Light-quark mass dependence of the Λ(1405) resonance

Abstract

We present the light-quark mass dependence of the Λ(1405) resonance at leading order in a renormalizable framework of covariant chiral effective field theory. The meson-baryon scattering amplitudes, which are obtained by solving the scattering equation within time-ordered perturbation theory, follow the quark mass trajectory of the Coordinated Lattice Simulations consortium. At Mπ≈200 MeV and MK≈487 MeV, our parameter-free prediction of Λ(1405) poles is consistent with the recent lattice results of BaSc Collaboration [Phys. Rev. Lett. 132, 051901 (2024)]. Varying the pion mass from 135 MeV to 400 MeV, we present the evolution of double-pole positions of Λ(1405): the higher pole remains a resonance around the K¯N threshold; whereas the lower pole undergoes a transition from resonance to a virtual state, and ultimately to a bound state of the πΣ system, which could be verified by the forthcoming lattice QCD simulations.

Keywords

• Kaon-nucleon interaction
• Chiral symmetry
• Λ(1405)