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Results of a detailed examination of the cascade nucleosynthesis resulting from the putative hadronic decay, evaporation, or annihilation of a primordial relic during the Big Bang nucleosynthesis (BBN) era are presented. It is found that…
Recent determinations of the deuterium abundance, $^2$H/H, in high redshift Lyman limit hydrogen clouds challenge the usual picture of primordial nucleosynthesis based on \lq\lq concordance\rq\rq\ of the calculated light element ($^2$H,…
Big Bang Nucleosynthesis (BBN) is an important stage of a homogeneous and isotropic expanding universe. The results of calculation of the synthesis of light elements during this epoch can then be compared with the abundances of the light…
We compute radiative corrections to nuclear reaction rates that determine the outcome of the Big-Bang Nucleosynthesis (BBN). Any nuclear reaction producing a photon with an energy above $2m_e$ must be supplemented by the corresponding…
The success of primordial nucleosynthesis as a cornerstone of the hot Big Bang model has been limited by the long-standing lithium problem. Recent work presented a self-consistent perturbative analysis of the effects of variations in…
The disagreement between theoretical predictions and observations for surface lithium abundance in stars is a long-standing problem, which indicates that the adopted physical treatment is still lacking in some points. However, thanks to the…
The cosmological Li problem is the observed discrepancy between Li abundance, A(Li), measured in Galactic dwarf, old and metal-poor stars (traditionally assumed to be equal to the initial value A(Li)_0), and that predicted by standard Big…
Angular distributions of 7Li(7Li,t), (7Li,alpha) and (7Li,6He) reactions were measured for laboratory energies from 2 - 16 MeV. Exact finite range DWBA analyses were performed with the aim to identify contributions of direct processes and…
We perform non-LTE calculations of lithium in late-type stars for a wide range of stellar parameters, including quantum mechanical cross-sections for collisions with neutral hydrogen and the negative hydrogen ion. Non-LTE abundance…
The synthesis of Li6 during the epoch of Big Bang nucleosynthesis (BBN) due to residual annihilation of dark matter particles is considered. By comparing the predicted Li6 to observations of this isotope in low-metallicity stars, generic…
We have investigated the possible existence of a $^7$H resonant state, considered as a five-body system consisting of a $^3$H core with four valence neutrons. To this aim, an effective n-$^3$H potential is constructed in order to reproduce…
Density functional calculations are performed for twelve $2l2l'$n$l"$ (n$\geq$2) triply excited hollow resonance series of Li, {\em viz.,} 2s$^2$ns $^2$S$^e$, 2s$^2$np $^2$P$^o$, 2s$^2$nd $^2$D$^e$, 2p$^2$ns $^2$D$^e$,$^4$P$^e$, 2s2pns…
According to standard stellar evolution, lithium abundance is believed to be a useful indicator of the stellar age. However, many evolved stars like red giants show huge fluctuations around expected theoretical abundances that are not yet…
Within the framework of the modified potential cluster model with forbidden states and their classification according to Young diagrams, the possibility of describing experimental data on the total cross sections of the neutron radiative…
We calculate the radiative capture cross section for $^7$Be($\alpha, \gamma$)$^{11}$C and its reaction rate of relevance for the big bang nucleosynthesis. The impact of this reaction on the primordial $^7$Li abundance is revised including…
The detection of $^6$Li in Spite plateau stars contradicts the standard Big Bang nucleosynthesis prediction, known as the second cosmological lithium problem. We measure the isotopic ratio $^6$Li/$^7$Li in three Spite plateau stars: HD…
Primordial nucleosynthesis, or big bang nucleosynthesis (BBN), is one of the three evidences for the big bang model, together with the expansion of the universe and the cosmic microwave background. There is a good global agreement over a…
Current three-dimensional (3D) hydrodynamical model atmospheres together with NLTE spectrum synthesis, permit to derive reliable atomic and isotopic chemical abundances from high-resolution stellar spectra. Not much is known about the…
A spectroscopic investigation of the lithium resonance doublet in $\xi$ Boo A and $\xi$ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new $R$=130\,000 spectra with a signal-to-noise ratio (S/N) per pixel of…
The 3He({\alpha},{\gamma})7Be reaction affects not only the production of 7Li in Big Bang nucleosynthesis, but also the fluxes of 7Be and 8B neutrinos from the Sun. This double role is exploited here to constrain the former by the latter. A…