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Etude des courants fermioniques sur les objets étendus

Abstract : This PhD thesis discusses the internal structure of topological defects, and branes in extra-dimensions, carrying fermionic currents.
The general framework in which these objects may appear, from spontaneous symmetry breaking, is at the frontier between particle physics and cosmology, and is presented in the first part. The second part is devoted to the dynamic of cosmic strings, a class of topological defects of uttermost importance to modern cosmology, as it can be obtained from a macroscopic covariant formalism. This formalism offers a unified description of cosmic strings, including the case for which they carry internal currents, and allows the study of their cosmological evolution, and implications, by means of numerical simulations. Its validity has already been confirmed for cosmic string carrying bosonic currents, and the third part provides new results concerning the fermionic currents case. First, the fermion mass spectrum in a cosmic string is computed, and suggests that fermionic currents are usually built on massive propagation modes. As a result, a new equation of state describing such cosmic strings is derived by means of a quantization of the relevant spinor fields along the string. This highlights that the usual one parameter macroscopic formalism is not always sufficient in case of fermionic currents. Moreover, contrary to the bosonic case, the dynamics stemming from this equation of state exhibits transitions between the subsonic and supersonic regimes whose consequences in cosmology could be important. The last part is an extension of these results to brane cosmology for which our universe is viewed as a four dimensional domain wall embedded in a five dimensional space-time. In the framework of the Randall-Sundrum model, the masses of the trapped fermions on the brane can be predicted.
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Contributor : Christophe Ringeval <>
Submitted on : Monday, November 18, 2002 - 6:37:17 PM
Last modification on : Wednesday, December 9, 2020 - 3:09:21 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 6:40:10 PM


  • HAL Id : tel-00001980, version 1


Christophe Ringeval. Etude des courants fermioniques sur les objets étendus. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2002. Français. ⟨tel-00001980⟩



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