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On the spin, parity and nature of the $Ξ(1620)$ resonance

A. Ramos·E. Oset·C. Bennhold
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Abstract

Using a unitary extension of chiral perturbation theory with a lowest-order s-wave SU(3) chiral Lagrangian we study low-energy meson-baryon scattering in the strangeness $S=-2$ sector. A scattering-matrix pole is found around 1606 MeV which corresponds to an s-wave $Ξ$ resonance with $J^P=1/2^-$. We identify this resonance with the $Ξ(1620)$ state, quoted in the Particle Data Book with $I=1/2$ but with unknown spin and parity. The addition of the $S=-2$ state to the recently computed $Λ(1670)$, $Σ(1620)$ and N(1535) states completes the octet of $J^P=1/2^-$ resonances dynamically generated in this chiral unitary approach.

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A. Ramos, E. Oset, C. Bennhold. 2002-04-16. On the spin, parity and nature of the $Ξ(1620)$ resonance. https://doi.org/10.1103/physrevlett.89.252001

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