Physics – Nuclear Physics
Scientific paper
May 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003nupha.718..386i&link_type=abstract
Nuclear Physics A, Volume 718, p. 386-388.
Physics
Nuclear Physics
1
Scientific paper
We analyze the observational constraints on brane-world cosmology whereby the universe is described as a three-brane embedded in a five-dimensional anti-de Sitter space. In this brane-universe cosmology, the Friedmann equation is modified by the appearance of extra terms which derive from existence of the extra dimensions. In the present work we concentrate on the ``dark radiation'' term which diminishes with cosmic scale factor as a-4. We show that, although the observational constraints from primordial abundances allow only a small contribution when this term is positive, a much wider range of negative between the observed primordial 4He and D abundances. We also discuss the possible constraints on this term from the power spectrum of CMB anisotropies in the limit of negligible cosmological perturbation on the brane world. We show that BBN limits the possible contribution from dark radiation just before the e+e- aniihilation epoch to lie between -123% and +11% of the background photon energy density. Combining this with the CMB constraint reduces this range to between -41% and +10.5% at the 2σ confidence level.
Ichiki Kiyotomo
Kajino Taka
Mathews Grant J.
Orito Manabu
Yahiro Masanobu
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