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1.
The gauge conditionx μ A μ =0 produces a theory which is free from Faddeev-Popov ghosts, but whose Green's functions obviously lack translational invariance. We present for the first time a consistent perturbation theory in this gauge. Besdes discussing example howlocal counter-terms in the action suffice for the one-loop renormalization ofS-matrix elements.  相似文献   

2.
The renormalization is performed in a manifestly covariant approach. The simplest form of the Ward identities z1=z2=…=zn=… is fulfilled automatically in every gauge. In the Yang-Mills theory the counter-terms are gauge-invariant and depend on the charge renormalization constant only. In pure gravitation the analysis of all divergences is reduced in the present approach to some special classification of the kth order scalar densities in a Riemannian space.  相似文献   

3.
4.
Some aspects of the renormalization program for the charm quartet model are discussed, with special emphasis on the role played by the Cabibbo angle. The cancellation of divergences in the W-quarks and Higgs-quarks sector is examined by explicit calculations at the one-loop level, both in the unitary and 't Hooft-Feyman gauges. The main analysis is based on a renormalization scheme which allows for the most general counter-terms generated by the Yukawa couplings. A second approach, equivalent at the S-matrix level, is briefly discussed. As a byproduct of our work we verify that the standard perturbative analysis leads to the same expressions for the coefficients of the divergent parts in the renormalization of the gauge coupling g0 as a recent current algebra formulation of the radiative corrections.  相似文献   

5.
Phase diagrams of lattice gauge theories have in several cases lines of first-order transitions ending at points at which continuous (second-order) transitions take place. In the vicinity of this critical point, a continuum field theory may be defined. We have analyzed here a Z2 gauge plus matter model (which has no formal continuum limit) and identified the critical point with a usual Ø4, globally Z2 invariant, field theory. The analysis relies on a mean field functional formalism and on a loop-wise expansion around it, which is reviewed.  相似文献   

6.
Let λ : U(1) → GL (V) be a linear representation. Lagrangians defined on J1(T*M × V)whose universal current form is gauge invariant, are described in terms of gauge invariant Lagrangians and invariant functions on V. A characterization of gauge invariant Lagrangians depending on matter fields only, that is, L : J1V → ?, is also obtained.  相似文献   

7.
《Physics letters. [Part B]》1986,173(3):284-288
Gauge invariant and gauge fixed BRS invariant actions are constructed in arbitrary dimensions for free massless integer spin fields carrying mixed representations of the Lorentz group described by Young tableaux (2, 1, 1, …, 1)n. The complete ghost spectrum is deduced by demanding nilpotency of the BRS transformations and leads to a correct count of the on-shell degrees of freedom. Dimensional reduction is used to study the corresponding gauge invariant massive theory. On-shell consistency is then ensured by the fact that the masses arise via a “telescopic Higgs effect”.  相似文献   

8.
The massless relativistic free string is studied in the gauge x0 = τ. It is found that the classical solutions include transverse and longitudinal vibrations. The problem is treated both in the Lagrangian and Hamiltonian formalism. Different ways of quantizing the system are investigated. The path integral quantization leads to a Poincaré invariant quantum theory in any number of dimensions.  相似文献   

9.
N = 1 supersymmetric gauge theories with global flavor symmetries contain a gauge invariant W-superalgebra which acts on its moduli space of gauge invariants. With adjoint matter, this superalgebra reduces to a graded Lie algebra. When the gauge group is SO(nc), with vector matter, it is a W-algebra, and the primary invariants form one of its representation. The same superalgebra exists in the dual theory, but its construction in terms of the dual fields suggests that duality may be understood in terms of a charge conjugation within the algebra. We extend the analysis to the gauge group E6.  相似文献   

10.
《Physics letters. [Part B]》1987,183(2):156-162
It is shown that the Euler invariant type action of an O(d) gauge theory in d dimensions is a surface term and becomes the (d − 1)-dimensional gauge theory of gravitation. Its Kaluza-Klein dimensional reduction gives a theory which contains the ordinary Einstein gravity.  相似文献   

11.
Massless particles represented by the fields with mixed spinor indices of SL(2,C) are generally shown to be forbidden in covariant field theory under the assumptions of positivity and covariiance alone. This remains true also in gauge theory (in which a negative metric appears) as far as the particles are gauge invariant. This in particular implies that any dynamical “gauge-type particle” (such as vector Aμ, Rarita-Schwinger ψμ etc.) cannot appear unless the system has a corresponding local invariance from the outset.  相似文献   

12.
SU(N) gauge systems are attracted to large orbits of the global gauge group by an invariant and calculable potential. In models the wave function becomes increasingly localized near the maximal orbit as N → ∞, which explains the success of semiclassical methods. Picturing the links Ui of the lattice as particles on an SU(N) group manifold, the effect favors large moments of inertia about U = 1. It thus opposes the magnetic interaction, and tends to destabilize the perturbative vacuum.  相似文献   

