scholarly journals Primordial nucleosynthesis

2017 ◽  
Vol 26 (08) ◽  
pp. 1741002 ◽  
Author(s):  
Alain Coc ◽  
Elisabeth Vangioni
Keyword(s):  
Cross Sections ◽  
Nuclear Physics ◽  
Big Bang ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
Expansion Of The Universe ◽  
Sensitivity Studies ◽  
Global Agreement ◽  
The Big Bang

Primordial nucleosynthesis, or big bang nucleosynthesis (BBN), is one of the three evidences for the big bang model, together with the expansion of the universe and the cosmic microwave background. There is a good global agreement over a range of nine orders of magnitude between abundances of 4He, D, 3He and 7Li deduced from observations, and calculated in primordial nucleosynthesis. However, there remains a yet-unexplained discrepancy of a factor [Formula: see text], between the calculated and observed lithium primordial abundances, that has not been reduced, neither by recent nuclear physics experiments, nor by new observations. The precision in deuterium observations in cosmological clouds has recently improved dramatically, so that nuclear cross-sections involved in deuterium BBN needs to be known with similar precision. We will briefly discuss nuclear aspects related to the BBN of Li and D, BBN with nonstandard neutron sources, and finally, improved sensitivity studies using a Monte Carlo method that can be used in other sites of nucleosynthesis.

scholarly journals A new tension in the cosmological model from primordial deuterium?

2021 ◽  
Vol 502 (2) ◽  
pp. 2474-2481
Author(s):  
Cyril Pitrou ◽  
Alain Coc ◽  
Jean-Philippe Uzan ◽  
Elisabeth Vangioni
Keyword(s):  
Big Bang ◽  
Reaction Cross ◽  
Light Elements ◽  
Neutron Lifetime ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Baryonic Density ◽  
The Status ◽  
Big Bang Model ◽  
The Big Bang

ABSTRACT Recent measurements of the D(p,γ)3He nuclear reaction cross-section and of the neutron lifetime, along with the reevaluation of the cosmological baryon abundance from cosmic microwave background (CMB) analysis, call for an update of abundance predictions for light elements produced during the big-bang nucleosynthesis (BBN). While considered as a pillar of the hot big-bang model in its early days, BBN constraining power mostly rests on deuterium abundance. We point out a new ≃1.8σ tension on the baryonic density, or equivalently on the D/H abundance, between the value inferred on one hand from the analysis of the primordial abundances of light elements and, on the other hand, from the combination of CMB and baryonic oscillation data. This draws the attention on this sector of the theory and gives us the opportunity to reevaluate the status of BBN in the context of precision cosmology. Finally, this paper presents an upgrade of the BBN code primat.

scholarly journals Cosmological Lithium Problems

2018 ◽  
Vol 184 ◽  
pp. 01002 ◽  
Author(s):  
C.A. Bertulani ◽  
Shubh chintak ◽  
A.M. Mukhamedzhanov
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Nuclear Physics ◽  
Theoretical Work ◽  
Big Bang ◽  
Electron Screening ◽  
Experimental Techniques ◽  
Big Bang Nucleosynthesis ◽  
Recent Theoretical Work ◽  
Parallel Universes

We briefly describe the cosmological lithium problems followed by a summary of our recent theoretical work on the magnitude of the effects of electron screening, thepossible existence of dark matter parallel universes and the use of non-extensive (Tsal-lis) statistics during big bang nucleosynthesis. Solutions within nuclear physics are also discussed and recent measurements of cross-sections based on indirect experimental techniques are summarized.

A Brief History of Cosmology

2017 ◽  
Author(s):  
John Iliopoulos
Keyword(s):  
Big Bang ◽  
Modern Theory ◽  
Microwave Background ◽  
Detailed Measurement ◽  
New Concepts ◽  
History Of Cosmology ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Big Bang ◽  
The Universe

We present the evolution of our ideas concerning the history of the Cosmos. They are based on Einstein’s theory of General Relativity in which E.P. Hubble and G. Lemaître brought two fundamental new concepts: the expansion of the Universe and the model of the Big Bang. They form the basic elements of the modern theory of Cosmology. We present very briefly the observational evidence which corroborates this picture based on a vast amount of data, among which the most recent ones come from the Planck mission with a detailed measurement of the cosmic microwave background (CMB) radiation. We show that during its evolution the Universe went through several phase transitions giving rise to the formation of particles, atoms, nuclei, etc. A particular phase transition, which occurred very early in the cosmic history, around 10–12 seconds after the Big Bang, is the Brout–Englert–Higgs (BEH) transition during which a fraction of the energy was transformed into mass, thus making it possible for most elementary particles to become massive.

Primordial Nucleosynthesis

1988 ◽  
Vol 20 (1) ◽  
pp. 658-660
Author(s):  
J. Audouze
Keyword(s):  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Big Bang ◽  
Cosmological Parameter ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
Baryonic Density ◽  
Cosmic Background ◽  
Expansion Of The Universe ◽  
The Universe

Primordial nucleosynthesis which is responsible for the formation of the lightest elements (D, 3He, 4HE and 7Li) might be as important as the overall expansion of the Universe and the cosmic background radiation to prove the occurrence of a dense and hot phase for the Unvierse about 15 billion years ago. As recalled in many reviews (e.g. refs. 1, 2) the standard Big Bang nucleosynthesis leads to two important conclusions regarding (i) a limitation of the baryonic density such that the corresponding cosmological parameter ΩB ≤ 0.1; (ii) a limitation of the number of neutrino flavours to 3-4 consistent with the results concerning the widths of the Z0 and W± particles3.

scholarly journals Introduction to big bang nucleosynthesis and modern cosmology

2017 ◽  
Vol 26 (08) ◽  
pp. 1741001 ◽  
Author(s):  
Grant J. Mathews ◽  
Motohiko Kusakabe ◽  
Toshitaka Kajino
Keyword(s):  
Nuclear Reactions ◽  
Big Bang ◽  
Cosmological Models ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
Current State ◽  
Modern Cosmology ◽  
Basic Equations ◽  
The Big Bang ◽  
The Universe

Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the testing ground upon which many cosmological models must ultimately rest. It is our only probe of the universe during the important radiation-dominated epoch in the first few minutes of cosmic expansion. This paper reviews the basic equations of space-time, cosmology, and big bang nucleosynthesis. We also summarize the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measurements are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we analyze the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field.

