Neutron anomaly in γN → ηN and the flavour SU(3) symmetry
Institute for Theoretical Physics II, Ruhr-University Bochum, 44801 Bochum, Germany
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Published online: 26 January 2017
We study the implications of the flavour SU(3) symmetry for various interpretations (existence of a narrow anti-decuplet resonance, interference of known resonances and a cusp effect) of the neutron anomaly in γN → ηN cross section. We show that the explanation of the neutron anomaly due to interference of known N(1535) and N(1650) resonances implies that N(1650) resonance should have a huge coupling to ϕ-meson – at least 5 times larger than the corresponding ρ0 coupling. In terms of quark degrees of freedom that implies that the well-known N(1650) resonance must be a “cryptoexotic pentaquark”– its wave function should contain predominantly an ss̄ component, implying that the N(1650) resonance is dominantly a pentaquark. The explanation of the neutron anomaly as a cusp effect implies very strong violation of the flavour SU(3) symmetry.
© The Authors, published by EDP Sciences, 2017
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