Primordial Nucleosynthesis

Abstract

Primordial or big bang nucleosynthesis (BBN) is now a parameter free theory whose predictions are in good overall agreement with observations. However, the 7 Li calculated abundance is significantly higher than the one deduced from spectroscopic observations. Most solutions to this lithium problem involve a source of extra neutrons that inevitably leads to an increase of the deuterium abundance. This seems now to be excluded by recent deuterium observations that have drastically reduced the uncertainty on D/H and also calls for improved precision on thermonuclear reaction rates.

New determination of proton spectroscopic factors and reduced widths forBe8states in the 16.5–18.0 MeV excitation energy region via the study of theLi7(Belhout1, Ouichaoui2, Beaumevieille3 et al. 2017Phys. Rev. C4000View full textAdd to dashboardCite

“…However, an experiment of the LUNA collaboration [22] constraining the 2 H(α, γ) 6 Li reaction cross section yieded a value of this ratio, 6 Li/ 7 Li = (1.5 ± 0.3) ×10 −5 , matching the BBN prediction [21], which has been also confirmed recently by theoretical calculations [23]. Then, as highlighted by Coc in [24], while a BBN 6 Li problem is no longer up-to-date, only the 7 Li problem still persists presently. But among other hardly searched for solutions (see [24] and references therein), the perspective of solving the latter puzzle via nuclear reaction rate evaluations seems not to hold any more actually [24].…”

“…Then, as highlighted by Coc in [24], while a BBN 6 Li problem is no longer up-to-date, only the 7 Li problem still persists presently. But among other hardly searched for solutions (see [24] and references therein), the perspective of solving the latter puzzle via nuclear reaction rate evaluations seems not to hold any more actually [24]. Note, besides, that following the recent observation of a 6.8σ…”

Particle and light motion in Lyra–Schwarzschild spacetime

“…The observations have done that not only through the three classical tests of general relativity (GR) [2][3][4][5][6], but also via the imaging of black hole shadows [7,8], the direct detection of gravitational waves [9] and the plethora of results coming from the cosmological model [10,11] stemming from GR. The standard cosmology predicts the primordial hot Big Bang state that is consistent with a cosmic microwave background radiation [12,13] measured with exquisite precision by several probes [14][15][16]; through the FRW cosmology, one is able to describe the large scale structure of the Universe [17,18] and to estimate the abundances of light nuclei produced in the first three minutes of primordial nucleosynthesis [19,20]. The very observational successes of GR's cosmology brings about some challenges: nucleosynthesis demands the existence of a dark matter component [21], which is also necessary to describing the peaks and troughs of the CMB power spectrum [22,23].…”