The Problem of the Quark-Lepton Mass Spectrum
  We review some approaches to the quark-lepton mass problem. The ideas of mass-protection and approximate chiral flavour symmetries as a framework for resolving the mass hierarchy problem are presented. Dynamical calculations of the top quark and Higgs particle masses, based on infra-red fixed points and the so-called multiple point principle respectively, are discussed. We also consider mass matrix texture and the neutrino mass puzzle. 
C.D. Froggatt