Particle multiplicity of unbiased gluon jets from e+e - three-jet events

G. Abbiendi, C. Ainsley, P. F. Åkesson, G. Alexander, J. Allison, G. Anagnostou, K. J. Anderson, S. Arcelli, S. Asai, D. Axen, G. Azuelos, I. Bailey, E. Barberio, R. J. Barlow, R. J. Batley, P. Bechtle, T. Behnke, K. W. Bell, P. J. Bell, G. BellaA. Bellerive, G. Benelli, S. Bethke, O. Biebel, I. J. Bloodworth, O. Boeriu, P. Bock, J. Böhme, D. Bonacorsi, M. Boutemeur, S. Braibant, L. Brigliadori, R. M. Brown, H. J. Burckhart, J. Cammin, S. Campana, R. K. Carnegie, B. Caron, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, P. E.L. Clarke, E. Clay, I. Cohen, J. Couchman, A. Csilling, M. Cuffiani, S. Dado, G. M. Dallavalle, S. Dallison, A. de Roeck, E. A. de Wolf, P. Dervan, K. Desch, B. Dienes, M. Donkers, J. Dubbert, E. Duchovni, G. Duckeck, I. P. Duerdoth, E. Etzion, F. Fabbri, L. Feld, P. Ferrari, F. Fiedler, I. Fleck, M. Ford, A. Frey, A. Fürtjes, D. I. Futyan, P. Gagnon, J. W. Gary, G. Gaycken, C. Geich-Gimbel, G. Giacomelli, P. Giacomelli, M. Giunta, J. Goldberg, K. Graham, E. Gross, J. Grunhaus, M. Gruwe, P. O. Günther, A. Gupta, C. Hajdu, M. Hamann, G. G. Hanson, K. Harder, A. Harel, M. Harin-Dirac, M. Hauschild, J. Hauschildt, C. M. Hawkes, R. Hawkings, R. J. Hemingway, C. Hensel, G. Herten, R. D. Heuer, J. C. Hill, K. Hoffman, R. J. Homer, D. Horváth, K. R. Hossain, R. Howard, P. Hüntemeyer, P. Igo-Kemenes, K. Ishii, A. Jawahery, H. Jeremie, C. R. Jones, P. Jovanovic, T. R. Junk, N. Kanaya, J. Kanzaki, G. Karapetian, D. Karlen, V. Kartvelishvili, K. Kawagoe, T. Kawamoto, R. K. Keeler, R. G. Kellogg, B. W. Kennedy, D. H. Kim, K. Klein, A. Klier, S. Kluth, T. Kobayashi, M. Kobel, T. P. Kokott, S. Komamiya, R. V. Kowalewski, T. Krämer, T. Kress, J. von Krogh, D. Krop, T. Kuhl, M. Kupper, P. Kyberd, G. D. Lafferty, H. Landsman, D. Lanske, I. Lawson, J. G. Layter, A. Leins, D. Lellouch, J. Letts, L. Levinson, J. Lillich, C. Littlewood, S. L. Lloyd, F. K. Loebinger, J. Lu, J. Ludwig, A. Macchiolo, A. Macpherson, W. Mader, S. Marcellini, T. E. Marchant, A. J. Martin, J. P. Martin, G. Martinez, G. Masetti, T. Mashimo, P. Mättig, W. J. McDonald, J. McKenna, T. J. McMahon, R. A. McPherson, F. Meijers, P. Mendez-Lorenzo, W. Menges, F. S. Merritt, H. Mes, A. Michelini, S. Mihara, G. Mikenberg, D. J. Miller, S. Moed, W. Mohr, T. Mori, A. Mutter, K. Nagai, I. Nakamura, H. A. Neal, R. Nisius, S. W. O'Neale, A. Oh, A. Okpara, M. J. Oreglia, S. Orito, C. Pahl, G. Pásztor, J. R. Pater, G. N. Patrick, J. E. Pilcher, J. Pinfold, D. E. Plane, B. Poli, J. Polok, O. Pooth, A. Quadt, K. Rabbertz, C. Rembser, P. Renkel, H. Rick, N. Rodning, J. M. Roney, S. Rosati, K. Roscoe, Y. Rozen, K. Runge, D. R. Rust, K. Sachs, T. Saeki, O. Sahr, E. K.G. Sarkisyan, A. D. Schaile, O. Schaile, P. Scharff-Hansen, M. Schröder, M. Schumacher, C. Schwick, W. G. Scott, R. Seuster, T. G. Shears, B. C. Shen, C. H. Shepherd-Themistocleous, P. Sherwood, A. Skuja, A. M. Smith, G. A. Snow, R. Sobie, S. Söldner-Rembold, S. Spagnolo, F. Spano, M. Sproston, A. Stahl, K. Stephens, D. Strom, R. Strühmer, L. Stumpf, B. Surrow, S. Tarem, M. Tasevsky, R. J. Taylor, R. Teuscher, J. Thomas, M. A. Thomson, E. Torrence, D. Toya, T. Trefzger, A. Tricoli, I. Trigger, Z. Trócsányi, E. Tsur, M. F. Turner-Watson, I. Ueda, B. Ujvári, B. Vachon, C. F. Vollmer, P. Vannerem, M. Verzocchi, H. Voss, J. Vossebeld, D. Waller, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, P. S. Wells, T. Wengler, N. Wermes, D. Wetterling, G. W. Wilson, J. A. Wilson, T. R. Wyatt, S. Yamashita, V. Zacek, D. Zer-Zion

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Abstract

The charged particle multiplicities of two- and three-jet events from the reaction e+e- → Z0 → hadrons are measured for Z0 decays to light quark (uds) flavors. Using recent theoretical expressions to account for biases from event selection, results corresponding to unbiased gluon jets are extracted over a range of jet energies from about 11 to 30 GeV. We find consistency between these results and direct measurements of unbiased gluon jet multiplicity from Γ and Z0 decays. The unbiased gluon jet data including the direct measurements are compared to corresponding results for quark jets. We perform fits based on analytic expressions for particle multiplicity in jets to determine the ratio r = Ng/Nq of multiplicities between gluon and quark jets as a function of energy. We also determine the ratio of slopes, r(1) ≡ (dNg/dy)/(dNq/dy), and of curvatures, r (2) ≡ (d2Ng/dy2)/(d 2Nq/dy2), where y specifies the energy scale. At 30 GeV, we find r - 1.422 ± 0.051, r(1) = 1.761 ± 0.071 and r(2) = 1.98 ± 0.13, where the uncertainties are the statistical and systematic terms added in quadrature. These results are in general agreement with theoretical predictions. In addition, we use the measurements of the energy dependence of Ng and Nq to determine an effective value of the ratio of QCD color factors, C A/CF. Our result, CA/CF = 2.23 ± 0.14 (total), is consistent with the QCD value of 2.25.

Original languageEnglish
Pages (from-to)597-613
Number of pages17
JournalEuropean Physical Journal C
Volume23
Issue number4
DOIs
Publication statusPublished - Apr 2002
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)

Cite this

Abbiendi, G., Ainsley, C., Åkesson, P. F., Alexander, G., Allison, J., Anagnostou, G., ... Zer-Zion, D. (2002). Particle multiplicity of unbiased gluon jets from e+e - three-jet events. European Physical Journal C, 23(4), 597-613. https://doi.org/10.1007/s100520200926