OFF-SHELL EFFECTS IN THE ENERGY-DEPENDENCE OF THE BE-7(P,GAMMA)B-8 ASTROPHYSICAL S-FACTOR

I show that off-shell effects, like antisymmetrization and Be-7 distor tions, can significantly influence the energy dependence of the nonres onant Be-7(p, gamma)B-8 astrophysical S factor at higher energies. The proper treatment of these effects results in a virtually flat El comp onent of the S factor at E(cm) = 0.3 - 1.5 MeV energies in the present eight-body model. The energy dependence of the nonresonant S factor, predicted by the present model, is in agreement with the low-energy ra diative capture data and the existing high-energy Coulomb dissociation data. Irrespective of whether or not the present energy dependence is correct, off-shell effects can cause 15-20% changes in the value of S (0) extrapolated from high-energy(E(cm) > 0.7 MeV) data.