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Pentaquark as a kaon-nucleon resonance

2004; American Physical Society; Volume: 69; Issue: 11 Linguagem: Inglês

10.1103/physrevd.69.117502

1550-7998

D. E. Kahana, S. Kahana,

Atomic and Subatomic Physics Research

Several recent experiments have reported evidence for a narrow feature in the ${K}^{+}$-neutron system, an apparent resonant state $\ensuremath{\sim}100\mathrm{MeV}$ above threshold and with a width $<~25\mathrm{MeV}.$ This state has been labeled as ${\ensuremath{\Theta}}^{+}$ (previously as ${Z}^{*}),$ and because of the implied inclusion of a strange antiquark is referred to as a pentaquark, that is, five quarks within a single bag. We present an alternative explanation for such a structure, as a higher angular momentum resonance in the isospin zero ${K}^{+}N$ system. One might call this an exit channel or molecular resonance. In a nonrelativistic potential model we find a possible candidate for the kaon-nucleon system with a relative angular momentum $L=3,$ while $L=1$ states possess centripetal barriers much too low to confine the kaon and nucleon at an energy so high above threshold. Under some circumstances, however, an $L=2$ state can exist.