The existence and uniqueness of solutions of Yang-Mills equations with bag boundary conditions

The Cauchy problem for the Yang-Mills equations in the Coulomb gauge is studied on a compact, connected and simply connected Riemannian manifold with boundary. An existence and uniqueness theorem for the evolution equations is proven for fields with Cauchy data in an appropriate Sobolev space. The proof is based the Hodge decomposition of the Yang-Mills fields and the theory of non-linear semigroups.Work partially supported by NSERC Research Grant A 8091Work supported by DFG Grant Schw 485/2-1     

Two- and three-dimensional instantons

The four-dimensional Yang-Mills Lagrangian implies corresponding structures in lower dimensions. Instantons, characterized by a zero energy-momentum tensor as well as finite action, emerge as the solutions of coupled first order equations. For the Abelian case all such solutions are determined by the non-linear Poisson-Boltzmann equation.     

Self-duality,helicity and coherent states in non-Abelian gauge theories

Solutions of the non-linear classical Yang-Mills field equations obtained by iteration from self-dual solutions of the linearized equations are shown to be themselves self-dual. In Minkowski space, such solutions are necessarily complex. We give a quantum theory interpretation of these solutions which relates them to the matrix element of the field operators between the vacuum state and a coherent state of spin-one quanta of definite helicity.     

The theory of overdetermined linear systems and its applications to non-linear field equations

We review some aspects of the theory of overdetermined linear systems of partial differential equations and use it to interpret some non-linear equations of classical field theory as integrability conditions of linear one. In particular, it is shown that the Einstein and the Yang-Mills equations are equivalent to the existence of flat connections in affine subspaces of connections on some vector bundles, i.e. they may be written as zero-curvature conditions.     

Infinite number of local conservation laws for the self-dual SU(2) Yang-Mills system within 't Hooft's ansatz

We derive infinite sets of local continuity equations for the four-dimensional classical self-dual SU(2) Yang-Mills fields subjected to 't Hooft's ansatz. In striking analogy to the two-dimensional CP(n) non-linear sigma model where local conservation laws obtain either from complex Cauchy-Riemann analyticity or from a matrix Riccati equation, our local sets derive from quaternionic Fueter analyticity or a Riccati equation associated with the geometric prolongation structure implied by the Belavin-Zakharov linear spectral problem for the self-dual Yang-Mills system. Our analysis underlines the close connection between local and non-local conservation laws and suggests that infinite sets of local continuity equations should be present in the general self-(antiself-)dual gauge field case.     

Witten's gauge field equations and an infinite-dimensional Grassmann manifold

Witten's gauge fields are interpreted as motions on an infinite-dimensional Grassmann manifold. Unlike the case of self-dual Yang-Mills equations in Takasaki's work, the initial data must satisfy a system of differential equations since Witten's equations comprise a pair of spectral parameters. Solutions corresponding to (anti-) self-dual Yang-Mills fields are characterized in the space of initial data and in application, some Yang-Mills fields which are not self-dual, anti-self-dual nor abelian can be constructed.     

A connection between the Einstein and Yang-Mills equations

It is our purpose here to show an unusual relationship between the Einstein equations and the Yang-Mills equations. We give a correspondence between solutions of the self-dual Einstein vacuum equations and the self-dual Yang-Mills equations with a special choice of gauge group. The extension of the argument to the full Yang-Mills equations yields Einstein's unifield equations. We try to incorporate the full Einstein vacuum equations, but the approach is incomplete. We first consider Yang-Mills theory for an arbitrary Lie-algebra with the condition that the connection 1-form and curvature are constant on Minkowski space. This leads to a set of algebraic equations on the connection components. We then specialize the Lie-algebra to be the (infinite dimensional) Lie-algebra of a group of diffeomorphisms of some manifold. The algebraic equations then become differential equations for four vector fields on the manifold on which the diffeomorphisms act. In the self-dual case, if we choose the connection components from the Lie-algebra of the volume preserving 4-dimensional diffeomorphism group, the resulting equations are the same as those obtained by Ashtekar, Jacobsen and Smolin, in their remarkable simplification of the self-dual Einstein vacuum equations. (An alternative derivation of the same equations begins with the self-dual Yang-Mills connection now depending only on the time, then choosing the Lie algebra as that of the volume preserving 3-dimensional diffeomorphisms.) When the reduced full Yang-Mills equations are used in the same context, we get Einstein's equations for his unified theory based on absolute parallelism. To incorporate the full Einsteinvacuum equations we use as the Lie group the semi-direct product of the diffeomorphism group of a 4-dimensional manifold with the group of frame rotations of anSO(1, 3) bundle over the 4-manifold. This last approach, however, yields equations more general than the vacuum equations.Andrew Mellon Postdoctoral fellow and Fulbright ScholarSupported in part by NSF grant no. PHY 80023     

Exact solutions of supergauge invariant Yang-Mills equations

We point our a new class of solutions of the supersymmetric Yang-Mills equations. This class provides solutions which cannot be generated from the solutions of the ordinary Yang-Mills equations by finite supersymmetry transformations and contains the supersymmetric generalization of the non-abelian plane waves.     

