Advertisement

Two-photon collisions and QCD

  • J. F. Gunion
Session X
Part of the Lecture Notes in Physics book series (LNP, volume 134)

Abstract

A critical review of the applications of QCD to low- and high-pT interactions of two photons is presented. The advantages of the two-photon high-pT tests over corresponding hadronic beam and/or target tests of QCD are given particular emphasis.

Keywords

Gluon Distribution High Twist Exclusive Reaction Meson Wave Function Vector Dominance 
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.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    See M. Greco's talk at the “Workshop on Two Photon Collisions,” Amiens, France (1980) and references therein.Google Scholar
  2. 2.
    F. E. Low, Phys. Rev. D12 (1975) 163; S. Nussinov, Phys. Rev. Lett. 34 (1975) 1286; J. F. Gunion and D. E. Soper, Phys. Rev. D15 (1977) 2617.Google Scholar
  3. 3.
    See the talks of Ch. Berger (PLUTO) and E. Hilger (TASSO) at the “Workshop on Two Photon Collisions,” Amiens, France (1980).Google Scholar
  4. 4.
    J. F. Gunion, Phys. Lett. 88B (1979) 150.Google Scholar
  5. 5.
    V. Chang and R. Hwa, Phys. Lett. 85B (1979) 285.Google Scholar
  6. 6.
    See for example, W. R. Frazer and J. F. Gunion, Phys. Rev. D20 (1979) 147.Google Scholar
  7. 7.
    The actual prediction incorporating spin is (1-x) 2 + constant, (1-x) is an adequate approximation over the moderate x domain. See G. Farrar and D. R. Jackson, Phys. Rev. Lett. 35 (1975) 1416.CrossRefGoogle Scholar
  8. 8.
    The actual prediction isa+b nl(1/1-x)indicating a logarithmic suppression as x → 1.See Ref. 6.Google Scholar
  9. 9.
    A. M. Boyarski et al., Phys. Rev. D14 (1976) 1733. This is 18 GeV γp → π+, πdata. Higher energy data from the tagged photon beam at FNAL will hopefully confirm this lower energy result.Google Scholar
  10. 10.
    See for example, W. Frazer and J. F. Gunion, Phys. Rev. D19 (1978) 2447 and references therein.Google Scholar
  11. 11.
    For a summary of recent progress in this area see S. J. Brodsky, SLAC-PUB-2447, presented at the Summer Institute on Particle Physics, SLAC (1979).Google Scholar
  12. 12.
    R. Blankenbecler, S. J. Brodsky and J. F. Gunion, Phys. Rev. D8 (1973) 4117; Phys. Lett. 39B (1972) 649; P. V. Landshoff and J. C. Polkinghorne, Phys. Rev. D10 (1974) 891 and references therein; M. K. Chase and W. J. Stirling, Nucl. Phys. B133 (1978) 157. For a general review see D. Sivers, R. Blankenbecler and S. J. Brodsky, Phys. Rep. 23C (1976) 1 and Ref. 11.Google Scholar
  13. 13.
    See Ref. 11 and G. P. Lepage and S. J. Brodsky, Phys. Rev. Lett. 87B (1979) 359.Google Scholar
  14. 14.
    R. K. Ellis, M. Furman, H. Haber and I. Hinchliffe, LBL-10304 (1979).Google Scholar
  15. 15.
    See L. F. Abbott and R. M. Barnett, SLAC-PUB-2227, submitted to Annals of Phys.; R. Blankenbecler and I. Schmidt, Phys. Rev. D16 (1979) 1318; W. R. Frazer and I. Schmidt, Phys. Rev. D16 (1979) 1318; W. R. Frazer and J. F. Gunion, SLAC PUB-2489 (1980). The general form of higher twist contributions was first discussed in R. Blankenbecler, S. J. Brodsky and J. F. Gunion, Phys. Rev. D12 (1975) 3469.Google Scholar
