Hyperbolic inflation in the Jordan frame

TL;DR

This paper explores a multi-scalar field model in the Jordan frame, demonstrating its reduction to hyperbolic inflation and analyzing its cosmological solutions and attractor behavior.

Contribution

It introduces a novel multi-scalar Jordan frame model that reduces to hyperbolic inflation and studies its asymptotic dynamics and attractor solutions.

Findings

Scaling solutions and de Sitter universe are supported by the theory.

The attractor is always a spiral, analogous to hyperbolic inflation.

All fluid sources contribute in the cosmological fluid at the attractor.

Abstract

We consider a multi-scalar field model in the Jordan frame which can be seen as a two-scalar field model where the Brans-Dicke field interacts in the kinetic part with the second scalar field. This theory under a conformal transformation reduces to the hyperbolic inflation. We show that scaling solutions and the de Sitter universe are provided by theory. In the study of asymptotic dynamics, we determine an attractor where all the fluid sources contribute in the cosmological fluid. This attractor is always a spiral and it can be seen as the analogue of the hyperbolic inflation in the Jordan frame.