A Quintessential Axion

Abstract

The model independent axion of string theory has a decay constant of order of the Planck scale. We explore the properties of this quintessence candidate (quintaxion) in the scheme of hidden sector supergravity breakdown. In models allowing for a reasonable $\mu$ term, the hidden sector dynamics may lead to an almost flat potential responsible for the vacuum energy of $(0.003\mathrm{eV}{)}^4$. A solution to the strong CP-problem is provided by an additional hidden sector pseudoscalar (QCD axion) with properties that make it an acceptable candidate for cold dark matter of the universe.

Comments: 11 pages, Revtex, 1 figure