Nonlocal matching condition and scale-invariant spectrum in bouncing cosmology

Chong Sun Chu*, Ko Furuta, Feng Li Lin


研究成果: 雜誌貢獻期刊論文同行評審

3 引文 斯高帕斯(Scopus)


In cosmological scenarios such as the pre-big bang scenario or the ekpyrotic scenario, a matching condition between the metric perturbations in the pre-big bang phase and those in the post big bang phase is often assumed. Various matching conditions have been considered in the literature. Nevertheless obtaining a scale-invariant CMB spectrum via a concrete mechanism remains impossible. In this paper, we examine this problem from the point of view of local causality. We begin with introducing the notion of local causality and explain how it constrains the form of the matching condition. We then prove a no-go theorem: independent of the details of the matching condition, a scale-invariant spectrum is impossible as long as the local causality condition is satisfied. In our framework, it is easy to show that a violation of local causality around the bounce is needed in order to give a scale-invariant spectrum. We study a specific scenario of this possibility by considering a nonlocal effective theory inspired by noncommutative geometry around the bounce and show that a scale-invariant spectrum is possible. Moreover we demonstrate that the magnitude of the spectrum is compatible with observations if the bounce is assumed to occur at an energy scale which is a few orders of magnitude below the Planckian energy scale.

期刊Physical Review D - Particles, Fields, Gravitation and Cosmology
出版狀態已發佈 - 2006

ASJC Scopus subject areas

  • 核能與高能物理
  • 物理與天文學(雜項)


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