Leading order relativistic hyperon-nucleon interactions in chiral effective field theory

Abstract

We apply a recently proposed covariant power counting in nucleon-nucleon\ninteractions to study strangeness $S=-1$ $\\Lambda N-\\Sigma N$ interactions in\nchiral effective field theory. At leading order, Lorentz invariance introduces\n12 low energy constants, in contrast to the heavy baryon approach, where only\nfive appear. The Kadyshevsky equation is adopted to resum the potential in\norder to account for the non-perturbative nature of hyperon-nucleon\ninteractions. A fit to the $36$ hyperon-nucleon scattering data points yields\n$\\chi^2\\simeq 16$, which is comparable with the sophisticated phenomenological\nmodels and the next-to-leading order heavy baryon approach. However, one cannot\nachieve a simultaneous description of the nucleon-nucleon phase shifts and\nstrangeness $S=-1$ hyperon-nucleon scattering data at leading order.\n