Cosmological attractors and initial conditions for inflation

By J. J. Carrasco, R. Kallosh, Andrei Linde. Physical Review D, 2015

168 citations recorded by the source corpus.

Inflationary $\alpha$-attractor models in supergravity, which provide excellent fits to the latest observational data, are based on the Poincare disk hyperbolic geometry. We refine these models by constructing Kahler potentials with built-in inflaton shift symmetry and by making a canonical choice of the goldstino Kahler potential. The refined models are stable with respect to all scalar fields at all $\alpha$, no additional stabilization terms are required. The scalar potential $V$ has a nearly Minkowski minimum at small values of the inflaton field $\varphi$, and an infinitely long dS valley of constant depth and width at large $\varphi$. Because of the infinite length of this shift-symmetric valley, the initial value of the inflaton field at the Planck density is expected to be extremely large. We show that the inflaton field $\varphi$ does not change much until all fields lose their energy and fall to the bottom of the dS valley at large $\varphi$. This provides natural initial conditions for inflation driven by the inflaton field slowly rolling along the dS valley towards the minimum of the potential at small $\varphi$. A detailed description of this process is given for $\alpha$-attractors in supergravity, but we believe that our general conclusions concerning naturalness of initial conditions for inflation are valid for a broad class of inflationary models with sufficiently flat potentials.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Oceanography

View Paper: https://www.semanticscholar.org/paper/a010f31beae109b7aa3fb0823e49627cf98786b6

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Citations in the corpus

Dark energy, α-attractors, and large-scale structure surveys (2017, background): “[60], and a generalized version of the model studied in refs.”
α-attractors: Planck, LHC and dark energy (2015, methodology): “We will now perform a Kähler transformation [15,27] so that our new Kähler potential is inflaton shift-symmetric.”
Beginning inflation in an inhomogeneous universe (2015, methodology): “[11]).”
The evidence for a spatially flat Universe (2020, background): “For many models of inflation, e.g. α-attractors (Carrasco et al. 2015), the number of e-foldings can be much greater than N∗, in which case our Universe is expected to be spatially flat to high accuracy.”