Asymptotic normalization coefficients for synthesis and the -factor for radiative capture
A. M. Mukhamedzhanov · R. J. deBoer · B. F. Irgaziev · L. D. Blokhintsev · A. S. Kadyrov · D. A. Savin
The O reaction, determining the survival of carbon in red giants, is of interest for nuclear reaction theory and nuclear astrophysics. A specific feature of the O nuclear structure is the presence of two subthreshold bound states, (6.92 MeV, 2) and (7.12 MeV, 1), that dominate the behavior of the low-energy -factor. The strength of these subthreshold states is determined by their asymptotic normalization coefficients (ANCs), which need to be known with high accuracy. Recently, using a model-independent extrapolation method, Blokhintsev {\it et al.} [Eur. Phys. J. A {\bf 59} (2023) 162] determined the ANCs for the -particle removal taking into account three subthreshold states in O. The goal of this paper is to address four main problems elucidating the impact of the subthreshold ANCs on the low-energy -factor. Firstly, we analyse the connection between variations of the subthreshold ANCs and the low-energy -factor, in particular, at the most effective energy of keV. Secondly, we calculate contributions to the -factor from the subthreshold and resonances, that are controlled by the subthreshold ANCs. We also evaluate the contribution of the uncertainties of the subthreshold ANCs to the budget of the low-energy -factor uncertainty, especially, the -factor. Thirdly, we analyse interference of the subthreshold resonances (SRs) with higher resonances and with the and direct captures to the ground state. Finally, we investigate a correlated effect of the subthreshold and ground-state ANCs on the low-energy -factor and, in particular, on the -factor.