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

Abstract

The full width of the light isovector hybrid meson $H_{\mathrm{V}}$ with spin-parities $1^{\mathrm{-+}}$ 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.