Cluster phenomena using few-body and Lattice QCD theories
With the advancement of first-principles calculations for baryon-baryon interactions, it becomes possible to obtain reliable hyperon-nucleon potentials by lattice QCD simulations with the HAL QCD method. High-precision few-body methods, such as the Gaussian Expansion Method (GEM), are applicable to solve quantum few-body systems up to four- and five-body systems. By combining the HAL QCD potentials with the GEM, one can predict the level structure of novel hypernuclei prior to experimental observation. In this review, we utilize the lattice QCD $NΞ$ potential obtained by the HAL QCD method to investigate the few-body systems $NNΞ$ and $NNNΞ$. Our analysis indicates that the lightest bound $Ξ$ hypernucleus is the $NNNΞ$ system. To extract detailed information on the isospin and spin components of the $NΞ$ interaction, we perform a four-body calculation for the $ααNΞ$ system with the total isospin $T = 0$ and $T = 1$. We demonstrate that the level structure of this system is sensitive to the isospin and spin dependencies of the $NΞ$ interaction. Furthermore, we propose experimental investigations to produce the $NNNΞ$ and $ααNΞ$ systems via the $(K^-, K^+)$ and $(K^-, K^0)$ reactions on $^4$He and $^{10}$B targets, respectively.