Probing chiral symmetry of nucleon by threshold $\eta \pi$ production

Abstract

Double meson production of the eta and pion at the threshold region is investigated in order to determine chiral property of the nucleon. The eta can be used as a probe for the negative parity nucleon $N^* \equiv N^*(1535)$ produced in the intermediate state. The coupling of the low energy pion in the final state is then used to extract the sign of the Yukawa coupling, $\gpRR$, which distinguishes the two realizations of chiral symmetry, either naive or mirror, for the nucleon.