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 Impact of neutrino properties and dark matter on the primordial Lithium production

2019 ◽  
Vol 28 (08) ◽  
pp. 1950065 ◽  
Author(s):  
Tahani R. Makki ◽  
Mounib F. El Eid ◽  
Grant J. Mathews
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Nuclear Physics ◽  
Big Bang ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Chemical Potentials ◽  
The Creation ◽  
The Universe

The light elements and their isotopes were produced during standard big bang nucleosynthesis (SBBN) during the first minutes after the creation of the universe. Comparing the calculated abundances of these light species with observed abundances, it appears that all species match very well except for lithium (7Li) which is overproduced by the SBBN. This discrepancy is rather challenging for several reasons to be considered on astrophysical and on nuclear physics ground, or by invoking nonstandard assumptions which are the focus of this paper. In particular, we consider a variation of the chemical potentials of the neutrinos and their temperature. In addition, we investigated the effect of dark matter on 7Li production. We argue that including nonstandard assumptions can lead to a significant reduction of the 7Li abundance compared to that of SBBN. This aspect of lithium production in the early universe may help to resolve the outstanding cosmological lithium problem.

PRIMORDIAL NUCLEOSYNTHESIS CONSTRAINTS ON NEUTRINO DEGENERACY

1993 ◽  
Vol 02 (04) ◽  
pp. 381-400
Author(s):  
HO-SHIK KANG
Keyword(s):  
Critical Density ◽  
Big Bang ◽  
Baryon Density ◽  
Electron Neutrino ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
Extended Range ◽  
Free Parameters ◽  
Η Value

Based on the work by Kang and Steigman, I review the effects of neutrino degeneracy on big bang nucleosynthesis (BBN). Since the electron-neutrino degeneracy and the non-electron-neutrino degeneracy play a different role in the synthesis of the light elements ( D , 3 He , 4 He , 7 Li ), besides the baryon asymmetry (the nucleon-to-photon ratio; η ≡ nB/nγ) there are two additional free parameters in our scenario of degenerate BBN. An extended range of these parameters has been explored. It is shown that at a given η value, the agreement of the predicted primordial abundances of the light elements with those observationally inferred abundances restricts the permitted range of neutrino degeneracies, particularly the electron-neutrino degeneracy. Furthermore, we find that a large baryon density, even baryon-dominated, critical density (ΩB=1) Universe successfully provides the consistency between the predicted and observed abundances of all the light elements if neutrinos are degenerate enough. For an ΩB=1 Universe, for example, η10=80 is permitted if the electron-neutrino degeneracy and the expansion rate due to the non-electron-neutrino degeneracies fall in the ranges 1.2 ≲ ξνe ≲ 1.5, 17 ≲ S (ξνμ,τ) ≲ 33, respectively.

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 Insights Into Chemical Reactions at the Beginning of the Universe: From HeH+ to H3+

2021 ◽  
Vol 9 ◽  
Author(s):  
Soumya Ranjan Dash ◽  
Tamal Das ◽  
Kumar Vanka
Keyword(s):  
Big Bang ◽  
Light Elements ◽  
Hydrogen Atoms ◽  
Big Bang Nucleosynthesis ◽  
Special Cases ◽  
The Big Bang ◽  
The Universe ◽  
Dynamics Method ◽  
Positively Charged ◽  
Dense Atmosphere

At the dawn of the Universe, the ions of the light elements produced in the Big Bang nucleosynthesis recombined with each other. In our present study, we have tried to mimic the conditions in the early Universe to show how the recombination process would have led to the formation of the first ever formed diatomic species of the Universe: HeH+, as well as the subsequent processes that would have led to the formation of the simplest triatomic species: H3+. We have also studied some special cases: higher positive charge with fewer number of hydrogen atoms in a dense atmosphere, and the formation of unusual and interesting linear, dicationic He chains beginning from light elements He and H in a positively charged atmosphere. For all the simulations, the ab initio nanoreactor (AINR) dynamics method has been employed.

CP violating vacuum transition and Big Bang Nucleosynthesis

2005 ◽  
Vol 201 ◽  
pp. 451-452
Author(s):  
H. L. Duorah ◽  
R. K. Das
Keyword(s):  
Transition Temperature ◽  
Early Universe ◽  
Chemical Potential ◽  
Big Bang ◽  
Helium Abundance ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
The Universe ◽  
Limiting Value ◽  
Made In

An analysis of primordial nucleosynthesis is made in the perspective of transition in the early universe from quark gluon to a hadronic phase in a CP violating vacuum. The universe opaque to color, quarks and anti quarks binds into globally colorless hadrons. u, d and s quarks are considered in a sea of degenerate neutrinos for the case of μve = μvμ = μvτ. The nn/np ratio is calculated for a transition temperature ˜ 100 − 200MeV for various values of neutrino degeneracy ξve = μve/T, μve being the chemical potential of electron type neutrino. The limiting value of ξve is found to be 2.38, if the upper bound of fractional helium abundance Yp is 0.26.

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)).

Construction of neutrino models with non-vanishing θ13 and leptogenesis

2015 ◽  
Vol 93 (12) ◽  
pp. 1561-1565
Author(s):  
Ng. K. Francis
Keyword(s):  
Neutrino Mass ◽  
Big Bang ◽  
Baryon Asymmetry ◽  
Daya Bay ◽  
Mass Model ◽  
Big Bang Nucleosynthesis ◽  
Great Discovery ◽  
Neutrino Mass Models ◽  
The Universe ◽  
Inflationary Models

We construct the neutrino mass models with non-vanishing θ13 and estimate the baryon asymmetry of the universe and subsequently derive the constraints on the inflaton mass and the reheating temperature after inflation. The great discovery of this decade, the detection of Higgs boson of mass 126 GeV and nonzero θ13, makes leptogenesis all the more exciting. Besides, the neutrino mass model is compatible with inflaton mass 1010–1013 GeV corresponding to reheating temperature TR ∼ 105–107 GeV to overcome the gravitino constraint in supersymmetry and big bang nucleosynthesis. When Daya Bay data θ13 ≈ 9° is included in the model, τ predominates over e and μ contributions, which are indeed a good sign. It is shown that neutrino mass models for a successful leptogenesis can be accommodated for a variety of inflationary models with a rather wide ranging inflationary scale.

SPACE-TIME VARIATION OF COUPLING CONSTANTS AND FUNDAMENTAL MASSES

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3342-3353 ◽  
Author(s):  
V. V. FLAMBAUM ◽  
J. C. BERENGUT
Keyword(s):  
Structure Constant ◽  
Big Bang ◽  
Coupling Constants ◽  
Fine Structure Constant ◽  
Fundamental Constants ◽  
Big Bang Nucleosynthesis ◽  
Temporal And Spatial Variation ◽  
Physical Systems ◽  
Temporal And Spatial ◽  
The Universe

We review recent works discussing the effects of variation of fundamental "constants" on a variety of physical systems. These are motivated by theories unifying gravity with other interactions that suggest the possibility of temporal and spatial variation of the fundamental constants in an expanding Universe. The effects of any potential variation of the fine-structure constant and fundamental masses could be seen in phenomena covering the lifespan of the Universe, from Big Bang nucleosynthesis to quasar absorption spectra to modern atomic clocks. We review recent attempts to find such variations and discuss some of the most promising new systems where huge enhancements of the effects may occur.

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
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