Abstract
The dynamics of a tachyon attached to a Dvali, Gabadadze and Porrati (DGP) brane is investigated. Exponential potential and inverse power law potential are explored, respectively. The quasi-attractor behavior, for which the universe will eventually go into a phase similar to the slow-roll inflation, is discovered in both cases of exponential potential and inverse power law potential. The equation of state (EOS) of the virtual dark energy for a single scalar can cross the phantom divide in the branch θ=−1 for both potentials, while the EOS of the virtual dark energy for a single scalar cannot cross this divide in the branch θ=1.
Highlights
E8 × E8 heterotic string emerges when one compacts the 11-dim super gravity on an S1/Z2 orbifold (Horava-Witten proposal) [1]
The behavior of the string theory in the energy region below the unification scale is not sensitive to the fine structure of the inner Calabi-Yau space, that is, the universe can be effectively described by some 5-dim theory, in which the standard model particles are confined to the 3-brane, while the gravitation can propagate in the whole spacetime
One is “high energy theory”, that is, its phenomenology becomes different in high energy region from general relativity (GR), but recovers to GR in low energy region, for example Randall-Sundrum (RS) model [3]
Summary
E8 × E8 heterotic string emerges when one compacts the 11-dim super gravity on an S1/Z2 orbifold (Horava-Witten proposal) [1]. The behavior of the string theory in the energy region below the unification scale is not sensitive to the fine structure of the inner Calabi-Yau space, that is, the universe can be effectively described by some 5-dim theory, in which the standard model particles are confined to the 3-brane, while the gravitation can propagate in the whole spacetime. Such string-inspired phenomenological model, called brane world, has been set up and studied extensively [2], especially in the fields of high energy physics and cosmology.
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