Are the chiral based $\bar{K}N$ potentials really energy dependent?

Abstract

It is shown, that the energy dependence of the chiral based $\bar{K}N$ potentials, responsible for the occurrence of two poles in the $I=0$ sector, is the consequence of applying the on-shell factorization introduced in [E. Oset, A. Ramos, Nucl. Phys. A 635(1998)99]. When the dynamical equation is solved without this approximation, the $T$-matrix has only one pole in the energy region of the $\Lambda(1405)$ resonance.