SÉMINAIRE DU GRECO
"Effective gravity of the Gauss-Bonnet braneworld" |
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Nicolas Chatillon |
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Five dimensional warped braneworlds a la Randall-Sundrum (RS) are attractive scenarios from the point of view of the particle physics hierarchy problems, and allow for a 4D effective gravity even in the case of an infinite extra dimension. However in five dimensions, contrary to the 4D case, the Einstein-Hilbert action with cosmological constant is not the most general gravity action yielding well-defined equations of motion (with no more than two derivatives of the metric) : a specific R^2 order combination, the Gauss-Bonnet term, is also allowed and should be added to generalize the RS setup. Ricci scalars localized on the 4D boundary branes are also considered. We study the effective gravity deduced from the 5D linearized equations of motion in the two-brane scenario, and we take the large and small distance limits. Large distance observers see effectively a 4D tensor-scalar gravity qualitatively similar to the RS one. At very small distances, gravity is again 4D tensor-scalar while for an intermediate distance regime it is a mixture of 5D tensor-scalar and 4D scalar forces. |
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jeudi 17 mars 2005 - 11:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris |
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