Wormhole effect on the superstring axion.

Abstract

Wormhole solutions can arise from the third-rank field strength ${H}_{\ensuremath{\mu}\ensuremath{\nu}\ensuremath{\rho}}$ which has a gluon anomaly. The superstring axion has this property. The effect of these wormholes on axion cosmology is studied. To save the superstring axion energy-density problem, \ensuremath{\theta}\ifmmode\bar\else\textasciimacron\fi{} is \ensuremath{\sim}${10}^{\mathrm{\ensuremath{-}}3}$ or ${\ensuremath{\Lambda}}_{0}^{1/4}$ is \ensuremath{\sim}10 keV at the QCD chiral-symmetry-breaking scale.