We consider Galerkin finite element methods for the nonlinear Klein-Gordon equation, giving the first optimal-order energy norm semidiscrete error estimates for non-Lipschitz nonlinearity. The result holds quite generally in one and two space dimensions and under a certain growth restriction in three. We also discuss some time stepping strategies and present numerical results.

Pointing out the difference between the Discrete Nonlinear Schrödinger equation with the classical power law nonlinearity-for which solutions exist globally, independently of the sign and the degree of the nonlinearity, the size of the initial data and the dimension of the lattice-we prove either global existence or nonexistence in time, for the Discrete Klein-Gordon equation with the same type...

In this paper, we study the persistence of spatial analyticity for solutions to Klein-Gordon-Schrödinger system, which describes a physical system nucleon field interacting with neutral meson field, analytic initial data. Unlike case single nonlinear dispersive equation, not much is known about systems as it harder show coupled equations simultaneously. The only results so far are rather recent...

We demonstrate for the first time the possibility for explicit construction in a discrete Hamiltonian model of an exact solution of the form exp(−|n|), i.e., a discrete peakon. These discrete analogs of the well-known, continuum peakons of the Camassa-Holm equation [Phys. Rev. Lett. 71, 1661 (1993)] are found in a model different from their continuum siblings. Namely, we observe discrete peakon...

Pointing out the difference between the Discrete Nonlinear Schrödinger equation with the classical power law nonlinearity-for which solutions exist globally, independently of the sign and the degree of the nonlinearity, the size of the initial data and the dimension of the lattice-we prove global nonexistence in time, for the Discrete Klein-Gordon equation with the same type of nonlinearity (bu...

In inviscid fluid flows instability arises generically due to a resonance between two wave modes. Here, it is shown that the structure of the weakly nonlinear régime depends crucially on whether the modal structure coincides, or remains distinct, at the resonance point where the wave phase speeds coincide. Then in the weakly nonlinear, long-wave limit the generic model consists either of a Bous...

We present a new step in the foundation of quantum field theory with the tools of scale relativity. Previously, quantum motion equations (Schrödinger, Klein–Gordon, Dirac, Pauli) have been derived as geodesic equations written with a quantum-covariant derivative operator. Then, the nature of gauge transformations, of gauge fields and of conserved charges have been given a geometric meaning in t...