Inflation from N-forms and its stability

We investigate whether inflation, either isotropic or anisotropic, may be supported by n-forms. Canonical field strengths and their duals are taken into account, and they are allowed to have a potential and also, when necessary for slow-roll, a nonminimal curvature coupling. New isotropic solutions are found for three-forms. It is also shown that some n-form actions are equivalent to f(R) gravity and scalar field models with possible nonminimal couplings. Anisotropic solutions are found for two-forms, generalising vector inflation. However, as the later also the two-form is unstable during inflation due to the nonminimal coupling to curvature. The stability of the isotropic background solutions supported by a triad of vectors is also analysed.