Contributions of $2\ddot{I}€$-exchange, $1\ddot{I}€$-exchange, and contact three-body forces in NNLO ChEFT to ${}_{\hat{I}}{›}^3$H

Abstract

Faddeev calculations of hypertriton (${}_{\hat{I}}{›}^3$H) separation energy are performed, incorporating all next-to-next-to-leading-order $\hat{I}›$NN three-body forces (3BFs) in chiral effective field theory: $2\ddot{I}€$-exchange, $1\ddot{I}€$-exchange, and contact interactions. The $1\ddot{I}€$-exchange and contact interactions are rewritten in a form suitable for evaluating partial-wave matrix elements. The $\hat{I}›$-deuteron folding potentials constructed from these 3BFs are evaluated to demonstrate their contributions to \h3t. The $1\ddot{I}€$-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 $2\ddot{I}€$-exchange and contact 3BFs. Faddeev calculations show that the net effect of the 3BFs to the \h3t 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.

6 pages, 4 figures