A general classification of Starobinsky-like inflationary avatars of SU(2,1)/SU(2)×U(1) no-scale supergravity

Abstract Measurements of the cosmic microwave background (CMB) favour models of inflation with a small tensor-to-scalar ratio r, as predicted by the Starobinsky R + R 2 model. It has been shown previously that various models based on no-scale supergravity with different forms of superpotential make predictions similar to those of the Starobinsky model. In this paper we present a unified and general treatment of Starobinsky avatars of no-scale supergravity, using the underlying non-compact SU(2,1)/SU(2)×U(1) symmetry to demonstrate equivalences between different models, exhibiting 6 specific equivalence classes.