Light-Quark Spectroscopy from Charmonium Decay

  • Clemens A. Heusch
Part of the The Subnuclear Series book series (SUS, volume 25)


Hadron phenomenology inspired by quantum chromodynamics (QCD) has made great progress in explaining, in a semi-quantitative way, the spectroscopy and decay rates of mesons containing heavy (b, c) quarks. Light (u, d, s) quark spectroscopy was vital for the early successes of the SU6 quark model; these early successes were, however, never permitted to grow into a quantitatively descriptive, much less a predictive, theory of light quarks and antiquarks bound together by gluons, in a rigorous QCD framework. In the present lecture, we restrict ourselves to meson spectroscopy in the low-mass region ≲ 2.2 GeV/c2, and to the attempts to understand their mass and symmetry structure. We point up some particularly vexing open questions and problems. We then review the information that has recently become available from heavy quarkonium (mainly charmonium) decays into light-quark-based mesons. It turns out that these decays, observable largely in the center-of-mass frame, with large counting rates and low multiplicities, are able to permit valuable insights into the quark content and symmetry structure of this regime of u, d, s-based mesons. The lecture is organized as follows:
  1. 2.

    Open questions in the lowest-mass \( q\bar{q} \) nonets.

  2. 3.

    The use of charmonium decays to define projection operators of quark content and symmetry structure.

  3. 4.

    Information available from hadronic and radiative \( c\bar{c} \) decays: a case-by-case review.

  4. 5.

    Do gluonia show up in radiative decays?

  5. 6.

    Exotic candidates: do \( c\bar{c} \) decays have unique information to contribute?

  6. 7.

    A score sheet.



Vector Meson Radiative Decay Quantum Chromo Dynamic Hadronic Decay Quark Content 


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Copyright information

© Plenum Press, New York 1990

Authors and Affiliations

  • Clemens A. Heusch
    • 1
  1. 1.Institute for Particle PhysicsUniversity of CaliforniaSanta CruzUSA

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