Unified description of BaBar and Belle data on the bottomonia decays Upsilon(mS) -> Upsilon(nS) pi+ pi-

TL;DR

This paper provides a unified, model-independent analysis of bottomonia and charmonia decays involving dipion transitions, demonstrating that a common mechanism explains the data across various excited states and collaborations.

Contribution

It extends previous studies to higher excited bottomonia states and confirms that a unified, analyticity-based approach describes all observed dipion mass distributions.

Findings

Data for higher radially excited states fit the model without specific features.

Dipion mass distributions are explained by coupled-channel final-state interactions.

Unified mechanism applies to both charmonia and bottomonia decays.

Abstract

We present a unified analysis of the decays of bottomonia Upsilon(mS) -> Upsilon(nS) pi pi (m>n, m=2,3,4,5, n=1,2,3), charmonia J/psi -> phi (pi pi, K antiK), psi(2S) -> J/psi pi pi and the isoscalar S-wave processes pi pi -> pi pi, K antiK, eta eta. In this analysis we extend our recent study of low-lying (m=2,3) radial excitations of bottomonia to modes involving higher (m=4,5) excited states. Similarly as for the data on lower radial excitations, we confirm that the data for higher radially excited states from the BaBar and Belle collaborations can be described under conditions that the final bottomonium is a spectator and the multichannel pi pi scattering is considered in a model-independent approach based on analyticity, unitarity and the uniformization procedure. Indeed we show that the dipion mass distributions in the two-pion transitions of both charmonia and bottomonia states are explained by a unified mechanism based on the contribution of the pi pi and K antiK coupled channels including their interference (final-state interactions). Therefore, our main result is that the lower and higher radially excited states of charmonia and bottomonia have no specific features in mutual comparison and can be understood in a unified picture, e.g. proposed by our approach.