1,353 research outputs found
Algebraic characterization of constraints and generation of mass in gauge theories
The possibility of non-trivial representations of the gauge group on
wavefunctionals of a gauge invariant quantum field theory leads to a generation
of mass for intermediate vector and tensor bosons. The mass parameters "m" show
up as central charges in the algebra of constraints, which then become of
second-class nature. The gauge group coordinates acquire dynamics outside the
null-mass shell and provide the longitudinal field degrees of freedom that
massless bosons need to form massive bosons.Comment: 4 pages, LaTeX, no figures; uses espcrc2.sty (twocolumn).
Contribution to the "Third Meeting on Constrained Dynamics and Quantum
Gravity QG99" held in Sardinia, Italy, on Sept. 1999. To appear in Nucl.
Phys. B (Proc. Suppl.
Gauge Transformation Properties of Vector and Tensor Potentials Revisited: a Group Quantization Approach
The possibility of non-trivial representations of the gauge group on
wavefunctionals of a gauge invariant quantum field theory leads to a generation
of mass for intermediate vector and tensor bosons. The mass parameters m show
up as central charges in the algebra of constraints, which then become of
second-class nature. The gauge group coordinates acquire dynamics outside the
null-mass shell and provide the longitudinal field degrees of freedom that
massless bosons need to form massive bosons. This is a `non-Higgs' mechanism
that could provide new clues for the best understanding of the symmetry
breaking mechanism in unified field theories. A unified quantization of
massless and massive non-Abelian Yang-Mills, linear Gravity and Abelian
two-form gauge field theories are fully developed from this new approach, where
a cohomological origin of mass is pointed out.Comment: 22 pages, LaTeX, no figures; final version to appear in Int. J. Mod.
Phys.
Identifying topological-band insulator transitions in silicene and other 2D gapped Dirac materials by means of R\'enyi-Wehrl entropy
We propose a new method to identify transitions from a topological insulator
to a band insulator in silicene (the silicon equivalent of graphene) in the
presence of perpendicular magnetic and electric fields, by using the
R\'enyi-Wehrl entropy of the quantum state in phase space. Electron-hole
entropies display an inversion/crossing behavior at the charge neutrality point
for any Landau level, and the combined entropy of particles plus holes turns
out to be maximum at this critical point. The result is interpreted in terms of
delocalization of the quantum state in phase space. The entropic description
presented in this work will be valid in general 2D gapped Dirac materials, with
a strong intrinsic spin-orbit interaction, isoestructural with silicene.Comment: to appear in EP
Group Quantization on Configuration Space: Gauge Symmetries and Linear Fields
A new, configuration-space picture of a formalism of group quantization, the
GAQ formalism, is presented in the context of a previous, algebraic
generalization. This presentation serves to make a comprehensive discussion in
which other extensions of the formalism, particularly to incorporate gauge
symmetries, are developed as well. Both images are combined in order to
analyse, in a systematic manner and with complete generality, the case of
linear fields (abelian current groups). To ilustrate these developments we
particularize them for several fields and, in particular, we carry out the
quantization of the abelian Chern-Simons models over an arbitrary closed
surface in detail.Comment: Plain LaTeX, 31 pages, no macros. To appear in J. Math. Phy
The Electromagnetic and Proca Fields Revisited: a Unified Quantization
Quantizing the electromagnetic field with a group formalism faces the
difficulty of how to turn the traditional gauge transformation of the vector
potential, , into a
group law. In this paper it is shown that the problem can be solved by looking
at gauge transformations in a slightly different manner which, in addition,
does not require introducing any BRST-like parameter. This gauge transformation
does not appear explicitly in the group law of the symmetry but rather as the
trajectories associated with generalized equations of motion generated by
vector fields with null Noether invariants. In the new approach the parameters
of the local group, , acquire dynamical content outside the
photon mass shell, a fact which also allows a unified quantization of both the
electromagnetic and Proca fields.Comment: 16 pages, latex, no figure
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