The Cauchy problem for the Klein–Gordon equation under quartic potential is considered in de Sitter spacetime. existence of global solutions small rough initial data shown based on mechanism spontaneous symmetry breaking positive Hubble constant. effects spatial expansion and contraction are considered.

Nowadays NLEEs have been the subject of allembracing studies in various branches of nonlinear sciences. Most of the phenomena in real world can be described using non-linear equations. A nonlinear phenomenon plays a vital role in applied mathematics, physics and engineering branches. Many complex nonlinear phenomenons in plasma physics, fluid dynamics, chemistry, biology, mechanics, elastic med...

The exact traveling wave solutions of the nonlinear variable coefficients Burgers-Fisher equation and the generalized Gardner equation with forced terms can be found in this article using the generalized ( ′ G )-expansion method. As a result, hyperbolic, trigonometric and rational function solutions with parameters are obtained. When these parameters are taken special values, the solitary wave ...

An approximate method for describing the evolution of solitonlike initial conditions to solitons for the sine-Gordon equation is developed. This method is based on using a solitonlike pulse with variable parameters in an averaged Lagrangian for the sine-Gordon equation. This averaged Lagrangian is then used to determine ordinary differential equations governing the evolution of the pulse parame...

In this paper, the ( / ) G G  -expansion method is extended to solve fractional differential equations in the sense of modified Riemann-Liouville derivative. Based on a nonlinear fractional complex transformation, certain fractional partial differential equations can be turned into ordinary differential equations of integer order. For illustrating the validity of this method, we apply it to fi...

In this paper, nonlinear Klein-Gordon equation with quadratic term is solved by means of an analytic technique, namely the Homotopy analysis method (HAM).Comparisons are made between the Adomian decomposition method (ADM), the exact solution and homotopy analysis method. The results reveal that the proposed method is very effective and simple.

The Klein-Gordon equations were recently solved in general relativity for the case of a plane-symmetric static massless scalar field with cosmological constant. By analytic continuation, time-dependent solutions can be obtained that correspond to cosmologies. These spacetimes are studied here, and include among them a solution exhibiting both early inflation and later continued rapid expansion ...

Complete discrimination system for polynomial and direct integral method were discussed systematically. In particularly, we pointed out some mistaken viewpoints. Combining with complete discrimination system for polynomial, direct integral method was developed to become a powerful method and was applied to a lot of nonlinear mathematical physics equations. All single traveling wave solutions to...

Abstract: Haar wavelet method for solving the Klein–Gordon and the sine-Gordon equations has been implemented. Application to partial differential equations is exemplified by solving the sine-Gordon equation. The efficiency of the method is demonstrated by five numerical examples. Computer simulation is carried out for problems the exact solution of which is known. This allows us to estimate th...

The Einstein–Klein–Gordon field equations are solved in a inhomogeneous shear–free universe containing a material fluid, a self–interacting scalar field, a variable cosmological term, and a heat flux. A quintessence– dominated scenario arises with a power–law accelerated expansion compatible with the currently observed homogeneous universe.