Light single-gluon hybrid states with various exotic quantum numbers

Abstract

We apply the QCD sum rule method to study the light single-gluon hybrid states with various (exotic) quantum numbers. We construct 24 single-gluon hybrid currents and use 18 of them to calculate the masses of 44 single-gluon hybrid states with the quark-gluon contents q¯qg (q=u/d) and s¯sg. We concentrate on the hybrid states with the exotic quantum number JPC=1−+, whose masses and widths are calculated to be M|q¯qg;1−1−+⟩=1.67−0.17+0.15  GeV, Γ|q¯qg;1−1−+⟩=530−330+540  MeV, M|q¯qg;0+1−+⟩=1.67−0.17+0.15  GeV, Γ|q¯qg;0+1−+⟩=120−110+160  MeV, M|s¯sg;0+1−+⟩=1.84−0.15+0.14  GeV, and Γ|s¯sg;0+1−+⟩=100−80+110  MeV. Our results support the interpretations of the π1(1600) and η1(1855) as the hybrid states |q¯qg;1−1−+⟩ and |s¯sg;0+1−+⟩, respectively. Considering the uncertainties, our results suggest that the π1(1600) and η1(1855) may also be interpreted as the hybrid states |q¯qg;1−1−+⟩ and |q¯qg;0+1−+⟩, respectively. To differentiate these two assignments and to verify whether they are hybrid states or not, we propose to examine the a1(1260)π decay channel in future experiments. Published by the American Physical Society 2024