The Decay Properties of the 1^{-+} Hybrid State

TL;DR

This paper uses QCD sum rules to analyze the decay properties of the 1^{-+} hybrid meson, predicting decay widths and suggesting experimental search strategies for the 600 state.

Contribution

It provides a novel calculation of the pionic coupling constants and decay widths of the 1^{-+} hybrid meson using QCD sum rules, with specific predictions for decay modes.

Findings

The 600 hybrid meson has a P-wave decay width around 180 MeV for 600 3c 3c.

Decay widths of S-wave modes increase rapidly with meson mass and decay momentum.

The 600 state can be searched for in specific decay channels at BESIII and via existing BELLE/BABAR data.

Abstract

Within the framework of the QCD sum rules, we consider the three-point correlation function, work at the limit q^2 -> 0 and m_\pi -> 0, and pick out the singular term ~ {1\over q^2} to extract the pionic coupling constants of the 1^{-+} hybrid meson. Then we calculate the decay widths of different modes. The decay width of the S-wave modes b_1 \pi, f_1\pi increases quickly as the hybrid meson mass and decay momentum increase. But for the low mass hybrid meson around 1.6 GeV, the P-wave decay mode \rho \pi is very important and its width is around 180 MeV, while the widths of \eta \pi and \eta^\prime \pi are strongly suppressed. We suggest the experimental search of \pi_1(1600) through the decay chains at BESIII: e^+e^- -> J/\psi(\psi') -> \pi_1 +\gamma or e^+e^- -> J/\psi(\psi') -> \pi_1 +\rho where the \pi_1 state can be reconstructed through the decay modes \pi_1 -> \rho\pi -> \pi^+\pi^-\pi^0 or \pi_1 -> f_1(1285)\pi^0. It is also interesting to look for \pi_1 using the available BELLE/BABAR data through the process e^+e^- -> \gamma^\ast -> \rho\pi_1, b_1\pi_1, \gamma \pi_1 etc.