We develop an alternative approach to study the effect of the generic perturbation (in addition to explicitly considering the loss term) in the nonlinear Klein-Gordon equations. By a change of the variables that cancel the dissipation term we are able to write the Lagrangian density and then, calculate the Lagrangian as a function of collective variables. We use the Lagrangian formalism togethe...

We introduce mountain-pass type arguments in the context of orbital instability for Klein-Gordon equations. Our aim is to illustrate on two examples how these arguments can be useful to simplify proofs and derive new results of orbital stability/instability. For a power-type nonlinearity, we prove that the ground states of the associated stationary equation are minimizers of the functional acti...

Abstract In [1] Varsha and Jaferi proposed an iterative method for solving nonlinear functional equations, viz. nonlinear Voltera integral equations, algebraic equations and system of ordinary differential equations. Then Sachin and Varsha [2] implemented this method to solve linear and nonlinear partial differential equations of integer and fractional order. The aim of this article is to propo...

Witten's non-relativistic formalism of supersymmetric quantum mechanics was based on a factorization and partnership between Schrödinger equations. We show how it accommodates a transition to the partnership between relativistic Klein-Gordon equations.

We investigate the orbital stability and instability of standing waves for two classes of Klein-Gordon equations in the semi-classical regime.

In the paper we consider the nonexistence of global solutions of the Cauchy problem for coupled Klein-Gordon equations of the form

In this paper we prove the existence of a ground state solution for the nonlinear Klein-Gordon-Maxwell equations in the electrostatic case.

We introduce the Dunkl--Klein--Gordon (DKG) equation in 2D by changing standard partial derivatives Dunkl Klein--Gordon (KG) equation. show that generalization with derivative of $z$-component angular momentum is what allows separation variables DKG Then, we compute energy spectrum and eigenfunctions equations for Coulomb potential oscillator analytically from an ${\rm su}(1,1)$ algebraic point...