Helium in Three H II Galaxies and the Helium Abundance

1990 ◽  
Vol 8 (3) ◽  
pp. 243-245
Author(s):  
B. E. J. Pagel ◽  
E. A. Simonson
Keyword(s):  
Particle Physics ◽  
Hubble Constant ◽  
Big Bang ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Hadron Phase ◽  
The Mean ◽  
The Big Bang ◽  
The Universe

Extended abstractThe mass-fraction Y of helium in the interstellar medium is between 0.22 and 0.30 wherever it has been measured and it is believed to be the sum of two components: YP from Big Bang nucleosynthesis (BBNS) at about 100 s after the Big Bang (ABB) and a temperature near 0.1 MeV, and ΔY due to processing in stars. Precise measurements of Yp, along with balances of trace elements D, 3He, 7Li also resulting from BBNS, provide important tests of BBNS theory and of parameters of cosmology and particle physics, notably the contribution ΩBO of baryons to the mean density of matter in the universe (in units of the closure density), the number Nv of light neutrino flavours (or families of quarks and leptons) and the half-life т½ of the neutron (Shaver et al. 1983; Yang et al. 1984; Boesgaard and Steigman 1985). Figure 1 shows the predicted abundances from Standard BBNS theory (SBBN) as a function of η = μB/nλ the ratio of baryons to photons (unchanged since e± annihilation a few seconds ABB), which is proportional (through the known temperature of the microwave background) to ΩBOh20 where h0 is the Hubble constant in units of 100 km s−1 Mpc−1. SBBN theory (which assumes a homogeneous Friedmann universe and small lepton numbers), when combined with reasonable ideas on Galactic chemical evolution that predict a primordial (D + 3He)/H ratio below 10−4, imply that η ≥ 3 × 10−10 (shown by the tall vertical line in Fig. 1), which in turn implies YP≥0.210 if Nv = 3 and т½≥10.4 minutes. But this limit can be somewhat relaxed if т½ is smaller (current measurements permit values down to 9.0 minutes, e.g. Last et al. 1988) and/or if the quark-hadron phase transition around 200 MeV is first-order and leads to significant density fluctuations (Kurki-Sunonio et al. 1989; Reeves 1989).

scholarly journals Dynamo effects in gravity

2019 ◽  
Vol 127 ◽  
pp. 02009
Author(s):  
Boris Shevtsov
Keyword(s):  
Gravitational Constant ◽  
Nonlinear Oscillations ◽  
Big Bang ◽  
Baryon Asymmetry ◽  
System Of Equations ◽  
Fractal Structures ◽  
Expansion Of The Universe ◽  
The Big Bang ◽  
The Universe ◽  
Made In

Nonlinear oscillations in the dynamic system of gravitational and material fields are considered. The problems of singularities and caustics in gravity, expansion and baryon asymmetry of the Universe, wave prohibition of collapse into black holes, and failure of the Big Bang concept are discussed. It is assumed that the effects of the expansion of the Universe are coupling with the reverse collapse of dark matter. This hypothesis is used to substantiate the vortex and fractal structures in the distribution of matter. A system of equations is proposed for describing turbulent and fluctuation processes in gravitational and material fields. Estimates of the di usion parameters of such a system are made in comparison with the gravitational constant.

scholarly journals Li isotopes in metal-poor halo dwarfs: a more and more complicated story

2009 ◽  
Vol 5 (S268) ◽  
pp. 201-210
Author(s):  
Monique Spite ◽  
François Spite
Keyword(s):  
Cosmic Rays ◽  
Big Bang ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Lithium Abundance ◽  
The Galaxy ◽  
Li Isotope ◽  
Low Metallicity ◽  
The Big Bang ◽  
Early Galaxy

AbstractThe nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis.The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the ν process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient) warm galactic stars should retain the signature of these processes if, (as it had been often expected) lithium is not depleted in these stars. The existence of a “plateau” of the abundance of 7Li (and of its slope) in the warm metal-poor stars is discussed. At very low metallicity ([Fe/H] < −2.7dex) the star to star scatter increases significantly towards low Li abundances. The highest value of the lithium abundance in the early stellar matter of the Galaxy (logϵ(Li) = A(7Li) = 2.2 dex) is much lower than the the value (logϵ(Li) = 2.72) predicted by the standard Big Bang nucleosynthesis, according to the specifications found by the satellite WMAP. After gathering a homogeneous stellar sample, and analysing its behaviour, possible explanations of the disagreement between Big Bang and stellar abundances are discussed (including early astration and diffusion). On the other hand, possibilities of lower productions of 7Li in the standard and/or non-standard Big Bang nucleosyntheses are briefly evoked.A surprisingly high value (A(6Li)=0.8 dex) of the abundance of the 6Li isotope has been found in a few warm metal-poor stars. Such a high abundance of 6Li independent of the mean metallicity in the early Galaxy cannot be easily explained. But are we really observing 6Li?

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