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The charmonium model, formulated in detail in an earlier publication, is compared in a comprehensive fashion with the data on the $ family. The parameters of the "naive" model, in which the system is described as a cF pair, are determined from the observed positions of $, +', and the P states. The model then yields a successful description of the spectrum of spin-triplet states above the charm threshold. It also accounts for the ratio of the leptonic widths of $' and +. When the cF potential is applied to the 'T family, it accounts, without any readjustment of parameters, for the positions of the 2s and 3s levels and for the leptonic widths of 'T and T' relative to that of q. The model does not give acceptable values of the absolute leptonic widths, a shortcoming which is ascribed to large quantum-chromodynamic corrections to the van Royen-Weisskopf formula. The calculated E 1 rates are about twice the values observed in the + family. This naive model is also extended with considerable success to mesons composed of one heavy and one light quark. A significant extension of the model is achieved by incorporating coupling to charmedmeson decay channels. This gives a satisfactory understanding of +(3772) as the 13D, c? state, mixed via open and closed decay channels to 23S. The model has decay amplitudes that are oscillatory functions of the decay momentum; these oscillations are a direct consequence of the radial nodes in the c? parent states. These amplitudes provide a qualitative understanding of the observed peculiar branching ratios into various charmed-meson channels near the resonance at 4.03 GeV, which is assigned to 33S. The coupling of the cF states below the charm threshold to closed decay channels modifies the bound states and leads to reduction of about 20% in E 1 rates in comparison to those of the naive model.

Eichten et ah summarize the motivation for exploring the 1-TeV (=10 12 eV) energy scale in elementary particle interactions and explore the capabilities of proton-(anti)proton colliders with beam energies between 1 and 50 TeV. The authors calculate the production rates and characteristics for a number of conventional processes, and discuss their intrinsic physics interest as well as their role as backgrounds to more exotic phenomena. The authors review the theoretical motivation and expected signatures for several new phenomena which may occur on the 1-TeV scale. Their results provide a reference point for the choice of machine parameters and for experiment design.

If quarks and leptons are composite at the energy scale A, the strong forces binding their constituents induce flavor-diagonal contact interactions, which have significant effects at reaction energies well below A. Consideration of their effect on Bhabha scattering produces a new, stronger bound on the scale of electron compositeness: A> 750 GeV. Collider experiments now being planned will be sensitive to A~ 1-5 TeV for both electrons and light quarks.PACS numbers: 12.35.Kw, 13.10 + q, 14.60-z,The proliferation of quarks and leptons has naturally led to the speculation that they are composite structures, bound states of more fundamental constituents which are often called "preons." 1 Many authors have proposed models of such composite structure, but no obviously correct or compelling model has yet emerged. There is not even consensus on the most fundamental aspect of quark and lepton substructure -the value of the mass scale A which characterizes the strength of preon-binding interactions and the physical size of composite states. It is therefore important to devise experiments which probe this potential substructure as deeply as possible and which, at the same time, test the widest possible variety of models. In this Letter, we identify new observable consequences of quark and lepton substructure which do just that. 2 As immediate result of these is that existing Bhabha-scattering measurements imply that A >750 GeV for the electron, a factor of 5 larger than previous lower bounds.Before spelling out our tests, let us review what is known about A. At present, high-energy cross sections are well explained by the standard SU(3) <8>SU(2) <8>U(1) gauge theory with elementary quarks and leptons. If these fermions are composite, then A is much larger than their masses, completely unlike the situation in nuclear and hadron physics. However, 't Hooft has argued that gauge theories of preon binding quite naturally produce composite fermions much less mass-811 14.80.Dq sive than the binding scale provided certain symmetry constraints are satisfied. 3 Since the energy A EW =0(1 TeV) at which electroweak symmetry is broken is the lowest new dynamical scale we foresee, we expect A ^ A E w .Modifications of gauge-field (y, Z°, etc.) propagators and vertices with fermions occur in any preon model, though their precise form is model dependent. In a favored parametrization, 4 one simply multiplies the gauge propagator by a form factor F(q 2 ) = 1 +q 2 /A 2 . Measurements of e + e~ -~iljf(ip=e, n,T,q) up to Vs = 35 GeV at PETRA have excluded photon form factors for A^> 100-200 GeV. 5 Composite fermions also possess new contact interactions generated by constituent exchange. These four-fermion interactions have strength ±g 2 /A 2 , where ^is an effective strongcoupling constant analogous to the p coupling g 2 / 477 =2.1. If contact interactions mediate flavorchanging processes such as K L°-+ \je and D°-D° and K°-K° mixing, the lower limits on A range from -30 TeV to -800 TeV. 6 While these bounds are impressive, it is possible to c...

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