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Relativite Generale et champs quantiques: quelques aspects de physique des trous noirs et de cosmologie en gravite de Lovelock, espaces de Sitter et dimensions supplementaires

Abstract : At the frontier of modern physics, the black hole evaporation process is undoubtedly the most favored phenomenon to get informations on quantum gravity. After a brief introduction to Einstien's General Relativity and to one of its extension as a Taylor expansion in scalar curvature, this thesis deals with the Hawking process focusing on the computation of greybody factors, i.e. the tunnel probablity for a particle, coming from the breaking of quantum vacuum fluctuations, to escape from the black hole's gravitational attraction. I have developped an analytical technique, based on semi-classical expansions, to study the dynamic of scalar fields propagating in static and spherically symmetric space-times as well as a numerical method to exactly compute those greybody factors for fields with an arbitrary spin. These methods are applied to the case of Schwarzschild black holes in the framework of the second order Lovelock gravity (Gauss-Bonnet gravity) with extra-dimensions, to get an exact determination of the radiation spectra, needed to check the principles of black hole's thermodynamics. Possible constrains on the gravitational Lagrangian using the black hole's evaporation process are also investigated in the framework of braneworld models a la Arkani-Hamed, Dimopoulos & Dvali (ADD), in which the Planck scale is around a TeV openning the possible production of black hole via the collsion of particles in the cosmos or at colliders: it is shown in this manuscript that the ADD scenarii are not in conflict with current data from cosmology and cosmic rays and that it will be possible, at the LHC, to distinguish between an Einstein-Hilbert Lagrangian with or without au Gauss-Bonnet term. The questions of primordial inhomogeneities and of dark matter are also explored in this thesis, respectively in the light of primordial black holes and extra-dimensional theories.
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https://tel.archives-ouvertes.fr/tel-00104399
Contributor : Julien Grain <>
Submitted on : Friday, October 6, 2006 - 2:39:10 PM
Last modification on : Thursday, November 19, 2020 - 12:58:19 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 6:50:40 PM

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Julien Grain. Relativite Generale et champs quantiques: quelques aspects de physique des trous noirs et de cosmologie en gravite de Lovelock, espaces de Sitter et dimensions supplementaires. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00104399⟩

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