Inflation with strongly non-geodesic motion: theoretical motivations and observational imprints

Understand

A new class of inflationary attractors characterized by a strongly non-geodesic motion has been discovered and explored in the past few years.

• I describe how they naturally arise in negatively curved field space, allowing to inflate on potentials that are steep in Planck units, albeit without alleviating the ever-present naturalness issue of inflation.
• In these scenarios, fluctuations often experience a transient tachyonic instability, which can be described by a single-field effective field theory with an imaginary speed of sound.
• Independently of the precise ultraviolet origin of the latter, this leaves a peculiar imprint in the form of a high-level of primordial non-Gaussianities of flattened type for all higher-order correlation functions.