Brane Quintessence

Abstract

We propose a new quintessence scenario in the brane cosmology, assuming that a quintessence field $Q$ is confined in our 3-dimensional brane world. With a potential $V(Q)={\mu }^{\alpha +4}{Q}^{-\alpha }(\alpha \ge 2)$, we find that the density parameter of the scalar field decreases as ${\Omega }_Q\sim a^{-4(\alpha -2)/(\alpha +2)}$ in the epoch of quadratic energy density dominance, if $\alpha \le 6$. This attractor solution is followed by the usual tracking quintessence scenario after a conventional Friedmann universe is recovered. With an equipartition of initial energy density, we find a natural and successful quintessence model for $\alpha \text{gsim}4$.

Comments: 4 pages, 2 figures