Status on 12C +12C fusion at deep subbarrier energies: impact of resonances on astrophysical S∗ factors

Since the discovery of molecular resonances in 1²C+1²C in the early sixties a great deal of research work has been undertaken to study α -clustering and resonant effects of the fusion process at sub-Coulomb barrier energies. The modified astrophysical S^∗ factors of 1²C+1²C fusion have been extracted from direct fusion measurements at deep sub-barrier energies near the Gamow window. They were also obtained by the indirect Trojan horse method (THM). A comparison of direct measurements and the THM, which elucidates problems in the analysis of the THM, is discussed in this Letter to the Editor.