Enhancement of axion decay constants in type IIA theory?
  We investigate the possibility of enhancement of effective axion decay
constant in well controlled constructions in string theory. To this end, we
study the dynamics of axions arising in the compactifications of type IIA
string theory on Calabi-Yau orientifolds with background fluxes (with
non-perturbative effects included to ensure stabilization of all moduli). In
this setup, we attempt to obtain large effective axion decay constant in two
different ways: by searching for a direction in field space in which the
potential is sufficiently flat and by arriving at a very explicit stringy
embedding of the Kim-Nilles-Peloso (KNP) alignment mechanism. We do not find
super-Planckian effective decay constants by either of the approaches.
Furthermore, we find that the alignment angle of KNP mechanism can not be made
arbitrarily small by adjusting the fluxes.
