LHC Probe of Quark Substructure at the Early Stages of Running

We explore the opportunity to look for quark compositeness in the early stages of the LHC running by analyzing high-$E_T$ dijet production. The quark substructure that will manifest itself by affecting various kinematic distributions at the center-of-mass energy $E_{CM}$=10 TeV and in the integrated luminosity range from 0.5 to 10 fb$^{-1}$ is investigated. The estimation of the characteristic energy scale $\Lambda$, based on the novel, potentially powerful observable, is found to be sensitive to the sign of the interference between Standard Model and four-fermion contact interactions. We find the lower limits on $\Lambda$ at the LHC to be about 10.5(15.0) TeV for constructive interference and 8.5(11.5) TeV for destructive one at the integrated luminosity 0.5(10) fb$^{-1}$ and $E_{CM}=10$ TeV.