Primordial nucleosynthesis with a varying fine structure constant: An improved estimate

Abstract

We compute primordial light-element abundances for cases with fine structure constant α different from the present value, including many sources of α dependence neglected in previous calculations. Specifically, we consider contributions arising from Coulomb barrier penetration, photon coupling to nuclear currents, and the electromagnetic components of nuclear masses. We find the primordial abundances to depend more weakly on α than previously estimated, by up to a factor of 2 in the case of 7 Li. We discuss the constraints on variations in α from the individual abundance measurements and the uncertainties affecting these constraints. While the present best measurements of primordial D/H, 4 He/H, and 7 Li/H may be reconciled pairwise by adjusting α and the universal baryon density, no value of α allows all three to be accommodated simultaneously without consideration of systematic error. The combination of measured abundances with observations of acoustic peaks in the cosmic microwave background favors no change in α within the uncertainties.PACS numbers: 26.35.+c,98.80Ft,98.80.Es

Effects of the variation of fundamental constants on Population III stellar evolution

“…Martins et al 2004;Stefanescu 2007;Nakashima et al 2008;Scóccola et al 2008) and from big bang nucleosynthesis (BBN) (z ∼ 10 10 ) (e.g. Kolb et al 1986;Campbell & Olive 1995;Bergström et al 1999;Nollett & Lopez 2002;Ichikawa & Kawasaki 2002;Flambaum & Shuryak 2002;Müller et al 2004;Ichikawa & Kawasaki 2004;Landau et al 2006;Coc et al 2007;Dent et al 2007). We refer to Uzan (2003Uzan ( , 2004Uzan ( , 2009b for recent reviews on this topic.…”

Big bang nucleosynthesis constraints on universal extra dimensions and varying fundamental constants

“…Then the heavier nuclei ( 4 He, 3 He, 3 H) abundances begin to follow the deuteron NSE value. Finally, the deuteron bottleneck is passed at T ∼ 0.1 MeV and a significant amount of deuterium is produced; the free neutrons are mostly rapidly assimilated into 4 He, in which process some 3 He and 3 H are synthesized as the reaction ashes. These produced nuclei interact and lead to the production of tiny abundances of 7 Li, 6 Li and 7 Be, the last of which is finally turned into 7 Li by the electron capture process.…”

“…At least down to the temperature ∼ 0.8 MeV the nuclear reactions are capable of keeping the nuclei D, 3 H, 3 He, 4 He in both kinetic and chemical equilibrium or the nuclear statistical equilibrium (NSE) with corresponding abundances [40] …”

“…Because the BBN predictions are sensitive to a set of physical quantities which depend on various fundamental constants such as the gauge couplings, the Yukawa couplings and gravitational constant (see Sections III and IV for details), it would provide stringent constraints on the cosmological variations of these constants. For example, in [2,3,4] the authors use BBN to constrain the change of fine structure constant, in [5,6,7] constraints on the change of Higgs vacuum expectation value are considered, and the effects of a varying strong coupling are discussed in e.g. [8,9]; the variation of gravitational constant has also been investigated [10,11,12,13,14] in the context of BBN.…”

“…The standard Big Bang Nucleosynthesis (BBN) theory is a successful marriage between standard Friedmann cosmology and nuclear physics, explaining the origin and abundances of the light elements D, 4 He, 3 He and 7 Li. Its only one input parameter, the baryon-to-photon ratio η = n b /n γ (where n b and n γ are respectively the number density of baryons and photons) has now been determined by the observations of the Wilkinson Microwave Anisotropy Probe (WMAP) with rather good accuracy [1], so that there are essentially no free parameters in this scenario.…”