On the Elko inflation model

Abstract

We argue that it is difficult to investigate the stability of de Sitter inflationary solution in an effective model of Elko fields due to the existence of third-order derivatives of fields, which are unfortunately unconstrained since the number of perturbation equations is not enough. This issue leads to an important question of whether the Elko inflation model is free from an instability or not.

16 pages. Accepted for publication in International Journal of Geometric Methods in Modern Physics