DREB Conference 2024

The direct reaction theory widely used to study single-particle spectroscopic strength in nucleon transfer experiments is based on a Hamiltonian with two-nucleon interactions only. We point out that in reactions where three-body effects are important, for example, such as $(d,p)$ and $(p,2p)$, an additional three-body force arises due to three-nucleon ($3N$) interaction between nucleons belonging to different fragments. We develop calculations of this $3N$-induced force for one-nucleon removal reactions thus making an essential step towards bringing together nuclear structure theory, where 3N force is routinely used, and nuclear direct reaction theory, based on two-nucleon interactions only.

We study the effects of the $3N$ force on nucleon transfer in $(d,p)$ and $(d,n)$ reactions on ${}^{56}$Ni, ${}^{48}$Ca, ${}^{26m}$Al and ${}^{24}$O targets at deuteron incident energies between 4 and 40 MeV/nucleon. Deuteron breakup is treated exactly within a continuum discretized coupled-channel approach. We found that an additional three-body force can noticeably alter the angular distributions at forward angles, with consequences for spectroscopic factors' studies. We also present the study of transfer to $2p$ continuum in the ${}^{25}$F$(p,2p{)}^{24}$O reaction, involving the same overlap function as in the ${}^{24}$O($d,n{)}^{25}$F case, quantifyng the differences in the spectroscopic factors due to additional $3N$-induced force.