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We consider how gauge theories can be described by matrix models. Conventional matrix regularization is defined for scalar functions and is not applicable to gauge fields, which are connections of fiber bundles. We clarify how the degrees of freedom of gauge fields are related to the matrix degrees of freedom, by formulating the Seiberg-Witten map between them., Comment: 32 pages, 0 figures

We propose a matrix regularization of vector bundles over a general closed K\"ahler manifold. This matrix regularization is given as a natural generalization of the Berezin-Toeplitz quantization and gives a map from sections of a vector bundle to matrices. We examine the asymptotic behaviors of the map in the large-$N$ limit. For vector bundles with algebraic structure, we derive a beautiful correspondence of the algebra of sections and the algebra of corresponding matrices in the large-$N$ limit. We give two explicit examples for monopole bundles over a complex projective space $CP^n$ and a torus $T^{2n}$., Comment: 47 pages, made minor changes

We propose a novel matrix regularization for tensor fields. In this regularization, tensor fields are described as rectangular matrices and both area-preserving diffeomorphisms and local rotations of the orthonormal frame are realized as unitary similarity transformations of matrices in a unified way. We also show that the matrix commutator corresponds to the covariantized Poisson bracket for tensor fields in the large-$N$ limit., Comment: 27 pages

We consider the matrix regularization of scalar fields on a Riemann surface with a general gauge-field background. We propose a construction of the fuzzy version of the Laplacian., Comment: 23 pages

We consider the matrix regularization of fields on a Riemann surface which couple to gauge fields with a nonvanishing magnetic flux. We show that such fields are described as rectangular matrices in the matrix regularization. We construct the matrix regularization explicitly for the case of the sphere and torus based on the Berezin-Toeplitz quantization, and also discuss a possible generalization to cases with higher genera. We also discuss the matrix version of the Laplacian acting on the rectangular matrices., Comment: 42 pages, 1 figure; v3: some references and 1 figure with some comments added, minor modifications

We investigate the velocity statistics by calculating the Biot--Savart velocity induced by vortex filaments in steady counterflow turbulence investigated in a previous study [Phys. Rev. B {\bf 81}, 104511 (2010)]. The probability density function (PDF) obeys a Gaussian distribution in the low-velocity region and a power-law distribution $v^{-3}$ in the high-velocity region. This transition between the two distributions occur at the velocity characterized by the mean inter-vortex distance. Counterflow turbulence causes anisotropy of the vortex tangle, which leads to a difference in the PDF for the velocities perpendicular to and parallel to the counterflow., Comment: 4 pages, 7 figures

We perform a numerical simulation of quantum turbulence produced by thermal counterflow in superfluid $^4$He by using the vortex filament model with the full Biot--Savart law. The pioneering work of Schwarz has two shortcomings: it neglects the non-local terms of the Biot--Savart integral (known as the localized induction approximation, LIA) and it employs an unphysical mixing procedure to sustain the statistically steady state of turbulence. For the first time we have succeeded in generating the statistically steady state under periodic boundary conditions without using the LIA or the mixing procedure. This state exhibits the characteristic relation $L=\gamma^2 v_{ns}^2$ between the line-length density $L$ and the counterflow relative velocity $v_{ns}$ and there is quantitative agreement between the coefficient $\gamma$ and some measured values. The parameter $\gamma$ and some anisotropy parameters are calculated as functions of temperature and the counterflow relative velocity. The numerical results obtained using the full Biot--Savart law are compared with those obtained using the LIA. The LIA calculation constructs a layered structure of vortices and does not proceed to a turbulent state but rather to another anisotropic vortex state; thus, the LIA is not suitable for simulations of turbulence., Comment: 8 pages, 11 figures

We study theoretically the dynamics of charged quantized vortices (CQVs). CQVs (ion-vortex complexes) have been used as an important probe in the field of quantum hydrodynamics. Recent experimental studies of quantum turbulence at very low temperatures utilize CQVs. In this work we propose the equation of motion of CQVs based on the vortex filament model. An analytical solution for a charged vortex ring shows how it expands under an electric field. Numerical simulation reveals the characteristic behavior of CQVs under an electric field., Comment: 6 pages, 4 figures. accepted by J. Low. Temp. Phys. accepted by J. Low. Temp. Phys

We performed the numerical simulation of quantum turbulence produced by thermal counterflow in superfluid $^{4}${\rm He} by using the vortex filament model. The pioneering work was made by Schwarz, which has two defects. One is neglecting non-local terms of the Biot-Savart integral (localized induction approximation, LIA), and the other is the unphysical mixing procedure in order to sustain the statistically steady state of turbulence. We succeeded in making the statistically steady state without the LIA and the mixing. This state shows the characteristic relation $L=\gamma^2 v_{ns}^2$ between the line-length-density $L$ and the counterflow relative velocity $v_{ns}$ with the quantitative agreement of the coefficient $\gamma$ with some typical observations. We compare our numerical results to the observation of experiment by Paoletti {\it et al}, where thermal couterflow was visualized by solid hydrogen particles., Comment: 6 pages, 12 figures, svjour3.sty