QCD Axial Anomaly Enhances the ηη′ Decay of the Hybrid Candidate η1 (1855)

We study the hybrid mesons with the exotic quantum number I-G J(PC) = 0(+)1(-+) and investigate their decays into the eta eta', a(1)(1260)pi, f(1)(1285)eta, f(1)(1420)eta, K*(892)(K) over bar, K-1(1270)(K) over bar, and K-1(1400)(K) over bar channels. It is found that the QCD axial anomaly enhances the decay width of the eta eta' channel although this mode is strongly suppressed by the small p-wave phase space. Our results support the interpretation of the eta(1)(1855) recently observed by BESIII as the (s) over bar sg hybrid meson of I(G)J(PC) = 0(+)1(-+). The QCD axial anomaly ensures the eta eta' decay mode to be a characteristic signal of the hybrid nature of the eta(1)(1855).

Automated summary

In this study, we investigated the decay patterns of hybrid mesons with exotic quantum numbers. Our results showed that the decay width of certain channels is enhanced by the QCD axial anomaly, despite the small p-wave phase space. The results also supported the interpretation of a recently observed meson as a hybrid meson with certain quantum numbers.