Science with the space-based interferometer LISA. IV: Probing inflation with gravitational waves

TL;DR

This paper explores how the LISA space-based interferometer could detect gravitational waves from various inflationary mechanisms, potentially revealing new physics beyond standard inflationary models.

Contribution

It assesses LISA's sensitivity to multiple inflationary scenarios, including particle production, spectator fields, symmetry breaking, and primordial black holes, in a model-independent manner.

Findings

LISA can detect gravitational wave backgrounds from inflationary particle production.

LISA's sensitivity extends beyond vacuum tensor modes, probing additional inflationary physics.

Different inflationary models produce distinguishable gravitational wave signatures.

Abstract

We investigate the potential for the LISA space-based interferometer to detect the stochastic gravitational wave background produced from different mechanisms during inflation. Focusing on well-motivated scenarios, we study the resulting contributions from particle production during inflation, inflationary spectator fields with varying speed of sound, effective field theories of inflation with specific patterns of symmetry breaking and models leading to the formation of primordial black holes. The projected sensitivities of LISA are used in a model-independent way for various detector designs and configurations. We demonstrate that LISA is able to probe these well-motivated inflationary scenarios beyond the irreducible vacuum tensor modes expected from any inflationary background.