B. G. Fulsom et al. (Belle Collaboration)WEI-SHU HOU2021-07-282021-07-282018319007https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058089146&doi=10.1103%2fPhysRevLett.121.232001&partnerID=40&md5=ac01d4872be1a93bcef145f5736cdfd4https://scholars.lib.ntu.edu.tw/handle/123456789/574671We report the observation of I(2S)→γηb(1S) decay based on an analysis of the inclusive photon spectrum of 24.7 fb-1 of e+e- collisions at the I(2S) center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure a branching fraction of B[I(2S)→γηb(1S)]=(6.1-0.7-0.6+0.6+0.9)×10-4 and derive an ηb(1S) mass of 9394.8-3.1-2.7+2.7+4.5 MeV/c2, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode. ? 2018 authors. Published by the American Physical Society.Atomic physics; Asymmetric energy; Belle detectors; Branching fractions; Center-of-mass energies; Decay mode; E+e- collider; Photon spectra; Standard deviation; Physics[SDGs]SDG7journal article10.1103/PhysRevLett.121.232001305762072-s2.0-85058089146