Probing the early universe: a review of primordial nucleosynthesis beyond the standard big bang

Malaney, Robert; Mathews, Grant J.

doi:10.1016/0370-1573(93)90134-y

Cited by 208 publications

(224 citation statements)

References 420 publications

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“…By means of comparing the predicted and observationally inferred light element abundances the cosmic conditions as early as a few seconds after the Big Bang may be scrutinized. Nucleosynthesis has thus been used to constrain, for example, inhomogeneities in the baryon-to-photon ratio or abundances and properties of decaying particles during the BBN era (for reviews on non-standard BBN see [1]). …”

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Big Bang Nucleosynthesis with Matter-Antimatter Domains

1998

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We i n v estigate Big Bang nucleosynthesis (hereafter, BBN) in a cosmic environment c haracterised by a distribution of small-scale matter{antimatter domains. Production of antimatter domains in a baryo-asymmetric universe is predicted in some electroweak baryogenesis scenarios. We nd that cosmic antimatter domains of size exceeding the neutron-di usion length at temperature T 1 MeV signi cantly a ect the light-element production. Annihilation of antimatter preferentially occurs on neutrons such that antimatter domains may yield a reduction of the 4 He abundance relative to a standard BBN scenario. In the limiting case, all neutrons will be removed before the onset of light-element production, and a universe with net baryon number but without production of light elements results. In general, antimatter domains spoil agreement b e t w een BBN abundance yields and observationally inferred primordial abundances limits which allows us to derive limits on their presence in the early universe. However, if only small amounts of antimatter are present, BBN with low deuterium and low 4 He, as seemingly favored by current observational data, is possible. 26.35.+c,98.80Cq,25.43.+t Big Bang Nucleosynthesis is one of the furthest back{ reaching cosmological probes available. By means of comparing the predicted and observationally inferred light element abundances the cosmic conditions as early as a few seconds after the Big Bang may be scrutinized. Nucleosynthesis has thus been used to constrain, for example, inhomogeneities in the baryon-to-photon ratio or abundances and properties of decaying particles during the BBN era (for reviews on non-standard BBN see [1]).In this Letter we examine the BBN process in a universe where matter and antimatter are segregated. A segregation of matter and antimatter may a ect BBN abundance yields even if the average segregation scale is very small in terms of characteristic astrophysical scales. Such small scales imply annihilation of antimatter well before the present epoch. We are therefore particularly interested in the case where the universe contains net baryon number, as for example, through an excess of matter domains over antimatter domains. A baryo-asymmetric universe lled with a distribution of small-scale matter{ antimatter domains may arise during an epoch of baryogenesis at the electroweak scale. It has been shown within the minimal supersymmetric standard model, and under the assumption of explicit as well as spontaneous CP violation, that during a rst-order electroweak phase transition the baryogenesis process may result in individual bubbles containing either net baryon number, or net antibaryon number [2]. Recently, it has been argued that pre-existing stochastic (hyper)magnetic elds in the early universe, in conjunction with an era of electroweak baryogenesis, may cause the production of regions containing either matter or antimatter [3]. In general, any segregation of matter and antimatter either produced on scales larger than the neutron di usion length at weak freeze...

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“…1,85748 Garching,Germany (June 15, 1998) We i n v estigate Big Bang nucleosynthesis (hereafter, BBN) in a cosmic environment c haracterised by a distribution of small-scale matter{antimatter domains. Production of antimatter domains in a baryo-asymmetric universe is predicted in some electroweak baryogenesis scenarios.…”

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confidence: 99%

Big Bang Nucleosynthesis with Matter-Antimatter Domains

1998

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“…The main resonant peak at ∼0.60 MeV above the deuteron+ 7 Li threshold in the 9 Be spectrum (corresponding to deuterons of ∼0.78 MeV kinetic energy), needs to be accurately measured in order to calibrate the mean areal density of 7 Be atoms in the targets used in the proton-capture measurement [30]. Moreover, the mechanism of destruction of 7 Li through scattering of deuterons has been considered [31] as a possible explanation for what is known as cosmic lithium depletion problem [32], in particular in the context of non-standard (inhomogeneous) Big Bang Nucleosynthesis models [33].…”

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confidence: 99%

Deuteron-induced nucleon transfer reactions within anab initioframework: First application top-shell nuclei

et al. 2016

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Background: Low-energy transfer reactions in which a proton is stripped from a deuteron projectile and dropped into a target play a crucial role in the formation of nuclei in both primordial and stellar nucleosynthesis, as well as in the study of exotic nuclei using radioactive beam facilities and inverse kinematics. Ab initio approaches have been successfully applied to describe the 3 H(d, n) 4 He and 3 He(d, p) 4 He fusion processes.Purpose: An ab initio treatment of transfer reactions would also be desirable for heavier targets. In this work, we extend the ab initio description of (d, p) reactions to processes with light p-shell nuclei. As a first application, we study the elastic scattering of deuterium on 7 Li and the 7 Li(d,p) 8 Li transfer reaction based on a two-body Hamiltonian. Methods:We use the no-core shell model to compute the wave functions of the nuclei involved in the reaction, and describe the dynamics between targets and projectiles with the help of microscopic-cluster states in the spirit of the resonating group method.Results: The shape of the excitation functions for deuteron impinging on 7 Li are qualitatively reproduced up to the deuteron breakup energy. The interplay between d-7 Li and p-8 Li particle-decay channels determines some features of the 9 Be spectrum above the d+ 7 Li threshold. Our prediction for the parity of the 17.298 MeV resonance is at odds with the experimental assignment.Conclusions: Deuteron stripping reactions with p-shell targets can now be computed ab initio, but calculations are very demanding. A quantitative description of the 7 Li(d,p) 8 Li reaction will require further work to include the effect of three-nucleon forces and additional decay channels, and improve the convergence rate of our calculations.

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“…The BBN limits can be relaxed in nonstandard BBN (NSBBN) scenarios [12]. One well-known NSBBN scenario which is very effective in this respect is BBN with electron neutrino degeneracy (degenerate BBN, DBBN) [13,14].…”

Section: Introductionmentioning

confidence: 99%

Big bang nucleosynthesis, matter-antimatter regions, extra relativistic species, and relic gravitational waves

2002

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Provided that matter-antimatter domains are present at the onset of big bang nucleosynthesis (BBN), the number of allowed additional relativistic species increases, compared to the standard scenario when matter-antimatter domains are absent. The extra relativistic species may take the form of massless fermions or even massless bosons, like relic gravitons. The number of additional degrees of freedom compatible with BBN depends, in this framework, upon the typical scale of the domains and the antimatter fraction. Since the presence of matter-antimatter domains allows a reduction of the neutron to proton ratio prior to the formation of 4 He, large amounts of radiation-like energy density are allowed. Our results are compared with other constraints on the number of supplementary relativistic degrees of freedom and with different nonstandard BBN scenarios where the reduction of the neutron to proton ratio occurs via a different physical mechanism. The implications of our considerations for the upper limits on stochastic gravitational waves backgrounds of cosmological origin are outlined.

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Probing the early universe: a review of primordial nucleosynthesis beyond the standard big bang

Cited by 208 publications

References 420 publications

Big Bang Nucleosynthesis with Matter-Antimatter Domains

Big Bang Nucleosynthesis with Matter-Antimatter Domains

Deuteron-induced nucleon transfer reactions within anab initioframework: First application top-shell nuclei

Big bang nucleosynthesis, matter-antimatter regions, extra relativistic species, and relic gravitational waves

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