Anisotropic power-law inflation for a model of two scalar and two vector fields

Abstract

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.

Anisotropic hyperbolic inflation

“…This is the generalization of de Sitter solution whose parameter and its derivative are both zero = ˙ = 0 and can be attractors that describe a class of inflationary evolutions at late times. The exponential potential also gives rise to analytical anisotropic inflationary solutions [28][29][30][31][32][33][34][35]. In these cases, the gauge kinetic function is also exponential and the anisotropy remains constant.…”

Anisotropic power-law inflation for a generalized model of two scalar and two vector fields

“…In this paper, we would like to generalize our recent work [61], which is a multi-field extension of the KSW model, by proposing a more general scenario that two scalar fields can be simultaneously non-minimally coupled to each vector field. As a result, a set of anisotropic solutions of this model can be easily reduced to that found in [61] by taking suitable limits. Furthermore, this set of solutions will be shown to be attractive and stable, similar to many counterexamples found in the previous papers.…”

Formalizing Anisotropic Inflation in Modified Gravity

“…In this paper we shall adopt the last line of research and we shall formalize anisotropic inflation [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] in the context of modified gravity. The most natural generalization of the isotropic FRW geometry is provided by the Bianchi metrics classification.…”