Faddeev calculations of hypertriton (${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$) separation energy are carried out, incorporating all next-to-next-to-leading-order $\mathrm{\Lambda }NN$ three-body forces (3BFs) in chiral effective field theory: $2\pi$ exchange, $1\pi$ exchange, and contact interactions. The $1\pi$ exchange and contact interactions are rewritten in a form suitable for evaluating partial-wave matrix elements. The $\mathrm{\Lambda }$-deuteron folding potentials constructed from these 3BFs are evaluated to demonstrate their contributions to ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$. The $1\pi$ exchange interaction provides an attractive effect in which the $d$-state component of the deuteron wave function plays an important role. The attractive contribution tends to cancel the repulsive ones from the $2\pi$ exchange and contact 3BFs. Faddeev calculations show that the net effect of the 3BFs to the ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ separation energy is small in a range between $-5$ to $+20$ keV, depending on the $NN$ interaction used. Although these results are based on speculative low-energy constants, they can serve as a reference for further investigations.

• Received 21 November 2023
• Accepted 29 January 2024

DOI:https://doi.org/10.1103/PhysRevC.109.024003