17 research outputs found
Physical unitarity in the Lagrangian Sp(2)-symmetric formalism
The structure of state vector space for a general (non-anomalous) gauge
theory is studied within the Lagrangian version of the -symmetric
quantization method. The physical {\it S}-matrix unitarity conditions are
formulated. The general results are illustrated on the basis of simple gauge
theory models.Comment: 26 pages, LaTE
One-loop effective action for Einstein gravity in special background gauge
The one-loop effective action for Einstein gravity in a special one-parameter
background gauge is calculated up to first order in a gauge parameter. It is
shown that the effective action does not depend upon the gauge parameter on
shell.Comment: 17 pages, Latex, no figure
Production of Neutral Fermion in Linear Magnetic Field through Pauli Interaction
We calculate the production rate of neutral fermions in linear magnetic
fields through the Pauli interaction. It is found that the production rate is
exponentially decreasing function with respect to the inverse of the magnetic
field gradient, which shows the non-perturbative characteristics analogous to
the Schwinger process. It turns out that the production rate density depends on
both the gradient and the strength of magnetic fields in 3+1 dimension. It is
quite different from the result in 2+1 dimension, where the production rate
depends only on the gradient of the magnetic fields, not on the strength of the
magnetic fields. It is also found that the production of neutral fermions
through the Pauli interaction is a magnetic effect whereas the production of
charged particles through minimal coupling is an electric effect.Comment: 11 pages, 2 figure
Superfield quantization of general gauge theories
A superfield version on superspace is proposed for the
-- covariant Lagrangian quantization of general gauge theories. The
BRST- and antiBRST- transformations are realized on superfields as
supertranslations in the -- directions. A new (geometric)
interpretation of the Ward identities in the quantum gauge theory is given.Comment: 15 pages, Latex, no figure
Effective Potential for Uniform Magnetic Fields through Pauli Interaction
We have calculated the explicit form of the real and imaginary parts of the
effective potential for uniform magnetic fields which interact with spin-1/2
fermions through the Pauli interaction. It is found that the non-vanishing
imaginary part develops for a magnetic field stronger than a critical field,
whose strength is the ratio of the fermion mass to its magnetic moment. This
implies the instability of the uniform magnetic field beyond the critical field
strength to produce fermion pairs with the production rate density
in the
presence of Pauli interaction.Comment: 9 pages with 1 figur
The effective action and quantum gauge transformations
The local symmetry transformations of the quantum effective action for
general gauge theory are found. Additional symmetries arise under consideration
of background gauges. Together with "trivial" gauge transformations, vanishing
on mass shell, they can be used for construction simple gauge generators. For
example, for the Yang-Mills theory the classically invariant effective action
is obtained, reproducing DeWitt's result. For rank one theories a natural
generalization is proposed.Comment: Revtex, 11 pages; added reference
Particles with anomalous magnetic moment in external e.m. fields: the proper time formulation
In this paper we evaluate the expression for the Green function of a
pseudo-classical spinning particle interacting with constant electromagnetic
external fields by taking into account the anomalous magnetic and electric
moments of the particle. The spin degrees of freedom are described in terms of
Grassmann variables and the evolution operator is obtained through the
Fock-Schwinger proper time method.Comment: 10 page
Gauge dependence of effective action and renormalization group functions in effective gauge theories
The Caswell-Wilczek analysis on the gauge dependence of the effective action
and the renormalization group functions in Yang-Mills theories is generalized
to generic, possibly power counting non renormalizable gauge theories. It is
shown that the physical coupling constants of the classical theory can be
redefined by gauge parameter dependent contributions of higher orders in
in such a way that the effective action depends trivially on the gauge
parameters, while suitably defined physical beta functions do not depend on
those parameters.Comment: 13 pages Latex file, additional comments in section