IS THE Z ” OBSERVED IN pfj COLLISIONS A COMPOSITE OBJECT ?

z-If the Z0 boson is made of colored subconstituents it can be produced in pp (and pp) collisions through the subprocess gluon + gluon-) Z " + gluon. Rate is estimated from Z "-7 mixing parameter and found comparable to that of Drell-Yan process.-Events with a large PT 2' and a large PT balancing gluon should be observed at pp collider. The possibility that the weak W* and 2' bosons together with quarks and leptons are composite particles has been considered from various point of views [I]. At low energies with respect to the compositeness scale (fi << AH) the weak interaction is described by an effective theory resulting from a hidden interaction among subcon-stituents (like low energy strong hadronic interactions are the result of QCD among quarks). Under special constraints (unification [2], good high energy behaviour [3], renormalizability [4], current algebra [5], W b oson dominance [6]) this effective theory can at low energy reproduce most of the results of the standard gauge model. The recent discovery of W* and 2' bosons at CERN pp collider [7] render particularly exciting the comparison of the predictions of the composite models with those of the standard model. Especially models with low compositeness scale (i.e. G,-l/2 <-AH s 1 TeV) are phenomonologically appealing [&lo]. In addition to obvious depar-2-tures from standard model predictions at moderately high energies (,/S 2 A,) one expects several new couplings should exist as residual interactions. These are for example anomalous multiboson couplings (photon or gluon couplings to weak bosons) or _-fermion-boson contact interactions [ll] as well as Cfermion contact interactions [12]. In this note we show that Z " production in pp (or pp) collisions offer such a possibility of testing the nature of the weak bosons. In addition to Drell-Yan type of production mechanism (q q annihilation and QCD correction terms with q-gluon interactions) (131 effective weak interactions may allow new types of production modes through gluon-gluon collisions (i.e. gg-+ Pg, Z " y, Z " Ho... as well as gg + W+W-WfHF H+H-, 9. . .). Rates and transverse momentum distributions of W*, Z " bosons may also be modified by contact terms like gq-P Z " q or gq + W*q'.-Here we discuss the case of gg-+ Zag which seems to be particularly promising leaving the other ones for further studies. Let us suppose that subconstituents carry color (and electric) charges so that they …