Analysis of the $^{3}{\rm He}(\alpha, \gamma)^{7}{\rm Be}$ and $^{3}{\rm H}(\alpha,\gamma)^{7}{\rm Li}$ astrophysical direct capture reactions in a modified potential-model approach

TL;DR

This paper uses a modified potential model to analyze astrophysical reactions involving helium and lithium isotopes, improving the description of reaction rates and aligning predicted lithium abundance with recent measurements.

Contribution

It introduces a modified two-body potential approach that enhances the modeling of helium and lithium capture reactions in astrophysics.

Findings

Improved fit of the astrophysical S factor for $^{3}{ m He}( ext{α}, ext{γ})^{7}{ m Be}$ at energies above 0.5 MeV.

Predicted $^{7}{ m Li/H}$ abundance ratio of $(4.89 extpm 0.18) imes 10^{-10}$.

Good agreement of lithium abundance with recent LUNA measurements.

Abstract

Astrophysical $S$ factors and reaction rates of the direct radiative capture processes $^{3}{\rm He}(\alpha, \gamma)^{7}{\rm Be}$ and $^{3}{\rm H}(\alpha,\gamma)^{7}{\rm Li}$, as well as the primordial abundance of the $^{7}{\rm Li}$ element, are estimated in the framework of a modified two-body potential model. It is shown that suitable modification of phase-equivalent $\alpha-^{3}{\rm He}$ potentials in the $d$ waves can improve the description of the astrophysical $S$ factor for the direct $^{3}{\rm He}(\alpha, \gamma)^{7}{\rm Be}$ radiative capture reaction at energies above 0.5 MeV. An estimated $^{7}{\rm Li/H}$ abundance ratio of $(4.89\pm 0.18 )\times 10^{-10}$ is in very good agreement with the recent measurement of $(5.0\pm 0.3) \times 10^{-10}$ by the LUNA collaboration.