Upsilon particles at 9.4 and 10 GeV suggest new quark

OCT 01, 1977

Possible evidence for a new kind of quark has been reported by a group working at Fermilab. The team of experimenters from Columbia University, Fermilab and the State University of New York at Stony Brook observed a dimuon resonance, which they called upsilon, Υ, at 9.4 GeV, by far the most massive resonance ever found. They reported their results at the European Physical Society Particle‐Physics Conference held in Budapest in July. Since then the group reported evidence for $Υ^{'}$ at 10.0 GeV and preliminary indications for a third resonance at about 10.4 GeV. Both upsilon and upsilon prime have widths less than or equal to 200 MeV. These latest results were announced at the International Symposium on Lepton–Photon Interactions held in Hamburg late in August.

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