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

A bstract We study the processes χ bJ ω and χ bJ (π + π − π 0) 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 χ bJ ω but not into χ bJ (π + π − π 0) non −ω, while the Υ (10860) state, in contrast, decays into χ bJ (π + π − π 0) non −ω but not into χ bJ ω. The mass and width of the Υ (10753) state are measured to be (10756. 1 ± 3. 4 (stat. ) ± 2. 7 (syst. ) ) MeV/ c 2 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) → χ b 1 ω and Υ (10753) → χ b 2 ω are (1. 57 ± 0. 27 (stat. ) ± 0. 22 (syst. ) ) eV and (1. 39 ± 0. 41 (stat. ) ± 0. 33 (syst. ) ) eV.