Asymptotic normalization coefficients and the ⁷Be(p,γ)⁸B astrophysical S factor

We consider the results of two proton transfer reactions, ¹⁰B(⁷Be,⁸B)⁹Be and ¹⁴N(⁷Be,⁸B)¹³C, to obtain a weighted average of the measured asymptotic normalization coefficients for the virtual transition ⁷Be+p↔⁸B. These coefficients specify the amplitude of the tail of the ⁸B overlap function in the ⁷Be+p channel, and are used to calculate the astrophysical S factor for the direct capture reaction ⁷Be(p,γ)⁸B at solar energies, S₁₇(0). In light of recent improvements in the determination of optical-model potentials, including detailed understanding of the correlations between the DWBA analyses of the two experiments, and a new experimental measurement of the asymptotic normalization coefficients for the virtual transition ¹³C+p↔¹⁴N,y we report a weighted average asymptotic normalization coefficient of C_p3/2²=0.388±0.039 fm^-1 for ⁸B ↔⁷Be+p, which implies S₁₇(0)=17.3±1.8 eV b.