Detailed study of the astrophysical direct capture reaction $^{6}{\rm Li}(p, \gamma)^{7}{\rm Be}$ in a potential model approach

TL;DR

This study models the $^{6}$Li(p,$ extgamma)^{7}$Be reaction using a potential approach, accurately reproducing experimental data and contributing to understanding primordial lithium abundance.

Contribution

It introduces a potential model fitting phase shifts and ANCs to predict astrophysical $S$ factors and reaction rates with high accuracy, aligning with experimental results.

Findings

The model reproduces experimental $S$ factors and reaction rates.

Predicted primordial $^{7}$Li/H ratio aligns with recent BBN results.

Results match energy and temperature dependence observed in experiments.

Abstract

The astrophysical $S$ factor and reaction rates of the direct capture process $^{6}$Li(p,$\gamma)^{7}$Be are estimated within a two-body single-channel potential model approach. Central potentials of the Gaussian-form in the $^2P_{3/2}$ and $^2P_{1/2}$ waves are adjusted to reproduce the binding energies and the empirical values of the asymptotic normalization coefficients (ANC) for the $^7$Be(3/2$^-$) ground and $^7$Be(1/2$^-$) excited bound states, respectively. The parameters of the potential in the most important $^2S_{1/2}$ scattering channel were fitted to reproduce the empirical phase shifts from the literature and the low-energy astrophysical $S$ factor of the LUNA collaboration. The obtained results for the astrophysical $S$ factor and the reaction rates are in a very good agreement with available experimental data sets. The numerical estimates reproduce not only the absolute values, but also the energy and temperature dependence of the $S$ factor and reaction rates of the LUNA collaboration, respectively. The estimated $^{7}{\rm Li/H}$ primordial abundance ratio $(4.67\pm 0.04 )\times 10^{-10}$ is well consistent with recent BBN result of $(4.72\pm 0.72) \times 10^{-10}$ after the Planck observation.