Calculating the local-type fNL for slow-roll inflation with a non-vacuum initial state

Дата и время публикации : 2011-04-01T20:00:04Z

Авторы публикации и институты :
Jonathan Ganc

Ссылка на журнал-издание: Phys. Rev. D 84, 063514 (2011)
Коментарии к cтатье: 8 pages, 1 figure. v2: Version accepted for publication in PRD. Added greatly expanded discussion of the phase angle theta_k; this allows the possibility of enhanced fNL, as mentioned in abstract. More explicit comparisons with earlier work
Первичная категория: astro-ph.CO

Все категории : astro-ph.CO, hep-th

Краткий обзор статьи: Single-field slow-roll inflation with a non-vacuum initial state has an enhanced bispectrum in the local limit. We numerically calculate the local-type fNL signal in the CMB that would be measured for such models (including the full transfer function and 2D projection). The nature of the result depends on several parameters, including the occupation number N_k, the phase angle theta_k between the Bogoliubov parameters, and the slow-roll parameter epsilon. In the most conservative case, where one takes theta_k approx eta_0 k (justified by physical reasons discussed within) and epsilonlesssim 0.01, we find that 0 < fNL < 1.52 (epsilon/0.01), which is likely too small to be detected in the CMB. However, if one is willing to allow a constant value for the phase angle theta_k and N_k=O(1), fNL can be much larger and/or negative (depending on the choice of theta_k), e.g. fNL approx 28 (epsilon/0.01) or -6.4 (epsilon/0.01); depending on epsilon, these scenarios could be detected by Planck or a future satellite. While we show that these results are not actually a violation of the single-field consistency relation, they do produce a value for fNL that is considerably larger than that usually predicted from single-field inflation.

Category: Physics