Has the Substructure of Quarks Been Found by the Collider Detector at   Fermilab?
  The significant excess recently found by the CDF Collaboration in the inclusive jet cross section for jet transverse energies $E_T \ge 200$ GeV over current QCD predictions can be explained either by possible production of excited bosons (excited gluons, weak bosons, Higgs scalars, etc.) or by that of excited quarks. The masses of the excited boson and the excited quark are estimated to be around 1600 GeV and 500 GeV, respectively. 
Keiichi Akama (Saitama Medical College) and Hidezumi Terazawa (INS,   University of Tokyo)