Possible evidence for “dark radiation” from Big Bang Nucleosynthesis data

¹ School of Physics, The University of New South Wales - Sydney NSW 2052, Australia
² Physics Division, Argonne National Laboratory - Argonne, IL 60439-4843, USA
³ Department of Physics and Astronomy, State University of New York Stony Brook, NY 11794-3800, USA

Received: 22 March 2006
Accepted: 3 April 2006

Abstract

We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a “dark radiation” component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved.