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arXiv · 1411.6396

String Theory clues for the low-$\ell$ CMB ?

N. Kitazawa·A. Sagnotti
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Abstract

"Brane Supersymmetry Breaking" is a peculiar string-scale mechanism that can unpair Bose and Fermi excitations in orientifold models. It results from the simultaneous presence, in the vacuum, of collections of D-branes and orientifolds that are not mutually BPS, and is closely tied to the scale of string excitations. It also leaves behind, for a mixing of dilaton and internal breathing mode, an exponential potential that is just too steep for a scalar to emerge from the initial singularity while descending it. As a result, in this class of models the scalar can generically bounce off the exponential wall, and this dynamics brings along, in the power spectrum, an infrared depression typically followed by a pre-inflationary peak. We elaborate on a possible link between this type of bounce and the low-$\ell$ end of the CMB angular power spectrum. For the first 32 multipoles, one can reach a 50 % reduction in $\chi^{\,2}$ with respect to the standard $\Lambda$CDM setting.

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N. Kitazawa, A. Sagnotti. 2014-11-24. String Theory clues for the low-$\ell$ CMB ?. https://arxiv.org/abs/1411.6396

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