 jets),...,(W+N jets)/(Z+N jets), with N as large as 6 (the number of jets in tt-barH). These ratios can also be formed for the case where one or more of the jets is tagged as a b or a c quark. Existing measurements of the individual cross sections for W→eν+N jets at the Fermilab Tevatron have systematic uncertainties that grow rapidly with N, being dominated by uncertainties in the identification of jets and the jet energy scale. These systematics, and also those associated with the luminosity, parton distribution functions (PDF's), detector acceptance and efficiencies, and systematics of jet finding and b tagging, are expected to substantially cancel in calculating the ratio of W to Z production in each N-jet channel, allowing a greater sensitivity to new contributions in these channels in run II at the Tevatron and at the CERN LHC