LIMITS ON QUARK COMPOSITENESS FROM HIGH ENERGY JETS IN ${\bar P}P$ COLLISIONS AT 1.8 TEV

Events in collisions at 1.8 TeV with total transverse energy exceeding 500 GeV are used to set limits on quark substructure. The data are consistent with next-to-leading order QCD calculations. We set a lower limit of 2.0 TeV at 95% confidence on the energy scale ΛLL for compositeness in quarks, assuming a model with a left-left isoscalar contact interaction term. The limits on ΛLL are found to be insensitive to the sign of the interference term in the Lagrangian.