Towards an ab initio description of the light-nuclei radiative captures

The ${}^3\mathrm{H}\mathrm{e}(\alpha ,\gamma ){}^7\mathrm{B}\mathrm{e}$ and ${^3{\rm H}}(\alpha,\gamma){^7{\rm Li}}$astrophysical$S$ factors are evaluated at low collision energies (less than 2.5 MeV in the centre-of-mass frame) within the no-core shell model with continuum approach using a renormalized chiral nucleon-nucleon interaction.