Abstract
Recent BICEP/Keck data on the cosmic microwave background, in combination with previous WMAP and Planck data, impose strong new constraints on the tilt in the scalar perturbation spectrum, ${n}_{s}$, as well as the tensor-to-scalar ratio, $r$. These constrain the number of $e$-folds of inflation, ${N}_{*}$, the magnitude of the inflaton coupling to matter, $y$, and the reheating temperature, ${T}_{\mathrm{reh}}$, which we evaluate in attractor models of inflation as formulated in no-scale supergravity. The 68% C.L. region of $({n}_{s},r)$ favors large values of ${N}_{*},y$, and ${T}_{\mathrm{reh}}$ that are constrained by the production of gravitinos and supersymmetric dark matter.
Highlights
Successive releases of data on perturbations in the cosmic microwave background (CMB) [1] have provided increasingly strong upper limits on the tensor-to-scalar ratio, r, and sharpened focus on models of inflation that favor small values of r, such as the original Starobinsky model [2] that predicts r ∼ 0.004 for 55 e-folds
(26) and using the observed dark matter density today, ΩCDMh2 ≃ 0.12, we find the following upper limit on the Yukawa-like inflaton coupling, assuming that the gravitino decays after the lightest supersymmetric particle (LSP)
We derive the corresponding limits on y. These are compared to the 68% and 95% C.L. on N and y from the BICEP/Keck constraints on ns
Summary
Successive releases of data on perturbations in the cosmic microwave background (CMB) [1] have provided increasingly strong upper limits on the tensor-to-scalar ratio, r, and sharpened focus on models of inflation that favor small values of r, such as the original Starobinsky model [2] that predicts r ∼ 0.004 for 55 e-folds. A common feature of these no-scale supergravity models is a quadratic singularity in the kinetic term for the inflaton This feature leads generically to an effective potential for the canonically normalized inflaton field with a plateau that. For the attractor models discussed here, increasing the value of α reduces the flatness of the plateau at the inflaton field value at the horizon crossing of the CMB scale, φÃ, which affects the cosmological observables ns and r. It was argued in [10–12,15,16,18] that broad classes of attractor models lead to identical predictions of ns and r in the limit of a large number of e-folds, NÃ.. Based on [4], the 68% C.L. ranges are (0.4, 12) and (0.5, 7) for the α-Starobinsky and T models, respectively, and the 95% C.L. ranges are (0, 24) and (0, 12).
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