\phi^2 or Not \phi^2: Testing the Simplest Inflationary Potential

PAOLO CREMINELLI; DIANA LÓPEZ NACIR; MARKO SIMONOVIC; GABRIELE TREVISAN; MATIAS ZALDARRIAGA

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Lugar: New York; Año: 2014 vol. 112 p. 1 - 5

0031-9007

The simplest inflationary model V=m^2\phi^2/2 represents the benchmark for future constraints. For a quadratic potential, the quantity (n_s-1)+r/4+11(n_s-1)^2/24 vanishes (up to corrections which are cubic in slow roll) and can be used to parametrize small deviations from the minimal scenario. Future constraints on this quantity will be able to distinguish a quadratic potential from a pseudo-Nambu-Goldstone boson with f\lesssim 30 Mpl and set limits on the deviation from unity of the speed of sound |c_s-1|\lesssim 3\times10^{-2} (corresponding to an energy scale \Lambda \gtrsim 2 \times 10^{16} GeV), and on the contribution of a second field to perturbations (\lesssim 6 \times10^{-2}). The limiting factor for these bounds will be the uncertainty on the spectral index. The error on the number of e-folds will be \Delta N \simeq 0.4, corresponding to an error on the reheating temperature \Delta T_{rh}/T_{rh} \simeq 1.2. We comment on the relevance of non-Gaussianity after BICEP2 results.