7,709 research outputs found
Phase structure of Abelian Chern-Simons gauge theories
We study the effect of a Chern-Simons (CS) term in the phase structure of two
different Abelian gauge theories. For the compact Maxwell-Chern-Simons theory,
we obtain that for values of the CS coupling with ,
the theory is equivalent to a gas of closed loops with contact interaction,
exhibiting a phase transition in the universality class. We also employ
Monte Carlo simulations to study the noncompact U(1) Abelian Higgs model with a
CS term. Finite size scaling of the third moment of the action yields critical
exponents and that vary continuously with the strength of the CS
term, and a comparison with available analytical results is made.Comment: RevTex4, 4 pages, 1 figure; v3: improvements and corrections made in
the first part of the paper; references added. To be published in Europhysics
Letter
Compact U(1) gauge theories in 2+1 dimensions and the physics of low dimensional insulating materials
Compact abelian gauge theories in dimensions arise often as an
effective field-theoretic description of models of quantum insulators. In this
paper we review some recent results about the compact abelian Higgs model in
in that context.Comment: 5 pages, 3 figures; based on talk by F.S. Nogueira in the Aachen
HEP2003 conferenc
A note on the phase transition in a topologically massive Ginzburg-Landau theory
We consider the phase transition in a model which consists of a
Ginzburg-Landau free energy for superconductors including a Chern-Simons term.
The mean field theory of Halperin, Lubensky and Ma [Phys. Rev. Lett. 32, 292
(1974)] is applied for this model. It is found that the topological mass,
, drives the system into different regimes of phase transition. For
instance, there is a such that for a
fluctuation induced first order phase transition occurs. On the other hand, for
only the second order phase transition exists. The 1-loop
renormalization group analysis gives further insight to this picture. The fixed
point structure exhibits tricritical and second order fixed points.Comment: Revised version; uses a more physical parametrization of the
renormalization group equations; new references added; one figure added;
EuroLatex, 6 page
A non-perturbative approach to the Coleman- Weinberg mechanism in massless scalar QED
We rederive non-perturbatively the Coleman-Weinberg expression for the
effective potential for massless scalar QED. Our result is not restricted to
small values of the coupling constants. This shows that the Coleman- Weinberg
result can be established beyond the range of validity of perturbation theory.
Also, we derive it in a manifestly renormalization group invariant way. It is
shown that with the derivation given no Landau ghost singularity arises. The
finite temperature case is discussed.
Pacs number: 11.10.Ef,11.10.Gh
Quantum critical scaling behavior of deconfined spinons
We perform a renormalization group analysis of some important effective field
theoretic models for deconfined spinons. We show that deconfined spinons are
critical for an isotropic SU(N) Heisenberg antiferromagnet, if is large
enough. We argue that nonperturbatively this result should persist down to N=2
and provide further evidence for the so called deconfined quantum criticality
scenario. Deconfined spinons are also shown to be critical for the case
describing a transition between quantum spin nematic and dimerized phases. On
the other hand, the deconfined quantum criticality scenario is shown to fail
for a class of easy-plane models. For the cases where deconfined quantum
criticality occurs, we calculate the critical exponent for the decay of
the two-spin correlation function to first-order in . We also
note the scaling relation connecting the exponent
for the decay to the correlation length exponent and the crossover
exponent .Comment: 4.1 pages, no figures, references added; Version accepted for
publication in PRB (RC
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