We classify the operator content of local hermitian scalar operators in the Sinh-Gordon model by means of independent solutions of the form-factor bootstrap equations. The corresponding linear space is organized into a tower-like structure of dimension n for the form factors F 2n and F 2n−1. Analyzing the cluster property of the form factors, a particular… (More)
Finite temperature correlation functions in integrable quantum field theories are formulated only in terms of the usual, temperature-independent form factors, and certain thermodynamic filling fractions which are determined from the thermodynamic Bethe ansatz. Explicit expressions are given for the one and two-point functions.
The scaling form of the free energy near a critical point allows for the definition of various thermodynamical amplitudes and the determination of their dependence on the microscopic nonuniversal scales. Universal quantities can be obtained by considering special combinations of the amplitudes. Together with the critical exponents they characterize the… (More)
We determine the semiclassical energy levels for the φ 4 field theory in the broken symmetry phase on a 2D cylindrical geometry with antiperiodic boundary conditions by quantizing the appropriate finite–volume kink solutions. The analytic form of the kink scaling functions for arbitrary size of the system allows us to describe the flow between the twisted… (More)
We derive the recursive equations for the form factors of the local hermitian operators in the Bullough-Dodd model. At the self-dual point of the theory, the form factors of the fundamental field of the Bullough-Dodd model are equal to those of the fundamental field of the Sinh-Gordon model at a specific value of the coupling constant.
Exact expressions of the boundary state and the form factors of the Ising model are used to derive differential equations for the one-point functions of the energy and magnetization operators of the model in the presence of a boundary magnetic field. We also obtain explicit formulas for the massless limit of the one-point and two-point functions of the… (More)
In this paper we present an elementary derivation of the semi-classical spectrum of neutral particles in a field theory with kink excitations. In the non-integrable cases, we show that each vacuum state cannot generically support more than two stable particles, since all other neutral exitations are resonances , which will eventually decay. A phase space… (More)
Form Factor Perturbation Theory is applied to study the spectrum of the O(3) non– linear sigma model with the topological term in the vicinity of θ = π. Its effective action near this value is given by the non–integrable double Sine–Gordon model. Using previous results by Affleck and the explicit expressions of the Form Factors of the exponential operators… (More)
We present an analytic study of the finite size effects in Sine–Gordon model, based on the semiclassical quantization of an appropriate kink background defined on a cylindrical geometry. The quasi–periodic kink is realized as an elliptic function with its real period related to the size of the system. The stability equation for the small quantum… (More)
The non-perturbative mapping between different Quantum Field Theories and other features of two-dimensional massive integrable models are discussed by using the Form Factor approach. The computation of ultraviolet data associated to the massive regime is illustrated by taking as an example the scattering theory of the Ising Model with boundary.