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 ${\rm Y}(5S)$, whose calculated masses are close to each other, have very different widths for such decays. A comparison with data from ${\rm Y}(10860)$, an experimental resonance whose mass is similar to that of ${\rm Y}(5S)$ and $H(1P)$, is carried out. Neither a ${\rm Y}(5S)$ nor a $H(1P)$ assignment can explain the measured decay widths. However, a ${\rm Y}(5S)$-$H(1P)$ mixing may give account of them supporting previous analyses of dipion decays of ${\rm Y}(10860)$ and suggesting a possible experimental evidence of $H(1P)$.

Comments: 9 pages; v2: new title, major additions and modifications in the article body; v3: slight change in the title, new reference, clarifications and minor modifications in the article body