Hyperon-nucleon three-body forces and strangeness in neutron stars

Understand

Three-body forces acting on a $\Lambda$ hyperon in a nuclear medium are investigated, with special focus on the so-called hyperon puzzle in neutron stars.

• The hyperon-nucleon two-body interaction deduced from SU(3) chiral effective field theory is employed at next-to-leading order.
• Hyperon-nucleon three-body forces are approximated using saturation by decuplet baryons and are transcribed to density-dependent effective two-body interactions.
• These together are taken as input in a Brueckner-Bethe-Goldstone equation with explicit treatment of the $\Lambda N\leftrightarrow\Sigma N$ and $\Lambda NN\leftrightarrow\Sigma NN$ coupled channels.