4,339 research outputs found
The Epstein-Glaser causal approach to the Light-Front QED. I: Free theory
In this work we present the study of light-front field theories in the realm
of axiomatic theory. It is known that when one uses the light-cone gauge
pathological poles arises, demanding a prescription to be
employed in order to tame these ill-defined poles and to have correct Feynman
integrals due to the lack of Wick rotation in such theories. In order to shed a
new light on this long standing problem we present here a discussion based on
the use rigorous mathematical machinery of distributions combined with physical
concepts, such as causality, to show how to deal with these singular
propagators in a general fashion without making use of any prescription. The
first step of our development will consist in showing how analytic
representation for propagators arises by requiring general physical properties
in the framework of Wightman's formalism. From that we shall determine the
equal-time (anti)commutation relations in the light-front form for the scalar,
fermionic fields and for the dynamical components of the electromagnetic field.
In conclusion, we introduce the Epstein-Glaser causal method in order to have a
mathematical rigorous treatment of the free propagators of the theory, allowing
us to discuss the general treatment for propagators of the type . Moreover, we show that at given conditions our results reproduce known
prescriptions in the literature.Comment: 34 pages, v2 matching the published versio
Causal approach for the electron-positron scattering in Generalized Quantum Electrodynamics
In this paper we study the generalized electrodynamics contribution for the
electron-positron scattering process, , the
Bhabha scattering. Within the framework of the standard model, for energies
larger when compared to the electron mass, we calculate the cross section
expression for the scattering process. This quantity is usually calculated in
the framework of the Maxwell electrodynamics and, by phenomenological reasons,
corrected by a cut-off parameter. On the other hand, by considering the
generalized electrodynamics instead of Maxwell's, we can show that the effects
played by the Podolsky mass is actually a natural cut-off parameter for this
scattering process. Furthermore, by means of experimental data of Bhabha
scattering we will estimate its lower bound value. Nevertheless, in order to
have a mathematically well defined description of our study we shall present
our discussion in the framework of the Epstein-Glaser causal theory.Comment: 24 pages, V2 to match published versio
Comments on regularization ambiguities and local gauge symmetries
We study the regularization ambiguities in an exact renormalized
(1+1)-dimensional field theory. We show a relation between the regularization
ambiguities and the coupling parameters of the theory as well as their role in
the implementation of a local gauge symmetry at quantum level.Comment: Latex 2e, 4 pages. To appear in Modern Physics Letters
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
An Exact Test of Fit for the Gaussian Linear Model using Optimal Nonbipartite Matching
Fisher tested the fit of Gaussian linear models using replicated observations. We refine this method by (1) constructing near-replicates using an optimal nonbipartite matching and (2) defining a distance that focuses on predictors important to the model’s predictions. Near-replicates may not exist unless the predictor set is low-dimensional; the test addresses dimensionality by betting that model failures involve a subset of predictors important in the old fit. Despite using the old fit to pair observations, the test has exactly its stated level under the null hypothesis. Simulations show the test has reasonable power even when many spurious predictors are present
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