Anisotropic power-law inflation for a model of two scalar and two vector
  fields
  Inspired by an interesting counterexample to the cosmic no-hair conjecture
found in a supergravity-motivated model recently, we propose a multi-field
extension, in which two scalar fields are allowed to non-minimally couple to
two vector fields, respectively. This model is shown to admit an exact Bianchi
type I power-law solution. Furthermore, stability analysis based on the
dynamical system method is performed to show that this anisotropic solution is
indeed stable and attractive if both scalar fields are canonical. Nevertheless,
if one of the two scalar fields is phantom then the corresponding anisotropic
power-law inflation turns unstable as expected.
