Influence of the axial anomaly on the decay N ( 1535 ) → N η

• Published in: Physical review. D 2018-01, Vol.97 (1), Article 014007
• Main Authors: Olbrich, Lisa, Zétényi, Miklós, Giacosa, Francesco, Rischke, Dirk H.
• Format: Article
• Language: English
• Subjects: Baryons; Coupling; Decay; Eta-mesons; Flavor (particle physics); Symmetry
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.97.014007

The decay width of N(1535)→Nη is as large as that of N(1535)→Nπ. This is in evident conflict with simple expectations based on flavor symmetry and phase space. Similarly, the decay width of Λ(1670)→Λ(1116)η is larger than predicted by flavor symmetry. In this work, we propose that the axial U(1)A anomaly is responsible for an enhanced coupling of (some) excited baryons to the η meson. We test this idea by including a new, chirally symmetric but U(1)A anomalous, term in an effective hadronic model describing baryons and their chiral partners in the mirror assignment. This term enhances the decay of the chiral partners into baryons and an η meson, such as N(1535)→Nη. Moreover, a strong coupling of N(1535) to Nη′ emerges (this is important for studies of η′ production processes). Our approach shows that N(1535) is predominantly the chiral partner of N(939), and Λ(1670) the chiral partner of Λ(1116). Finally, our formalism can be used to couple the pseudoscalar glueball G˜ to baryons. We expect a large cross section for the reaction p¯p→G˜→p¯p(1535), which can be experimentally tested in the future PANDA experiment.