Improved measurement of Born cross sections for χbJω and χbJ (π⁺π⁻π⁰)non−ω (J = 0, 1, 2) at Belle and Belle II

We study the processes χbJω and χbJ (π⁺π⁻π⁰)non−ω (J = 0, 1, 2) at center-of-mass energies √s from 10.73 to 11.02 GeV using a 142.5 fb⁻¹ data sample collected with the Belle detector at the KEKB asymmetric-energy e⁺e⁻ collider; and at √s~ 10.75 GeV using a 19.8 fb⁻¹ sample collected with Belle II at SuperKEKB. We find that the Υ(10753) state decays into χbJω but not into χbJ (π⁺π⁻π⁰)non−ω, while the Υ(10860) state, in contrast, decays into χbJ (π⁺π⁻π⁰)non−ω but not into χbJω. The mass and width of the Υ(10753) state are measured to be (10756.1 ± 3.4(stat.) ± 2.7(syst.)) MeV/c² and (32.2 ± 11.3(stat.) ± 14.9(syst.)) MeV. The products of the partial width to e⁺e⁻ and branching fractions for Υ(10753) → χb1ω and Υ(10753) → χb2ω are (1.57 ± 0.27(stat.) ± 0.22(syst.)) eV and (1.39 ± 0.41(stat.) ± 0.33(syst.)) eV.[graphic not available: see fulltext]