Big Bang Nucleosynthesis With a Non-Maxwellian Distribution

Bertulani, C. A.; Fuqua, John; Hussein, M. S.

doi:10.1088/0004-637x/767/1/67

Cited by 34 publications

(73 citation statements)

References 83 publications

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“…In this framework, an extra parameter q characterizes the deviation from a Maxwell-Boltzmann (MB) distribution. When q = 1, the distribution function is the classical Maxwell-Boltzmann distribution (Bertulani et al 2013). Several physical sources of the parameter q have been discussed (Lutz 2003;Bernui et al 2007;Rossani & Scarfone 2009;Livadiotis & McComas 2010;Pavlos 2012).…”

Section: Introductionmentioning

confidence: 99%

Big Bang Nucleosynthesis with an Inhomogeneous Primordial Magnetic Field Strength

Luo

Kajino

Kusakabe

et al. 2019

ApJ

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We investigate the effect on the Big Bang Nucleosynthesis (BBN) from the presence of a stochastic primordial magnetic field (PMF) whose strength is spatially inhomogeneous. We assume a uniform total energy density and a gaussian distribution of field strength. In this case, domains of different temperatures exist in the BBN epoch due to variations in the local PMF. We show that in such case, the effective distribution function of particle velocities averaged over domains of different temperatures deviates from the Maxwell-Boltzmann distribution. This deviation is related to the scale invariant strength of the PMF energy density ρ Bc and the fluctuation parameter σ B . We perform BBN network calculations taking into account the PMF strength distribution, and deduce the element abundances as functions of the baryon-to-photon ratio η, ρ Bc , and σ B . We find that the fluctuations of the PMF reduces the 7 Be production and enhances D production. We analyze the averaged thermonuclear reaction rates compared with those of a single temperature, and find that the averaged charged-particle reaction rates are very different. Finally, we constrain the parameters ρ Bc and σ B from observed abundances of 4 He and D, and find that the 7 Li abundance is significantly reduced. We also find that if the η value during BBN was larger than the present-day value due to a dissipation of the PMF or a radiative decay of exotic particles after BBN or if the stellar depletion of 7 Li occurred, abundances of all light elements can be consistent with observational constraints. * ydong.luo@nao.ac.jp arXiv:1810.08803v2 [astro-ph.CO]

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Section: Introductionmentioning

confidence: 99%

Big Bang Nucleosynthesis with an Inhomogeneous Primordial Magnetic Field Strength

Luo

Kajino

Kusakabe

et al. 2019

ApJ

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“…This distribution function is manifestly different from that employed in previous studies [12,13], which adopted exactly the same Tsallis function as the single particle velocity distribution with the mass replaced by the reduced mass. Thus, E 1 E 2 is replaced by (µv 2 /2)(M V 2 /2) in Eq.…”

Section: B Tsallis Distributionmentioning

confidence: 78%

“…These are based upon the same formulation as in Ref. [12]. Therefore, for the case of a pure Tsallis distribution the results in [13] are also inconsistent with momentum conservation.…”

Section: B Tsallis Distributionmentioning

confidence: 95%

“…Bertulani et al [12] analyzed effects of the Tsallis distribution function for nuclear velocities on BBN. They assumed the Tsallis distribution for the whole energy range and found that the thermonuclear reaction rates strongly depend on the Tsallis parameter q.…”

Section: Introductionmentioning

confidence: 99%

“…In such models, a direct application of the Tsallis distribution to the relative velocity distribution as in Ref. [12] is justified.…”

Section: Introductionmentioning

confidence: 99%

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On the relative velocity distribution for general statistics and an application to big-bang nucleosynthesis under Tsallis statistics

et al. 2019

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The distribution function of the relative velocity in a two-body reaction of nonrelativistic uncorrelated particles is derived for general cases of given distribution functions of single particle velocities. The distribution function is then used in calculations of thermonuclear reaction rates. As an example, we take the Tsallis non-Maxwellian distribution, and show that the distribution function of the relative velocity is different from the Tsallis distribution. We identify an inconsistency in previous studies of nuclear reaction rates within Tsallis statistics, and derive revised nuclear reaction rates. Utilizing the revised rates, accurate results of big bang nucleosynthesis are obtained for the Tsallis statistics. For this application it is more difficult to reduce the primordial 7 Li abundance while keeping other nuclear abundances within the observational constraints. A small deviation from a Maxwell-Boltzmann distribution can increase the D abundance and slightly reduce 7 Li abundance. Although it is impossible to realize a 7 Li abundance at the level observed in metal-poor stars, a significant decrease is possible while maintaining a consistency with the observed D abundance.

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Current Status of Nuclear Physics Research

Bertulani

Hussein

2015

Braz J Phys

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In this review we discuss the current status of research in nuclear physics which is being carried out in different centers in the World. For this purpose we supply a short account of the development in the area which evolved over the last 9 decades, since the discovery of the neutron. The evolution of the physics of the atomic nucleus went through many stages as more data become available. We briefly discuss models introduced to discern the physics behind the experimental discoveries, such as the shell model, the collective model, the statistical model, the interacting boson model, etc., some of these models may be seemingly in conflict with each other, but this was shown to be only apparent.The richness of the ideas and abundance of theoretical models attests to the important fact that the nucleus is a really singular system in the sense that it evolves from two-body bound states such as the deuteron, to few-body bound states, such as 4 He, 7 Li, 9 Be etc. and up the ladder to heavier bound nuclei containing up to more than 200 nucleons. Clearly statistical mechanics, usually employed in systems with very large number of particles, would seemingly not work for such finite systems as the nuclei, neither do other theories which are applicable to condensed matter. The richness of nuclear physics stems from these restrictions. New theories and models are presently being developed. Theories of the structure and reactions of neutron-rich and proton-rich nuclei, called exotic nuclei, halo nuclei, or Borromean nuclei, deal with the wealth of experimental data that became available in the last 35 years. Further, nuclear astrophysics and stellar and Big Bang nucleosynthesis have become a more mature subject. Due to limited space, this review only covers a few selected topics, mainly those with which the authors have worked on. Our aimed potential readers of this review are nuclear physicists and physicists in other areas, as well as graduate students interested in pursuing a career in nuclear physics.

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Big Bang Nucleosynthesis With a Non-Maxwellian Distribution

Cited by 34 publications

References 83 publications

Big Bang Nucleosynthesis with an Inhomogeneous Primordial Magnetic Field Strength

Big Bang Nucleosynthesis with an Inhomogeneous Primordial Magnetic Field Strength

On the relative velocity distribution for general statistics and an application to big-bang nucleosynthesis under Tsallis statistics

Current Status of Nuclear Physics Research

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