Remarks on decays of h_b(2P)

TL;DR

This paper analyzes hadronic transitions of the bottomonium state h_b(2P), questioning existing models of its decay rates and suggesting a potentially significant branching fraction for a specific transition, which challenges current theoretical pictures.

Contribution

It provides a critical examination of decay mechanisms of h_b(2P), highlighting possible contradictions with the parton model and proposing that certain decay fractions may be larger than previously thought.

Findings

Branching ratios relate to similar transitions from χ_b1(2P).

Potential contradiction with the parton picture of bottomonium decay.

The transition h_b(2P) to Υ(1S) η may have a significant branching fraction.

Abstract

We consider hadronic transitions from the $h_b(2P)$ bottomonium resonance to lower states of bottomonium with emission of either $\omega$ meson, or two pions, or $\eta$ meson. For the former two transitions the branching ratios are related to similar transitions from $\chi_{b1}(2P)$ and the recently measured by Belle fractions of the radiative decays of $h_b(2P)$. We argue that the fraction of the $h_b(2P)$ total decay rate remaining for the annihilation rate is on the verge of contradiction with the `parton' picture of bottomonium annihilation resulting in similarity between the decays of $h_b(1,2P)$ and $\chi_{b1}(1,2P)$. The contradiction gets even stronger, if the transition $h_b(2P) \to \Upsilon(1S) \, \eta$ has branching fraction of a few percent or more. We argue that, although quite uncertain, the latter fraction may indeed be that significant.