scholarly journals Lepton asymmetry, neutrino spectral distortions, and big bang nucleosynthesis

2017 ◽  
Vol 95 (6) ◽  
Author(s):  
E. Grohs ◽  
George M. Fuller ◽  
C. T. Kishimoto ◽  
Mark W. Paris
Keyword(s):  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Lepton Asymmetry

scholarly journals Big Bang Nucleosynthesis and Lepton Number Asymmetry in the Universe

1999 ◽  
Vol 183 ◽  
pp. 312-312
Author(s):  
K. Kohri ◽  
M. Kawasaki ◽  
Katsuhiko Sato
Keyword(s):  
Chemical Potential ◽  
High Redshift ◽  
Big Bang ◽  
Electron Neutrino ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Lepton Asymmetry ◽  
Stringent Constraint ◽  
Likelihood Analysis ◽  
The Universe

Recently it has been reported that there may be a discrepancy between big bang nucleosynthesis theory and observations (BBN crisis) (Hata et al., 1995). One way to solve the discrepancy might be to adopt some modifications of standard physics used in SBBN (Kawasaki et al, 1997). We show that BBN predictions agree with the primordial abundances of light elements, 4He, D, 3He and 7Li inferred from the observational data if the electron neutrino has a net chemical potential ξve due to lepton asymmetry (Kohri et al., 1997). We study BBN with the effects of the neutrino degeneracy in details using Monte Carlo simulation and make a likelihood analysis using the most recent data. We estimate that (95% C.L.) and (95% C.L.) adopting the presolar Deuterium abundance as the primordial values. If we adopted the low D abundance which is obtained by the observation of the high redshift QSO absorption systems, (95% C.L.) and The estimated chemical potential of ve is about 10−5 eV which is much smaller than experiments can detect (≃ 1 eV). In other words, BBN gives the most stringent constraint on the chemical potential of ve.

scholarly journals Big bang nucleosynthesis constraints on sterile neutrino and lepton asymmetry of the Universe

2020 ◽  
Vol 2020 (09) ◽  
pp. 051-051 ◽  
Author(s):  
Graciela B. Gelmini ◽  
Masahiro Kawasaki ◽  
Alexander Kusenko ◽  
Kai Murai ◽  
Volodymyr Takhistov
Keyword(s):  
Sterile Neutrino ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Lepton Asymmetry ◽  
The Universe

scholarly journals Neutrinos and Big Bang Nucleosynthesis

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Gary Steigman
Keyword(s):  
Particle Physics ◽  
Weak Interactions ◽  
Big Bang ◽  
Baryon Density ◽  
Big Bang Nucleosynthesis ◽  
Lepton Asymmetry ◽  
Lithium Abundance ◽  
Dark Radiation ◽  
Cosmic Neutrino Background ◽  
Neutrino Background

According to the standard models of particle physics and cosmology, there should be a background of cosmic neutrinos in the present Universe, similar to the cosmic microwave photon background. The weakness of the weak interactions renders this neutrino background undetectable with current technology. The cosmic neutrino background can, however, be probed indirectly through its cosmological effects on big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) radiation. In this BBN review, focused on neutrinos and more generally on dark radiation, the BBN constraints on the number of “equivalent neutrinos” (dark radiation), on the baryon asymmetry (baryon density), and on a possible lepton asymmetry (neutrino degeneracy) are reviewed and updated. The BBN constraints on dark radiation and on the baryon density following from considerations of the primordial abundances of deuterium and helium-4 are in excellent agreement with the complementary results from the CMB, providing a suggestive, but currently inconclusive, hint of the presence of dark radiation, and they constrain any lepton asymmetry. For all the cases considered here there is a “lithium problem”: the BBN-predicted lithium abundance exceeds the observationally inferred primordial value by a factor of~3.

scholarly journals THE νμ↔νs INTERPRETATION OF THE ATMOSPHERIC NEUTRINO DATA AND COSMOLOGICAL CONSTRAINTS

