On the superstring-inspired quantum correction to the Starobinsky model of inflation

TL;DR

This paper explores quantum corrections from superstring theory to the Starobinsky inflation model by adding a Bel-Robinson tensor squared term, analyzing its effects on inflationary dynamics and observational consistency.

Contribution

It introduces a superstring-inspired quantum correction to the Starobinsky model and derives bounds on the correction parameter based on physical and observational constraints.

Findings

Bounded the parameter eta to ensure ghost-free inflation

Derived inflationary observables consistent with CMB data

Extended the Starobinsky model with quantum corrections

Abstract

Superstring/M-theory is the theory of quantum gravity that can provide the UV-completion to viable inflation models. We modify the Starobinsky inflation model by adding the Bel-Robinson tensor $T^{\mu\nu\lambda\rho}$ squared term proposed as the leading quantum correction inspired by superstring theory. The $(R+\frac{1}{6m^2}R^2 -\frac{\beta}{8m^6}T^2)$ model under consideration has two parameters: the inflaton mass $m$ and the string-inspired positive parameter $\beta$. We derive the equations of motion in the Friedmann-Lemaitre-Robertson-Walker universe and investigate its solutions. We find the physical bounds on the value of the parameter $\beta$ by demanding the absence of ghosts and consistency of the derived inflationary observables with the measurements of the cosmic microwave background radiation.