Exotic bound states of two baryons in light of chiral effective field theory

Abstract

Baryon–baryon bound states in the strangeness S=−2, S=−3, and S=−4 sectors are investigated. In particular, the dependence of the corresponding binding energies on the quark mass (or equivalently the pion mass) is explored in the framework of chiral effective field theory, in order to connect with current lattice QCD calculations. For a bound state in the ΞΞ S01 channel, predicted by our leading-order effective field theory interaction, binding energies are inferred that are roughly in line with a recent lattice QCD result at meson and baryon masses that correspond to those in the lattice simulation. With regard to the so-called H-dibaryon it is shown that the SU(3) breaking effects induced by the differences of the pertinent two-baryon thresholds (ΛΛ, ΞN, ΣΣ) have a very pronounced impact on its binding energy. A bound H-dibaryon as found in two lattice calculations could be shifted above the ΛΛ- or even above the ΞN threshold for physical masses of the involved baryons.