Kan-ichi Yokoyama

Gauge Covariance in Non-Abelian Gauge Theories

Manifestly Lorentzand gauge-covariant formulation of the canonical Yang-Mills :field theory is presented. It is exhibited that a local gauge transformation forms an invariant gauge family to which relevant.. one-parameter gauges belong. Gauge symmetries prescribed by the theory are realized by combination of a non-Abelian global gauge transformation and an Abelian local gauge transformation. A renormalization scheme is developed in connection with problems inherent in the theory.

Gauge independence as a consequence of gauge covariance

Abstract Gauge independence of the physical S -matrix is proved without perturbation in a satisfactory gauge-field theory with gauge covariance. The proof goes through both for abelian and non-abelian cases, and the independence is a consequence of gauge covariance and asymptotic completeness.

Neutral-Vector Field Theory with Invariant Gauge Families

By a generalization of canonical quantum electrodynamics with invariant one-parameter gauge families, a wide theory of neutral vector fields is formulated in a unified way that describes massive and massless fields on the same basis. Similarly to the case of quantum electrodynamics, there exist two invariant gauge families in the sense that any two gauges belonging to the same family are connected with each other by a generalized q-number gauge transformation. It is shown that the theory is manifestly renormalizable and the unitarity of the S-matrix is guaranteed by conservation of currents. Renormalization problems in this formalism are investigated.

Possible Nonvanishing Mass of Photon

(Received May 18, 1985) From phenomenological and field-theoretical considerations on photon mass, we first show that photon is not limited to being massless at the present stage. Next we illustrate a possibility of formulating a local field theory for massive photons coupled with nonconserved currents, while we cannot formulate it for massless photons.

Renormalizability of massive Yang-Mills theory

In this note, we aim at revealing the renormalizable structure of massive Yang-Mills (YM) theories on the basis of the formalism in our previous work, l) quoted as [I], though there had so far been found several counter-observations. 2) Our formalism consists of four kinds of auxiliary scalar fields other than a massive gauge a field A~; a massless scalar fields ~a, in addition to the usual Lagrange multiplier field H a and a pair of Faddeev-Popov ghost fields C a and ~a. In terms of these fields, the Lagrangian density in [I], takes the form in the Landau gauge

The Higgs-Kibble Model on the Basis of a Canonical Yang-Mills Field Theory with Gauge Covariance. I

A renormalization scheme of a canonical Yang-Mills field theory proposed previously is applied to the SU(2) Biggs-Kibble model. After the spontaneous breakdown of symmetry under the gauge group SU (2), a complex spinor scalar field is represented by its components being assigned as a singlet and a triplet of the global gauge group, while it still corresponds to a doublet under the Becchi-Rouet-Stora transformation. The transformation properties of these components under a q-number local gauge transformation, which varies values of gauge parameters, are exactly determined. The triplet corresponds to a massless Goldstone-bason field, and it exhibits a dipole-ghost character, the origin of which is due to a gaugeon field introduced into the theory. The Becchi-Rouet-Stora symmetry presents a useful piece of information about vacuum expectation values of field commutators, as well as it guarantees the unitarity of a physical S-matrix. All renormalization constants are given as being inde-