Revisiting the modified Starobinsky model with cosmological constant

TL;DR

This paper extends the modified Starobinsky inflationary model to include a non-zero cosmological constant and radiative corrections, demonstrating that the inflationary solution remains stable under these conditions.

Contribution

It generalizes the MSt model by incorporating a non-zero cosmological constant and radiative corrections, showing the robustness of inflationary solutions.

Findings

Inflation remains stable with non-zero $\Lambda$.

The model's solutions are robust against radiative corrections.

Inflationary transition occurs due to SUSY particle decoupling.

Abstract

The Starobinsky model is a natural inflationary scenario in which inflation arises due to quantum effects of the massless matter fields. A modified version of the Starobinsky (MSt) model takes the masses of matter fields and the cosmological constant, $\Lambda$, into account. The equations of motion become much more complicated however approximate analytic and numeric solutions are possible. In the MSt model, inflation starts due to the supersymmetric (SUSY) particle content of the underlying theory and the transition to the radiation dominated epoch occurs due to the relatively heavy s-particles decoupling. For $\Lambda=0$ the inflationary solution is stable until the last stage, just before decoupling. In the present paper we generalize this result for $\Lambda\neq 0$, since $\Lambda$ should be non-vanishing at the SUSY scale. We also take into account the radiative corrections to $\Lambda$. The main result is that the inflationary solution of the MSt model remains robust and stable.