Dark Matter and Inflation in $R+\zeta R^{2}$ Supergravity

Understand

As is well known, the gravitational degrees of freedom contained in $R+\zeta R^{2}$ (super)gravity lead to Starobinsky's potential, in a one-field setting for inflationary Cosmology that appears favored by Planck data.

• In this letter we discuss another interesting aspect of this model, related to gravitino production, with emphasis on the corresponding mass spectrum.
• Assuming that supersymmetry is broken at a very high scale, Super Heavy Gravitino Dark Matter (SHGDM) and Starobinsky's inflation can be coherently unified in a $R+\zeta R^{2}$ supergravity.
• Gravitinos are assumed to be the Lightest Supersymmetric Particles (LSP) and are non-thermally produced during inflation, in turn originated by a scalar with a Starobinsky's potential.