International Journal of Modern Physics A

New experimental results on the production of hadrons in deep-inelastic lepton–nucleon and lepton–nucleus collisions are reviewed. The following topics are covered: multiplicities, nuclear effects, intermittency, Bose–Einstein correlations, and production of neutral strange particles.

The low-energy theorem, derived by Terent'ev within the framework of current algebra, is proved at the quark level within the framework of the Extended Nambu–Jona-Lasinio model. The proposed method allows to evaluate a vacuum expectation value of any time-ordered product of QCD-hadronic currents in terms of constituent-quark loops and low-lying meson exchanges.

The problem of asymptotic expansion of Green functions in perturbative QFT is studied for the class of Euclidean asymptotic regimes. Phenomenological applications are analyzed to obtain a meaningful mathematical formulation of the problem. It is shown that the problem reduces to studying asymptotic expansion of products of a class of singular functions in the sense of the distribution theory. Existence, uniqueness and explicit expressions for such expansions. (As-operation for products of singular functions) in dimensionally regularized form are obtained using the so-called extention principle.

It is shown that spontaneous CP violation can occur in a two generation left–right symmetric horizontal model if there are two Higgs bi-doublets with the same horizontal hypercharge quantum number. The contributions to the K_L − K_S mass difference (Δm) and CP violating effects (∊, ∊′/∊, D_n) to the box and tree level diagrams are discussed to demonstrate that the experimental values of Δm and ∊ can be explained with suitable choice of the model parameters.

It is demonstrated that it is possible to expand Feynman Integrals in axial gauges to arbitrary orders in a small mass-like parameter, and in so doing, replace ad hoc prescriptions by the limit of a gauge-fixing term imposed within the Lagrangian. Both the Landshoff and Principle Value prescriptions are related to the canonical form of the integrals and the expansions associated with them, and the values for a subset of the Landshoff Integrals are tabulated to second order in the mass-like parameter. The expansion technique relies 011 the method of Analytic Regularization, which includes Dimensional Regularization as one of a number of limiting cases.