Non-equivalence between Heisenberg XXZ spin chain and Thirring model

The Bethe ansatz equations for the spin 1/2 Heisenberg XXZ spin chain are numerically solved, and the energy eigenvalues are determined for the anti-ferromagnetic case. We examine the relation between the XXZ spin chain and the Thirring model, and show that the spectrum of the XXZ spin chain is different from that of the regularized Thirring model.Comment: 10 pages. 2figure

Series Expansions for the Massive Schwinger Model in Hamiltonian lattice theory

It is shown that detailed and accurate information about the mass spectrum of the massive Schwinger model can be obtained using the technique of strong-coupling series expansions. Extended strong-coupling series for the energy eigenvalues are calculated, and extrapolated to the continuum limit by means of integrated differential approximants, which are matched onto a weak-coupling expansion. The numerical estimates are compared with exact results, and with finite-lattice results calculated for an equivalent lattice spin model with long-range interactions. Both the heavy fermion and the light fermion limits of the model are explored in some detail.Comment: RevTeX, 10 figures, add one more referenc

The (1+1)-dimensional Massive sine-Gordon Field Theory and the Gaussian Wave-functional Approach

The ground, one- and two-particle states of the (1+1)-dimensional massive sine-Gordon field theory are investigated within the framework of the Gaussian wave-functional approach. We demonstrate that for a certain region of the model-parameter space, the vacuum of the field system is asymmetrical. Furthermore, it is shown that two-particle bound state can exist upon the asymmetric vacuum for a part of the aforementioned region. Besides, for the bosonic equivalent to the massive Schwinger model, the masses of the one boson and two-boson bound states agree with the recent second-order results of a fermion-mass perturbation calculation when the fermion mass is small.Comment: Latex, 11 pages, 8 figures (EPS files

Characteristics of Magnesium-Diboride Superconducting Wires Required for a Liquid Hydrogen Level Sensor

Possibilities of the future society with hydrogen utilization have been discussed as one of the advanced technologies for the improvement of the energy and environmental problems in recent decades. In order to go on generating the effective energies by oxidizing the hydrogen with a fuel cell etc., it is necessary to establish the total system for producing, transporting, storing and transferring the hydrogen safely and stably. At that time, it can also be essential to use the hydrogen as a liquefied gas as well as a compressed gas. In this study, the operation of a superconducting level sensor for liquid hydrogen with a magnesium-diboride wire is numerically simulated on the basis of experimental results carried out previously. The time evolution of temperature distribution along the wire is calculated with a heat balance equation including the cooling effects of liquid hydrogen and its vaporized gas. The influences of the wire size and material properties on minimum propagating current and power consumption in the gaseous hydrogen are evaluated toward the optimal design of the level sensor

液体水素用液位センサに要求される二ホウ化マグネシウム超伝導線材の特性

Possibilities of the future society with hydrogen utilization have been discussed as one of the advanced technologies for the improvement of the energy and environmental problems in recent decades. In order to go on generating the effective energies by oxidizing the hydrogen with a fuel cell etc., it is necessary to establish the total system for producing, transporting, storing and transferring the hydrogen safely and stably. At that time, it can also be essential to use the hydrogen as a liquefied gas as well as a compressed gas. In this study, the operation of a superconducting level sensor for liquid hydrogen with a magnesium-diboride wire is numerically simulated on the basis of experimental results carried out previously. The time evolution of temperature distribution along the wire is calculated with a heat balance equation including the cooling effects of liquid hydrogen and its vaporized gas. The influences of the wire size and material properties on minimum propagating current and power consumption in the gaseous hydrogen are evaluated toward the optimal design of the level sensor