Searcharxiv⌕ Search

arXiv subjects

Koichi Ohta

Publications and source records attributed to Koichi Ohta.

4 recordsLinked to original sources
arXiv2004

Skyrmions coupled with the electromagnetic field via the gauged Wess-Zumino term

In soliton models expressed in terms of the non-linear chiral field, the electric current has an anomalous gauge-field contribution as the baryon current does. We study the spin polarized Skyrmions coupled with the electromagnetic field via the gauged Wess-Zumino term and calculate configurations of the Skyrmion and the gauge field with boundary conditions to ensure the physical charge number for baryons. Although the electromagnetic field via the gauged Wess-Zumino term affects physical quantities in small amounts, we find that the magnetic field forms a dipole structure owing to a circular electric current around the spin quantization axis of the soliton. This is understood on an analogy with the Meissner effect in the super conductor.The electric charge distributions turn out to have characteristic structures depending on the total charge, which suggests the intrinsic deformation of baryons due to orbital motions of the constituents.

hep-ph↗
arXiv2001

Explicit conversion from the Casimir force to Planck's law of radiation

The Casimir force has its origin in finite modification of the infinite zero-point energy induced by a specific boundary condition for the spatial configuration. In terms of the imaginary-time formalism at finite temperature, the root of Planck's law of radiation can be traced back to finite modification of the infinite vacuum energy induced by the periodic boundary condition in the temporal direction. We give the explicit conversion from the Casimir force to Planck's law of radiation, which shows the apparent correspondence between the system bounded by parallel conducting plates and the thermodynamic system. The temperature inversion symmetry and the duality relation in the thermodynamics are also discussed. We conclude that the effective temperature characterized by the spatial extension should no longer be regarded as genuine temperature.

quant-ph↗
arXiv1994

Quantum Hamiltonian Reduction of the Schwinger Model

We reexamine a unitary-transformation method of extracting a physical Hamiltonian from a gauge field theory after quantizing all degrees of freedom including redundant variables. We show that this {\it quantum Hamiltonian reduction} method suffers from crucial modifications arising from regularization of composite operators. We assess the effects of regularization in the simplest gauge field theory, the Schwinger model. Without regularization, the quantum reduction yields the identical Hamiltonian with the classically reduced one. On the other hand, with regularization incorporated, the resulting Hamiltonian of the quantum reduction disagrees with that of the classical reduction. However, we find that the discrepancy is resolved by redefinitions of fermion currents and that the results are again consistent with those of the classical reduction.

hep-th↗