Starobinsky Inflation with T-Model Kähler Geometries

We present novel implementations of Starobisky-like inflation within supergravity adopting Kähler potentials for the inflaton which parameterizes hyperbolic geometries known from T-model inflation. The associated superpotentials are consistent with an R and a global or gauge U(1)X symmetries. The inflaton is represented by a gauge-singlet or non-singlet superfield and is accompanied by a gauge-singlet superfield successfully stabilized thanks to its compact contribution into the total Kähler potential. Keeping the Kähler manifold intact, a conveniently violated shift symmetry is introduced which allows for slight variation in the predictions of Starobinsky inflation: The (scalar) spectral index exhibits an upper bound which lies close to its central observational value whereas the constant scalar curvature of the inflaton-sector Kähler manifold increases with the tensor-to-scalar ratio.