Cosmology with non-minimal derivative couplings: perturbation analysis and observational constraints

Understand

We perform a combined perturbation and observational investigation of the scenario of non-minimal derivative coupling between a scalar field and curvature.

• First we extract the necessary condition that ensures the absence of instabilities, which is fulfilled more sufficiently for smaller coupling values.
• Then using Type Ia Supernovae (SNIa), Baryon Acoustic Oscillations (BAO), and Cosmic Microwave Background (CMB) observations, we show that, contrary to its significant effects on inflation, the non-minimal derivative coupling term has a negligible effect on the universe acceleration, since it is driven solely by the usual scalar-field potential.
• Therefore, the scenario can provide a unified picture of early and late time cosmology, with the non-minimal derivative coupling term responsible for inflation, and the usual potential responsible for late-time acceleration.