Testing $\alpha$-attractor quintessential inflation against CMB and low-redshift data

Understand

Due to universality and attractor properties, $\alpha$-attractor quintessential inflation establishes direct relations between inflationary observables such as the scalar tilt $n_s$ and the tensor-to-scalar ratio $r$, and late-time dark energy equation of state parameters $w_0$ and $w_a$.

• In this work, we examine three different physically motivated regimes, considering complete freedom in the parameter $\alpha$, models inspired by supergravity where $\alpha$ takes on values up to $\alpha=7/3$, and Starobinsky inflation ($\alpha=1$).
• We investigate the consistency and constraints imposed by Cosmic Microwave Background measurements from the Planck satellite, B-mode polarization data from the BICEP/Keck collaboration, and low-redshift observations.
• Additionally, we consider small-scale CMB measurements released by the Atacama Cosmology Telescope, which give results approaching the Harrison-Zel'dovich spectrum ($n_s \approx 1$).