High-temperature limit of Landau-gauge Yang-Mills theory

The infrared properties of the high-temperature limit of Landau-gauge Yang-Mills theory are investigated. In a first step the high-temperature limit of the Dyson-Schwinger equations is taken. The resulting equations are identical to the Dyson-Schwinger equations of the dimensionally reduced theory, a three-dimensional Yang-Mills theory coupled to an effective adjoint Higgs field. These equations are solved analytically in the infrared and ultraviolet, and numerically for all Euclidean momenta. We find infrared enhancement for the Faddeev-Popov ghosts, infrared suppression for transverse gluons and a mass for the Higgs. These results imply long-range interactions and over-screening in the chromomagnetic sector of high-temperature Yang-Mills theory while in the chromoelectric sector only screening is observed.Received: 5 August 2004, Published online: 21 September 2004     

On spherically symmetric fields in gauge theories

Gauge fields admitting spherical symmetry are listed. Spherically symmetric solutions of Yang-Mills equations and spherically symmetric magnetic monopoles are studied. A simple exact solution of the Yang-Mills and Einstein equations is found.     

On non-Lie ansatzes and new exact solutions of the classical Yang-Mills equations

Abstract

We ssuggest an effective method for reducing Yang-Mills equations to systems of ordinary differential equations. With the use of this method, we construct wide families of new exact solutions of the Yang-Mills equations. Analysis of the solutions obtained shows that they correspond to conditional symmetry of the equations under study.     

Gauge fields and gravitational field equations

It is shown that the gravitational field equations in free space have a similar form to the free Yang-Mills field equations, where the group SL (2, C) replaces the group SU(2). The Ricci rotation coefficients take the role of the Yang-Mills like potentials, whereas the Riemann tensor takes the role of the gauge fields.     

Yang-Mills gauge theory and gravitation

We point out that Yang's and Einstein's gravitational equations can be obtained from a geometric approach of Yang-Mills gauge theory in a sourceless case, under a decomposition of the Poincaré algebra. Otherwise, Einstein's equations cannot be derived from a Yang-Mills gauge equation when sources are inserted in the rotational sector of that algebra. A gauge Lagrangian structure is also discussed.     

A geometric notion of complete integrability

A system of partial differential equations which can be described as a harmonic mapping of riemannian manifolds is called completely integrable when the corresponding n-dimensional manifold of fields admits 2n?1 independent Killing vector fields. It is conjectured that, for systems of two independent variables, complete integrability in the present sense implies the existence of a Lax pair for the system, for which the theory of the inverse scattering method is applicable. The stationary axisymmetric Einstein and Einstein-Maxwell equations, the SU(n) self-dual Yang-Mills fields in 1+1 dimensions, and the two-dimensional non-linear σ-models are shown to satisfy the conjecture; the conjecture is also proved for any system of n = 2 and n = 3 partial differential equations for n unknown scalar fields.     

规范场与主纤维丛上的联络

本文较详细地给出物理上的规范场与数学上的主纤维丛上的联络论之间的对应关系,从而以联络论的观点统一地处理杨振宁所说的规范场的“微分方法”与“积分”方法,并指出存在有更广泛的规范场的可能性。此外,讨论了引力场如何作为规范场及比较了一些已知的引力场方程。     

The twistor theory of equations of KdV type: I

This article is the first of two concerned with the development of the theory of equations of KdV type from the point of view of twistor theory and the self-dual Yang-Mills equations. A hierarchy on the self-dual Yang-Mills equations is introduced and it is shown that a certain reduction of this hierarchy is equivalent to then-generalized KdV-hierarchy. It also emerges that each flow of then-KdV hierarchy is a reduction of the self-dual Yang-Mills equations with gauge group SL _n . It is further shown that solutions of the self-dual Yang-Mills hierarchy and their reductions arise via a generalized Ward transform from holomorphic vector bundles over a twistor space. Explicit examples of such bundles are given and the Ward transform is implemented to yield a large class of explicit solutions of then-KdV equations. It is also shown that the construction of Segal and Wilson of solutions of then-KdV equations from loop groups is contained in our approach as an ansatz for the construction of a class of holomorphic bundles on twistor space.A summary of the results of the second part of this work appears in the Introduction.Most of this work was done while Darby Fellow of Mathematics at Lincoln College, Oxford     

YANG-MILLS EDUATIONS,ITS DAUGHTERS,HIDDEN SYMMETRY ALGEBRA AND THEIR EXTENSIONS

Self-dual Yang-Mills equations can be reduced to many nonlinear equations. A systematic procedure is presented in deriving the hidden symmetry algebras and the related Backlund trahsformations(BT).We find that by imposing the Riemann-Hilbert transform on the linearization equations of N>2 extended super Yang-Mills fields, the theory provides no more self-duality information in the super-space. The corresponding hidden symmetrg algebra and BT are discussed within the super-space.