Identifying the inflaton with primordial gravitational waves

TL;DR

This paper investigates how future measurements of primordial gravitational waves and other observables could help identify the fundamental structure of the inflationary gravitational Lagrangian, reducing degeneracy in inflation models.

Contribution

It demonstrates that precise measurements of the tensor spectral index from primordial gravitational waves can significantly constrain the inflaton potential and underlying inflationary physics.

Findings

Future gravitational wave observations can reduce inflationary model degeneracy.

Additional observables like non-Gaussianity may further constrain inflation models.

Precise tensor spectral index measurements are crucial for understanding inflation.

Abstract

We explore the ability of experimental physics to uncover the underlying structure of the gravitational Lagrangian describing inflation. While the observable degeneracy of the inflationary parameter space is large, future measurements of observables beyond the adiabatic and tensor two-point functions, such as non-Gaussianity or isocurvature modes, might reduce this degeneracy. We show that even in the absence of such observables, the range of possible inflaton potentials can be reduced with a precision measurement of the tensor spectral index, as might be possible with a direct detection of primordial gravitational waves.