G Mussardo

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We study the ground state energy of integrable 1+1 quantum field theories with boundaries (the genuine Casimir effect). In the scalar case, this is done by introducing a new, " R-channel TBA " , where the boundary is represented by a boundary state, and the thermodynamics involves evaluating scalar products of boundary states with all the states of the(More)
The scattering theory of the integrable statistical models can be generalized to the case of systems with extended lines of defect. This is done by adding the reflection and transmission amplitudes for the interactions with the line of inhomegeneity to the scattering amplitudes in the bulk. The factorization condition for the new amplitudes gives rise to a(More)
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)
The factorization condition for the scattering amplitudes of an integrable model with a line of defect gives rise to a set of Reflection-Transmission equations. The solutions of these equations in the case of diagonal S-matrix in the bulk are only those with S = ±1. The choice S = −1 corresponds to the Ising model. We compute the transmission and reflection(More)
We use the recently conjectured exact S-matrix of the massive O(n) model to derive its form factors and ground state energy. This information is then used in the limit n → 0 to obtain quantitative results for various universal properties of self-avoiding chains and loops. In particular, we give the first theoretical prediction of the amplitude ratio C/D(More)
We study an integrable quantum field theory of a single stable particle with an infinite number of resonance states. The exact S–matrix of the model is expressed in terms of Jacobian elliptic functions which encode the resonance poles inherently. In the limit l → 0, with l the modulus of the Jacobian elliptic function, it reduces to the Sinh–Gordon(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)