Dynamics of inflation with mutually orthogonal vector fields in a closed universe
Tomoaki Murata, Tsutomu Kobayashi
Abstract
We study the dynamics of a homogeneous, isotropic, and positively curved universe in the presence of a SU(2) gauge field or a triplet of mutually orthogonal vector fields. In the SU(2) case we use the previously known ansatz for the gauge-field configuration, but the case without non-Abelian symmetries is more nontrivial and we develop a new ansatz. We in particular consider axion-SU(2) inflation and inflation with vector fields having $\mathrm{U}(1)\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ symmetry, and analyze their dynamics in detail numerically. Novel effects of the spatial curvature come into play through vector fields, which causes unconventional preinflationary dynamics. It is found that the closed universe with vector fields is slightly more stable against collapse than that filled solely with an inflaton field.