Department
Physics
Document Type
Article
Publication Date
10-2-2015
Abstract
Using a sample of 771.6×106 ΥΥ(4S) decays collected by the Belle experiment at the KEKB e+e− collider, we observe, for the first time, the transition Υ(4S)→ηhb(1P) with the branching fraction B[Υ(4S)→ηhb(1P)]=(2.18±0.11±0.18)×10−3 and we measure the hb(1P) mass Mhb(1P)=(9899.3±0.4±1.0) MeV/c2, corresponding to the hyperfine (HF) splitting ΔMHF(1P)=(0.6±0.4±1.0) MeV/c2. Using the transition hb(1P)→γηb(1S), we measure the ηb(1S) mass Mηb(1S)=(9400.7±1.7±1.6) MeV/c2, corresponding to ΔMHF(1S)=(59.6±1.7±1.6) MeV/c2, the ηb(1S) width Γηb(1S)=(8+6−5±5) MeV/c2and the branching fraction B[hb(1P)→γηb(1S)]=(56±8±4)%.
Journal Title
Physical Review Letters
Journal ISSN
1079-7114
Volume
115
Issue
14
Digital Object Identifier (DOI)
10.1103/PhysRevLett.115.142001