scholarly journals Photon Creation in the Universe and Primordial Nucleosynthesis

2000 ◽  
Vol 198 ◽  
pp. 113-115
Author(s):  
J.A. S. Lima ◽  
J. S. Alcaniz ◽  
J. Santos ◽  
R. Silva
Keyword(s):  
Irreversible Process ◽  
Big Bang ◽  
Radiation Temperature ◽  
Thermodynamic Approach ◽  
Phenomenological Parameter ◽  
Primordial Nucleosynthesis ◽  
Stringent Constraint ◽  
The Universe ◽  
Creation Rate

In hot big bang cosmologies, the irreversible process of continous photon creation may phenomenologically be described through a thermodynamic approach. In these models, the radiation temperature law depends on a phenomenological parameter β which is closely related to the photon creation rate. It is shown that a stringent constraint on the value of this parameter is imposed from primordial nucleosynthesis.

scholarly journals A New Measurement of the Geometry of Space

1987 ◽  
Vol 124 ◽  
pp. 217-221
Author(s):  
Edwin D. Loh
Keyword(s):  
Big Bang ◽  
Recent Measurement ◽  
Density Parameter ◽  
Confidence Limits ◽  
Dimensionless Form ◽  
Primordial Nucleosynthesis ◽  
Geometrical Effects ◽  
Age Of The Universe ◽  
The Universe ◽  
Inflationary Models

This paper discusses the recent measurement of the number of galaxies vs. redshift and flux and presents new results pertaining to the two dimensionless geometrical quantities that describe the geometry of the conventional big-bang cosmology, the density parameter Ω and the dimensionless form λ = Λ/(3H02) of the cosmological constant. In contrast to the classical redshift-magnitude test as applied to the brightest galaxies in clusters, this new method is able to separate the effects of evolution from geometrical effects and is therefore able to measure the geometry of space. The 95% confidence limits are Ω - λ = 0.9−0 5+0 7 and −1.5 < Ω + λ < 7.1. The principal conclusions are these: (1) For both λ = 0 and inflationary models of the universe, this measurement and primordial nucleosynthesis imply a large density of nonbaryonic matter. (2) Hubble's constant H0 and the age of the universe τ are constrained by 0.60 < H0τ < 0.88 (95% confidence).

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 Primordial nucleosynthesis and finite temperature QED

2014 ◽  
Vol 23 (06) ◽  
pp. 1450059 ◽  
Author(s):  
Mahnaz Q. Haseeb ◽  
Obaidullah Jan ◽  
Omair Sarfaraz
Keyword(s):  
Finite Temperature ◽  
Big Bang ◽  
Light Nuclei ◽  
Neutron Decay ◽  
Electron Mass ◽  
Total Energy Density ◽  
Primordial Nucleosynthesis ◽  
Big Bang Model ◽  
Relative Change ◽  
The Universe

Abundances of light nuclei formed during primordial nucleosynthesis are predicted by Standard Big Bang Model (SBBM). Here, we evaluate the second-order quantum electro dynamics (QED) corrections to the change in these parameters during primordial nucleosynthesis due to modifications to mass and coupling using finite temperature effects. These are the contributions from the dynamically generated masses for electrons and photons in the finite temperature background. Relative variations in neutron decay rate, total energy density of the universe, relative change in neutrino temperature etc. with two-loops corrections to electron mass, at the timescale when QED corrections were relevant, have been estimated.

scholarly journals On the Possibility of a Higher Baryonic Contribution to Dark Matter

1988 ◽  
Vol 130 ◽  
pp. 592-592
Author(s):  
Rosa Dominguez-Tenreiro ◽  
Gustavo Yepes
Keyword(s):  
Dark Matter ◽  
Limited Range ◽  
Primordial Nucleosynthesis ◽  
Stringent Constraint ◽  
The Universe ◽  
Baryonic Dark Matter

The most stringent constraint against baryonic dark matter is provided by primordial nucleosynthesis. Agreement between theory and observations is reachedonly for a limited range of the baryon-to-photon ratio ‘LR, namely , which implies that, in standard cosmological frameworks, the universe cannot be closed by baryons.

scholarly journals PRIMORDIAL NUCLEOSYNTHESIS: SUCCESSES AND CHALLENGES

2006 ◽  
Vol 15 (01) ◽  
pp. 1-35 ◽  
Author(s):  
GARY STEIGMAN
Keyword(s):  
Particle Physics ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Big Bang ◽  
Primordial Nucleosynthesis ◽  
The Status ◽  
Independent Observations ◽  
Controlling Element ◽  
Standard Models ◽  
The Universe

