Falsifying Tree Level String Motivated Bouncing Cosmologies

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dc.creatorConstantinidis, C. P.
dc.creatorFabris, J. C.
dc.creatorFurtado, R. G.
dc.creatorPinto-Neto, N.
dc.creatorGonzalez, D.
dc.date2005-12-16
dc.date.accessioned2026-07-07T10:45:31Z
dc.date.available2026-07-07T10:45:31Z
dc.descriptionThe string effective action at tree level contains, in its bosonic sector, the Einstein-Hilbert term, the dilaton, and the axion, besides scalar and gauge fields coming from the Ramond-Ramond sector. The reduction to four dimensions brings to scene moduli fields. We generalize this effective action by introducing two arbitrary parameters, $ω$ and $m$, connected with the dilaton and axion couplings. In this way, more general frameworks can be analyzed. Regular solutions with a bounce can be obtained for a range of (negative) values of the parameter $ω$ which, however, exclude the pure string configuration ($ω= - 1$). We study the evolution of scalar perturbations in such cosmological scenarios. The predicted primordial power spectrum decreases with the wavenumber with spectral index $n_s=-2$, in contradiction with the results of the $WMAP$. Hence, all such effective string motivated cosmological bouncing models seem to be ruled out, at least at the tree level approximation.
dc.descriptionLatex file, 19 pages, 3 figures in eps format
dc.identifierhttps://arxiv.org/abs/hep-th/0512209
dc.identifierhttp://arxiv.org/abs/hep-th/0512209
dc.identifierPhys.Rev.D73:123513,2006
dc.identifierdoi:10.1103/PhysRevD.73.123513
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/182937
dc.subjectHigh Energy Physics - Theory
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.titleFalsifying Tree Level String Motivated Bouncing Cosmologies
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