2,555 research outputs found
On three dimensional bosonization
We discuss Abelian and non-Abelian three dimensional bosonization within the
path-integral framework. We present a systematic approach leading to the
construction of the bosonic action which, together with the bosonization recipe
for fermion currents, describes the original fermion system in terms of vector
bosons.Comment: 15 pages, LaTe
Gravitational Interactions of integrable models
We couple non-linear -models to Liouville gravity, showing that
integrability properties of symmetric space models still hold for the matter
sector. Using similar arguments for the fermionic counterpart, namely
Gross--Neveu-type models, we verify that such conclusions must also hold for
them, as recently suggested.Comment: 8 pages, final version to appear in Physics Letters B Revised
version, with misprints corrected and some references adde
Wess-Zumino-Witten and fermion models in noncommutative space
We analyze the connection between Wess-Zumino-Witten and free fermion models
in two-dimensional noncommutative space. Starting from the computation of the
determinant of the Dirac operator in a gauge field background, we derive the
corresponding bosonization recipe studying, as an example, bosonization of the
U(N) Thirring model. Concerning the properties of the noncommutative
Wess-Zumino-Witten model, we construct an orbit-preserving transformation that
maps the standard commutative WZW action into the noncommutative one.Comment: 27 pages, 1 figure. LaTex fil
On the Electric Charge of Monopoles at Finite Temperature
We calculate the electric charge at finite temperature for non-Abelian
monopoles in spontaneously broken gauge theories with a CP violating
-term. A careful treatment of dyon's gauge degrees of freedom shows
that Witten formula for the dyon charge at , ,
remains valid at .Comment: 13 pages, latex file, no figure
Knot polynomial invariants in classical Abelian Chern-Simons field theory
Kauffman knot polynomial invariants are discovered in classical abelian
Chern-Simons field theory. A topological invariant is constructed for a link , where is the abelian
Chern-Simons action and a formal constant. For oriented knotted vortex
lines, satisfies the skein relations of the Kauffman R-polynomial; for
un-oriented knotted lines, satisfies the skein relations of the
Kauffman bracket polynomial. As an example the bracket polynomials of trefoil
knots are computed, and the Jones polynomial is constructed from the bracket
polynomial.Comment: 15 pages, 8 figure
Finite size effects on measures of critical exponents in d=3 O(N) models
We study the critical properties of three-dimensional O(N) models, for
N=2,3,4. Parameterizing the leading corrections-to-scaling for the
exponent, we obtain a reliable infinite volume extrapolation, incompatible with
previous Monte Carlo values, but in agreement with -expansions. We
also measure the critical exponent related with the tensorial magnetization as
well as the exponents and critical couplings.Comment: 12 pages, 2 postscript figure
The random lattice as a regularization scheme
A semi-analytic method to compute the first coefficients of the
renormalization group functions on a random lattice is introduced. It is used
to show that the two-dimensional non-linear -model regularized
on a random lattice has the correct continuum limit. A degree of
``randomness'' in the lattice is introduced and an estimate of the ratio
for two rather opposite values of
in the -model is also given. This ratio turns out to depend on
.Comment: PostScript file. 22 pages. Revised and enlarged versio
The flat phase of fixed-connectivity membranes
The statistical mechanics of flexible two-dimensional surfaces (membranes)
appears in a wide variety of physical settings. In this talk we discuss the
simplest case of fixed-connectivity surfaces. We first review the current
theoretical understanding of the remarkable flat phase of such membranes. We
then summarize the results of a recent large scale Monte Carlo simulation of
the simplest conceivable discrete realization of this system \cite{BCFTA}. We
verify the existence of long-range order, determine the associated critical
exponents of the flat phase and compare the results to the predictions of
various theoretical models.Comment: 7 pages, 5 figures, 3 tables. LaTeX w/epscrc2.sty, combined
contribution of M. Falcioni and M. Bowick to LATTICE96(gravity), to appear in
Nucl. Phys. B (proc. suppl.
Diagonal deformations of thin center vortices and their stability in Yang-Mills theories
The importance of center vortices for the understanding of the confining
properties of SU(N) Yang-Mills theories is well established in the lattice.
However, in the continuum, there is a problem concerning the relevance of
center vortex backgrounds. They display the so called Savvidy-Nielsen-Olesen
instability, associated with a gyromagnetic ratio for the
off-diagonal gluons.
In this work, we initially consider the usual definition of a {\it thin}
center vortex and rewrite it in terms of a local color frame in SU(N)
Yang-Mills theories. Then, we define a thick center vortex as a diagonal
deformation of the thin object. Besides the usual thick background profile,
this deformation also contains a frame defect coupled with gyromagnetic ratio
, originated from the charged sector. As a consequence, the
analysis of stability is modified. In particular, we point out that the defect
should stabilize a vortex configuration formed by a pair of straight components
separated by an appropriate finite distance.Comment: 20 pages, LaTe
High-gradient operators in perturbed Wess-Zumino-Witten field theories in two dimensions
Many classes of non-linear sigma models (NLSMs) are known to contain
composite operators with an arbitrary number 2s of derivatives ("high-gradient
operators") which appear to become strongly relevant within RG calculations at
one (or fixed higher) loop order, when the number 2s of derivatives becomes
large. This occurs at many conventional fixed points of NLSMs which are
perturbatively accessible within the usual epsilon-expansion in d=2+\epsilon
dimensions. Since such operators are not prohibited from occurring in the
action, they appear to threaten the very existence of such fixed points. At the
same time, for NLSMs describing metal-insulator transitions of Anderson
localization in electronic conductors, the strong RG-relevance of these
operators has been previously related to statistical properties of the
conductance of samples of large finite size ("conductance fluctuations"). In
this paper, we analyze this question, not for perturbative RG treatments of
NLSMs, but for 2d Wess-Zumino-Witten (WZW) models at level k, perturbatively in
the current-current interaction of the Noether current. WZW models are special
("Principal Chiral") NLSMs on a Lie Group G with a WZW term at level k. In
these models the role of high-gradient operators is played by homogeneous
polynomials of order 2s in the Noether currents, whose scaling dimensions we
analyze. For the Lie Supergroup G=GL(2N|2N) and k=1, this corresponds to
time-reversal invariant problems of Anderson localization in the so-called
chiral symmetry classes, and the strength of the current-current interaction, a
measure of the strength of disorder, is known to be completely marginal (for
any k). We find that all high-gradient (polynomial) operators are, to one loop
order, irrelevant or relevant depending on the sign of that interaction.Comment: 22 page
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