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Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

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Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

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dc.contributor.author	Mangano, Gianpiero
dc.contributor.author	Miele, Gennaro
dc.contributor.author	Pastor Carpi, Sergio
dc.contributor.author	Pisanti, Ofelia
dc.contributor.author	Sarikas, Srdjan
dc.date.accessioned	2014-07-31T11:34:18Z
dc.date.available	2014-07-31T11:34:18Z
dc.date.issued	2011
dc.identifier.citation	Mangano, Gianpiero Miele, Gennaro Pastor Carpi, Sergio Pisanti, Ofelia Sarikas, Srdjan 2011 Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis Journal Of Cosmology And Astroparticle Physics 1103 035 035-1 035-19
dc.identifier.uri	http://hdl.handle.net/10550/37348
dc.description.abstract	The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos Neff. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on Neff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, etanu= eta(nue)+eta(numb)+eta(nutau) and the initial electron neutrino asymmetry, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the nue-antinue asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2H/H density ratio and 4He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2H/H abundance plays a relevant role in constraining the allowed regions in the plane of neutrino asymmetries. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to Neff as a function of the mixing parameter theta13, and point out the upper bound Neff < 3.4. Comparing these results with the forthcoming measurement of Neff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.
dc.language.iso	eng
dc.relation.ispartof	Journal Of Cosmology And Astroparticle Physics, 2011, vol. 1103, num. 035, p. 035-1-035-19
dc.subject	Física
dc.title	Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis
dc.type	journal article	es_ES
dc.date.updated	2014-07-31T11:34:18Z
dc.identifier.doi	10.1088/1475-7516/2011/03/035
dc.identifier.idgrec	069176
dc.rights.accessRights	open access	es_ES