paper

Entropy of Anisotropic Universe and Fractional Branes

arXiv:hep-th/0702202 · doi:10.1007/s10714-007-0488-1

Abstract

We obtain the entropy of a homogeneous anisotropic universe applicable, by assumption, to the fractional branes in the universe in the model of Chowdhury and Mathur. The entropy for the 3 or 4 charge fractional branes thus obtained is not of the expected form E^{3/2} or E^2. One way the expected form is realised is if p \to ρfor the transverse directions and if the compact directions remain constant in size. These conditions are likely to be enforced by brane decay and annihilation, and by the S, T, U dualities. T duality is also likely to exclude high entropic cases, found in the examples, which arise due to the compact space contracting to zero size. Then the 4 charge fractional branes may indeed provide a detailed realisation of the maximum entropic principle we proposed recently to determine the number (3 + 1) of large spacetime dimensions.

arXiv commentVersion 2: 21 pages. More discussion and references added. To appear in General Relativity and Gravitation

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