Abstract :
A mechanism for lifting the cosmological upper bound on the axion decay constant, fa, is proposed. It entails the near masslessness of the radial mode whose vacuum expectation value is fa. Energy in the coherent oscillations of the axion field in the early universe gets fed into the motion of the radial mode, from which it is then redshifted away. It is found that the initial value of fa can be at scales between 2×1014 GeV and 1016 GeV. This evolves with time to values close to the Planck scale. It is suggested that the nearly massless radial mode might play the role of quintessence.
