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Summary

My main research area lies between probability theory, differential geometry and mathematical physics. It consists in studying the links between the geometry of pseudo-Riemannian manifolds, especially Lorentzian manifolds, and the behavior of random curves, such as Brownian motions, drawn on these manifolds.

In my Ph.D [2], I studied in detail the (long time) asymptotic behavior of a relativistic Brownian motion in a large class of Lorentzian manifolds : Robertson-Walker spacetimes. The Brownian motion in question takes values in the unitary tangent bundle of the underlying manifold, its infinitesimal generator is a perturbation of the geodesic flow by the vertical Laplacian. I established precise links between the asymptotic behavior of Brownian paths and the asymptotic behavior of light-like geodesics of the manifolds [4]. I also made some connections between the Poisson boundary of the process and the causal boundary of the underlying manifolds [3, 4]. I am continuing my research in this area trying to determine the Poisson boundary of the Brownian motion in some geometrical situations not considered in my thesis.

I also am interested in various issues of mathematical physics involving stochastic processes in the context of the theory of relativity. With Jacques Franchi, we have thus established in [1, 2] a central limit theorem for a large class of Minkowskian diffusions that contains most of the examples of the physics literature. One of my research goal is to extend some results of [1] in the framework of general relativity [5]. Among my other projects is the study of discrete models of the theory of gravitation and their links with the concept of relativistic Brownian motion. 

Since my arrival in the very dynamic team of Mathematical Physics of University of Geneva, I also shared some of the interests of my colleagues, in particular I am interested in problems of harmonic analysis and Potential Theory in sets of irregular boundary.
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Publications et preprints

=> [5] Invariant measure for the ROUP in spatially flat Robertson-Walker space-times
_in preparation
=> [4] Asymptotic behavior of a relativistic Brownian motion in Robertson-Walker space-times
_in preparation
=> [3] Poisson boundary of a relativistic diffusion in spatially flat Robertson-Walker space-times
_submitted, preprint available here
=> [2] Etude de diffusions à valeurs dans des variétés lorentziennes
_Ph.D thesis, soutenue le 09.25.2009, university of Strasbourg
_available online tel-00418842
=> [1] A central limit theorem for a class of relativistic diffusions
_with J. Franchi
_published in Journal of Mathematical Physics, 48, 083101, 2007
_preprint ArXiv 0702481
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Talks at seminars

=>  Séminaire de géométrie et dynamique, 10/03/10, UMPA, ENS Lyon
_exposé : Construction et asymptotique du mouvement brownien sur une variété lorentzienne

=>  Séminaire de Mathématique Physique, 27/04/09, Genève
_exposé : Mouvement brownien et relativité

=>  Séminaire des doctorants, 23/10/08, Strasbourg
_exposé : Introduction au processus de Schramm (SLE)

=>  Séminaire de calcul stochastique, Strasbourg
_exposé : Mouvement brownien dans les espaces de Robertson-Walker

=>  Séminaire des doctorants, 17/04/08, Strasbourg
_exposé : Frontières de Poisson et de Martin, une introduction

=>  Séminaire de calcul stochastique, 26/03/07, Strasbourg
_exposé : Un théorème limite central pour une classe de diffusions relativites

=>  Séminaire des doctorants, 08/11/07, Strasbourg
_exposé : Une histoire du théorème des nombres premiers

=>  Séminaire des doctorants, 24/11/06, Strasbourg
_exposé : Le problème de Kakeya

=>  Séminaire des doctorants, 10/11/05, Strasbourg
_exposé : Une introduction au mouvement brownien


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Participation in conferences & summer schools 


=> Clay Mathematics Institute summer school, 11/07-07/08/10, Buzios (Brazil)

=> 85ème rencontre entre mathématiciens et physiciens théoriciens, 10-12/06/10, Strasbourg

=> Conformal maps : from Probability to Physics, 23-28/05/10, Ascona (Suisse) 

=> Rencontre de l'ANR Geodycos : Analysis, Geometry and Dynamics on Lorentz manifolds , 28-30/04/10, UMPA, ENS Lyon 

=> Workshop on 2D lattice models, 21-27/02/10, Les Diablerets (Suisse)

=> Journées de Probabilités 2009, 08-12/06/09, Poitiers

=> 82ème rencontre entre mathématiciens et physiciens théoriciens, 11-13/09/08, Strasbourg 

=> Journées de Probabilités 2008, 01-05/09/08, Lille

=> 38ème école d'été de Probabilités de Saint-Flour, 07/08, Saint-Flour 

=> 81ème rencontre entre mathématiciens et physiciens théoriciens, 29-31/05/08, Strasbourg 

=> Journées de Probabilités 2007, 09-14/09/07, La Londe (Toulon) 


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