Multimodel Analysis of the Astrophysical S ( E ) Factor for the 9 Be( p , α ) 6 Li Reaction and Its Impact on Astrophysical Reaction Rates

The 9 Be( p , α ) 6 Li reaction is a destruction process for 9 Be in stars and the Big Bang. The Trojan Horse method (THM) is a well-established indirect technique that enables the determination of reaction cross sections within the Gamow energy region while avoiding the uncertainties associated with low-energy extrapolations of the S ( E ) factor and electron-screening effects. In this work, the bare-nucleus THM data reported by Wen et al. are systematically analyzed using polynomial fitting, a double Breit–Wigner model, and the R -matrix formalism. The applicability and physical implications of these theoretical approaches in describing the low-energy S ( E ) factor of the 9 Be( p , α ) 6 Li reaction are investigated and compared. Since the THM data have been incorporated into the NACRE II reaction-rate compilation, leading to improved accuracy in reaction-rate evaluations, the refined theoretical analysis presented here provides further insight into the underlying reaction dynamics and establishes a more reliable foundation for stellar reaction-rate calculations. The results obtained in this work offer a valuable reference for future high-precision experimental investigations and the development of theoretical models in nuclear astrophysics.