Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-05-16
Astropart.Phys.19:303-312,2003
Astronomy and Astrophysics
Astrophysics
17 pages, 2 figures; matches Astropart. Phys. version
Scientific paper
10.1016/S0927-6505(02)00204-9
New results, namely the independent determination of the deuterium abundance in several quasar absorption systems, and the complementary determination of the cosmological baryon density by observations of anisotropies in the cosmic microwave background (CMB), allow for a reevaluation of the constraints on the relativistic particle content of the universe at primordial nucleosynthesis. Expressed in terms of the neutrino energy density, we find 1.7 < N_\nu < 3.5 (95% CL). In particular, we show that phenomenological four neutrino models including a sterile state (not participating in SU(2)_L x U(1)_Y interactions) unavoidably thermalize a fourth neutrino, and are highly disfavored in the standard minimal model of primordial nucleosynthesis, if the systematic uncertainty in the primordial helium abundance is small. We describe plausible extensions of the minimal model which evade this constraint.
No associations
LandOfFree
Telling Three from Four Neutrinos with Cosmology does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Telling Three from Four Neutrinos with Cosmology, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telling Three from Four Neutrinos with Cosmology will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-238800