Precession of classical spin and spin-orbit splitting

We present solutions of a fermion-boson model based on the supersymmetric (Susy) extension of theU(N) σ-models with the Wess-Zumino-Witten (WZW) term. We study some properties of these solutions. We point out that the obtained solutions are related to the components of the energy-momentum tensor of the purely bosonicU(N)σ-model and that some classes of these solutions are traceless.     

Static properties of multiple-sine-Gordon systems

In this paper, we examine some basic properties of the multiple-sine-Gordon (MSG) systems, which constitute a generalization of the celebrated sine-Gordon (SG) system. We start by showing how MSG systems can be viewed as a general class of periodic functions. Next, periodic and step-like solutions of these systems are discussed in some details. In particular, we study the static properties of such systems by considering slope and phase diagrams. We also use concepts like energy density and pressure to characterize and distinguish such solutions. We interpret these solutions as an interacting many body system, in which kinks and antikinks behave as extended particles. Finally, we provide a linear stability analysis of periodic solutions which indicates short wavelength solutions to be stable.     

Analytical studies on the (1 + 1)-dimensional nonlinear Dispersive Modified Benjamin–Bona–Mahony equation defined by seismic sea waves

In this study, we have studied to obtain some new analytical solutions to the (1?+?1)-dimensional nonlinear Dispersive Modified Benjamin–Bona–Mahony equation by using modified exp-function method. We have submitted the general structure of modified exp-function method. We have founded some new analytical solutions such as hyperbolic and rational function solutions. Afterward, we have plotted 2D and 3D surfaces of analytical solutions obtained in this study by using computer programming wolfram Mathematica 9.     

Charged Noncommutative Wormhole Solutions via Power-Law f(T) Models

In this paper, we explore static spherically symmetric charged wormhole solutions in extended teleparallel gravity taking power-law f(T) models. We consider noncommutative geometry under Lorentzian distribution. In order to obtain matter components, we develop field equations using effective energy-momentum tensor for non-diagonal tetrad. We explore solutions by considering various viable power-law f(T) models, which also include teleparallel gravity case. The violation of energy conditions obtain by exotic matter to form wormhole solutions in teleparallel case while, physical acceptable wormhole solutions exist for charged noncommutative wormhole solutions for some cases of power-law models. The effective energy-momentum tensor and charge are responsible for the violation of the energy conditions. Also, we check the equilibrium condition for these solutions. The equilibrium condition meets for the teleparallel case and some power-law solutions while remaining solutions are either in less equilibrium or in disequilibrium situation.     

Bäcklund transformations,kink soliton,breather- and travelling-wave solutions for a (3+1)-dimensional B-type Kadomtsev–Petviashvili equation in fluid dynamics

In this paper, we investigate a (3+1)-dimensional B-type Kadomtsev–Petviashvili (BKP) equation in fluid dynamics. Based on the Hirota method, we give a bilinear auto-Bäcklund transformation. Via the truncated Painlevé expansion, we get a Painlevé-type auto-Bäcklund transformation. With the aid of the symbolic computation, we derive some one- and two-kink soliton solutions. We present the oblique and parallel elastic interactions between the two-kink solitons. Via the extended homoclinic test technique, we construct some breather-wave solutions. Besides, we derive some lump solutions with the periods of the breather-wave solutions to the infinity. We observe that the shapes of a breather wave and a lump remain unchanged during the propagation. Based on the polynomial-expansion method, travelling-wave solutions are constructed.     

Lie symmetry analysis,new group invariant for the (3 + 1)-dimensional and variable coefficients for liquids with gas bubbles models

The explored solutions described some different solutions as, Lump soliton, a solitary wave and exponential solutions. These solutions are investigated through some new Lie infinitesimals for the (3 + 1) dimensional variable coefficients Kudryashov-Sinelshchikov (VCKS). We used the fourth prolongation to investigate fifteen cases of Lie vectors. In each case, there is an infinite number of possibilities of vectors due to the unknown arbitrary functions and the variable coefficients for the considered model. We selected one case and examined the commutative product between multi unknown Lie infinitesimals for the (3 + 1) dimensional (VCKS) equation and this complicated process resulted from some new Lie vectors. The commutative product generates a system of nonlinear ODEs which had been solved manually. Through three stages of Lie symmetry reduction using the equivalence transformation, (VCKS) equation is reduced to solvable nonlinear ODEs using various combinations of optimal Lie vectors. By solving these ODEs, we investigate new analytical solutions for these ODEs. Back substituting to the original variables generates new solutions for (VCKS). Some selected solutions are illustrated through three-dimensional plots.     

Solutions of the supersymmetricU(N) σ models with the Wess-Zumino-Witten term

We present finite action classical solutions of the supersymmetric (Susy)U(N) sigma models with and without the Wess-Zumino-Witten (WZW) term. We derive solutions of the model with the WZW-term from the solutions of the Lax-pair problem for the corresponding model without this term. We study some properties of these solutions such as the value of their action and show that this value is related to that of the purely bosonicU(N) σ-model. Moreover, we prove that all derived solutions are unstable.     

Mesons, baryons and waves in the baby Skyrmion model

We study various classical solutions of the baby-Skyrmion model in (2+1) dimensions. We point out the existence of higher energy states, interpret them as resonances of Skyrmions and anti-Skyrmions and study their decays. Most of the discussion involves a highly exited Skyrmion-like state with winding number one which decays into an ordinary Skyrmion and a Skyrmion-anti-Skyrmion pair. We also study wave-like solutions of the model and show that some of such solutions can be constructed from the solutions of the sine-Gordon equation. We also show that the baby-Skyrmion model has non-topological stationary solutions. We study their interactions with Skyrmions.     

New Exact Solutions to （2＋1）-Dimensional Dispersive Long Wave Equations

Based upon a further extended tanh method [Phys. Lett. A307 (2003) 269; Chaos, Solitons and Fractals 17 (2003) 669] and the symbolic computation system, Maple, we consider the (2 1)-dimensional dispersive long waveequations. We obtain many new solutions of the equation. These solutions contain solitomlike solutions, periodic form solutions, and some rational solutions.     

同伦分析法在求解非线性演化方程中的应用

利用同伦分析法求解了(2+1)维改进的 Zakharov-Kuznetsov方程, 得到了它的近似周期解,该解与精确解符合很好. 结果表明，同伦分析法在求解高维非线性演化方程时, 仍然是一种行之有效的方法. 同时,还对该方法进行了一定的扩展， 经过扩展后的方法能够更方便地求解更多非线性演化方程的高精度近似解析解. 关键词： 同伦分析法 改进的 Zakharov-Kuznetsov方程 周期解     

Exact Solutions to (2+1)-Dimensional Kaup--Kupershmidt Equation

In this paper, by using the symmetry method, the relationships between new explicit solutions and old ones of the (2+1)-dimensional Kaup-Kupershmidt (KK) equation are presented. We successfully obtain more general exact travelling wave solutions for (2+1)-dimensional KK equation by the symmetry method and the (G^, /G)-expansion 　method. Consequently, we find some new solutions of (2+1)-dimensional KK equation, 　including similarity solutions, solitary wave solutions, and 　periodic solutions.     

Comment on ``Application of the (G'/G)-Expansion Method for Nonlinear Evolution Equations' [Phys. Lett. A 372 (2008) 3400]

In this paper, some travelling wave solutions involving parameters of the Modified Zakharov-Kuznetsov equation [Phys. Lett. A 372 (2008) 3400] are investigated. We will how that these solutions are not new travelling wave solutions.     

(2+1)-Dimensional Analytical Solutions of the Combining Cubic-Quintic Nonlinear Schrdinger Equation

We investigate analytical solutions of the(2+1)-dimensional combining cubic-quintic nonlinear Schrdinger(CQNLS) equation by the classical Lie group symmetry method.We not only obtain the Lie-point symmetries and some(1+1)-dimensional partial differential systems,but also derive bright solitons,dark solitons,kink or anti-kink solutions and the localized instanton solution.     

