Direct Photon Production in pp and \(\overline{p}\)p Collisions

  • P. T. Cox
Part of the NATO ASI Series book series (NSSB, volume 197)


The simplicity of the leading-order production processes for direct (single) gamma production in pp and \(\overline{p}\)p collisions, i.e. the QCD-Compton process qg → γq and the annihilation process \(\overline{q}\)q → γg, is appealing, since the photon carries all the pT of the parton collision, and there is no confusion from fragmentation. Furthermore the ratio R = σ(\(\overline{p}\)p → γX)/σ(pp → γX) should be sensitive to the hardness of the gluon structure function of the nucleon. Since \(\overline{q}\)q annihilation is clearly more important in \(\overline{p}\)p than pp, due to the valence \(\overline{q}\) quarks, R is expected to be larger than one, and since the gluon structure function is known to be relatively soft so that \(\overline{q}\)q should become increasingly favoured over qg as pT increases, R is expected to increase with the pT of the emitted gamma ray.


Level Trigger Transition Radiation Detector Invariant Cross Section Direct Photon Production Parton Collision 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    The UA6 collaboration is: R. E. Breedon, L. Camilleri, R. L. Cool, P. T. Cox, G. von Dardel, L. Dick, E. C. Dukes, F. Gaille, P. Giacomelli, C. Joseph, W. Kubischta, J.-F. Loude, C. Morel, O. E. Overseth, J. L. Pages, J.-P. Perroud, P. Petersen, D. Ruegger, R. W. Rusack, G. Sozzi, G. R. Snow, L. Studer, M. T. Tran, A. Vacchi, and G. Valenti.Google Scholar
  2. [2]
    J. Antille et al., Phys. Lett. B194 (1987) 568.ADSGoogle Scholar
  3. [3]
    C. De Marzo et al., Phys. Rev. D36 (1987) 16.ADSGoogle Scholar
  4. [4]
    G.J. Donaldson et al., Phys. Rev. Lett. 40 (1978) 684ADSCrossRefGoogle Scholar
  5. F.W. Büsser et al., Phys. Lett. 55B (1975) 232ADSGoogle Scholar
  6. C. Kourkoumelis et al., Phys. Lett 84B (1979) 277ADSGoogle Scholar
  7. T. Akesson et al., Phys. Lett. 158B (1985) 282.ADSGoogle Scholar
  8. [5]
    P. Aurenche et al., Phys. Lett. 140B (1984) 87, and private communication.Google Scholar
  9. [6]
    D.W. Duke and J.F. Owens, Phys. Rev. D30 (1984) 49.ADSGoogle Scholar
  10. [7]
    A.P. Contogouris and H. Tanaka, Phys. Rev. D33 (1986) 1265, and private communication.Google Scholar

Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • P. T. Cox
    • 1
  1. 1.The Rockefeller UniversityNew YorkUSA

Personalised recommendations