CLEO (particle detector)
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The CLEO collaboration is a team of over 150 high energy physicists from 25 universities studying the production and decay of beauty and charm quarks and tau leptons produced in the Cornell Electron Storage Ring (CESR). Armed with the versatile and powerful CLEO III detector, and a large sample of B mesons accumulated with the CLEO II detector, the collaboration makes some of the most sensitive tests of the Standard Model of elementary particles, key to understanding the forces of nature and the fundamental structure of matter.
CLEO-c is a dedicated program of charm physics at (CESR). CLEO-c aims to elucide the weak physics behind both charm and bottom quark decays by helping to disentangle it from the confounding strong-interaction dynamics. In particular, measurements of D and Ds meson decays to leptonic and semileptonic final states are crucial tests of the Lattice QCD techniques used to compute important heavy quark processes. CLEO-c also aims to determine the hadronic branching fractions of D and Ds mesons, which normalize many measurements of both bottom and charm decays.
This physics is made possible in part by the very clean events at these energies. At the ψ(3770), each event produces only a pair of D mesons. Typically, CLEO-c analyses reconstruct one D (the tag) and then study the decay of the other D. Likewise, at the center-of-mass energy of 4170 MeV, many events contains a pair of Ds and/or Ds* mesons. The reconstruction strategy is pretty much the same as in the D anti-D case, though there is the extra complication of dealing with the presence of both Ds and Ds*.
CLEO-c also explores spectroscopy of heavy quarkonia and related states. In early 2006 analysis efforts uncovered new charmonium decay modes of the puzzling Y(4260) state, in addition to making the first confirmation of the BaBar discovery. In 2005 CLEO discovered the expected, but long-sought hc meson, the 1P1 state of charmonium. CLEO-c cleanly observed very rare non-DDbar decays of the ψ(3770) and dispelled any notion that they could be large. Efforts in the precision realm have yielded the world's best measurements of the dileptonic widths of J/ψ, ψ(2S), ψ(3770), and the Υ(1S,2S,3S) quarkonia as well as the dominant branching fractions of ψ(2S) decays.
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