  16. 16.
    R. M. Barnett, private communication.Google Scholar
  17. 17.
    See R. Blankenbecler, S. J. Brodsky and J. F. Gunion, Phys. Rev. D18 (1978) 900; D. Jones and J. F. Gunion, Phys. Rev. D20 (1979) 232.Google Scholar
  18. 18.
    S. D. Ellis, P. V. Landshoff and M. Jacob, Nucl. Phys. B108 (1978) 93.Google Scholar
  19. 19.
    Experimental points are from R. Stronowski, SLAC Summer Institute on Particle Physics (1979). Experimental references can be obtained there. TheV-s = 31/ = 53 neff extractions are removed from Stronowski's graph. A different range of PT is being probed compared to the Vs-= 53/yrs = 62 extractions (at xT =.4, PT = 6 to 10 vs. PT = 10 to 12). More higher twist-CIM component is expected (and seen) in the lower Y's extraction; correcting for this yields approximate agreement between the two extractions. I have also added to Stronowski's graph recent neff values obtained by the Athens, Athens, Brookhaven, CERN collaboration (A2BC), C. Kourkoumelis et al., CERN-EP/80-07.Google Scholar
  20. 20.
    See R. P. Feynman, R. D. Field and G. C. Fox, Nucl. Phys. B128 (1979) Phys. Rev. D18 (1978) 3320. A variety of others have also pursued such studies. For references see Refs. 11 and 19. See also R. Field, Proceedings of the Tokyo International Conference on High Energy Physics (1978).Google Scholar
  21. 21.
    See Ref. 19 for a discussion and further references.Google Scholar
  22. 22.
    W. E. Caswell, R. Horgan and S. J. Brodsky, Phys. Rev. D18 (1978) 2415; R. Horgan and P. Scharbach, Phys. Lett. 81B (1979) 215.Google Scholar
  23. 23.
    J. F. Gunion and B. Peterson, U.C. Davis preprint UCD-79-5, Phys. Rev. to be published. Elementary QCD processes were considered in more detail by R. Baier, J. Cleymans and B. Petersson, Phys. Rev. D17 (1978) 2310.Google Scholar
  24. 24.
    H. Frisch et al., Phys. Rev. Lett. 44 (1980) 511.Google Scholar
  25. 25.
    G. R. Farrar and G. C. Fox, Rutgers preprint, RU-79-170 (1980).Google Scholar
  26. 26.
    See P. Seyboth's contribution at the Rencontre de Moriond, Les Arcs, France (1980).Google Scholar
  27. 27.
    R. M. Baltrusaitis et al., FNAL-PUB-79/38 Exp (1979); E. Amaldi et al., Nucl. Phys. B150 (1979) 326; M. Diakonov et al., CERN-EP/80-02 and 80-63.Google Scholar
  28. 28.
    R. Ruckl, S. J. Brodsky and J. F. Gunion, Phys. Rev. D18 (1978) 2469.Google Scholar
  29. 29.
    A. P. Contogouris, S. Papadopoulos and M. Hongoh, Phys. Rev. D16 (1979) 2607.Google Scholar
  30. 30.
    L. Cormell and J. F. Owens, FSU-HEP-800307 (1980).Google Scholar
  31. 31.
    S. J. Brodsky and J. F. Gunion, in progress.Google Scholar
  32. 32.
    S. J. Brodsky, T. DeGrand, J. F. Gunion and J. Weis, Phys. Rev. Lett. 41 (1978) 672; and Phys. Rev. D19 (1979) 1418.CrossRefGoogle Scholar
  33. 33.
    C. H. Llewellyn Smith, Phys. Lett. 79B (1978) 83.Google Scholar
  34. 34.
    K. Kajantie, Phys. Scripta 29 (1979) 230; K. Kajantie and R. Raitio, Nucl. Phys. B159 (1979) 528.Google Scholar
  35. 35.
    M. Abud, R. Gatto and C. A. Savoy, Phys. Rev. D20 (1979) 2224; and Phys. Lett. 84B (1979) 229.Google Scholar
  36. 36.
