A big bang nucleosynthesis likelihood analysis of the baryontophoton ratio and the number of light particle degrees of freedom
Abstract
We extend the modelindependent likelihood analysis of big bang nucleosynthesis (BBN) based on ^{4}He and ^{7}Li to allow for numbers of degrees of freedom which differ from the standard model value characterized by N_{v} = 3. We use the twodimensional likelihood functions to simultaneously constrain the baryontophoton ratio and the number of light neutrinos. The upper limit thus obtained is N_{v} < 4.0 (at 95% C.L.). We also consider the consequences if recent observations of deuterium in highredshift QSO absorptionline systems (QSOALS) are confirmed.
 Publication:

Astroparticle Physics
 Pub Date:
 June 1997
 DOI:
 10.1016/S09276505(97)00008X
 arXiv:
 arXiv:hepph/9610319
 Bibcode:
 1997APh.....7...27O
 Keywords:

 High Energy Physics  Phenomenology;
 Astrophysics
 EPrint:
 12 pages, latex, 4 ps figures, requires epsf