Observation of the χb1(3P) and χb2(3P) and measurement of their masses

CMS Collaboration

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The χb1(3P) and χb2(3P) states are observed through their Υ(3S) γ decays, using an event sample of proton-proton collisions collected by the CMS experiment at the CERN LHC. The data were collected at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 80.0 fb−1. The Υ(3S) mesons are identified through their dimuon decay channel, while the low-energy photons are detected after converting to e+e pairs in the silicon tracker, leading to a χb(3P) mass resolution of 2.2 MeV. This is the first time that the J = 1 and 2 states are well resolved and their masses individually measured: 10 513.42 ± 0.41 (stat) ± 0.18 (syst) MeV and 10 524.02 ± 0.57 (stat) ± 0.18 (syst) MeV; they are determined with respect to the world-average value of the Υ(3S) mass, which has an uncertainty of 0.5 MeV. The mass splitting is measured to be 10.60 ± 0.64 (stat) ± 0.17 (syst) MeV.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2018 May 28

ASJC Scopus subject areas

  • General

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