New confining force solution of QCD axion domain wall problem
  The serious cosmological problems created by the
axion-string/axion-domain-wall system in standard axion models are alleviated
by positing the existence of a new confining force. The instantons of this
force can generate an axion potential that erases the axion strings long before
QCD effects become important, thus preventing QCD-generated axion walls from
ever appearing. Axion walls generated by the new confining force would decay so
early as not to contribute significantly to the energy in axion dark matter.
