Modified scalar and tensor spectra in spinor driven inflation

TL;DR

This paper investigates the scalar and tensor perturbations in spinflation driven by Elko fields, showing that the standard inflationary consistency relation may not hold, with implications for observational tests of inflation.

Contribution

It introduces a new spinor-driven inflation model and derives the perturbation equations, revealing deviations from the standard consistency relation.

Findings

Scalar perturbations are purely adiabatic with speed of sound equal to one.

Scalar and tensor spectra are nearly scale-invariant in the slow-roll limit.

Derived modified consistency relations for spinflation models.

Abstract

One of the firm predictions of the single-scalar field inflationary cosmology is the consistency relation between the scalar and tensor perturbations. It has been argued that such a relation, if observationally verified, would offer strong support for the idea of inflation. In this letter, we critically analyze the validity of the consistency relation in the context of spinflation. Spinflaton -- a scalar condensate of the Elko field -- has a single scalar degree of freedom and leads to the identical acceleration equation as the single canonical scalar field. We obtain the perturbation equations for the Einstein-Elko system and show that (i) The scalar perturbations are purely adiabatic and speed of the perturbations is identically one. (ii) In the slow-roll limit, the scalar and tensor perturbations are nearly scale-invariant and (iii) Obtain the consistency relations for the scalar and tensor spectra.