Study of e+e- => B(*) B(*)-bar pi+- at sqrt(s)=10.866 GeV

TL;DR

This paper reports the first observation of specific bottomonium-like states Zb(10610) and Zb(10650) in e+e- collisions at 10.866 GeV, measuring their production cross sections and exploring three-body B meson processes.

Contribution

It provides the first observation of Zb states decaying into B meson pairs and measures their production cross sections at the Y(5S) energy.

Findings

First observation of Zb(10610) and Zb(10650) decays into B meson pairs.

Measured cross sections for e+e- to B B*-bar pi and B* B*-bar pi.

Set upper limit on e+e- to B B-bar pi production.

Abstract

We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => [B B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => [B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.