    S. Berman, J. Bjorken and J. Kogut, Phys. Rev. D4 (1971) 3388.Google Scholar
  37. 37.
    See also M. Chanowitz, Proceedings of the XIIth Rencontre de Moriond (1977), edited by Tran Thanh Van; P. V. Landshoff, LEP Summer Study, 1-13 October 1978; and S. J. Brodsky and J. M. Weis, Memorial Symposium on Strong Inter actions (1978), University of Washington. H. Lipkin, Nucl. Phys. B155 (1979) 104, feels that color fluctuations invalidate this result; however the contribution is basically of a “Z-graph” type (refering to time ordered perturbation theory) which would not be affected by color fluctuations. The issue is not yet settled.Google Scholar
  38. 38.
    F. Berends, Z. Kunszt and R. Gastmans, DESY preprint, DESY-80/O8 (1980).Google Scholar
  39. 39.
    See the talks by Ch. Berger (PLUTO) and E. Hilger (TASSO) at the Amiens “TwoPhoton Workshop (1980).Google Scholar
  40. 40.
    R. Cahn and J. F. Gunion, Phys. Rev. D20 (1979) 2253.Google Scholar
  41. 41.
    K. Kajantie and R. Raitio, Phys. Lett. 87B (1979) 133.Google Scholar
  42. 42.
    See for example, S. J. Brodsky and J. F. Gunion, Phys. Rev. Lett. 37 (1976) 402; K. Konishi, A. Ukawa and G. Veneziano, Phys. Lett. 78B (1978) 243.Google Scholar
  43. 43.
    See G. Veneziano, XIXth International Conference on High Energy Physics, Tokyo (1978).Google Scholar
  44. 44.
    A. Devoto, J. Pumplin, W. Repko and G. L. Kane, Michigan State University preprint (1979).Google Scholar
  45. 45.
    S. J. Brodsky, T. A. DeGrand and R. F. Schwitters, Phys. Lett. 79B (1978) 244.Google Scholar
  46. 46.
    See the talks by P. Kessler, G. Parisi and J. Field at the Amiens “Two-Photon Workshop” (1980) for a critical review of various approximations to Gy/e. In the results quoted here I always use the equivalent photon spectrum.Google Scholar
  47. 47.
    E. Witten, Nucl. Phys. B120 (1977) 189.CrossRefGoogle Scholar
  48. 48.
    Y. Dokshitser, D. Dyakonov and S. Troyan, SLAC-TRAMS-183; R. J. DeWitt, L. Jones, J. Sullivan, D. Nillen and H. Wyld, Phys. Rev. D19 (1979) 2046.Google Scholar
  49. 49.
    W. Bardeen and A. Buras, Phys. Rev. D20 (1979) 166; D. Duke and J. Owens, Florida State University, FSU-HEP-802 401 (1980). These latter authors now agree with Bardeen and Buras.Google Scholar
  50. 50.
    T. Walsh, Amiens “Two-Photon Workshop” (1980); W. Bardeen, Lake Tahoe Two-Photon Conference (1979); W. Frazer, Lake Tahoe Two-Photon Conference (1979).Google Scholar
  51. 51.
    J. Field, E. Pietarinen and K. Kajantie, DESY preprint 79/85 (1979).Google Scholar
  52. 52.
    Actually(3.10) and (3.11)are still correct when the important kn Rn pT/Qn pT corrections to αs(P2 T) are included and thus the scale invariance of (3.12) is only corrected by terms down by a full power of ln p2 T Google Scholar
  53. 53.
    This section is based on work due to S. J. Brodsky and G. P. Lepage, Ref. 11 (and references therein) and work in progress.Google Scholar

Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • J. F. Gunion
    • 1
    • 2
  1. 1.University of California at DavisPhysics DepartmentDavis
  2. 2.Stanford Linear Accelerator CenterStanford UniversityStanford

Personalised recommendations