CMS Sensitivity to Quark Contact Interactions using Dijets

We estimate CMS sensitivity to quark contact interactions in the dijet final state. The canonical model of a contact interaction among left-handed composite quarks changes the dijet angular distribution at high dijet mass. The dijet ratio variable introduced at the Tevatron is used as a simple measure of the angular distribution as a function of dijet mass. The contact interaction signal and QCD background are estimated for the dijet ratio as a function of dijet mass from 0.3 to 6.5 TeV. Statistical uncertainties are estimated for integrated luminosities of 100 pb^-1, 1 fb^-1, and 10 fb^-1 and a realistic trigger table including multiple thresholds and prescales for the single jet triggers. Systematic uncertainties on the dijet ratio are estimated and are found to be small. The chisquard between the background and the signal is estimated, including systematics, and is used to find CMS sensitivity to the contact interaction scale Lambda^+. For an integrated luminosity of 100 pb^-1, 1 fb^-1, and 10 fb^-1, CMS can expect to exclude at 95% CL a Lambda^+ value of 6.2, 10.4, and 14.8 TeV or discover at 5 sigma significance a Lambda^+ value of 4.7, 7.8 and 12.0 TeV, respectively.