Primordial Nucleosynthesis And Evolution Of Early Universe

Author: Katsuhiko Sato
Publisher: Springer Science & Business Media
ISBN: 9401134103
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Primordial Nucleosynthesis And Evolution Of Early Universe from the Author: Katsuhiko Sato. The International Conference "Primordial Nucleosynthesis and Evolution of Early Universe" was held in the presence of Prof. William Fowler on 4 - 8 September 1990 at the Sanjo Conference Hall, the University of Tokyo. This conference was co-sponsored by IUPAP, the International Union of Pure and Applied Physics, and by the University of Tokyo. The number of participants was 156, 58 from 15 foreign countries and 98 from Japan. About 120 contributions were submitted orally or as posters. Originally this conference was planned as a small gathering on Primordial Nucleosynthesis as indicated in the title, since primordial nucleosynthesis is the most important probe of the early stage of the universe. As is well known, light element abundances strongly depend on the time evolution of temperature and density. In this sense we can say that primordial nucleosynthesis is both the thermometer and speedometer of the early universe. Moreover, recently it has been claimed that primordial nucleosynthesis is an indicator of inhomogeneity of the early universe too. Now research of the primordial nucleosynthesis is in a boom. We, however, decided to include observational cosmology, of observations. taking into account the recent remarkable results Nowadays, to reveal the large scale structure of the universe and discover its origin is a main subject in cosmology. We invited distinguished scientists from all over the world, and very fortunately almost all these people accepted to attend this conference.

Primordial Nucleosynthesis During The Kev Era

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Primordial Nucleosynthesis During The Kev Era from the Author: . Energetic hadronic and electromagnetic showers in the keV era of the hot big bang are produced by the decays of long lived particles. These showers initiate a new phase of nucleosynthesis. The abundance ratios of D, 3He, 6Li and 7Li are given by fixed points of rate equations, which are determined by nuclear physics not by the nature of the decaying particle. The fixed points are independent of prior abundances, so that constraints from the MeV era of nucleosynthesis evaporate, except for a requirement that 4He not be underproduced. For example, .cap omega./sub B/ = 1 and many more than four neutrino species are both possible. Within the accuracy of our calculation (there are uncertainties of at least a factor of three), the abundances agree with those inferred from observations. Considerable 6Li is produced and must be depleted in both population II halo stars and in the galactic disk. We predict 6Li, 3He and D abundances in primordial material which are higher than conventional nucleosynthesis. 8 refs.

Inhomogeneous Primordial Nucleosynthesis And New Abundance Constraints On Omega Sub B H2

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Inhomogeneous Primordial Nucleosynthesis And New Abundance Constraints On Omega Sub B H2 from the Author: . We discuss the upper limit to the baryonic contribution to the closure density. We consider effects of new observational and theoretical uncertainties in the primordial light element abundances, and the effects of fluctuation geometry on the inhomogeneous nucleosynthesis yields. We also consider implications of the possible detection of a high D/H abundance in a Lyman-[alpha] absorption cloud at high redshift and the implied chemical evolution effects of a high deuterium abundance. We show that there exists a region of the parameter space for inhomogeneous models in which a somewhat higher baryonic contribution to the closure density is possible than that allowed in standard homogeneous models. This result is contrary to some other recent studies and is due to both geometry and recently revised uncertainties in primordial light-element abundances, particularly 7Li. We find that the presently adopted abundance constraints are consistent with a contribution of baryons to the closure density as high as [Omega]{sub b}h502 ≤ 0.11 ([eta] ≤ 7 × 10−1°). This corresponds to a 20% increase over the limit from standard homogeneous models ([Omega]{sub b}h502 ≤ 0.08, [eta] ≤ 5.8 × 10−1°). With a high deuterium abundance the upper limits for the inhomogeneous and homogeneous models would be [Omega]{sub b}h502 ≤ 0.04 and 0.03 ([eta] ≤ 2.6 × 10−1° and 1.9 × 10−1°), respectively. Even higher limits could be obtained by further relaxing the presently accepted primordial lithium abundance constraint as some have proposed.

Effect Of Interacting Particles On Primordial Nucleosynthesis

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Effect Of Interacting Particles On Primordial Nucleosynthesis from the Author: . We modify the standard model for big-bang nucleosynthesis to allow for the presence of a generic particle species, i.e., one which maintains good thermal contact with either the photons or the light neutrino species throughout the epoch of primordial nucleosynthesis. The production of D, 3He, 4He, and 7Li is calculated as a function of the mass, degrees of freedom, and spin statistics of the generic particle. We show that in general, the effect of an additional generic species cannot simply be parameterized as the equivalent number of additional light neutrino species. The presence of generic particles also affects the predicted value for the neutrino-to-photon temperature ratio.

Primordial Nucleosynthesis In Inhomogeneous Cosmologies

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Primordial Nucleosynthesis In Inhomogeneous Cosmologies from the Author: . We consider the constraints on .cap omega. from primordial nucleosynthesis in inhomogeneous cosmologies. We find that allowance for isothermal fluctuations significantly weakens the upper bound on the average value of .cap omega. derived from the standard big bang. Under the plausible additional assumption that regions of high baryon density are preferentially absorbed into cold dark matter, the constraints from primordial nucleosynthesis can be satisfied for large values of .cap omega., including .cap omega. = 1. 22 refs., 2 figs.

Density Fluctuations From The Quark Hadron Epoch And Primordial Nucleosynthesis

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Density Fluctuations From The Quark Hadron Epoch And Primordial Nucleosynthesis from the Author: . We present a simple thermodynamic model of the quark-hadron transition in the early universe and use this model to estimate how the size of isothermal baryon number fluctuations which emerge from this epoch depend on the temperature of the transition and other uncertain quantities of the underlying QCD physics. We calculate primordial nucleosynthesis in the presence of these fluctuations and find that .cap omega. = 1 in baryons is possible only if the measured abundances of 7Li and 2H reflect substantial destruction during the evolution of the galaxy. 29 refs., 7 figs.

Corrections To Primordial Nucleosynthesis

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Corrections To Primordial Nucleosynthesis from the Author: . The changes in primordial nucleosynthesis resulting from small corrections to rates for weak processes that connect neutrons and protons are discussed. The weak rates are corrected by improved treatment of Coulomb and radiative corrections, and by inclusion of plasma effects. The calculations lead to a systematic decrease in the predicted 4He abundance of about .delta. Y = 0.0025. The relative changes in other primoridal abundances are also 1 to 2%.