Strong decays of the lowest bottomonium hybrid within an extended Born-Oppenheimer framework

Abstract

We analyze the decays of the theoretically predicted lowest bottomonium hybrid $H(1P)$ to open bottom two-meson states. We do it by embedding a quark pair creation model into the Born-Oppenheimer framework which allows for a unified, QCD-motivated description of bottomonium hybrids as well as bottomonium. A new $^{1}\!P_{1}$ decay model for $H(1P)$ comes out. The same analysis applied to bottomonium leads naturally to the well-known $^{3}\!P_{0}$ decay model. We show that $H(1P)$ and the theoretically predicted bottomonium state $\Upsilon(5S)$, whose calculated masses are close to each other, have very different widths for such decays. A comparison with data from $\Upsilon(10860)$, an experimental resonance whose mass is similar to that of $\Upsilon(5S)$ and $H(1P)$, is carried out. Neither a $\Upsilon(5S)$ nor a $H(1P)$ assignment can explain the measured decay widths. However, a $\Upsilon(5S)$-$H(1P)$ mixing may give account of them supporting previous analyses of dipion decays of $\Upsilon(10860)$ and suggesting a possible experimental evidence of $H(1P)$.