22 research outputs found
Functional integral approach to multipoint correlators in 2d critical systems
We extend a previously developed technique for computing spin-spin critical
correlators in the 2d Ising model, to the case of multiple correlations. This
enables us to derive Kadanoff-Ceva's formula in a simple and elegant way. We
also exploit a doubling procedure in order to evaluate the critical exponent of
the polarization operator in the Baxter model. Thus we provide a rigorous proof
of the relation between different exponents, in the path-integral framework.Comment: 10 pages, LaTex, no figure
Path-integral fermion-boson decoupling at finite temperature
We show how to extend the standard functional approach to bosonisation, based
on a decoupling change of path-integral variables, to the case in which a
finite temperature is considered. As examples, in order to both illustrate and
check the procedure, we derive the thermodynamical partition functions for the
Thirring and Schwinger models.Comment: 12 pages, latex, no figure
Duality and bosonization in Schwinger-Keldysh formulation
We present a path-integral bosonization approach for systems out of
equilibrium based on a duality transformation of the original Dirac fermion
theory combined with the Schwinger-Keldysh time closed contour technique, to
handle the non-equilibrium situation. The duality approach to bosonization that
we present is valid for space-time dimensions leading for to
exact results. In this last case we present the bosonization rules for fermion
currents, calculate current-current correlation functions and establish the
connection between the fermionic and bosonic distribution functions in a
generic, nonequilibrium situation.Comment: 16 pages, 1 figur
Path-integral Bosonization of PT symmetric models
We discuss bosonization of non-Hermitian PT invariant fermion models in
space-time dimensions within the path-integral approach in which the generating
functionals associated to the fermion and boson models can be related. We first
discuss the PT symmetric Thirring-sine-Gordon connection and then extend the
treatment to bosonize the Gross-Neveu model.Comment: 12 pages, no figure
Non local Thirring model with spin flipping interactions
We extend a non local and non covariant version of the Thirring model in order to describe a many-body system with spin-flipping interactions By introducing a model with two fermion species we are able to avoid the use of non abelian bosonization which is needed in a previous approach. We obtain a bosonized expression for the partition function, describing the dynamics of the collective modes of this system. By using the self-consistent harmonic approximation we found a formula for the gap of the spin-charge excitations as functional of arbitrary electron-electron potentials
Vacuum properties of a Non-Local Thirring-Like Model
We use path-integral methods to analyze the vacuum properties of a recently
proposed extension of the Thirring model in which the interaction between
fermionic currents is non-local. We calculate the exact ground state wave
functional of the model for any bilocal potential, and also study its
long-distance behavior. We show that the ground state wave functional has a
general factored Jastrow form. We also find that it posess an interesting
symmetry involving the interchange of density-density and current-current
interactions.Comment: 25 pages, latex, no figure
Friedel oscillations in a Luttinger liquid with long-range interactions
We introduce a path-integral approach that allows to compute charge density
oscillations in a Luttinger liquid with impurities. We obtain an explicit
expression for the envelope of Friedel oscillations in the presence of
arbitrary electron-electron potentials. As examples, in order to illustrate the
procedure, we show how to use our formula for contact and Coulomb potentials.Comment: 11 pages, no figures, latex. Revised version to appear in PR
Improved harmonic approximation and the 2D Ising model at and
We propose a new method to determine the unknown parameter associated to a
self-consistent harmonic approximation. We check the validity of our technique
in the context of the sine-Gordon model. As a non trivial application we
consider the scaling regime of the 2D Ising model away from the critical point
and in the presence of a magnetic field . We derive an expression that
relates the approximate correlation length , and .Comment: 11 pages, Latex, 3 figures. Accepted for publication in Journal of
Physics