2,277 research outputs found
Gauge parameter dependence in gauge theories (revised: subsection 2.3)
Dependence on the gauge parameters is an important issue in gauge theories:
physical quantities have to be independent. Extending BRS transformations by
variation of the gauge parameter into a Grassmann variable one can control
gauge parameter dependence algebraically. As application we discuss the anomaly
coefficient in the Slavnov-Taylor identity, -matrix elements, the vector
two-point-function and the coefficients of renormalization group and
Callan-Symanzik equation.Comment: 6, MPI-PhT/94-34, BUTP-94/1
A nilpotent symmetry of quantum gauge theories
For the Becchi-Rouet-Stora-Tyutin (BRST) invariant extended action for any
gauge theory, there exists another off-shell nilpotent symmetry. For linear
gauges, it can be elevated to a symmetry of the quantum theory and used in the
construction of the quantum effective action. Generalizations for nonlinear
gauges and actions with higher order ghost terms are also possible.Comment: RevTeX, 9 pages, several changes to include generalizations to
quartic and higher ghost terms and non-linear gauges. Abstract changed. Final
version to be publishe
Further comments on the background field method and gauge invariant effective actions
The aim of this paper is to give a firm and clear proof of the existence in
the background field framework of a gauge invariant effective action for any
gauge theory ({\it background gauge equivalence}). Here by effective action we
mean a functional whose Legendre transform restricted to the physical shell
generates the matrix elements of the connected -matrix. We resume and
clarify a former argument due to Abbott, Grisaru and Schaefer based on the
gauge-artifact nature of the background fields and on the identification of the
gauge invariant effective action with the generator of the proper, background
field, vertices.Comment: 21 pages, Latex 2
Gauge dependence in topological gauge theories
We parametrize the gauge-fixing freedom in choosing the Lagrangian of a
topological gauge theory. We compute the gauge-fixing dependence of correlators
of equivariant operators when the compactified moduli space has a non-empty
boundary and verify that only a subset of these has a gauge independent
meaning. We analyze in detail a simple example of such anomalous topological
theories, 4D topological Yang-Mills on the four-sphere and instanton number
k=1.Comment: 12 pages, TeX , harvma
Axial anomalies in gauge theory by exact renormalization group method
The global chiral symmetry of a gauge theory is studied in the
framework of renormalization group (RG). The theory is defined by the RG flow
equations in the infrared cutoff \L and the boundary conditions for the
relevant couplings. The physical theory is obtained at \L=0. In our approach
the symmetry is implemented by choosing the boundary conditions for the
relevant couplings not at the ultraviolet point \L=\L_0\to\infty but at the
physical value \L=0. As an illustration, we compute the triangle axial
anomalies.Comment: 11 pages + 1 appended EPS figure, LaTeX, UPRF 94-39
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