Ground State Masses of Charmonium Hybrids from QCD Sum-Rules

ORAL

Abstract

Over the past decade or so, a number of new, charmonium-like resonances have been observed. However, few of these particles, collectively dubbed the XYZ resonances, can be neatly accommodated by a conventional charmonium meson interpretation as there are major discrepancies between theory and experiment with regards to masses, resonance widths, decay modes, and branching ratios. Quite naturally, this has fuelled a great deal of speculation that at least some of the newly discovered particles lie outside of the constituent quark model. Hybrids, hadrons with explicit quark and gluon degrees of freedom, represent one such possibility. In an effort to identify hybrid content within the XYZ resonances, we have performed a comprehensive QCD sum-rules analysis of ground state charmonium hybrid masses for a wide variety of quantum numbers. We present our findings and comment on the phenomenological implications.

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Authors

  • Derek Harnett

    University of the Fraser Valley

  • Tom Steele

    University of Saskatchewan

  • Jason Ho

    University of the Fraser Valley

  • William H. Dowd

    Oregon State University, University of Washington, University of Hong Kong, University of Tennessee, Oak Ridge National Laboratory, University of British Columbia, Univ of Washington, Univ of Cambridge, Michigan State University, Universit\'e de Caen, Argonne National Laboratory, Texas A\&M University -Commerce, Texas A\&M University, Department of Physics, University of Idaho, Moscow, Idaho 83844, USA, Universidad de Salamanca, E-37008 Salamanca, Spain, Department of Physics, Florida State University, Tallahassee, Florida 32306, USA, University of Cambridge, Institute of Astronomy, University of Cambridge, Canadian Institute for Theoretical Astrophysics, University of Toronto, Seoul National University, Chungnam National University, Department of Physics, Oregon State University, TRIUMF, Roosevelt High School, Department of Physics, University of Washington, Oregon State Department of Chemistry, Oregon State School of Electrical Engineering and Computer Science, Oregon State Department of Physics, University of Idaho, Lawrence Livermore National Laboratory, Idaho National Laboratory, Pacific Northwest National Laboratory, Carnegie Institution of Washington, Department of Chemistry, Oregon State University, School of Electrical Engineering and Computer Science, Oregon State University, Washington State University, Harvard University, Idaho Accelerator Center, Idaho Accelerator Center, Idaho State University, 1500 Alvin Ricken drive, Pocatello, ID 83201, USA, CENPA, University of Washington, Physics Division, ANL, NSCL, Michigan State University, Division, ANL, LPC, CAEN, France, Paul Scherrer Institute, US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA, 20192, USA, University of Calgary Department of Physics and Astronomy, University of Calgary Department of Geoscience, None, University of the Fraser Valley, Univ of California, Berkeley, Simon Fraser University, Los Alamos Natl. Lab., University of Science and Technology of China, Hefei, U of Washington, Georgia Institute of Technology, Washington State Univ, National Institute of Standards and Technology and University of Maryland, American University

  • Timothy Richards

    University of the Fraser Valley

  • Ryan Berg

    University of the Fraser Valley

  • Robin Kleiv

    University of Saskatchewan

  • Wei Chen

    University of Saskatchewan

  • Shi-Lin Zhu

    State Key Laboratory of Nuclear Physics and Technology, Peking University