On small breathers of nonlinear Klein-Gordon equations via exponentially small homoclinic splitting

Fuente: arXiv
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Autori principali: Gomide, Otávio M. L., Guardia, Marcel, Seara, Tere M., Zeng, Chongchun
Natura: Preprint
Pubblicazione: 2021
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author Gomide, Otávio M. L.
Guardia, Marcel
Seara, Tere M.
Zeng, Chongchun
author_facet Gomide, Otávio M. L.
Guardia, Marcel
Seara, Tere M.
Zeng, Chongchun
contents Breathers are nontrivial time-periodic and spatially localized solutions of nonlinear dispersive partial differential equations (PDEs). Families of breathers have been found for certain integrable PDEs but are believed to be rare in non-integrable ones such as nonlinear Klein-Gordon equations. In this paper we show that small amplitude breathers of \emph{any} temporal frequency do not exist for semilinear Klein-Gordon equations with generic analytic odd nonlinearities. A breather with small amplitude exists only when its temporal frequency is close to be resonant with the linear Klein-Gordon dispersion relation. Our main result is that, for such frequencies, we rigorously identify the leading order term in the exponentially small (with respect to the small amplitude) obstruction to the existence of small breathers in terms of the so-called \emph{Stokes constant}, which depends on the nonlinearity analytically, but is independent of the frequency. This gives a rigorous justification of a formal asymptotic argument by Kruskal and Segur \cite{KS87} in the analysis of small breathers. We rely on the spatial dynamics approach where breathers can be seen as homoclinic orbits. The birth of such small homoclinics is analyzed via a singular perturbation setting where a Bogdanov-Takens type bifurcation is coupled to infinitely many rapidly oscillatory directions. The leading order term of the exponentially small splitting between the stable/unstable invariant manifolds is obtained through a careful analysis of the analytic continuation of their parameterizations. This requires the study of another limit equation in the complexified evolution variable, the so-called \emph{inner equation}.
format Preprint
id arxiv_https___arxiv_org_abs_2107_14566
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle On small breathers of nonlinear Klein-Gordon equations via exponentially small homoclinic splitting
Gomide, Otávio M. L.
Guardia, Marcel
Seara, Tere M.
Zeng, Chongchun
Analysis of PDEs
Dynamical Systems
37K50, 37C29, 35B25, 35B10
Breathers are nontrivial time-periodic and spatially localized solutions of nonlinear dispersive partial differential equations (PDEs). Families of breathers have been found for certain integrable PDEs but are believed to be rare in non-integrable ones such as nonlinear Klein-Gordon equations. In this paper we show that small amplitude breathers of \emph{any} temporal frequency do not exist for semilinear Klein-Gordon equations with generic analytic odd nonlinearities. A breather with small amplitude exists only when its temporal frequency is close to be resonant with the linear Klein-Gordon dispersion relation. Our main result is that, for such frequencies, we rigorously identify the leading order term in the exponentially small (with respect to the small amplitude) obstruction to the existence of small breathers in terms of the so-called \emph{Stokes constant}, which depends on the nonlinearity analytically, but is independent of the frequency. This gives a rigorous justification of a formal asymptotic argument by Kruskal and Segur \cite{KS87} in the analysis of small breathers. We rely on the spatial dynamics approach where breathers can be seen as homoclinic orbits. The birth of such small homoclinics is analyzed via a singular perturbation setting where a Bogdanov-Takens type bifurcation is coupled to infinitely many rapidly oscillatory directions. The leading order term of the exponentially small splitting between the stable/unstable invariant manifolds is obtained through a careful analysis of the analytic continuation of their parameterizations. This requires the study of another limit equation in the complexified evolution variable, the so-called \emph{inner equation}.
title On small breathers of nonlinear Klein-Gordon equations via exponentially small homoclinic splitting
topic Analysis of PDEs
Dynamical Systems
37K50, 37C29, 35B25, 35B10
url https://arxiv.org/abs/2107.14566