Entropy Fluctuations in Brane Inflation Models

Abstract

We study the development of entropy fluctuations in brane inflation in a warped throat, including the brane-antibrane tachyon as the waterfall field. We find that there is a period at the end of inflation during which the entropy mode associated with the tachyon field increases exponentially. In turn, the induced entropy seeds a contribution to the curvature fluctuation on cosmological scales which grows rapidly and could exceed the primordial curvature perturbation. We identify parameter values for which in the absence of back-reaction the induced curvature fluctuations are larger than the primordial adiabatic ones. In the specific model we study, however, back-reaction limits the growth of the entropy fluctuations. We discuss situations in which back-reaction effects are less constraining. The lesson of our investigation is that the study of the development of entropy fluctuations at the end of the period of inflation can lead to constraints on models of brane inflation and suggests that the curvaton mechanism may contribute significantly to the spectrum of cosmological perturbations.

28 pg + refs; v2. added refs, clarified initial value T_0, added comparison to refs [49,50]; v3. added discussion of backreaction, reduces effects of entropy modes; v4. added model w/o backreaction, to be published in IJMPA; v5. corrected LaTeX bug with citations

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Cited by in corpus (9)

• Encyclopaedia Inflationaris
• Reheating in Inflationary Cosmology: Theory and Applications
• The hybrid inflation waterfall and the primordial curvature perturbation
• On higher derivative corrections to Wess-Zumino and Tachyonic actions in type II super string theory
• Contribution of the hybrid inflation waterfall to the primordial curvature perturbation
• Preheating and Entropy Perturbations in Axion Monodromy Inflation
• Analytical Study of Mode Coupling in Hybrid Inflation
• Preheating in an Asymptotically Safe Quantum Field Theory
• Inflation in a scalar-vector gravity theory