Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 44: Electromagnetic and Hadronic Probes VII

HK 44.5: Talk

Thursday, March 11, 2004, 18:00–18:15, B

Compatibility of a θ⁺(1540) resonance with K⁺N data — •Johann Haidenbauer¹ and Gastão Krein² — ¹Forschungszentrum Jülich, IKP, 52425 Jülich — ²Universidade Estadual Paulista, São Paulo, Brazil

Recently experimental indications have been found for the existence of a narrow baryon resonance with strangeness S=+1. The resonance parameters extracted from these experiments (mass around 1540 MeV and width around 20 MeV), lie convincingly close to a pentaquark state with the quantum numbers I=0, J^P=1/2⁺ predicted by Diakonov et al. within their chiral quark-soliton model.

We examine the impact of a θ⁺(1540) resonance with a width of 20 MeV or less on the K⁺N (I=0) elastic cross section and on the P₀₁ phase shift within the KN meson-exchange model of the Jülich group [1]. It is shown that the rather strong enhancement of the cross section caused by the presence of a θ⁺ with the above properties is not compatible with the existing empirical information on KN scattering. Only a much narrower θ⁺ state could be reconciled with the existing data – or, alternatively, the θ⁺ state must lie at an energy much closer to the KN threshold [2].

[1] M. Hoffmann et al., Nucl. Phys. A593, 341 (1995).

[2] J. Haidenbauer et al., hep-ph/0309243