Cosmological models with gauge fields
  We discuss cosmological models involving homogeneous and isotropic Yang-Mills
(YM) fields. Such models were proposed recently as an alternative to scalar
models of cosmic acceleration. There exists a unique SU(2) YM configuration
(generalizable to larger gauge groups) whose energy-momentum tensor is
homogeneous and isotropic in space. It is parameterized by a single scalar
field with a quatric potential. In the case of the closed universe the coupled
YM -- doublet Higgs system admits homogeneous and isotropic configurations too.
While pure Einstein-Yang-Mills (EYM) cosmology with the standard conformally
invariant YM action gives rise to the hot universe, Einstein-Yang-Mills-Higgs
(EYMH) cosmology has a variety of regimes which include inflationary stages,
bounces, and exhibits global cycling behavior reminiscent of the Multiverse
developed in time. We also discuss other mechanisms of conformal symmetry
breaking such as string-inspired Born-Infeld (BI) modification of the YM action
or field-theoretical quantum corrections.
