Behavior of the 7Be(p, γ)8B astrophysical S factor near zero energy -: art. no. 065803

The astrophysical S factor of the Be-7(p,gamma)B-8 radiative capture reaction is analyzed at zero energy in a simplified potential model where the scattering wave function and its energy derivative at zero energy are replaced by their asymptotic expressions. A positive (negative) scattering length in the initial s wave reduces (increases) the value of S(0). The ratio S'(0)/S(0) is much more sensitive to the scattering length than S(0). The effective range of the initial wave is found to play a negligible role. Existing models suggest a negative value for the scattering length, but not large enough to lead to important corrections.