TY  - JOUR
AU  - de Salas, P. F.
AU  - Pastor, S.
PY  - 2016
DA  - 2016//
TI  - Relic neutrino decoupling with flavour oscillations revisited
T2  - J. Cosmol. Astropart. Phys.
JO  - Journal of Cosmology and Astroparticle Physics
SP  - 051
EP  - 18pp
VL  - 07
IS  - 7
PB  - Iop Publishing Ltd
KW  - cosmological neutrinos
KW  - particle physics – cosmology connection
KW  - physics of the
KW  - early universe
KW  - neutrino properties
AB  - We study the decoupling process of neutrinos in the early universe in the presence of three-flavour oscillations. The evolution of the neutrino spectra is found by solving the corresponding momentum-dependent kinetic equations for the neutrino density matrix, including for the first time the proper collision integrals for both diagonal and off-diagonal elements. This improved calculation modifies the evolution of the off-diagonal elements of the neutrino density matrix and changes the deviation from equilibrium of the frozen neutrino spectra. However, it does not vary the contribution of neutrinos to the cosmological energy density in the form of radiation, usually expressed in terms of the effective number of neutrinos, N-eff. We find a value of N-eff = 3.045, in agreement with previous theoretical calculations and consistent with the latest analysis of Planck data. This result does not depend on the ordering of neutrino masses. We also consider the effect of non-standard neutrino-electron interactions (NSI), predicted in many theoretical models where neutrinos acquire mass. For two sets of NSI parameters allowed by present data, we find that Neff can be reduced down to 3.040 or enhanced up to 3.059.
SN  - 1475-7516
UR  - http://arxiv.org/abs/1606.06986
UR  - https://doi.org/10.1088/1475-7516/2016/07/051
DO  - 10.1088/1475-7516/2016/07/051
LA  - English
N1  - WOS:000381830000052
ID  - deSalas+Pastor2016
ER  -