Large violation of the flavour SU(3) symmetry in $\eta$MAID2018 isobar model

Abstract

We demonstrate that the explanation of the neutron anomaly around $W\sim 1685$MeV in $\gamma N\to \eta N$ 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.