Related papers: Precision Rates for Nucleon Weak Interactions in P…
We report on the results of a recent evaluation of all percent level corrections to weak rates of processes converting n <-> p, which are crucial for the determination of the 4He mass fraction produced during primordial nucleosynthesis.
A new accurate evaluation of primordial light nuclei abundances is presented. The proton to neutron conversion rates have been corrected to take into account radiative effects, finite nucleon mass, thermal and plasma corrections. The…
We have calculated the small effect of finite nucleon mass on the weak-interaction rates that interconvert protons and neutrons in the early Universe. We have modified the standard code for primordial nucleosynthesis to include these…
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. Now that the number of neutrino families and the baryonic densities…
We have modified the standard code for primordial nucleosynthesis to include the effect of finite nucleon mass on the weak-interaction rates as calculated by Seckel \cite{seckel}. We find a small, systematic increase in the $^4$He yield,…
The thermal rates for converting neutrons to protons, and vice versa, are calculated, including corrections of order 1 MeV divided by a nucleon mass. The results imply that the primodial helium abundance predicted for big bang…
We calculate the weak interaction rates of selected light nuclei during the epoch of Big Bang Nucleosynthesis (BBN), and we assess the impact of these rates on nuclear abundance flow histories and on final light element abundance yields. We…
We have reexamined the electromagnetic corrections to the weak interaction rates for the transformation of neutrons to protons, and protons to neutrons, in the early universe, before freeze-out. We derive compact expressions for these rates…
We report the results of a new accurate evaluation of light nuclei yields in primordial nucleosynthesis. All radiative effects, finite nucleon mass, thermal and plasma corrections are included in the proton to neutron conversion rates. The…
Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of \he to a theoretical uncertainty of less than $0.1 \pct$ $(\delta Y_P < \pm 0.0002)$, improving the…
We analyze in details the standard Primordial Nucleosynthesis scenario. In particular we discuss the key theoretical issues which are involved in a detailed prediction of light nuclide abundances, as the weak reaction rates, neutrino…
Precision on primordial abundances, deduced from observations, have now reached the percent level for 4He and deuterium. Precision on big bang nucleosynthesis (BBN) predictions should, hence, reach the same level. The uncertainty on the 4He…
We have modified the standard code for primordial nucleosynthesis to include the effect of the slight heating of neutrinos by $e^\pm$ annihilations. There is a small, systematic change in the $^4$He yield, $\Delta Y \simeq +1.5\times…
We constrain the possible time variation of the Higgs vacuum expectation value ($v$) by recent results on the primordial $^4$He abundance ($Y_P$). For that, we improve the analytic models of the key-processes in our previous analytic…
The project aims to investigate most important weak interaction nuclei in the presupernova evolution of massive stars. To achieve the goal, an ensemble containing 728 nuclei in the mass range A = 1--100 was considered. We computed the mass…
In this thesis, which is in the field of few-body systems, I am studying low-energy electro-weak interactions in light nuclear systems whose number of nucleons, $A$, is smaller than 4 ({\it i.e.,} $d$, $^3$H, $^3$He), where the main purpose…
The weak interaction charged current processes ($\nu_e+n\leftrightarrow p+e^-$, $\bar\nu_e +p\leftrightarrow n+e^+$, $n\leftrightarrow p+e^-+\bar\nu_e$) interconvert neutrons and protons in the early universe and have significant influence…
Nuclear weak interaction rates for fp-shell nuclei in stellar matter and the associated energy losses are calculated using a modified form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. The stellar weak rates…
We study the effect of neutrino degeneracy on primordial nucleosynthesis in a universe in which the cosmological scale factor evolves linearly with time. The degeneracy parameter of electron type neutrinos ($\xi_e$) determines the $n/p$…
We have applied a fully relativistic Coulomb wave correction to the weak reactions in the full Kawano/Wagoner Big Bang Nucleosynthesis (BBN) code. We have also added the zero temperature radiative correction. We find that using this higher…