2000 ◽  
Vol 15 (15) ◽  
pp. 2289-2328 ◽  
Author(s):  
PASQUALE DI BARI ◽  
PAOLO LIPARI ◽  
MAURIZIO LUSIGNOLI
Keyword(s):  
Atmospheric Neutrino ◽  
Big Bang ◽  
Large Contribution ◽  
Atmospheric Neutrinos ◽  
Big Bang Nucleosynthesis ◽  
Potential Conflict ◽  
Lepton Asymmetry ◽  
Cosmological Constraints ◽  
Physical Insight ◽  
Boltzmann Method

The data on atmospheric neutrinos can be explained assuming the existence of oscillations between νμ's and a light sterile neutrino with mixing close to maximal, and δm2~3×10-3 eV 2. This interpretation of the data is in potential conflict with the successes of big bang nucleosynthesis (BBN), since oscillations can result in a too large contribution of the sterile state to the energy density of the universe at the epoch of nucleosynthesis. The possibility to evade these cosmological constraints has been recently the object of some controversy. In this work we rediscuss this problem and find that the inclusion of a small mixing of the sterile state with ντ can result in the generation of a large lepton asymmetry that strongly suppress the νμ↔νs oscillations eliminating the possible conflict with BBN bounds. In this scheme the mass of the tau neutrino must be larger than few eV's and is compatible with cosmological bounds. Our calculations are performed using a Pauli–Boltzmann method. In this approach it is also possible to develop analytic calculations that allow physical insight in the processes considered and give support to the numerical results.

Refined big bang nucleosynthesis constraints onΩBandNν

1994 ◽  
Vol 72 (21) ◽  
pp. 3309-3312 ◽  
Author(s):  
Peter J. Kernan ◽  
Lawrence M. Krauss
Keyword(s):  
Big Bang ◽  
Big Bang Nucleosynthesis

scholarly journals Searching for space-time variation of the fine structure constant using QSO spectra: overview and future prospects

2009 ◽  
Vol 5 (H15) ◽  
pp. 304-304
Author(s):  
J. C. Berengut ◽  
V. A. Dzuba ◽  
V. V. Flambaum ◽  
J. A. King ◽  
M. G. Kozlov ◽  
...  
Keyword(s):  
Nuclear Reactor ◽  
Structure Constant ◽  
Big Bang ◽  
The Other ◽  
Fine Structure Constant ◽  
Spatial And Temporal Variation ◽  
Fundamental Constants ◽  
Future Prospects ◽  
Big Bang Nucleosynthesis ◽  
The Universe

Current theories that seek to unify gravity with the other fundamental interactions suggest that spatial and temporal variation of fundamental constants is a possibility, or even a necessity, in an expanding Universe. Several studies have tried to probe the values of constants at earlier stages in the evolution of the Universe, using tools such as big-bang nucleosynthesis, the Oklo natural nuclear reactor, quasar absorption spectra, and atomic clocks (see, e.g. Flambaum & Berengut (2009)).

Big Bang nucleosynthesis as a probe of varying fundamental “constants”

2007 ◽  
Author(s):  
Thomas Dent ◽  
Steffen Stern ◽  
Christof Wetterich ◽  
Arttu Rajantie ◽  
Carlo Contaldi ◽  
...  
Keyword(s):  
Big Bang ◽  
Fundamental Constants ◽  
Big Bang Nucleosynthesis

scholarly journals Big-bang nucleosynthesis in a Brans-Dicke cosmology with a varying $\mathsf{\Lambda}$ term related to WMAP

2006 ◽  
Vol 448 (1) ◽  
pp. 23-27 ◽  
Author(s):  
R. Nakamura ◽  
M. Hashimoto ◽  
S. Gamow ◽  
K. Arai
Keyword(s):  
Big Bang ◽  
Big Bang Nucleosynthesis
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