Chiral Three-Nucleon Interaction and Structure of Light Nuclei

Modern high-precision nucleon-nucleon (NN) interactions derived from the two nucleon system fail to describe systems of more than two-nucleons; therefore, they need to be augmented by three-nucleon interactions (TNI). Compared to the NN-interaction, the form and parameters of the TNI are much less explored. Chiral perturbation theory (${\chi}PT$) at next-to-next-to-leading order (N$^2$LO) predicts three types of TNI terms. A two-pion exchange term, which is frequently used, has parameters determined from the two-nucleon ${\chi}PT$-potential and/ or pion-nucleon scattering data. The other two terms, the one-pion exchange with NN-contact term and the NNN-contact term, are accompanied by undetermined low-energy constants. We include all three TNI terms in {\it ab initio} no-core shell model (NCSM) calculations. The two undetermined TNI constants are fit to binding energies of $s$-shell nuclei. The impact of the N$^2$LO TNI on the nuclear structure is then studied in NCSM calculations for p-shell nuclei, such as $^{10,11}$B that are particularly known to be poorly described by the modern NN potentials.