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Cosmolgical Phase Transition and Inhomogeneous Primordial Nucleosynthesis
Cosmolgical Phase Transition and Inhomogeneous Primordial Nucleosynthesis
折戸, 学
オリト, マナブ
ORITO, Manabu
総合研究大学院大学
博士（理学）
We study the quark-hadron phase transition in the early Universe and the effect of baryon density inhomogeneities that emerge from this transition on primordial nucleosynthesis. We try to make clear the relation between the QCD parameters and the astronomical observable and to find the observational constraints on these parameters. We calculate the amplitude of baryon-number fluctuations and the mean separation distance between fluctuations using the finite temperature effective theory. We then analyze primordial nucleosynthesis in an environment with these inhomogeneous distribution of baryon density and compare the predicted elemental abundance with observation. Through the comparison of these calculation with the observation, we discuss the sensitivity of elemental abundance to the physical condition of baryon density inhomogeneities.
We first estimate the nucleation rate of hadron bubble during the supercooling epoch and study the evolution of baryon-number density at the constant-temperature coexistence epoch. We calculate the baryon permeability through the phase boundary using the chromoelectric flux tube model. In this calculation, we consider the temperature dependence of the constituent quark mass and that of the string tension suggested from lattice QCD simulation. We find that although the flux of baryons evaporating from QGP is strongly depend on the quark mass and string tension at critical temperature, this flux is still sufficiently small, suggesting that the baryon number is no easily transferred from QGP to hadron phase. For realistic value of quark mass and string tension, the resultant amplitude of baryon density fluctuation is very huge and have a significant effect on primordial nucleosynthesis yields.
We then study the inhomogeneous primordial nucleosynthesis in order to compare with observational constraints. We consider the effects of fluctuation geometry on primordial nucleosynthesis. For the first time we consider condensed cylinder and cylindrical-shell fluctuation geometries in addition to condensed spheres and spherical shells. We also consider implications of the possible detection of a high D/H abundance in a Lyman-alpha absorption cloud at high redshift and implied chemical evolution effects of a high deuterium abundance. We find that a cylindrical shell geometry allows for an appreciably higher baryonic contribution to be the closure density (Ωb < 0.2) than that allowed in spherical inhomogeneous or standard homogeneous big bang model. We also find that inhomogeneous primordial nucleosynthesis in the cylindrical shell geometry can lead to significant Be and B production. [Be] = 12+log(Be/ H) 〓 -3 is possible while still satisfying all of the usually adopted light-element abundance constraints.
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総研大甲第263号
thesis
1997-03-24
AM
application/pdf
application/pdf
https://ir.soken.ac.jp/record/365/files/甲263_要旨.pdf
https://ir.soken.ac.jp/record/365/files/甲263_本文.pdf
eng