We derive sum rules for the structure functionV(x) for the ‘three-photon’ processe^±+p→e^±+γ+X which can distinguish between various colour models below colour threshold, independently of the quark and gluon distributions. A careful study of the sum rule forV(x) in the broken colour gauge theory model can in principle be used to determine the colour gluon mass. Invoking the specific assumptions of the dominance ofp-type quarks and neglecting the sea of quark-antiquark pairs, we also obtain bounds forV(x) in terms ofvW₂ (x) which can distinguish between various colour models below colour threshold.

We consider two types of scale breaking models—one based on asymptotically free gauge theory and the other phenomenological—which have already been fitted to the electron and muon data. Their predictions for the neutrino scattering are worked out and the sensitivity on the model parameters and the input electron data studied. The effects of scale breaking at very lowQ² and of a finite longitudinal cross-section are incorporated in analogy withep data. The predictions are compared with the recent neutrino scattering data.

We examine the predictions of gauge theories with colour excitation for the processpp →μ⁺μ⁻X. Relative to the predictions of quark parton model (with three colours) we find enhancements as large as a factor 3 – 4 for the cross-sectionM³d²σ/dMdy|_y=0 in the region 0·03 ≲M/√s ≲ 0·2 at √s=62 GeV,M being the invariant mass andy the rapidity of the muon pair. We study the sensitivity of this result to the colour gluon mass and the underlying parametrisation of the quark and gluon distribution functions.

The effect of radiative corrections on the Higgs masses and couplings in supersymmetric models is summarized. Radiative corrections in both the minimal and nonminimal models are discussed. It is pointed out that large singlet Higgs vacuum expectation values are screened out from the radiative corrections to the lightest Higgs mass in nonminimal models. In supersymmetric models the crucial mass limit for the Higgs search may be around 150 GeV.