4,643 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
Hamilton-Jacobi formalism for Linearized Gravity
In this work we study the theory of linearized gravity via the
Hamilton-Jacobi formalism. We make a brief review of this theory and its
Lagrangian description, as well as a review of the Hamilton-Jacobi approach for
singular systems. Then we apply this formalism to analyze the constraint
structure of the linearized gravity in instant and front-form dynamics.Comment: To be published in Classical and Quantum Gravit
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
Renormalizability of generalized quantum electrodynamics
In this work we present the study of the renormalizability of the Generalized
Quantum Electrodynamics (). We begin the article by reviewing the
on-shell renormalization scheme applied to . Thereafter, we calculate
the explicit expressions for all the counter-terms at one-loop approximation
and discuss the infrared behavior of the theory as well. Next, we explore some
properties of the effective coupling of the theory which would give an
indictment of the validity regime of theory: .
Afterwards, we make use of experimental data from the electron anomalous
magnetic moment to set possible values for the theory free parameter through
the one-loop contribution of Podolsky mass-dependent term to Pauli's form
factor .Comment: 9 page
Fermionic bound states in Minkowski-space: Light-cone singularities and structure
The Bethe-Salpeter equation for two-body bound system with spin
constituent is addressed directly in the Minkowski space. In order to
accomplish this aim we use the Nakanishi integral representation of the
Bethe-Salpeter amplitude and exploit the formal tool represented by the exact
projection onto the null-plane. This formal step allows one i) to deal with
end-point singularities one meets and ii) to find stable results, up to
strongly relativistic regimes, that settles in strongly bound systems. We apply
this technique to obtain the numerical dependence of the binding energies upon
the coupling constants and the light-front amplitudes for a fermion-fermion
state with interaction kernels, in ladder approximation, corresponding to
scalar-, pseudoscalar- and vector boson exchanges, respectively. After
completing the numerical survey of the previous cases, we extend our approach
to a quark-antiquark system in state, taking both constituent-fermion and
exchanged boson masses, from lattice calculations. Interestingly, the
calculated light-front amplitudes for such a mock pion show peculiar signatures
of the spin degrees of freedom.Comment: 22 pages, 7 figures, bst file include
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