4,664 research outputs found
Causal Propagators for Algebraic Gauges
Applying the principle of analytic extension for generalized functions we
derive causal propagators for algebraic non-covariant gauges. The so generated
manifestly causal gluon propagator in the light-cone gauge is used to evaluate
two one-loop Feynman integrals which appear in the computation of the
three-gluon vertex correction. The result is in agreement with that obtained
through the usual prescriptions.Comment: LaTex, 09 pages, no figure
A possible way to relate the "covariantization" and the negative dimensional integration methods in the light cone gauge
In this work we present a possible way to relate the method of covariantizing
the gauge dependent pole and the negative dimensional integration method for
computing Feynman integrals pertinent to the light-cone gauge fields. Both
techniques are applicable to the algebraic light-cone gauge and dispense with
prescriptions to treat the characteristic poles.Comment: 9 page
K\"all\'en-Lehmann representation of noncommutative quantum electrodynamics
Noncommutative (NC) quantum field theory is the subject of many analyses on
formal and general aspects looking for deviations and, therefore, potential
noncommutative spacetime effects. Within of this large class, we may now pay
some attention to the quantization of NC field theory on lower dimensions and
look closely at the issue of dynamical mass generation to the gauge field. This
work encompasses the quantization of the two-dimensional massive quantum
electrodynamics and three-dimensional topologically massive quantum
electrodynamics. We begin by addressing the problem on a general dimensionality
making use of the perturbative Seiberg-Witten map to, thus, construct a general
action, to only then specify the problem to two and three dimensions. The
quantization takes place through the K\"all\'en-Lehmann spectral representation
and Yang-Feldman-K\"all\'en formulation, where we calculate the respective
spectral density function to the gauge field. Furthermore, regarding the photon
two-point function, we discuss how its infrared behavior is related to the term
generated by quantum corrections in two dimensions, and, moreover, in three
dimensions, we study the issue of nontrivial {\theta}-dependent corrections to
the dynamical mass generation
Interacting spin 0 fields with torsion via Duffin-Kemmer-Petiau theory
Here we study the behaviour of spin 0 sector of the DKP field in spaces with
torsion. First we show that in a Riemann-Cartan manifold the DKP field presents
an interaction with torsion when minimal coupling is performed, contrary to the
behaviour of the KG field, a result that breaks the usual equivalence between
the DKP and the KG fields.
Next we analyse the case of Teleparallel Equivalent of General Relativity
Weitzenbock manifold, showing that in this case there is a perfect agreement
between KG and DKP fields. The origins of both results are also discussed.Comment: 10 pages, no figures, uses REVTEX. Changes in the presentation, minor
misprints and one equation corrected. References updated. To appear in
General Relativity and Gravitatio
Quantum gauge boson propagators in the light front
Gauge fields in the light front are traditionally addressed via the
employment of an algebraic condition in the Lagrangian density,
where is the gauge field (Abelian or non-Abelian) and is the
external, light-like, constant vector which defines the gauge proper. However,
this condition though necessary is not sufficient to fix the gauge completely;
there still remains a residual gauge freedom that must be addressed
appropriately. To do this, we need to define the condition with . The implementation of this
condition in the theory gives rise to a gauge boson propagator (in momentum
space) leading to conspicuous non-local singularities of the type where . These singularities must be conveniently
treated, and by convenient we mean not only matemathically well-defined but
physically sound and meaningfull as well. In calculating such a propagator for
one and two noncovariant gauge bosons those singularities demand from the
outset the use of a prescription such as the Mandelstam-Leibbrandt (ML) one. We
show that the implementation of the ML prescription does not remove certain
pathologies associated with zero modes. However we present a causal,
singularity-softening prescription and show how to keep causality from being
broken without the zero mode nuisance and letting only the propagation of
physical degrees of freedom.Comment: 10 page
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