Kazuo Hida

Rigorous derivation of the distribution of the eigenstates of the quantum Heisenberg-Ising chain with XY-like anisotropy

Abstract The distribution of the eigenstates of the quantum Heisenberg-Ising chain with XY -like anisotropy is obtained rigoruously. It is shown that the assumptions made by Takahashi and Suzuki can be derived from the boundary conditions for the wave functions.

Thermodynamics of the massive-Thirring and the quantum sine-Gordon system

Abstract The Bethe Ansatz approach is applied to calculate the specific heat of the massive-Thirring model with a Debye cutoff. Near the “classical” limit, the results are close to that of the classical sine-Gordon system. Specific heat is given by a super-position of Debye-type behavior and the “soliton” peak.

Commensurate-incommensurate crossover in quantum sine-Gordon model

The thermodynamics of the quantum sine-Gordon model with finite winding numbers is investigated by the Bethe ansatz method. The temperature dependences of the specific heat and the winding number are calculated. The crossover from the case with the commensurate ground state to that with the incommensurate ground state is discussed. The quantum effect is shown to be significant in the thermodynamic properties of the system.

Soliton dynamics in the discrete classical Heisenberg chain: velocity modulation and stochastic depinning

Abstract The effect of lattice discreteness on the dynamics of solitons in a classical Heisenberg chain in a periodic external field is investigated. Velocity modulation and stochastic depinning of a soliton is shown to take place.

The thermodynamics of the anisotropic s-d model

Abstract The thermodynamics of the anisotropic s-d model is formulated on the basis of the exact solution. The impurity part of the specific heat is calculated.

Statistical mechanics of one-dimensional xyz spin chain, massive thirring model and quantum sine-Gordon system

Abstract The specific heat is calculated in the massive Thirring/quantum sine-Gordon limit on the one-dimensional XYZ model with the help of the Bethe ansatz approach. The Schottky-type anomaly appears asa contribution from the quantum soliton. The finite-temperature excitations are also discussed for these models.

Quantum statistical mechanics of the sine-Gordon model dissipation

Abstract The Dynamical properties of the quantum sine-Gordon model are discussed in the presence of dissipation. The tunnelling decay rate of the metastable state induced by the external field is calculated near the classical depinning field. The Brownian motion of a siliton due to quantum noise is also discussed. The possibility of the experimental detection of the present result in real system is suggested.

Thermodynamics of the quantum sine-Gordon model with finite winding number

Abstract Thermodynamics of the quantum sine-Gordon model is formulated in the presence of finite winding number. Several asymptotic cases are studied analytically.

GL theory of the upper critical fields of coupled fibrous superconductors

Abstract The upper critical fields of fibrous superconductors with interfiber coupling are calculated in the framework of GL theory. The crossover behavior from the coupled fiber behavior to the isolated fiber behavior is expected from our theory. The results explain the measurement for (SN) x qualitatively.