CMB Fluctuations and String Compactification Scales

Abstract

We propose a mechanism for the generation of temperature fluctuations of cosmic microwave background. We consider a large number of fields, such as Kaluza-Klein modes and string excitations. Each field contributes to the gravitational potential by a small amount, but an observable level of temperature fluctuations is achieved by summing up the contribution of typically of order 10^{14} fields. Tensor fluctuations are hardly affected by these fields. Our mechanism is based on purely quantum effects, and is different from the "slow-roll" or "curvaton" scenario. Using the observed data, we find constraints on the parameters of this model, such as the size of the extra dimensions and the string scale. Our model predicts a particular pattern of non-gaussianity with a small magnitude.

4 pages, 2 figures; v2: Corrected a mistake in eq. (11), which does not affect the subsequent context. Added a comment on inflaton fluctuations at the end of the paper. Final version to appear in Phys. Lett. B

References in corpus (4)

• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Vector Inflation
• A Holographic Framework for Eternal Inflation
• Census Taking in the Hat: FRW/CFT Duality

Cited by in corpus (3)

• Evolution of vacuum fluctuations generated during and before inflation
• Possible origin of CMB temperature fluctuations: Vacuum fluctuations of Kaluza-Klein and string states during inflationary era
• A new mechanism of realizing inflationary universe with recourse to backreaction of quantized free fields -- Inflation without inflaton --