- Accepted Paper
First measurement of the masses of the and states and the energy dependence of the cross sections for and
Phys. Rev. Lett. - Accepted 20 October, 2026
DOI: https://doi.org/10.1103/9wrm-99hg
Phys. Rev. Lett. - Accepted 20 October, 2026
DOI: https://doi.org/10.1103/9wrm-99hg
We study the processes and at center-of-mass energies =(10.73 – 11.02) GeV using a data sample, including 122~fb near the (10860) peak ( = 10.866 GeV), collected with the Belle detector at the KEKB asymmetric-energy collider. From the peak sample, the products of Born cross section times branching fraction are obtained for $\sigma_{\rm Born}(e^+e^-\to\Upsilon_J(1D)\eta)$ or $\sigma_{\rm Born}(e^+e^-\to\Upsilon_J(1D)\pi^+\pi^-)$ and ${\cal B}(\Upsilon_J(1D)\to\chi_{b1}\gamma)$ or ${\cal B}(\Upsilon_J(1D)\to\chi_{b2}\gamma)$ for each state. The corresponding branching fractions for decays are also obtained. The significances of the , , and signals are 4.8, , and 3.0, respectively, including systematic uncertainties. The mass for is measured to be MeV/, where the first and second uncertainties are statistical and systematic. The mass splittings and are MeV/ and MeV/, respectively. We determine the energy dependence of the cross sections for and for the , , and states, combined.
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