13.
The superspace formulation of new D = 10, N = 1 supergravity is developed. It is shown that the background superspace of the new theory can be coupled to a test superstring in such a way that the local symmetries of the superstring are intact. This formulation necessarily makes use of the Vainberg construction so the action is analogous to the effective action for QCD with the WZW term. The results suggest that the ambiguity between the massless two-form and six-form in the SO(32) or E8 × E8 superstring theories can only be resolved by a gauge invariant, Lorentz-covariant formulation of superstring field theory.  相似文献   

14.
The explicit form of linearized gauge arid generalized “Weyl invariant” interactions of scalar and general higher even spin fields in the AdS D space constructed in [1] is reviewed. Also a linearized interaction of vector field with general higher even spin, gauge field is obtained. It is shown that the gauge invariant action of linearized vector field interacting with the higher spin field also includes the whole tower of invariant actions for couplings of the same vector field with the gauge fields of smaller even spin.  相似文献   

15.
We discuss the implications of gauge invariance in the problem of the on-shell extrapolation of the electroproduction low-energy theorems. We show that there is an invariant amplitude which can be evaluated at the Breit threshold either using gauge invariance and on-shell dispersion relations or following the Fubini and Furlan [5] extrapolation method starting from the current-algebra low-energy value of the amplitude. Comparing the two expressions, we find a relation between the electromagnetic pion form factor, Fπ (k2), and the axial-vector nucleon form factors, gA (k2) and hA (k2).  相似文献   

16.
The normal fluid density is defined through the moment of inertia of a cylinder rotating about its axis, in the limit of infinitesimal angular velocity. The angular momentum may be calculated from the one particle Green function, and this leads to the relation between ?n and the Green function.We then consider an ensemble in which the fluid is constrained to irrotational flow. For statistical states which are “locally gauge invariant” we show that ρn, as defined previously, is identical to the full density. This demonstrates the connection between superfluidity and the breaking of local gauge symmetry.Finally, we apply the result to the gas of non-interacting quasi-particles and the fully interacting Bose fluid in the limit of very low temperatures. In both cases we reproduce the Landau expression for ρn in terms of the quasiparticle occupation numbers, and derive the well-known result for real superfluid helium that ρnT4 as T→0.  相似文献   

17.
We use the light-cone axial gauge of proper-time ordered perturbation theory and study the soft-IR properties of the two-loop virtuals' diagrams considered by Bodwin, Brodsky and Lepage for ππμ+μ- + X. It is shown that although the systematic summation over all possible spectator interactions removes the outside soft-IR divergences in the non-overlapping ladder Glauber diagrams, unphysical inside soft-IR divergences persist. So, in the light-cone axial gauge the on-shell Glauber region is not a gauge invariant concept which can be physically isolated from radiative corrections which non-trivially involve other diagrammatic regions. Due to gauge invariance it can be potentially misleading in eikonal phenomenologies based on perturbative QCD to assume an ad hoc inside soft-IR cutoff in analyzing possible non-abelian effects in multiple scatterings involving spectators.  相似文献   

18.
Although it has been known for a long time that the special case nμAμ = 0 for an axial gauge of a vector field Aμ, characterized by a direction nμ, is free from the peculiar loop complications inherent in all other known gauges of non-Abelian gauge theories, practical use of this ghost-free gauge has often met with some reserve. The reasons were always difficulties in the development of the theoretical formalism, all of which can be traced back to a singularity at nμpμ = 0 where p is some four-momentum. This paper, which is a sequel to an earlier one by one of the authors, is intended to show that within the functional integration formalism a consistent field theory can be developed. Here we first prove the gauge invariance of the renormalized theory, allowing for the presence of an arbitrary number of scalar and fermion fields with spontaneous symmetry breaking. Then it is shown that all on-shell elements for the physical S-matrix between properly selected physical sources are independent of nμ (gauge invariant) and so are the renormalized masses.  相似文献   

19.
R. Flume 《Nuclear Physics B》1983,217(2):531-543
It is assumed that N = 1 supersymmetric Yang-Mills fields coupled to chiral matter fields can be renormalized in a covariant Wess-Zumino gauge with a minimal number of subtractions so that the Ward identities of supersymmetry, ordinary gauge invariance and matter-field-flavour symmetries are satisfied. The chiral Yukawa couplings are supposed to remain unrenormalized. I show that on the basis of these assumptions an N = 4 extended manifestly O(4) invariant theory can be constructed with finite Yukawa and φ4 couplings. A consequence of these non-renormalizations is the vanishing of the renormalization group β function.  相似文献   

20.
Gauge invariant expectation values for lattice gauge theory with a general local action in two dimensions may be expressed as functions of the single plaquette averages. The value of these averages at the fixed point of the renormalization group can be determined exactly, and the corresponding lattice theory is shown to reproduce the continuum results. The limit Ne = ∞ is investigated in detail, and fixed point values for all the averages are explicitly determined. Wilson's action results agree only to first order in weak coupling.  相似文献   

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