Resonating-Group Calculation of Radiative Capture Reactionsα(He3,γ)Be7andα(t,γ)Li7at Astrophysical Low Energies

Total cross sections and astrophysical $S$ factors of the radiative capture reactions $\ensuremath{\alpha}(^{3}\mathrm{He},\ensuremath{\gamma})^{7}\mathrm{Be}$ and $\ensuremath{\alpha}(t,\ensuremath{\gamma})^{7}\mathrm{Li}$ are investigated by the resonating-group method. The theoretical value of the $S$ factor at ${E}_{\mathrm{c}.\mathrm{m}.}=10$ keV is predicted to be 0.508 keV\ifmmode\cdot\else\textperiodcentered\fi{}b without the use of any artificial parameters. An interesting difference between the mirror reactions is found and theoretically explained.