Decays of the light hybrid meson $1^{-+}$

Abstract

The full width of the light isovector hybrid meson $H_{\mathrm{V}}$ with spin-parities $1^{-+}$ and content $(\overline{u}gu-\overline{d}gd)/\sqrt{2}$ is evaluated by considering the decays $H_{\mathrm{V}}\to {\rho }^{\pm }{\pi }^{\mp }$, $b_1^{\pm }{\pi }^{\mp }$, $f_1(1285)\pi$, $f_1(1420)\pi$, $\eta \pi$, and ${\eta }^{\prime }\pi$. To calculate the partial widths of these channels, we use QCD three-point sum rule method which is necessary to determine strong couplings at the corresponding hybrid-meson-meson vertices. It turns out that the main contribution to the full width $\Gamma [H_{\mathrm{V}}]=(109.7\pm 16.0)\mathrm{MeV}$ of the hybrid meson comes from the processes $H_{\mathrm{V}}\to {\rho }^{\pm }{\pi }^{\mp }$ partial width of which amounts to $\approx 67\mathrm{MeV}$. The effects of the decays $H_{\mathrm{V}}\to b_1\pi$ and $H_{\mathrm{V}}\to f_1\pi ,f_1^{\prime }\pi$ are also sizeable: Their partial widths are equal to $13\mathrm{MeV}$ and $20\mathrm{MeV}$, respectively. The decays to $\eta \pi$ and ${\eta }^{\prime }\pi$ mesons are subdominant reactions, nevertheless they form $\approx 9\%$ of the full width $\Gamma [H_{\mathrm{V}}]$. Results obtained in this work may be interesting to unravel the tangle of predictions about $H_{\mathrm{V}}$ existing in the literature, as well as useful in analyses of different resonances.

Comments: 12 Pages and 5 Figures