\textit{Ab initio} study of the $^3{\rm He}(\alpha,\gamma)^7{\rm Be}$ and $^3{\rm H}(\alpha,\gamma)^7{\rm Li}$ radiative captures

An \textit{ab initio} description of the $^3{\rm He}(\alpha,\gamma)^7{\rm Be}$ and $^3{\rm H}(\alpha,\gamma)^7{\rm Li}$ radiative captures from the no-core shell model with continuum (NCSMC)~[1] is presented. The study of the $^3{\rm He}(\alpha,\gamma)^7{\rm Be}$ reaction, complemented by the study of the $^3{\rm He}(^3{\rm He},2p)^4{\rm He}$ reaction, should enable one to determine the fractions of $pp$-chain terminations resulting in $^7{\rm Be}$ or ${^8}{\rm B}$ neutrinos~[2]. The NCSMC approach has the key feature to describe both bound and scattering states in a unified formalism and to deal with realistic nucleon-nucleon interactions. Within this approach, the bound-state properties of $^7{\rm Be}$ and $^7{\rm Li}$ are calculated and compared with the experiment. The scattering wave functions of $\alpha+^3{\rm H}/^3{\rm He}$ are also evaluated and tested by comparing the theoretical phase shifts and resonance properties with the experimental ones. From these bound and scattering wave functions, the astrophysical $S$ factors of the radiative captures are determined by considering the dominant $E1$ transitions.\\[4pt] [1] S. Baroni, P. Navratil, and S. Quaglioni, Phys. Rev. Lett 110 (2013) 022505;Phys. Rev. C 87 (2013) 034326.\\[0pt] [2] E. G. Adelberger et al., Rev. Mod. Phys. 70 (1998)