Axion Cosmology with a Stronger QCD in the Early Universe
  We examine in the context of supersymmetric models whether the usual cosmological upper bound on the axion decay constant can be relaxed by assuming a period of stronger QCD in the early universe. By evaluating the axion potential in the early universe and also taking into account the dilaton potential energy, it is argued that a stronger QCD is not useful for raising up the bound. 
Kiwoon Choi, Hang Bae Kim, and Jihn E. Kim