The Mass and Decay Properties of the $1^{-+}$ Light Hybrid Meson

Abstract

We calculate the complete form of the dimension-8 condensate contributions in the two-point correlator of the ($1^{-+}$,$0^{++}$) light hybrid current considering the operator mixing under renormalization. We find the inclusion these higher power corrections as well as the update of $⟨g^3{G}^3⟩$ increase the QCD sum rule mass prediction for the $1^{-+}$ light hybrid. The obtained conservative mass range 1.72--2.60 GeV does not favor the ${\pi }_1(1400)$ and the ${\pi }_1(1600)$ to be pure hybrid states and suggests the ${\pi }_1(2015)$ observed by E852 is more likely to have much of a hybrid constituent. We also study the $b_1\pi$ and $\rho \pi$ decay patterns of the $1^{-+}$ light hybrid with light-cone QCD sum rules. We obtain a relatively large partial decay width of the $b_1\pi$ mode, which is consistent with the predictions from the flux tube models and lattice QCD. More interestingly, using the tensor interpolating current we find the partial decay width of the $\rho \pi$ mode is small due to the absence of the leading twist contribution in the light-cone expansion of the correlation function.

Comments: 5 pages, 2 tables, 1 figure. Proceedings article for the 20th High-Energy Physics International Conference in Quantum Chromodynamics (QCD17) in Montpellier, France July 3-7 2017