Construction of Chiral Cosmological Models Unifying Inflation and Primordial Black Hole Formation

TL;DR

This paper introduces a new $F(R,\xi)$ gravity model that unifies inflation and primordial black hole formation, based on a quadratic polynomial extension of the Starobinsky model, with a two-field chiral cosmological framework.

Contribution

It develops a novel $F(R,\xi)$ gravity model that generalizes hybrid inflation to simultaneously describe inflation and primordial black hole formation.

Findings

The model is based on a quadratic polynomial of Ricci scalar R.

The potential in the Einstein frame can be expressed with elementary functions.

The model successfully unifies inflation and black hole formation scenarios.

Abstract

We propose the method for construction of $F(R,\xi)$ gravity model, unifying inflation and primordial black hole formation. The proposed models are based on the Starobinsky $R+R^2$ inflationary model, so, the function $F(R,\xi)$ is a quadratic polynomial of the Ricci scalar $R$. We show that the potential of the corresponding two-field chiral cosmological model in the Einstein frame can be always found in terms of the elementary functions. The special choice of the function $F(R,\xi)$ allows us to get such a generalization of the hybrid inflation that can describe both inflation, and the primordial black hole formation.