Dynamics of sine-Gordon kinks in the presence of rapidly varying periodic perturbations of different physical origins is described analytically and numerically. The analytical approach is based on asymptotic expansions, and it allows to derive, in a rigorous way, an effective nonlinear equation for the slowly varying field component in any order of the asymptotic procedure as expansions in the ...

We consider a space-fractional wave equation with singular mass term depending on the position and prove that it is very weak well-posed. The uniqueness proved in some appropriate sense. Moreover, we consistency of solution classical solutions when they exist. In order to study behaviour near singularities coefficient, numerical experiments are conducted where appearance wall effect for masses ...

We study the scattering theory for charged Klein-Gordon equations:  (∂t − iv(x))2φ(t, x) + (x,Dx)φ(t, x) = 0, φ(0, x) = f0, i−1∂tφ(0, x) = f1, where: (x,Dx) = − ∑ 1≤j,k≤n ( ∂xj − ibj(x) ) a(x) (∂xk − ibk(x)) +m (x), describing a Klein-Gordon field minimally coupled to an external electromagnetic field described by the electric potential v(x) and magnetic potential ~b(x). The flow of the Kle...