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Jean-Francois Bony

Publications and source records attributed to Jean-Francois Bony.

28 records · Page 2Linked to original sources
arXiv2010

Local energy decay for several evolution equations on asymptotically euclidean manifolds

Let P be a long range metric perturbation of the Euclidean Laplacian on R^d, d>1. We prove local energy decay for the solutions of the wave, Klein-Gordon and Schroedinger equations associated to P. The problem is decomposed in a low and high frequency analysis. For the high energy part, we assume a non trapping condition. For low (resp. high) frequencies we obtain a general result about the local energy decay for the group exp(itf(P)) where f has a suitable development at zero (resp. infinity).

math.AP↗
arXiv2009

Spectral projection, residue of the scattering amplitude, and Schrodinger group expansion for barrier-top resonances

We study the spectral projection associated to a barrier-top resonance for the semiclassical Schrodinger operator. First, we prove a resolvent estimate for complex energies close to such a resonance. Using that estimate and an explicit representation of the resonant states, we show that the spectral projection has a semiclassical expansion in integer powers of h, and compute its leading term. We use this result to compute the residue of the scattering amplitude at such a resonance. Eventually, we give an expansion for large times of the Schrodinger group in terms of these resonances.

math.AP↗
arXiv2008

The semilinear wave equation on asymptotically euclidean manifolds

We consider the quadratically semilinear wave equation on R^d, d>=3, equipped with a Riemannian metric. This metric is non-trapping and approaches the Euclidean metric polynomially at infinity. Using Mourre estimates and the Kato theory of smoothness, we obtain a Keel-Smith-Sogge type inequality for the linear equation. Thanks to this estimate, we prove long time existence (d=3) and global existence (d>3) for the nonlinear problem with small initial data.

math.AP↗
arXiv2007

Spectrum of the product of Toeplitz matrices with application in probability

We study the spectrum of the product of two Toeplitz operators. Assume that the symbols of these operators are continuous and real-valued and that one of them is non-negative. We prove that the spectrum of the product of finite section Toeplitz matrices converges to the spectrum of the product of the semi-infinite Toeplitz operators. We give an example showing that the supremum of this set is not always the supremum of the product of the two symbols. Finally, we provide an application in probability which is the first motivation of this study. More precisely, we obtain a large deviation principle for Gaussian quadratic forms.

math.FA↗
arXiv2007

Resolvent and scattering matrix at the maximum of the potential

We study the microlocal structure of the resolvent of the semi-classical Schrodinger operator with short range potential at an energy which is a unique non-degenerate global maximum of the potential. We prove that it is a semi-classical Fourier integral operator quantizing the incoming and outgoing Lagrangian submanifolds associated to the fixed hyperbolic point. We then discuss two applications of this result to describing the structure of the spectral function and the scattering matrix of the Schrodinger operator at the critical energy.

math.AP↗
arXiv2007

Mesures limites pour l'equation de Helmholtz dans le cas non captif

Cet article est consacre a l'etude des mesures limites associees a la solution de l'equation de Helmholtz avec un terme source se concentrant en un point. Le potentiel est suppose regulier et l'operateur non-captif. La solution de l'equation de Schrodinger semi-classique s'ecrit alors micro-localement comme somme finie de distributions lagrangiennes. Sous une hypothese geometrique, qui generalise l'hypothese du viriel, on en deduit que la mesure limite existe et qu'elle verifie des proprietes standard. Enfin, on donne un exemple d'operateur qui ne verifie pas l'hypothese geometrique et pour lequel la mesure limite n'est pas unique. Le cas de deux termes sources est aussi traite.

math.AP↗
arXiv2007

Semiclassical scattering amplitude at the maximum point of the potential

We compute the scattering amplitude for Schrödinger operators at a critical energy level, corresponding to the maximum point of the potential. We follow the wrok of Robert and Tamura, '89, using Isozaki and Kitada's representation formula for the scattering amplitude, together with results from Bony, Fujiie, Ramond and Zerzeri '06 in order to analyze the contribution of trapped trajectories.

math.AP↗
arXiv2004

Scattering theory for the Schrodinger equation with repulsive potential

We consider the scattering theory for the Schrodinger equation with $-Δ-|x|^α$ as a reference Hamiltonian, for $0< α\leq 2$, in any space dimension. We prove that when this Hamiltonian is perturbed by a potential, the usual short range/long range condition is weakened: the limiting decay for the potential depends on the value of $α$, and is related to the growth of classical trajectories in the unperturbed case. The existence of wave operators and their asymptotic completeness are established thanks to Mourre estimates relying on new conjugate operators. We construct the asymptotic velocity and describe its spectrum. Some results are generalized to the case where $-|x|^α$ is replaced by a general second order polynomial.

math.AP↗