Calculation of primordial abundances of light nuclei including a heavy sterile neutrino

Abstract

Abstract. We include the coupling of a heavy sterile neutrino with active neutrinos in the calculation of primordial abundances of light-nuclei. We calculate neutrino distribution functions and primordial abundances, as functions depending on a renormalization of the sterile neutrino distribution function (a), the sterile neutrino mass (m s ) and the mixing angle (φ). Using the observable data, we set constrains on these parameters, which have the values a < 0.60, sin 2 φ = 0.15 and m s ≈ 4 keV, for a fixed value of the baryon to photon ratio. When the baryon to photon ratio is allowed to vary, its extracted value is in agreement with the values constrained by Planck observations and by the Wilkinson Microwave Anisotropy Probe (WMAP). It is found that the anomaly in the abundance of 7 Li persists, in spite of the inclusion of a heavy sterile neutrino.

Time variation of fundamental constants in nonstandard cosmological models

“…The theoretical abundances computed by using the baryon density determined by the CMB data are consistent with the observed abundances of deuterium and helium, but not with the lithium data. This problem, called the lithium problem, was studied by several authors and by several different points of view, such as the turbulent transport in radiative zones of the stars [3], the existence of lithium depletion [4,5], the inclusion of resonant cross sections [6][7][8][9], sterile neutrinos [10][11][12][13][14][15][16][17][18][19][20][21][22], variation of fundamental constants [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37], and the inclusion of cosmological scalar fields and brane cosmology [33].…”