83 research outputs found
Dual embedding of the Lorentz-violating electrodinamics and Batalin-Vilkovisky quantization
Modifications of the electromagnetic Maxwell Lagrangian in four dimensions
have been considered by some authors. One may include an explicit massive term
(Proca) and a topological but not Lorentz-invariant term within certain
observational limits.
We find the dual-corresponding gauge invariant version of this theory by
using the recently suggested gauge embedding method. We enforce this
dualisation procedure by showing that, in many cases, this is actually a
constructive method to find a sort of parent action, which manifestly
establishes duality. We also use the gauge invariant version of this theory to
formulate a Batalin-Vilkovisky quantization and present a detailed discussion
on the excitation spectrum.Comment: 8 page
Implicit Regularization and Renormalization of QCD
We apply the Implicit Regularization Technique (IR) in a non-abelian gauge
theory. We show that IR preserves gauge symmetry as encoded in relations
between the renormalizations constants required by the Slavnov-Taylor
identities at the one loop level of QCD. Moreover, we show that the technique
handles divergencies in massive and massless QFT on equal footing.Comment: (11 pages, 2 figures
Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function
We present a both ultraviolet and infrared regularization independent
analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta
function to two loop order. We show explicitly that off-shell infrared
divergences as well as the overall two loop ultraviolet divergence cancel out
whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte
Ultraviolet and Infrared Divergences in Implicit Regularization: a Consistent Approach
Implicit Regularization is a 4-dimensional regularization initially conceived
to treat ultraviolet divergences. It has been successfully tested in several
instances in the literature, more specifically in those where Dimensional
Regularization does not apply. In the present contribution we extend the method
to handle infrared divergences as well. We show that the essential steps which
rendered Implicit Regularization adequate in the case of ultraviolet
divergences have their counterpart for infrared ones. Moreover we show that a
new scale appears, typically an infrared scale which is completely independent
of the ultraviolet one. Examples are given.Comment: 9 pages, version to appear in Mod. Phys. Lett.
Classical Solutions in a Lorentz-violating Maxwell-Chern-Simons Electrodynamics
We take as starting point the planar model arising from the dimensional
reduction of the Maxwell Electrodynamics with the (Lorentz-violating)
Carroll-Field-Jackiw term. We then write and study the extended Maxwell
equations and the corresponding wave equations for the potentials. The solution
to these equations show some interesting deviations from the usual MCS
Electrodynamics, with background-dependent correction terms. In the case of a
time-like background, the correction terms dominate over the MCS sector in the
region far from the origin, and establish the behaviour of a massless
Electrodynamics (in the electric sector). In the space-like case, the solutions
indicate the clear manifestation of spatial anisotropy, which is consistent
with the existence of a privileged direction is space.Comment: latex, 8 page
Mass generation for abelian spin-1 particles via a symmetric tensor
In the topologically massive BF model (TMBF) the photon becomes massive via
coupling to an antisymmetric tensor, without breaking the U(1) gauge symmetry .
There is no need of a Higgs field. The TMBF model is dual to a first-order (in
derivatives) formulation of the Maxwell-Proca theory where the antisymmetric
field plays the role of an auxiliary field. Since the Maxwell-Proca theory also
admits a first-order version which makes use of an auxiliary symmetric tensor,
we investigate here a possible generalization of the TMBF model where the
photon acquires mass via coupling to a symmetric tensor. We show that it is
indeed possible to build up dual models to the Maxwell-Proca theory where the
U(1) gauge symmetry is manifest without Higgs field, but after a local field
redefinition the vector field eats up the trace of the symmetric tensor and
becomes massive. So the explicit U(1) symmetry can be removed unlike the TMBF
model.Comment: 15 pages, no figures, one reference added, two typos on page 3 fixe
Gauge Theories with Lorentz-Symmetry Violation by Symplectic Projector Method
The violation of Lorentz symmetry is studied from the point of view of a
canonical formulation. We make the usual analysis on the constraints structure
of the Carroll-Field-Jackiw model. In this context we derive the equations of
motion for the physical variables and check out the dispersion relations
obtained from them. Therefore, by the analysis using Symplectic Projector
Method (SPM), we can check the results about this type of Lorentz breaking with
those in the recent literature: in this sense we can confirm that the
configuration of space-like is stable, and the time-like
carry tachionic modes.Comment: 7 pages and no figure
Aspects of Causality and Unitarity and Comments on Vortex-like Configurations in an Abelian Model with a Lorentz-Breaking Term
The gauge-invariant Chern-Simons-type Lorentz- and CPT-breaking term is here
reassessed and a spin-projector method is adopted to account for the breaking
(vector) parameter. Issues like causality, unitarity, spontaneous
gauge-symmetry breaking and vortex formation are investigated, and consistency
conditions on the external vector are identified.Comment: 12 pages, late
Chiral Anomaly and CPT invariance in an implicit momentum space regularization framework
This is the second in a series of two contributions in which we set out to
establish a novel momentum space framework to treat field theoretical
infinities in perturbative calculations when parity-violating objects occur.
Since no analytic continuation on the space-time dimension is effected, this
framework can be particularly useful to treat dimension-specific theories.
Moreover arbitrary local terms stemming from the underlying infinities of the
model can be properly parametrized. We (re)analyse the undeterminacy of the
radiatively generated CPT violating Chern-Simons term within an extended
version of and calculate the Adler-Bardeen-Bell-Jackiw triangle anomaly
to show that our framework is consistent and general to handle the subtleties
involved when a radiative corretion is finite.Comment: 16 pages, LaTeX, version to appear in PR
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