PHOBOS at RHIC: Some global observations

B. B. Back, M. D. Baker, D. S. Barton, R. R. Betts, M. Ballintijn, A. A. Bickley, R. Bindel, A. Budzanowski, W. Busza, A. Carroll, M. P. Decowski, E. García, N. George, K. Gulbrandsen, S. Gushue, C. Halliwell, J. Hamblen, G. A. Heintzelman, C. Henderson, D. J. HofmanR. S. Hollis, R. Holyński, B. Holzman, A. Iordanova, E. Johnson, J. L. Kane, J. Katzy, N. Khan, W. Kucewicz, P. Kulinich, C. M. Kuo, W. T. Lin, S. Manly, D. McLeod, J. Michalowski, A. C. Mignerey, R. Nouicer, A. Olszewski, R. Pak, I. C. Park, H. Pernegger, C. Reed, L. P. Remsberg, M. Reuter, C. Roland, G. Roland, L. Rosenberg, J. Sagerer, P. Sarin, P. Sawicki, W. Skulski, S. G. Steadman, P. Steinberg, G. S.F. Stephans, M. Stodulski, A. Sukhanov, J. L. Tang, R. Teng, A. Trzupek, C. Vale, G. J. Van Nieuwenhuizen, R. Verdier, B. Wadsworth, F. L.H. Wolfs, B. Wosiek, K. Woźniak, A. H. Wuosmaa, B. Wyslouch

Research output: Contribution to journalConference articlepeer-review


Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies for a large span of pseudorapidities, |η| < 5.4. Three empirical observations have emerged from this data set which require theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central Au + Au collisions, when expressed as dN/dη′ (η′ ≡ η - ybeam), becomes energy independent at high energy for a broad region of η′ around η′ = 0. This energy-independent region grows with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity between particle production in e+e- and Au + Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles and the longitudinal distribution of produced particles are approximately the same in e+e- and in scaled Au + Au. This observation was not predicted and has not been explained. Finally, particle production has been found to scale approximately with the number of participating nucleon pairs for <Npart> > 65. This scaling occurs both for the total multiplicity and for high pT particles (3 < pT < 4.5 GeV/c).

Original languageEnglish
Pages (from-to)865-876
Number of pages12
JournalPramana - Journal of Physics
Issue number5
StatePublished - Nov 2003
EventProceedings of the Workshop on Quantum Chromodynamics (QCD 2002) - Kanpur, India
Duration: 18 Nov 200222 Nov 2002


  • Comparison
  • Heavy ion
  • Multiplicity
  • RHIC


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