scholarly journals NEUTRINO SPECTRUM DISTORTION DUE TO OSCILLATIONS AND ITS BBN EFFECT

2004 ◽  
Vol 13 (05) ◽  
pp. 831-841 ◽  
Author(s):  
DANIELA KIRILOVA
Keyword(s):  
Sterile Neutrino ◽  
Big Bang ◽  
Neutrino Energy ◽  
Electron Neutrino ◽  
Initial Population ◽  
Neutrino Mixing ◽  
Big Bang Nucleosynthesis ◽  
Cosmological Constraints ◽  
Neutrino Spectrum ◽  
Primordial Abundance

We study the distortion of electron neutrino energy spectrum due to oscillations with the sterile neutrino νe↔νs, for different initial populations of the sterile state δNs at the onset of oscillations. The influence of this spectrum distortion on Big Bang Nucleosynthesis is analyzed. Only the case of an initially empty sterile state was studied in previous publications. The primordial abundance of 4He is calculated for all possible δNs:0≤δNs≤1 in the model of oscillations, effective after electron neutrino decoupling, for which the spectrum distortion effects on the neutron–proton transitions are the strongest. It is found that the spectrum distortion effect may be dominant, not only in the case of small δNs, but also in the case of large initial population of νs. For example, in the resonant case it may play a considerable role even for very large δNs~0.8. Cosmological constraints on neutrino mixing for small δNs are discussed.

scholarly journals BBN CONSTRAINTS ON NEUTRINO OSCILLATIONS PARAMETERS RELAXED OR STRENGTHENED

2007 ◽  
Vol 16 (07) ◽  
pp. 1197-1210 ◽  
Author(s):  
DANIELA KIRILOVA
Keyword(s):  
Energy Spectrum ◽  
Energy Density ◽  
Sterile Neutrino ◽  
Full Range ◽  
Big Bang ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Cosmic Expansion ◽  
Cosmological Constraints ◽  
Kinetic Effects

Big Bang Nucleosynthesis (BBN) with nonequilibrium νe ↔ νs oscillations, in the more general case of non-zero population of νs before oscillations δNs ≠ 0, is discussed. 4 He primordial production Yp(δNs) in the presence of νe ↔ νs oscillations for different initial populations of the sterile neutrino state 0 ≤ δ Ns ≤ 1 and the full range of oscillation parameters is calculated. Non-zero δNs has a two-fold effect on 4 He : (i) it enhances the energy density and hence increases the cosmic expansion rate, leading to Ypoverproduction, and (ii) it suppresses the kinetic effects of oscillations on BBN, namely, the effects on pre-BBN nucleon kinetics, caused by the νe energy spectrum distortion and the [Formula: see text] asymmetry generation by oscillations, leading to decreased Yp production. Depending on oscillation parameters one or the other effect may dominate, causing, correspondingly, either a relaxation of the cosmological constraints or their strengthening with the increase of δNs. More general BBN constraints on νe ↔ νs oscillation parameters, corresponding to 3% Yp overproduction, for different initial populations of the sterile state are calculated. Previous BBN constraints were derived assuming empty sterile state before oscillations. It is shown that the cosmological constraints strengthen with the increase of δNs value, the change being more considerable for nonresonant oscillations.

scholarly journals A Sterile Neutrino Scenario Constrained By Experiments and Cosmology

1997 ◽  
Vol 12 (21) ◽  
pp. 3669-3694 ◽  
Author(s):  
Nobuchika Okada ◽  
Osamu Yasuda
Keyword(s):  
Total Mass ◽  
Sterile Neutrino ◽  
Neutrinoless Double Beta Decay ◽  
Big Bang ◽  
Double Beta Decay ◽  
Big Bang Nucleosynthesis ◽  
Negative Results ◽  
Equivalent Number ◽  
Mixing Matrix ◽  
Model Independent

We analyze a scheme in which three active neutrinos and one sterile neutrino account for the solar, the atmospheric and the LSND neutrino anomalies in a model-independent way. It is shown that if the equivalent number, Nν, of the light neutrino species is less than 4, then the constraints from these anomalies, accelerator and reactor experiments and big bang nucleosynthesis force a general 4 × 4 mixing matrix to be effectively split into two 2 × 2 matrices. If these neutrinos are of the Majorana type, then negative results of neutrinoless double beta decay experiments imply that the total mass of neutrinos is not sufficient to account for all the hot dark matter components.