Calibrations and Intersecting Branes

We investigate the solutions of Nambu–Goto-type actions associated with calibrations. We determine the supersymmetry preserved by these solutions using the contact set of the calibration and examine their bulk interpretation as intersecting branes. We show that the supersymmetry preserved by such solutions is closely related to the spinor singlets of the subgroup G of Spin (9,1) or Spin (10,1) that rotates the tangent spaces of the brane. We find that the supersymmetry projections of the worldvolume solutions are precisely those of the associated bulk configurations. We also investigate the supersymmetric solutions of a Born–Infeld action. We show that in some cases this problem again reduces to counting spinor singlets of a subgroup of Spin (9,1) acting on the associated spinor representations. We also find new worldvolume solutions which preserve 1/8 of the supersymmetry of the bulk and give their bulk interpretation. Received: 20 May 1998 / Accepted: 16 November 1998     

B(a)cklund Transformation and Multiple Soliton Solutions for (3+1)-Dimensional Potential-YTSF Equation

We study an approach to constructing multiple soliton solutions of the (3 1)-dimensional nonlinear evolu tion equation. We take the (3 1)-dimensional potential-YTSF equation as an example. Using the extended homogeneous balance method, one can find a Backlund transformation to decompose the (3 1)-dimensional potential-YTSF equa tion into a set of partial differential equations. Starting from these partial differential equations, some multiple soliton solutions for the (3 1)-dimensional potential-YTSF equation are obtained by introducing a class of formal solutions.     

Baeicklund Transformation and Multiple Soliton Solutions for （3＋1）-Dimensional Potential-YTSF Equation

We study an approach to constructing multiple soliton solutions of the (3 1)-dimensional nonlinear evolution equation. We take the (3 1)-dimensional potential- YTSF equation as an example. Using the extended homogeneous balance method, one can find a Backlund transformation to decompose the (3 1)-dimensional potential-YTSF equation into a set of partial differential equations. Starting from these partial differential equations, some multiple soliton solutions for the (3 1)-dimensional potential-YTSF equation are obtained by introducing a class of formal solutions.     

New soliton solutions for Sasa–Satsuma equation

In this work, we survey exact solutions of Sasa–Satsuma equation (SSE). We utilize extended trial equation method (ETEM) and generalized Kudryashov method to acquire exact solutions of SSE. First of all, we gain some exact solutions such as soliton solutions, rational, Jacobi elliptic, and hyperbolic function solutions of SSE by means of ETEM. Furthermore, we procure dark soliton solution of this equation by the help of generalized Kudryashov method. Lastly, for certain parameter values, we draw two- and three-dimensional graphics of imaginary and real values of some exact solutions that we achieved using these methods.     

On stability of solutions of theU(N) chiral model in two dimensions

We discuss the stability properties of classical solutions of theU(N) sigma models in two Euclidean dimensions. We show that all nontrivial solutions are unstable. For a general case we exhibit one mode of instability; in some special cases (corresponding to a grassmannian solution and an instantonic grassannian embedding) we exhibit two such independent modes.     

非线性演化方程孤立波的同伦分析法求解

利用同伦分析法求解了Burgers方程，得到了其扭结形孤立波的近似解析解，该解非常接近于相应的精确解.结果表明，同伦分析法可用来求解非线性演化方程的孤立波解.同时，也对所用方法进行了一定扩展，得到了Kadomtsev-Petviashvili(KP)方程的钟形孤立子解.经过扩展后的方法能够更方便地用于求解更多非线性演化方程的高精度近似解析解. 关键词： Burgers方程 同伦分析法 KP方程 孤立波解     

Stability of plane-wave solutions of a dissipative generalization of the nonlinear Schrödinger equation

The modulational instability of perturbed plane-wave solutions of the cubic nonlinear Schrödinger (NLS) equation is examined in the presence of three forms of dissipation. We present two families of decreasing-in-magnitude plane-wave solutions to this dissipative NLS equation. We establish that all such solutions that have no spatial dependence are linearly stable, though some perturbations may grow a finite amount. Further, we establish that all such solutions that have spatial dependence are linearly unstable if a certain form of dissipation is present.