arXiv subjects

Katsuhiko Yoshida

Publications and source records attributed to Katsuhiko Yoshida.

8 recordsLinked to original sources

arXiv2018

Euclidean wormhole solutions of Einstein-Yang-Mills theory in diverse dimensions

We solve the Euclidean Einstein equations with non-Abelian gauge fields of sufficiently large symmetry in various dimensions. In higher-dimensional spaces, we find the solutions which are similar to so-called scalar wormholes. In four-dimensional space-time, we find singular wormhole solutions with infinite Euclidean action. Wormhole solutions in the three-dimensional Einstein-Yang-Mills theory with a Chern-Simons term are also constructed.

gr-qc↗

arXiv2014

A New Vector-Tensor Theory and Higher-Dimensional Cosmology

A new vector-tensor model of classical gravity, which contains coupling between the field strength of the vector field and the curvature tensors in six dimensions, is proposed. Cosmological solutions of the scale factors in this model with the compactified space are obtained. The generalization of the model is also considered.

gr-qc↗

arXiv2004

Hyper-elliptic Nambu flow associated with integrable maps

We study hyper-elliptic Nambu flows associated with some $n$ dimensional maps and show that discrete integrable systems can be reproduced as flows of this class.

math-ph↗

arXiv2004

Nambu-Hamiltonian flows associated with discrete maps

For a differentiable map $(x_1,x_2,..., x_n)\to (X_1,X_2,..., X_n)$ that has an inverse, we show that there exists a Nambu-Hamiltonian flow in which one of the initial value, say $x_n$, of the map plays the role of time variable while the others remain fixed. We present various examples which exhibit the map-flow correspondence.

math-ph↗

arXiv2002

A Hamiltonian Flows Associated with Two Dimensional Map

For a given differentiable map $(x,y)\to (X(x,y),Y(x,y))$, which has an inverse, we show that there exists a Hamiltonian flow in which x plays the role of the time variable while y is fixed.

nlin.SI↗

arXiv2001

A Characterization of Discrete Time Soliton Equations

We propose a method to characterize discrete time evolution equations, which generalize discrete time soliton equations, including the $q$-difference Painlevé IV equations discussed recently by Kajiwara, Noumi and Yamada.

nlin.SI↗

arXiv1998

Analytical Study of the Julia Set of a Coupled Generalized Logistic Map

A coupled system of two generalized logistic maps is studied. In particular influence of the coupling to the behaviour of the Julia set in two dimensional complex space is analyzed both analytically and numerically. It is proved analytically that the Julia set disappears from the complex plane uniformly as a parameter interpolates from the chaotic phase to the integrable phase, if the coupling strength satisfies a certain condition.

solv-int↗

arXiv1997

Complex Analysis of a Piece of Toda Lattice

We study a small piece of two dimensional Toda lattice as a complex dynamical system. In particular the Julia set, which appears when the piece is deformed, is shown analytically how it disappears as the system approaches to the integrable limit.

solv-int↗