A search for an N=2 inflaton potential

We consider N = 2 supergravity theories that have the same spectrum as the R + R-2 supergravity, as predicted from the off-shell counting of degrees of freedom. These theories describe standard N = 2 supergravity coupled to one or two long massive vector multiplets. The central charge is not gauged in these models and they have a Minkowski vacuum with N = 2 unbroken supersymmetry. The gauge symmetry, being non-compact, is always broken. alpha-deformed inflaton potentials are obtained, in the case of a single massive vector multiplet, with alpha = 1/3 and 2/3. The alpha = 1 potential (i.e. the Starobinsky potential) is also obtained, but only at the prize of having a single massive vector and a residual unbroken gauge symmetry. The inflaton corresponds to one of the Cartan fields of the non-compact quaternionic-Kahler cosets. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim