@Haidenbauer2017]. The present study builds on these results, with extensions in several directions. Special attention will be paid to the importance of the $\Lambda N\leftrightarrow\Sigma N$ transition potential, a necessary ingredient of any such calculation. In particular, the $\Lambda NN\leftrightarrow\Sigma NN$ coupled channels in the three-body sector, translated into density-dependent effective two-body potentials as in ref.[@Petschauer2017], will be treated explicitly when solving coupled-channel Bethe-Goldstone equations.

Basic baryonic interactions {#sec:int}
===========================

Hyperon-nucleon two-body interactions
-------------------------------------

For the description of the hyperon-nucleon two-body interaction, SU(3) chiral effective field theory is used up to NLO with the Weinberg power counting applied to the potential, as reported in detail in ref.[@Haidenbauer2013]. The leading order potential involves the exchange of a single pseudoscalar octet meson $(\pi, K, \eta)$ and non-derivative four-baryon contact terms. At NLO two-meson exchange diagrams at one-loop level arise together with additional contact terms with explicit momentum dependence of order $p^2$ (see fig.\[fig:pwrcounting\]). The set of SU(3)-symmetric contact terms represents unresolved short-distance dynamics. The corresponding low-energy constants (LECs) are fitted to low-energy hyperon-nucleon scattering data and the hypertriton ${}^3_\Lambda H$ binding energy (and partly to elastic $NN$-scattering phase shifts). SU(3) symmetry breaking is none- theless incorporated through the physical masses of the 