The N(p,γ)O low-energy S-factor

The ¹⁴N(p,γ)¹⁵O low-energy S-factor is analyzed using the R-matrix model. We find that the g.s. contribution is less than previously reported. The S-factor is mainly given by the 6.79 MeV state contribution which is determined by its asymptotic normalization constant (ANC). Consequently, the S-factor at zero energy is lower by a factor of 1.7 compared to the values given in recent compilations. This result may affect the nucleosynthesis and time scale evolution in massive stars. New measurements of the ¹⁴N(p,γ)¹⁵O cross section over a wide energy range, and especially at low energies, are highly desirable. Significant improvement could be also obtained from the ANC measurement of the 6.79 MeV state.