Bo-Wei Xu

The Scattering phase shifts in the sine-Gordon and sinh-Gordon field theories

Abstract Scattering two-particle states of the sine-Gordon and sinh-Gordon models in D + 1 dimensions are investigated for all values of the coupling constant with the Gaussian wave-functional approach. In 1 + 1 and 2 + 1 dimensions, the phase shifts of the scattering states are obtained. We find that the phase shifts are positive for the sine-Gordon field theory and negative for the sinh-Gordon field theory. In the higher dimensions, the phase shifts vanish, which is coincident with the triviality of the two field theories.

Excited States of the Double sine-Gordon Model*

Using the Gaussian wave functional as variational ground state, we study the excited states of the double sine-Gordon model in dimensions. We find, i) for there exist two particle bound states, their energy decreases with increasing coupling; ii) also for , the phase shift of the two-particle scattering state is always positive; iii) for the investigation on the interaction between the particles shows that the theory is trivial.

Equivalence of Bogoliubov Transformations to the Gaussian Wave-Functional Approach in sin-Gordon Model*

Through the calculation of the effective potential and the excited state energies for the sinh-Gordon and the sine-Gordon models in dimensions, we show that the variational technique of Bogoliubov transformations is equivalent to the Gaussian wave-functional approach.

Phase Transition in Two-Dimensional Classical Coulomb Plasma by Mapping to Quantum sine-Gordon System in Euclidean space

The phase transition of the two-dimensional Coulomb plasma is studied with the help of the equivalence to a quantum sine-Gordon system in Euclidean space. The minimum and the stability of the grand canonical potential are derived by making use of the variational effective potential method. The phase diagram thus obtained shows a larger region of plasma phase in the parameter plane than the parallel result in the -dimensional Minkowski space. The origin of this difference is discussed in connection with the manner of the large momentum cut off being taken.

Variational Study of the Discrete sine-Gordon Model*

By using the Gaussian wave functional method, the -dimensional discrete sine-Gordon model is studied. The ground state energy and the one-particle states and the two-particle bound state are calculated.

Phase Diagram of One-Dimensional Fermi Gas Model*

The phase diagrams of one-dimensional -ology model are studied. The known results of the XXZ spin 1/2 chain model are applied to extending the solutions to the massless range where the method of Gaussian wave functional is insufficient. The response functions of CDW, SDW, SS and TS are computed as temperature .

A discrete sine-Gordon model

Abstract The (1 + 1)-dimensional discrete sine-Gordon model is studied in the frame of the variational Gaussian wave functionals, the ground state and the phase diagram are investigated.

Variational calculation of the excited states in the sinh-Gordon field theory

The Gaussian wave-functional variational approximation is used to calculate the energy of one-particle state as well as the energy and wave function of two-particle state in the sinh-Gordon model in (1+1) dimensions. We find that there are no bound states in this model. The phase shifts of the scattering states are investigated in detail.