Related papers: The Crisis Confronting Standard Big Bang Nucleosyn…
Recently conformal Weyl gravity has been considered as a candidate alternative gravity theory. This fourth-order theory is attractive because it is the only metric theory of gravity which is invariant under local conformal transformations…
In the first thousand seconds of its evolution the Universe was a primordial nuclear reactor synthesizing the nuclides D, $^3$He, $^4$He and $^7$Li. These messengers from the Big Bang provide a unique window on the early, hot, dense…
Recent observational constraints on primodial deuterium and Li7 correspond to different values of the baryon-to-photon ratio when applied to the Standard Big Bang Nucleosynthesis (SBBN) model. In this article these constraints are applied…
The determined abundances of primordial $^4He$ and $^7Li$ provide a basis with which to test the standard model of big bang nucleosynthesis in conjunction with the other two light element isotopes $D$ and $^3He$, also produced in the big…
We extend the model-independent likelihood analysis of big bang nucleosynthesis (BBN) based on He4 and Li7 to allow for numbers of degrees of freedom which differ from the standard model value characterized by $N_\nu = 3$. We use the…
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…
Big Bang nucleosynthesis (BBN) is the earliest sensitive probe of the values of many fundamental particle physics parameters. We have found the leading linear dependences of primordial abundances on all relevant parameters of the standard…
Big Bang nucleosynthesis (BBN) theory predicts the abundances of the light elements D, $^3$He, $^4$He and $^7$Li produced in the early universe. The primordial abundances of D and $^4$He inferred from observational data are in good…
Of the light nuclides observed in the universe today, D, 3He, 4He, and 7Li are relics from its early evolution. The primordial abundances of these relics, produced via Big Bang Nucleosynthesis (BBN) during the first half hour of the…
We study effects of long-lived massive particles, which decay during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundances of light elements. Compared to the previous studies, (i) the reaction rates of the standard BBN…
In this paper we consider the effects on big bang nucleosynthesis (BBN) of the hadronic decay of a long-lived massive particle. If high-energy hadrons are emitted near the BBN epoch ($t \sim 10^{-2}$ -- $10^2 \sec$), they extraordinarily…
Big Bang Nucleosynthesis represents perhaps the first, and still perhaps the most powerful particle-astrophysics connection. As such, it should provide an example for other work in this area. I discuss the current status of standard model…
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 $n/p$…
Assuming the best numerical value for the cosmic baryonic density and the existence of three neutrino flavors, standard big bang nucleosynthesis is a parameter-free model. It is important to assess if the observed primordial abundances can…
Primordial nucleosynthesis is considered a success story of the standard big bang (SBB) cosmology. The cosmological and elementary particle physics parameters are believed to be severely constrained by the requirement of correct abundances…
I show that early-time (pre-recombination) solutions to the Hubble tension are generically expected to increase the preferred baryon density $\omega_b$. This puts these models in tension with Big Bang Nucleosynthesis (BBN), as measurements…
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…
According to the standard models of particle physics and cosmology, there should be a background of cosmic neutrinos in the present Universe, similar to the cosmic microwave photon background. The weakness of the weak interactions renders…
Recent measurements of deuterium abundances from QSO absorption spectra show two conflicting numbers, which differ by an order of magnitude. Allowing the neutrino degeneracy together with gravitational constant variation at the epoch of…
We use Big Bang Nucleosynthesis calculations and light element abundance data to constrain the relative variation of the deuteron binding energy since the universe was a few minutes old, $\delta Q = Q(BBN)-Q(present)$. Two approaches are…