Giuseppe Mussardo

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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)
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)