Bulg. J. Phys. vol.38 no.3 (2011), pp. 341-345

General BBN Bounds on Electron-Sterile Neutrino Oscillations

M. Panayotova
Institute of Astronomy and NAO, Bulg. Acad. Sci., Sofia 1784, Bulgaria
Abstract. I discuss BBN with late electron-sterile neutrino oscillations, effective after electron neutrino freezing. The primordial production of 4He in the presence of oscillations is numerically calculated for different initial population of the sterile neutrino 0 ≤ δNs < 1. General BBN bounds on oscillation parameters are presented, corresponding to ~ 5% overproduction of the primordial 4He and different initial population of the sterile neutrino, namely δNs=0; 0.5; 0.7; 0.9. The cosmological constraints corresponding to initially partially filled sterile state are relaxed, compared to the case of initially zero population of the sterile neutrino.

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