CLEO (particle Detector) - Physics Program - Quarkonium

Quarkonium

Quarkonium states provide experimental input for lattice QCD and non-relativistic QCD calculations. CLEO studied the Υ system until the end of the CUSB and CUSB-II experiments, then returned to the Υ system with the CLEO III detector. CLEO-c studied the lower mass ψ states. CLEO and CUSB published their first papers back-to-back, reporting observation of the first three Υ states. Earlier claims of the Υ(3S) relied on fits of one peak with three components; CLEO and CUSB's observation of three well separated peaks dispelled any remaining doubt about the existence of the Υ(3S). The Υ(4S) was discovered shortly after by CLEO and CUSB and was interpreted as decaying to B mesons because of its large decay width. An excess of electrons and muons at the Υ(4S) demonstrated the existence of weak decays and confirmed the interpretation of the Υ(4S) decaying to B mesons. CLEO and CUSB later reported the existence of the Υ(5S) and Υ(6S) states.

CLEO I through CLEO II had significant competition in Υ physics, primarily from the CUSB, Crystal Ball and ARGUS experiments. CLEO was able, however, to observe a number of Υ(1S) decays: τ+τ−, J/Ψ X and γ X X with X = π+, π0, 2π+, π+K+, π+p, 2K+, 3π+, 2π+K+, and 2π+p. The radiative decays are sensitive to the production of glueballs.

CLEO collected more data at the Υ(1-3S) resonances at the end of the CLEO III era. CLEO III discovered the Υ(1D) state, the χ_b1,2(2P)→ωΥ(1S) transitions, and Υ(3S)→τ+τ− decays among others.

CLEO-c measured many of the properties of the charmonium states. Highlights include confirmation of η_c', confirmation of Y(4260), pseudoscalar-vector decays of ψ(2S), ψ(2S)→J/ψ decays, observation of thirteen new hadronic decays of ψ(2S), observation of h_c(1P₁), and measurement of the mass and branching fractions of η in ψ(2S)→J/ψ decay.