The scale invariant power spectrum of the primordial curvature perturbations from the coupled scalar tachyon bounce cosmos

Abstract

We investigate the spectrum of cosmological perturbations in a bounce cosmos modeled by a scalar field coupled to the string tachyon field (CSTB cosmos).By explicit computation of its primordial spectral indexwe show the power spectrum of curvature perturbations, generated during the tachyon matter dominated contraction phase, to benearly scale invariant.We propose a unified parameter space for a systematic study of inflationary and bounce cosmologies.The CSTB cosmos is dual-in Wands's sense-to slow-roll inflation as can be visualized with the aid of this parameter space.Guaranteed by the dynamical attractor behavior of the CSTB Cosmos, the scale invariance of its power spectrum is free of the fine-tuning problem, in contrast to the slow-roll inflation model.