Primordial nucleosynthesis provides a probe of the Universe during its early evolution. Given the progress exploring the constituents, structure, and recent evolution of the Universe, it is timely to review the status of Big Bang Nucleosynthesis (BBN) and to confront its predictions, and the constraints which emerge from them, with those derived from independent observations of the Universe at much later epochs in its evolution. Following an overview of the key physics controlling element synthesis in the early Universe, the predictions of the standard models of cosmology and particle physics (SBBN) are presented, along with those from some non-standard models. The observational data used to infer the primordial abundances are described, with an emphasis on the distinction between precision and accuracy. These relic abundances are compared with predictions, testing the internal consistency of BBN and enabling a comparison of the BBN constraints with those derived from the WMAP Cosmic Background Radiation data. Emerging from these comparisons is a successful standard model along with constraints on (or hints of) physics beyond the standard models of particle physics and of cosmology.

scholarly journals New theoretical results for radiative 3H(p,γ)4He, 3He(2H,γ)5Li, 4He(2H,γ)6Li, 4He(3H,γ)7Li and 4He(3He,γ)7Be captures at astrophysical energies

2019 ◽  
Vol 28 (03) ◽  
pp. 1930004 ◽  
Author(s):  
Sergey Dubovichenko ◽  
Albert Dzhazairov-Kakhramanov ◽  
Nataliya Burkova
Keyword(s):  
Radiative Capture ◽  
Nuclear Astrophysics ◽  
Big Bang ◽  
Proton Proton ◽  
Capture Reaction ◽  
Primordial Nucleosynthesis ◽  
Proton Fusion ◽  
The Big Bang ◽  
The Universe ◽  
Theoretical Results

We have studied the proton capture reaction [Formula: see text]. It plays a role in the nucleosynthesis of primordial elements in the early Universe leading to the prestellar formation of [Formula: see text] nuclei. All results of our researches and more new data from works show that the contribution of the [Formula: see text] capture reaction into the processes of primordial nucleosynthesis is relatively small. However, it makes sense to consider this process for making the picture complete for the formation of prestellar [Formula: see text] and clearing of mechanisms of this reaction. Furthermore, we have considered the [Formula: see text] reaction in the low energy. This reaction also forms part of the nucleosynthesis chain of the processes occurring in the early stages of formation of stable stars. They are possible candidates for overcoming the well-known problem of the [Formula: see text] gap in the synthesis of light elements in the primordial Universe. Continuing the study, we have considered the radiative capture [Formula: see text] at superlow energies, which has a undeniable interest for nuclear astrophysics, since it takes part in the proton–proton fusion chain, and new experimental data on the astrophysical [Formula: see text]-factors of this process at energies down to 90 and 23[Formula: see text]keV and data on the radiative capture reaction [Formula: see text] down to 50[Formula: see text]keV appeared recently. Moreover, radiative capture reactions [Formula: see text] and [Formula: see text] may have played a certain role in prestellar nucleosynthesis after the Big Bang, when the temperature of the Universe decreased to the value of [Formula: see text].

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.

scholarly journals Quantum Space and Thermodynamic Approach to Understanding Cosmic Evolution

2020 ◽  
Author(s):  
Carlos Melendres
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Big Bang ◽  
Cooling Curve ◽  
Thermodynamic Approach ◽  
Quantum Space ◽  
Wave Particle Duality ◽  
Expansion Of The Universe ◽  
The Big Bang ◽  
The Universe

We present a thermodynamic approach in modeling the evolution of the universe based on a theory that space consists of energy quanta, the spaceons. From wave-particle duality, they can be treated as an ideal gas. The model is similar to the Big Bang but without Inflation. It provides an insight into the nature of dark energy and dark matter, and an explanation for the accelerated expansion of the universe. The universe started from an atomic size volume of spaceons at very high temperature and pressure. Upon expansion and cooling, phase transitions occurred resulting in the formation of fundamental particles, and matter. These nucleate and grow into stars, galaxies, and clusters due to the action of gravity. From the cooling curve of the universe we constructed a thermodynamic phase diagram of cosmic composition, from which we obtained the correlation between dark energy and the energy of space. Using Friedmann&rsquo;s equations, our model fits well the WMAP data on cosmic composition with an equation of state parameter, w= -0.7. The dominance of dark energy started at 7.25 x 109 years, in good agreement with BOSS measurements. The expansion of space is attributed to a scalar quantum space field. Dark Matter is identified as a plasma form of matter similar to that which existed during the photon epoch, prior to recombination. The thermodynamics of expansion of the universe was adiabatic and decelerating during the first 7 billion years after the Big Bang; it accelerated thereafter. A negative pressure for Dark Energy is required to sustain the latter. This is consistent with the theory of General Relativity and the law of conservation of energy. We propose a mechanism for the acceleration as due to consolidation of matter forming Dark Energy Stars (DES) and other compact objects. The resulting reduction in gravitational potential energy feeds back energy for the expansion. Space will continue to expand and dark energy will undergo phase transition to a Bose-Einstein condensate, a superfluid form of matter. Self-gravitation can cause a bounce and start a new Big Bang. We show how the interplay of gravitational and space forces leads to a cyclic, maybe eternal, universe.

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.

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.

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