52 research outputs found
One-point functions in integrable quantum field theory at finite temperature
We determine the form factor expansion of the one-point functions in
integrable quantum field theory at finite temperature and find that it is
simpler than previously conjectured. We show that no singularities are left in
the final expression provided that the operator is local with respect to the
particles and argue that the divergences arising in the non-local case are
related to the absence of spontaneous symmetry breaking on the cylinder. As a
specific application, we give the first terms of the low temperature expansion
of the one-point functions for the Ising model in a magnetic field.Comment: 10 pages, late
On mass spectrum in 't Hooft's 2D model of mesons
We study 't Hooft's integral equation determining the meson masses M_n in
multicolor QCD_2. In this note we concentrate on developing an analytic method,
and restrict our attention to the special case of quark masses
m_1=m_2=g/\sqrt{\pi}. Among our results is systematic large-n expansion, and
exact sum rules for M_n. Although we explicitly discuss only the special case,
the method applies to the general case of the quark masses, and we announce
some preliminary results for m_1=m_2.Comment: 26 pages, 4 figures; v2: refs added, typos correcte
Explicit Construction of Spin 4 Casimir Operator in the Coset Model
We generalize the Goddard-Kent-Olive (GKO) coset construction to the
dimension 5/2 operator for and compute the fourth order
Casimir invariant in the coset model with the generic unitary minimal
series that can be viewed as perturbations of the
limit, which has been investigated previously in the realization of
free fermion model.Comment: 11 page
The particle spectrum of the Tricritical Ising Model with spin reversal symmetric perturbations
We analyze the evolution of the particle spectrum of the Tricritical Ising
Model by varying the couplings of the energy and vacancy density fields. The
particle content changes from the spectrum of a supersymmetric theory (either
of an exact or a spontaneously broken supersymmetric theory) to the spectrum of
seven particles related to the underlying E_7 structure. In the low temperature
phase some of these excitations are topologically charged particles that are
stable under an arbitrary variation of the parameters. The high and low
temperature phases of the model are related by duality. In some regions of the
two couplings there are also present false vacua and sequences of bound states.
In order to study the non-integrable features of this model we employ the Form
Factor Perturbation Theory and the Truncated Conformal Space Approach.Comment: 34 pages, 14 figures, text misprints correcte
On scaling fields in Ising models
We study the space of scaling fields in the symmetric models with the
factorized scattering and propose simplest algebraic relations between form
factors induced by the action of deformed parafermionic currents. The
construction gives a new free field representation for form factors of
perturbed Virasoro algebra primary fields, which are parafermionic algebra
descendants. We find exact vacuum expectation values of physically important
fields and study correlation functions of order and disorder fields in the form
factor and CFT perturbation approaches.Comment: 2 Figures, jetpl.cl
The Baxter Q Operator of Critical Dense Polymers
We consider critical dense polymers , corresponding to a
logarithmic conformal field theory with central charge . An elegant
decomposition of the Baxter operator is obtained in terms of a finite
number of lattice integrals of motion. All local, non local and dual non local
involutive charges are introduced directly on the lattice and their continuum
limit is found to agree with the expressions predicted by conformal field
theory. A highly non trivial operator is introduced on the lattice
taking values in the Temperley Lieb Algebra. This function provides a
lattice discretization of the analogous function introduced by Bazhanov,
Lukyanov and Zamolodchikov. It is also observed how the eigenvalues of the
operator reproduce the well known spectral determinant for the harmonic
oscillator in the continuum scaling limit.Comment: improved version, accepted for publishing on JSTA
Exact Results for Thermodynamics of the Classical Field Theories: Sine- and Sinh-Gordon Models
Using the recently obtained exact results for the expectation values of
operators in the sine- and sinh-Gordon models [A. B. Zamolodchikov and S.
Lukyanov, Nucl. Phys. B{\bf 493}, 571 (1997), V. Fateev, S. Lukyanov, A. B.
Zamolodchikov and Al. B. Zamolodchikov, Phys. Lett. B{\bf 406}, 83 (1997)] we
calculate the specific heat of the corresponding two dimensional Euclidean
(classical) models.
We show that the temperature dependence of the specific heat of the
sine-Gordon model, in the commensurate phase, has a maximum well below the
Kosterlitz-Thouless transition and that the sinh-Gordon model is
thermodynamically unstable in the strong coupling regime. We give also the
temperature dependence of the specific heat in the incommensurate phase of the
sine-Gordon model.Comment: 14 pages, including 6 figures; updated version; submitted to Phys.
Rev.
Sine-Gordon description of the scaling three-state Potts antiferromagnet on the square lattice
The scaling limit as T->0 of the antiferromagnetic three-state Potts model on
the square lattice is described by the sine-Gordon quantum field theory at a
specific value of the coupling. We show that the correspondence follows
unambigously from an analysis of the sine-Gordon operator space based on
locality, and that the scalar operators carrying solitonic charge play an
essential role in the description of the lattice model. We then evaluate the
correlation functions within the form factor approach and give a number of
universal predictions that can be checked in numerical simulations.Comment: 10 pages, late
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