摘要:

AbstractIn the paper the perturbation theory is constructed for QED, for which the interaction with the external pair‐creating field is kept exactly. An explicit expression for the perturbation theory causal electron propagator is found. Special features of usage of the unitarity conditions for calculating the total probabilities of radiative processes in the case are discussed. Exact Green functions are introduced and the functional formulation is discussed. Perturbation theory for calculating the mean values of the Heisenberg operators, in particular, of the mean electromagnetic field is built in the case under consideration. Effective Lagrangian which generates the exact equation for the mean electromagnetic field is introduced. Functional representations for the generating functionals introduced in the paper are discusse

ISSN:0015-8208    

DOI:10.1002/prop.19810290902

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

ISSN:0015-8208    

DOI:10.1002/prop.19810290903

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractAnextended spacetime,M4+N, is a Riemannian (4 +N)‐dimensional manifold which admits anN‐parameter groupGof (spacelike) isometries and is such that ordinary spacetimeM4is the spaceM4+N/Gof the equivalence classes underG‐transformations ofM4+N. Amultidimensional unified theory(MUT) is a dynamical theory of the metric tensor onM4+N, the metric being determined from the Einstein‐Hilbert action principle: in absence of matter, the Lagrangian is (essentially) the total curvature scalar ofM4+N. A MUT is an extension of the Cho‐Freund generalization of Jordan's five‐dimensional theory. A MUT can be faithfully translated in four‐dimensional language: as a theory onM4, a MUT is a gauge field theory with gauge groupG. A unifying aspect of MUT's is that all fields occur as elements of the metric tensor onM4+N. When the isometry generators are subjected to strongest constraints, a MUT becomes the De Witt‐Trautman generalization of Kaluza's five‐dimensional theory; in four‐dimensional language, this is the theory of Yang‐Mills gauge fields coupled to gravity. With weaker constraints, a MUT appears to be more natural than a Yang‐Mills theory as a physical realization of the gauge principle for an exact symmetry of gauged confined color. Such weakly‐constrained MUT leads to bag‐type models without the need forad hocsurgery on the basic. Lagrangian. The present paper provides a detailed introduction to the formalism of multidimensional

ISSN:0015-8208    

DOI:10.1002/prop.19810290904

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

ISSN:0015-8208    

DOI:10.1002/prop.19810290901

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY