The Superworld II pp 265-301 | Cite as

# Light-Quark Spectroscopy from Charmonium Decay

Chapter

## Abstract

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 SU_{6}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/c^{2}, 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:- 2.
Open questions in the lowest-mass \( q\bar{q} \) nonets.

- 3.
The use of charmonium decays to define projection operators of quark content and symmetry structure.

- 4.
Information available from hadronic and radiative \( c\bar{c} \) decays: a case-by-case review.

- 5.
Do gluonia show up in radiative decays?

- 6.
Exotic candidates: do \( c\bar{c} \) decays have unique information to contribute?

- 7.
A score sheet.

## Keywords

Vector Meson Radiative Decay Quantum Chromo Dynamic Hadronic Decay Quark Content
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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## References

- 1.For a description of the basic non-relativistic quark model,
*see*R.H. Dalitz, in*High Energy Physics*,Les Houches 1965 Lectures, C. de Witt and M. Jacob, eds., Gordon & Breach, New York (1966) pp. 251 ff. The QCD-inspired version was first worked out by A. de Rujula, H. Georgi, S.L. Glashow,*Phys. Rev*.**D12**, 147 (1975).Google Scholar - 2.
- N. Isgur, in
*The New Aspects of Subnuclear Physics*,A Zichichi, ed., Plenum Press, New York, (1980).Google Scholar - 3.Such calculations were explicitly done for low-mass pseudoscalar mesons: J.F. Donoghue, and H. Gomm,
*Phys. Lett*.**121b**, 49 (1983).Google Scholar - 4.See also the summary talk of Hadron ‘87 by J.L. Rosner in the Proceedings volume, KEK 87–7(1987).Google Scholar
- 5.Ideal mixing corresponds in the standard mixing scheme (here illustrated for the case of the pseudoscalars), \( \eta =\cos \theta {{\eta }^{(8)}}+\sin \theta {{\eta }^{(1)}}, \) \(\eta ' = - \sin \theta {\eta ^{(8)}} + \cos \theta {\eta ^{(1)}},\) to an angle θ ≈ 35°. With the usual
*η*^{(8)},*η*^{(1)}quark assignments, it would lead to \( \eta =\frac{1}{\sqrt{2}}(u\bar{u}+d\bar{d}), \) \(\eta ' = - s\bar s.\) Google Scholar - 6.
- 7.
- 8.
- 9.V. Novikov
*et al*.,*Nucl. Phys*.**B165**, 67 (1980); for a lucid explanation of the instanton concept, read chapter 7 of S. Coleman,*Aspects of Symmetry*(Selected Erice Lectures), Cambridge Univ. Press (1985).Google Scholar - 10.
- 11.The MARK III detector is described in D. Bernstein
*et al*.,*Nucl. Instrum. & Methods***226**, 301 (1984);Google Scholar - 12.
- 13.
- 14.
- 15.
- 16.J. Adler
*et*al., (MARK III Collaboration), Contribution to the EPS Conference on High Energy Physics, Uppsala (1987), to be published; Z. Ajaltouni et al., (DM2 Collaboration),*Contributions to the 1987 Lepton-Photon Symposium*, Hamburg.Google Scholar - 17.Numerous such schemes have been suggested; see,
*e.g*., F. Caruso*et al*.,*Z. Phys*.**C30**, 493 (1986).Google Scholar - 18.
- 19.
- 20.
- G. Gidal
*et al*.,(MARK II Collaboration)*Phys. Rev. Lett*.**59**, 2016 (1987).PubMedCrossRefGoogle Scholar - 21.This signal is observed in the charge modes
*K*_{s}*K*^{±}*π*^{∓}, K^{+}K^{−}*π*^{0},*K*_{s}*K*_{s}*π*^{0}, by the MARK III Collaboration. (J. Richman, CalTech thesis (1983), unpublished), and by the DM2 Collaboration (J. Augustin,*et al*., LAL-85/27 1985)).Google Scholar - 22.This state (see J. Richman, previous ref.) was originally identified with
*ι*(1460); its important radiative width (Г(*X*) →*γρ*^{0}= 1.9 ± 0.7 MeV) was taken as an argument in opposition to the gluonium interpretation of*ι*(1460). See J. Donoghue in*Particles and Fields 1981*, C.A. Heusch and W.T. Kirk, eds. AIP, New York (1982).Google Scholar - 23.F. Close, in
*Quarks and Hadronic*Matter, Yukon Advanced Studies Institute (1984), originally proposed this test of the*ι*wavefunction, in the context of vector-dominance relations between photon and vector mesons.Google Scholar - 24.N. Wermes,
*Proc. 5th Conference on Physics in Collision*, Autun, France, World Scientific (1986).Google Scholar - 25.Note that S-wave qq scattering lengths would lead naturally to an appearance of 0
^{−+}characteristics. A quantitative evaluation is presently in progress.Google Scholar - 26.The recent DM2 results (D. Bisello
*et al*.,*Contributions to the 1987 Lepton-Photon Symposium*, Hamburg, and L. Stanco, Orsay preprint LAL-87–40) present the most consistent data sample. Note that the decay*η*_{c}→*φφ*permitted the MARK III Collaboration to confirm the identity of the state by way of a straightforward spin-parity analysis (R. Baltrusaitis*et al*.,*Phys. Rev*. Lett.**52**, 2126 (1984).Google Scholar - 27.L. Köpke (MARK III Collaboration),
*Proceedings of the XXIIrd International Conference on High Energy Physics*, S. Loken, ed., World Scientific, Singapore (1986).Google Scholar - 28.J.E. Augustin
*et al*., LAL 85/27 (1985).Google Scholar - 29.D.M. Coffman
*et*al., (MARK III Collaboration), SLAC-PUB-4460 (to be published).Google Scholar - 30.W. Lockman (MARK III Collaboration),
*Proceedings*,*1986 San Miniato Workshop*(to be published).Google Scholar - 31.W. Lockman (MARK III Collaboration),
*Proceedings*,*1986 Lake Louise Conference on Intersections of Nuclear and Particle Physics*. Google Scholar - 32.H. Kolanski and P. Zerwas, DESY Preprint 87–175 (1987).Google Scholar
- 33.D. Aston
*et al*., DPNU 87/15; SLAC-PUB-4279 (1987); to be published in Nucl. Phys. B.Google Scholar - 34.L. Köpke (MARK III Collaboration), SCIPP/MARK III Memo (1986). Unpublished.Google Scholar
- 35.See the contributions of C. Heusch and A. Seiden to the MARK III Pow-Wow; SLAC-Report 323 (1988).Google Scholar
- 36.J. Adler
*et*al., (MARK III), to be published. T. Bolton, Ph.D. thesis, M.I.T. (1988); unpublished.Google Scholar - 37.
- 38.C. Edwards
*et al*., (Crystal Ball Collaboration),*Phys. Rev. Lett*.**48**, 458 (1982).CrossRefGoogle Scholar - 39.J. Adler
*et al*.,(MARK III), Contribution to the*Proceedings of the EPS Conference*, Uppsala (1987), G. Dubois, editor. Note that the MARK III data are severely limited due to the absence of a neutral trigger; this is presently being installed.Google Scholar - 40.
- 41.Should this scenario turn out to be correct, the confusing nomenclature of these states would obviously be redefined.Google Scholar
- 42.
- 43.
- 44.The interest of the final state
*ηη*’ in the context of gluonium searches has been discussed by S.S. Gershtein*et al*.,*Z. Phys*.**C24**, 305 (1984).Google Scholar - 45.
- 46.
- 47.J. Adler
*et*al., (MARK III Collaboration), as quoted by G. Dubois in*Proceedings of the EPS Conference*, Uppsala (1987)Google Scholar - 48.L. Stanco
*et al*., (DM2 Collaboration), LAL 87–42 (1987).Google Scholar - 49.For recent gluonium reviews, see, e.g., F.E. Close, R/XL-87–072 to be published in Rep. Progr. Phys.; F. Couchot, LAL 87–40 (1987); C.A. Heusch,
*Proceedings*,*Multiparticle Symposium*, Seewinkel, World Scientific, Singapore (1986); M.S. Chanowitz, in*Hadron ‘87*, KEK, Tsukuba (1987).Google Scholar - 50.J.D. Bjorken,
*Proceedings*,*1979 SLAC Summer School*, A. Mosher ed., SLAC Report 224 (1980). See also M. Chanowitz, Ref. 53, and S. Gershtein*et al*., Ref. 44.Google Scholar - 51.
- 52.
- 53.M. Chanowitz (
*Proc. V**I*^{th}*International Workshop on Photon-Photon Colli**sions*, World Scientific, Singapore (1984)) defined this relative gluon affinity as “stickiness” \(S = {\left( {\frac{{ms}}{{k*(\not \upsilon \to \gamma X)}}} \right)^3}\frac{{\Gamma (Y \to \gamma X)}}{{\Gamma (X \to \gamma \gamma )}}.\). This measure can serve as a comparison of states with equal quantum number: for*J*^{PC}=0^{−+},*S*(*ι*):*S*(*η*′):*S*(*η*) =(>65):4:1; for*J*^{PC}=2^{++},*S*(Θ):*S*(*f*′):*S*(*f*)=(>20):3:1.Google Scholar - 54.The values for
*Rγ*and*R*_{V}, given by C.A. Heusch in Ref. 49 have to be updated using recent MARK II data on*γγ*→*ι*(1460) limits- G. Gidal,*et al*.,*Phys. Rev. Lett*.**59**, 2016 (1987).Google Scholar - 55.F. Binon (GAMS Collaboration),
*Proceedings of the Hadron ‘87 Conference*, KEK, Tsukuba (1987); a similar signal may have been seen by W.D. Apel*et al*.,*Nucl. Phys*.**B193**, 269 (1983).Google Scholar - 56.
- 57.F.S. Close, H.J. Lipkin, RAL 87/046 (1987), and M. Boutemeur, in
*Hadrons*,*Quarks*,*and Gluons*, J. Tran Thanh Van, ed., Editions Frontières, Paris (1987).Google Scholar - 58.This feature was postulated long ago: T. Barnes,
*Z. Phys*.**C10**, 275 (1981). Note, however, that preliminary data of both the DM2 and MARK III Collaborations show indications of a non-pseudoscalar enhancement at*m*(4*π*) 1285 MeV/c^{2}, in the radiative decay process*J/ψ*→*γπ*^{+}*π*^{−}*π*^{+}*π*^{−}. If this state is to be identified with*f*_{1}(1285), the argument has to be modified from “absence” to “suppression” of states not accessible to two transverse gluons.Google Scholar

## Copyright information

© Plenum Press, New York 1990