Kinetically stabilized inflation

TL;DR

This paper introduces a string-inspired two-field inflation model that naturally stabilizes inflation kinetically, producing a nearly scale-invariant spectrum consistent with CMB data and predicting low gravitational wave signals.

Contribution

It proposes a novel two-field inflation mechanism inspired by string theory that addresses fine-tuning and produces observationally consistent primordial perturbations.

Findings

Achieves over 62 e-folds of inflation with specific parameters.

Generates a nearly scale-invariant primordial spectrum.

Predicts a low tensor-to-scalar ratio compatible with current observations.

Abstract

In this work, we propose a string-inspired two fields inflation model to address the fine-tuning problem that the standard inflation model suffers. The fast-rolling tachyon $\mathcal{T}$ originated from the D-brane and anti-D-brane pair annihilation locks the inflaton $\varphi$ slowly rolling on a Higgs-like potential $V(\varphi)=-m_\varphi^2\varphi^2+\lambda \varphi^4$ and drives a kinetically stabilized (KS) inflation. Our numerical simulation confirms such a solution is a dynamic attractor. In particular, for $\lambda< 0.8\times 10^{-3}$, the e-folding number contributed by the KS inflation phase can be larger than $62$ to solve the horizon and flatness problems of Big Bang theory. Notably, this KS inflation generates a nearly scale-invariant primordial curvature perturbations spectrum consistent with current cosmic microwave background (CMB) observations. It predicts a low tensor-to-scalar ratio, which the current primordial gravitational wave background (the B-modes in CMB) searches favor.