123 research outputs found
Para-Grassmann Variables and Coherent States
The definitions of para-Grassmann variables and q-oscillator algebras are
recalled. Some new properties are given. We then introduce appropriate coherent
states as well as their dual states. This allows us to obtain a formula for the
trace of a operator expressed as a function of the creation and annihilation
operators.Comment: This is a contribution to the Proc. of the O'Raifeartaigh Symposium
on Non-Perturbative and Symmetry Methods in Field Theory (June 2006,
Budapest, Hungary), published in SIGMA (Symmetry, Integrability and Geometry:
Methods and Applications) at http://www.emis.de/journals/SIGMA
Magnetic structures and Z_2 vortices in a non-Abelian gauge model
The magnetic order of the triangular lattice with antiferromagnetic
interactions is described by an SO(3) field and allows for the presence of Z2
magnetic vortices as defects. In this work we show how these Z2 vortices can be
fitted into a local SU(2) gauge theory. We propose simple Ansatzes for vortex
configurations and calculate their energies using well-known results of the
Abelian gauge model. We comment on how Dzyaloshinskii-Moriya interactions could
be derived from a non-Abelian gauge theory and speculate on their effect on non
trivial configurations
Spinons as Composite Fermions
We show that gauge invariant composites in the fermionic realization of
conformal field theory explicitly exhibit the holomorphic
factorization of the corresponding WZW primaries. In the case we show
that the holomorphic sector realizes the spinon algebra, thus
allowing the classification of the chiral Fock space in terms of semionic
quasi-particle excitations created by the composite fermions.Comment: SU(N)_1 case included. Final version to appear in Mod. Phys. Lett. A.
Latex, 13 page
Quasiparticle operators with non-Abelian braiding statistics
We study the gauge invariant fermions in the fermion coset representation of
Wess-Zumino-Witten models which create, by construction, the physical
excitations (quasiparticles) of the theory. We show that they provide an
explicit holomorphic factorization of Wess-Zumino-Witten primaries
and satisfy non-Abelian braiding relations.Comment: 13 pages, no figures, final version to appear in Physics Letters
Duality in deformed coset fermionic models
We study the -parafermion model perturbed by its first thermal
operator. By formulating the theory in terms of a (perturbed) fermionic coset
model we show that the model is equivalent to interacting WZW fields modulo
free fields. In this scheme, the order and disorder operators of the
parafermion theory are constructed as gauge invariant composites. We find that
the theory presents a duality symmetry that interchanges the roles of the spin
and dual spin operators. For two particular values of the coupling constant we
find that the theory recovers conformal invariance and the gauge symmetry is
enlarged. We also find a novel self-dual point.Comment: 13 pages, LaTex. Minor corrections. One reference added. Version to
appear in Nuc. Phys.
Magnetization plateaus in dimerized spin-ladder arrays
We investigate the ground-state magnetization plateaus appearing in spin-½ two-leg ladders built up from dimerized antiferromagnetic Heisenberg chains and dimerized zig-zag interchain couplings. Using both Abelian bosonization and Lanczos methods we find that the system yields rather unusual plateaus and exhibits massive and massless phases for specific choices or “tuning” of exchange interactions. The relevance of this behavior in the study of NH4CuCl3 is discussed.Facultad de Ciencias Exacta
Explicit connection between conformal field theory and 2+1 Chern-Simons theory
We give explicit field theoretical representations for the observables of 2+1
dimensional Chern-Simons theory in terms of gauge invariant composites of 2D
WZW fields. To test our identification we compute some basic Wilson loop
correlators reobtaining known results.Comment: 13 pages, Latex file. To appear in Mod.Phys.Lett.
Propiedades conformes en modelos fermiónicos bidimensionales
Esta tesis está organizada en seis capítulos.
En el capítulo II se da una breve introducción a la Teoría de Campos Conforme y al estudio de teorías fuera del punto crítico. En el capítulo III se presenta la construcción de teorías del coset en términos de modelos fermiónicos constreñidos. En el capítulo IV se describe la generalización de la construcción fermiónica del coset que describe los modelos cosets anidados y se estudia la modificación de una teoría coset al incluir sectores topológicos. En el capítulo V, luego de un repaso de las propiedades conocidas del modelo de Gross-Neveu Quiral, se calcula la contribución a dos loops a la función C de Zamolodchikov. Finalmente, en el capítulo VI, se presentan las conclusiones.Tesis digitalizada en SEDICI gracias a la Biblioteca de Física de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta
Para-Grassmann variables and coherent states
The definitions of para-Grassmann variables and q-oscillator algebras are recalled. Some new properties are given. We then introduce appropriate coherent states as well as their dual states. This allows us to obtain a formula for the trace of a operator expressed as a function of the creation and annihilation operators.Facultad de Ciencias Exacta
- …