Inhomogeneous big bang nucleosynthesis and the high baryon density suggested by Boomerang and MAXIMA

2001 ◽  
Vol 63 (8) ◽  
Author(s):  
Hannu Kurki-Suonio ◽  
Elina Sihvola
Keyword(s):  
Big Bang ◽  
Baryon Density ◽  
Big Bang Nucleosynthesis

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 A BGO set-up for the direct measurement of the D(p,γ)3He fusion cross section at LUNA

2020 ◽  
Vol 1668 (1) ◽  
pp. 012028
Author(s):  
Viviana Mossa
Keyword(s):  
Cross Section ◽  
Cosmic Time ◽  
Fusion Cross Section ◽  
Big Bang ◽  
Baryon Density ◽  
Reaction Cross ◽  
Big Bang Nucleosynthesis ◽  
Primordial Abundance ◽  
Set Up ◽  
The Big Bang

Abstract The Big Bang Nucleosynthesis (BBN) describes the production of light nuclides occurred during the first minutes of cosmic time. It started with the accumulation of deuterium, whose primordial abundance is sensitive to the universal baryon density and to the amount of relativistic particles. Currently the main source of uncertainty to an accurate theoretical deuterium abundance evaluation is due to the poor knowledge of the D(p, γ)3He cross section at BBN energies. The present work wants to describe one of the two experimental approaches proposed by the LUNA collaboration, whose goal is to measure with unprecedented precision, the reaction cross section in the energy range 30 < Ecm[keV] < 300.

scholarly journals Bayesian Estimation of the D(p,γ)3He Thermonuclear Reaction Rate

2021 ◽  
Vol 923 (1) ◽  
pp. 49
Author(s):  
Joseph Moscoso ◽  
Rafael S. de Souza ◽  
Alain Coc ◽  
Christian Iliadis
Keyword(s):  
Reaction Rates ◽  
Big Bang ◽  
Baryon Density ◽  
Thermonuclear Reaction ◽  
Big Bang Nucleosynthesis ◽  
Highly Sensitive ◽  
Theoretical Predictions ◽  
Reliable Knowledge ◽  
Percent Accuracy ◽  
The Big Bang

Abstract Big bang nucleosynthesis (BBN) is the standard model theory for the production of light nuclides during the early stages of the universe, taking place about 20 minutes after the big bang. Deuterium production, in particular, is highly sensitive to the primordial baryon density and the number of neutrino species, and its abundance serves as a sensitive test for the conditions in the early universe. The comparison of observed deuterium abundances with predicted ones requires reliable knowledge of the relevant thermonuclear reaction rates and their corresponding uncertainties. Recent observations reported the primordial deuterium abundance with percent accuracy, but some theoretical predictions based on BBN are in tension with the measured values because of uncertainties in the cross section of the deuterium-burning reactions. In this work, we analyze the S-factor of the D(p,γ)3He reaction using a hierarchical Bayesian model. We take into account the results of 11 experiments, spanning the period of 1955–2021, more than any other study. We also present results for two different fitting functions, a two-parameter function based on microscopic nuclear theory and a four-parameter polynomial. Our recommended reaction rates have a 2.2% uncertainty at 0.8 GK, which is the temperature most important for deuterium BBN. Differences between our rates and previous results are discussed.

scholarly journals Big Bang Nucleosynthesis

2002 ◽  
Vol 187 ◽  
pp. 1-15
Author(s):  
D.N. Schramm
Keyword(s):  
Systematic Error ◽  
Big Bang ◽  
Baryon Density ◽  
Galactic Evolution ◽  
Big Bang Nucleosynthesis ◽  
X Ray ◽  
Baryonic Density ◽  
The Big Bang ◽  
The Universe

Big Bang Nucleosynthesis (BBN) is on the verge of undergoing a transformation now that extragalactic deuterium is being measured. Previously, the emphasis was on demonstrating the concordance of the Big Bang Nucleosynthesis model with the abundances of the light isotopes extrapolated back to their primordial values using stellar and Galactic evolution theories. Once the primordial deuterium abundance is converged upon, the nature of the field will shift to using the much more precise primordial D/H to constrain the more flexible stellar and Galactic evolution models (although the question of potential systematic error in 4He abundance determinations remains open). The remarkable success of the theory to date in establishing the concordance has led to the very robust conclusion of BBN regarding the baryon density. The BBN constraints on the cosmological baryon density are reviewed and demonstrate that the bulk of the baryons are dark and also that the bulk of the matter in the universe is non-baryonic. Comparison of baryonic density arguments from Lyman-α clouds, x-ray gas in clusters, the Sunyaev-Zeldovich effect, and the microwave anisotropy are made and shown to be consistent with the BBN value.

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 Constraints on Dark Matter from Primordial Nucleosynthesis

1987 ◽  
Vol 117 ◽  
pp. 499-523
Author(s):  
Jean Audouze
Keyword(s):  
Dark Matter ◽  
Chemical Evolution ◽  
Big Bang ◽  
Baryon Density ◽  
Cosmological Parameter ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
The Galaxy ◽  
Predicted Values ◽  
The Universe

Primordial nucleosynthesis which is responsible for the formation of the lightest elements (D, 3He, 4He and 7Li) provides a unique way to determine the present baryon density pB in the Universe and therefore the corresponding cosmological parameter ΩB. After a brief summary of the relevant abundance determinations and of the consequences of the Standard Big Bang nucleosynthesis, it is argued that one needs to call for specific models of chemical evolution of the Galaxy in order to reconcile the observations with the predictions of this model. In this context the predicted values for ΩB should range from 4 10−3 to 6 10−2. These values are significantly lower than those deduced from current M/L determinations.

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