scholarly journals THE STATUS OF NEUTRINO MASS

1998 ◽  
Vol 13 (25) ◽  
pp. 4409-4423 ◽  
Author(s):  
DAVID O. CALDWELL
Keyword(s):  
Dark Matter ◽  
Neutrino Mass ◽  
Heavy Element ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Atmospheric Neutrinos ◽  
Big Bang Nucleosynthesis ◽  
Robust Solution ◽  
The Status ◽  
Mass Pattern

New experimental results, if correct, require at least one light sterile neutrino, in addition to the three active ones, to accommodate the mass differences required to explain the solar νe deficit, the anomalous μ/e ratio produced by atmospheric neutrinos, and either the candidate events for νμ→ νe (or [Formula: see text]) from the LSND experiment, or the possible need for a hot component of dark matter. This neutrino mass pattern can not only accommodate all these four requirements, but also provide a robust solution to a problem presently making heavy-element synthesis by supernovae impossible and resolve a possible discrepancy between big bang nucleosynthesis theory and observations.

Sterile neutrinos and Big Bang Nucleosynthesis in the 3 + 1 scheme

2014 ◽  
Vol 23 (03) ◽  
pp. 1450014 ◽  
Author(s):  
Mercedes Elisa Mosquera ◽  
Osvaldo Civitarese
Keyword(s):  
Distribution Function ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Light Nuclei ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Normalization Constant ◽  
Big Bang Nucleosynthesis ◽  
Sterile Neutrinos ◽  
Mixing Angle ◽  
Free Parameters

We study the effects of adding a sterile neutrino to three active neutrinos (3 + 1 scheme) in the calculation of primordial abundances. Taking the normalization constant (a) of the occupation factor of the sterile neutrino and the active-sterile mixing angle (ϕ) as free parameters, we calculate the neutrino distribution function and primordial abundances of light nuclei. We set constrains on these parameters by using the available data on the abundances of D, 4 He and 7 Li . Results are consistent with small values of a and ϕ. The extracted value of the baryon-to-photon ratio (ηB), which is constrained by the Wilkinson Microwave Anisotropy Probe (WMAP) value [Formula: see text], and Planck observations, depends strongly on the inclusion of the lithium data in the fit.

BBN AND NEUTRINO OSCILLATIONS IN THE EARLY UNIVERSE: A BRIEF REVIEW

2005 ◽  
Vol 20 (11) ◽  
pp. 2431-2435
Author(s):  
F. L. VILLANTE
Keyword(s):  
Early Universe ◽  
Neutrino Oscillations ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Big Bang Nucleosynthesis

We briefly review the physics of Big Bang Nucleosynthesis (BBN). We present, moreover, some recent results on active-sterile neutrino oscillations in the early universe and on their effects on BBN.

scholarly journals Neutrino oscillations and the early universe

Open Physics ◽  
2004 ◽  
Vol 2 (3) ◽  
Author(s):  
Daniela Kirilova
Keyword(s):  
Early Universe ◽  
Neutrino Oscillation ◽  
Neutrino Oscillations ◽  
Atmospheric Neutrino ◽  
Short Review ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Cosmological Constraints ◽  
Theoretical Status

AbstractThe observational and theoretical status of neutrino oscillations in connection with solar and atmospheric neutrino anomalies is presented briefly. The effect of neutrino oscillations on the evolution of the early Universe is discussed in detail. A short review is given of the standard Big Bang Nucleosynthesis (BBN) and the influence of resonant and non-resonant neutrino oscillations on active neutrinos and on primordial synthesis of He-4. BBN cosmological constraints on neutrino oscillation parameters are discussed.

scholarly journals Neutrino energy transport in weak decoupling and big bang nucleosynthesis

2016 ◽  
Vol 93 (8) ◽  
Author(s):  
E. Grohs ◽  
G. M. Fuller ◽  
C. T. Kishimoto ◽  
M. W. Paris ◽  
A. Vlasenko
Keyword(s):  
Energy Transport ◽  
Big Bang ◽  
Neutrino Energy ◽  
Big Bang Nucleosynthesis

scholarly journals A model for mixed warm and hot right-handed neutrino dark matter

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Maíra Dutra ◽  
Vinícius Oliveira ◽  
C. A de S. Pires ◽  
Farinaldo S. Queiroz
Keyword(s):  
Dark Matter ◽  
Degrees Of Freedom ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Matter Density ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Sterile Neutrinos ◽  
Dark Matter Density ◽  
Model Features

Abstract We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same SU(3)L multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom.

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