Quark mass dependence of s-wave baryon resonances

Abstract

We study the quark mass dependence of $J^P={\frac{1}{2}}^{-}$ s-wave baryon resonances. Parameter free results are obtained in terms of the leading order chiral Lagrangian. In the 'heavy' SU(3) limit with $m_{\pi }=m_K\simeq$ 500 MeV the resonances turn into bound states forming two octets plus a singlet representations of the SU(3) group. A contrasted result is obtained in the 'light' SU(3) limit with $m_{\pi }=m_K\simeq$ 140 MeV for which no resonances exist. Using physical quark masses our analysis suggests to assign to the $S=-2$ resonances $\Xi (1690)$ and $\Xi (1620)$ the quantum numbers $J^P=1/2^{-}$.

Comments: 4 pages, 2 figure