Primordial Nucleosynthesis

Coc, A.

doi:10.5506/aphyspolb.44.521

Cited by 17 publications

(2 citation statements)

References 47 publications

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“…Indeed, the few experimental information available for this cross section at BBN energies are in very good agreement with theory (see Fig. 1 in Coc (2013)).…”

Section: Nuclear Network and Reaction Rates Uncertaintiessupporting

confidence: 76%

Precision big bang nucleosynthesis with improved Helium-4 predictions

et al. 2018

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Primordial nucleosynthesis is one of the three historical evidences for the big bang model, together with the expansion of the universe and the cosmic microwave background. There is a good global agreement between the computed primordial abundances of helium-4, deuterium, helium-3 and their values deduced from observations. Now that the number of neutrino families and the baryonic densities have been fixed by laboratory measurements or CMB observations, the model has no free parameter and its predictions are rigid. Since this is the earliest cosmic process for which we a priori know all the physics involved, departure from its predictions could provide hints or constraints on new physics or astrophysics in the early universe. Precision on primordial abundances deduced from observations has recently been drastically improved and reach the percent level for both deuterium and helium-4. Accordingly, the BBN predictions should reach the same level of precision. For most isotopes, the dominant sources of uncertainty come from those on the laboratory thermonuclear reactions. This article focuses on helium-4 whose predicted primordial abundance depends essentially on weak interactions which control the neutron-proton ratio. The rates of the various weak interaction processes depend on the experimentally measured neutron lifetime, but also includes numerous corrections that we thoroughly investigate here. They are the radiative, zero-temperature, corrections, finite nucleon mass corrections, finite temperature radiative corrections, weak-magnetism, and QED plasma effects, which are for the first time all included and calculated in a self consistent way, allowing to take into account the correlations between them, and verifying that all satisfy detailed balance. Finally, we include the incomplete neutrino decoupling and claim to reach a 10 −4 accuracy on the helium-4 predicted mass fraction of 0.24709 ± 0.00017 (when including the uncertainty on the neutron lifetime). In addition, we provide a Mathematica primordial nucleosynthesis code that incorporates, not only these corrections but also a full network of reactions, using the best available thermonuclear reaction rates, allowing the predictions of primordial abundances of helium-4, deuterium, helium-3 and lithium-7 but also of heavier isotopes up to the CNO region. * Electronic address: pitrou@iap.fr † Electronic address: coc@csnsm.in2p3.fr ‡ Electronic address: uzan@iap.fr § Electronic address: vangioni@iap.fr G. Finite nucleon mass corrections 21 H. Weak magnetism 23 I. Effect of incomplete neutrino decoupling 23 J. Total correction to the weak rates 23 IV. Nucleosynthesis 23 A. Thermonuclear reaction rates 24 B. General form 24 C. Nuclear network and reaction rates uncertainties 25 V. Numerical results 28 A. Overview of PRIMAT 28 B. Temperature of nucleosynthesis 29 C. Effect of corrections on abundances 29 D. Dependence on main parameters 32 E. Distribution of abundance predictions 33 F. Comparison with observations 33 VI. Cosmology with BBN 36 A. Cosmological pert...

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“…Indeed, the few experimental information available for this cross section at BBN energies are in very good agreement with theory (see Fig. 1 in Coc (2013)).…”

Section: Nuclear Network and Reaction Rates Uncertaintiessupporting

confidence: 76%

Precision big bang nucleosynthesis with improved Helium-4 predictions

et al. 2018

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“…With more relativistic density, the Universe is younger and fewer neutrinos decay, thereby producing a larger Helium fraction [8]. This has long been used to argue for N eff ≈ 3, and the data continues to support that [9]. That said, our ability to measure the Helium fraction to better than a few percent is currently limited by astrophysical systematics, limiting precision to perhaps 0.5-1 effective species.…”

Section: Relic Populations In the Radiation-dominated Epochmentioning

confidence: 94%

Neutrinos and large-scale structure

Eisenstein

2015

AIP Conference Proceedings

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Abstract. I review the use of cosmological large-scale structure to measure properties of neutrinos and other relic populations of light relativistic particles. With experiments to measure the anisotropies of the cosmic microwave anisotropies and the clustering of matter at low redshift, we now have securely measured a relativistic background with density appropriate to the cosmic neutrino background. Our limits on the mass of the neutrino continue to shrink. Experiments coming in the next decade will greatly improve the available precision on searches for the energy density of novel relativistic backgrounds and the mass of neutrinos.

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