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We demonstrate that the explanation of the neutron anomaly around $Wsim 1685$MeV in $gamma Nto eta N$ reactions provided by the $eta$MAID2018 isobar model is based on large violation of the flavour SU(3) symmetry in hadron interactions. This is yet another example of how conventional explanation (without invoking exotic narrow nucleon resonance) of the neutron anomaly metamorphoses into unconventional physics picture of hadron interactions. A possibility to mend the flavour SU(3) symmetry for some of resonances in $eta$MAID model is discussed.
The isobar model EtaMAID has been updated with new and high precision data for eta and etaprime photoproduction on protons and neutrons from MAMI, ELSA, GRAAL and CLAS. The background is described in a recently developed Regge-cut model, and for the
By extending the SU(3) flavour symmetry breaking expansion from up, down and strange sea quark masses to partially quenched valence quark masses we propose a method to determine charmed quark hadron masses including possible QCD isospin breaking effe
We shed light upon the eta mass in nuclear matter in the context of partial restoration of chiral symmetry, pointing out that the U_{A}(1) anomaly effects causes the eta-eta mass difference necessarily through the chiral symmetry breaking. As a conse
The proxy-SU(3) symmetry has been proposed for spin-orbit like nuclear shells using the asymptotic deformed oscillator basis for the single particle orbitals, in which the restoration of the symmetry of the harmonic oscillator shells is achieved by a
In-medium modification of the eta mass is discussed in the context of partial restoration of chiral symmetry in nuclear medium. We emphasize that the U_A(1) anomaly effects causes the eta-eta mass difference necessarily through the chiral symmetry br