The dynamics of two pairs of counter-propagating waves in two-component media is considered within the framework of two generally nonintegrable coupled Sine-Gordon equations. We consider the dynamics of weakly nonlinear wave packets, and using an asymptotic multiple-scales expansion we obtain a suite of evolution equations to describe energy exchange between the two components of the system. De...

A new time-domain theory for waveguides has been presented in the paper. The electromagnetic fields are first expanded by using the complete sets of vector modal functions derived from the transverse electric field. The expansion coefficients are then determined by solving inhomogeneous Klein-Gordon equation in terms of retarded Green’s function. The theory has been validated by considering pro...

Exact and explicit string solutions in de Sitter spacetime are found. (Here, the string equations reduce to a sinh-Gordon model). A new feature without flat spacetime analogy appears: starting with a single world-sheet, several (here two) strings emerge. One string is stable and the other (unstable) grows as the universe grows. Their invariant size and energy either grow as the expansion factor...

We discuss inflationary solutions of the coupled Einstein-Klein-Gordon equations for a complex field in a five dimensional spacetime with a compact x 5-dimension. As a new feature, the scalar field contains a dependence on the extra dimension of the form exp(imx 5), corresponding to Kaluza-Klein excited modes. In a four dimensional picture, a nonzero m implies the presence of a new term in the ...

a modified f-expansion method to find the exact traveling wave solutions of  two-component nonlinear partial differential equations (nlpdes) is discussed. we use this method to construct many new solutions to the nonlinear whitham-broer-kaup system (1+1)-dimensional. the solutions obtained include jacobi elliptic periodic wave solutions which exactly degenerate to the soliton solutions, triangu...

Klein/Sine-Gordon equations are very important in that they can accurately model many essential physical phenomena. In this paper, we propose a new spectral method using Legendre wavelets as basis for numerical solution of Klein\Sine-Gordon Equations. Due to the good properties of wavelets basis, the proposed method can obtain good spatial and spectral resolution. Moreover, the presented method...

Extended quantum mechanics using non-Hermitian (pseudo-Hermitian) Hamiltonians H = H is briefly reviewed. A few related mathematical experiments concerning supersymmetric regularizations, solvable simulations and large-N expansion techniques are summarized. We suggest that they could initiate a deeper study of non-localized structures (quasi-particles) and/or of their unstable and many-particle...

We discuss inflationary solutions of the coupled Einstein-Klein-Gordon equations for a complex field in a five dimensional spacetime with a compact x 5-dimension. As a new feature, the scalar field contains a dependence on the extra dimension of the form exp(imx 5), corresponding to Kaluza-Klein excited modes. In a four dimensional picture, a nonzero m implies the presence of a new term in the ...

The model under consideration is a two-dimensional two-component plasma, i.e., a continuous system of two species of pointlike particles of opposite charges ±1, interacting through the logarithmic Coulomb interaction. Using the exact results for the form-factors of an equivalent Euclidean sine-Gordon theory, we derive the largedistance behavior of the pair correlation functions between charged ...