Inflationary Dynamics with a Non-Abelian Gauge Field
  We study the dynamics of the universe with a scalar field and an SU(2)
non-Abelian Gauge (Yang-Mills) field. The scalar field has an exponential
potential and the Yang-Mills field is coupled to the scalar field with an
exponential function of the scalar field. We find that the magnetic component
of the Yang-Mills field assists acceleration of the cosmic expansion and a
power-law inflation becomes possible even if the scalar field potential is
steep, which may be expected from some compactification of higher-dimensional
unified theories of fundamental interactions. This power-law inflationary
solution is a stable attractor in a certain range of coupling parameters.
Unlike the case with multiple Abelian gauge fields, the power-law inflationary
solution with the dominant electric component is unstable because of the
existence of non-linear coupling of the Yang-Mills field. We also analyze the
dynamics for the non-inflationary regime, and find several attractor solutions.
