Comparison of particle production in quark and gluon fragmentation at s∼10GeV

R. A. Briere, T. Ferguson, G. Tatishvili, H. Vogel, M. E. Watkins, J. L. Rosner, N. E. Adam, J. P. Alexander, D. G. Cassel, J. E. Duboscq, R. Ehrlich, L. Fields, R. S. Galik, L. Gibbons, R. Gray, S. W. Gray, D. L. Hartill, B. K. Heltsley, D. Hertz, C. D. JonesJ. Kandaswamy, D. L. Kreinick, V. E. Kuznetsov, H. Mahlke-Krüger, P. U E Onyisi, J. R. Patterson, D. Peterson, J. Pivarski, D. Riley, A. Ryd, A. J. Sadoff, H. Schwarthoff, X. Shi, S. Stroiney, W. M. Sun, T. Wilksen, M. Weinberger, S. B. Athar, R. Patel, V. Potlia, J. Yelton, P. Rubin, C. Cawlfield, B. I. Eisenstein, I. Karliner, D. Kim, N. Lowrey, P. Naik, M. Selen, E. J. White, J. Wiss, R. E. Mitchell, M. R. Shepherd, D. Besson, H. K. Swift, T. K. Pedlar, D. Cronin-Hennessy, K. Y. Gao, J. Hietala, Y. Kubota, T. Klein, B. W. Lang, R. Poling, A. W. Scott, A. Smith, P. Zweber, S. Dobbs, Z. Metreveli, K. K. Seth, A. Tomaradze, J. Ernst, K. M. Ecklund, H. Severini, W. Love, V. Savinov, O. Aquines, Z. Li, A. Lopez, S. Mehrabyan, H. Mendez, J. Ramirez, G. S. Huang, D. H. Miller, V. Pavlunin, B. Sanghi, I. P J Shipsey, B. Xin, G. S. Adams, M. Anderson, J. P. Cummings, I. Danko, D. Hu, B. Moziak, J. Napolitano, Q. He, J. Insler, H. Muramatsu, C. S. Park, E. H. Thorndike, F. Yang, T. E. Coan, Y. S. Gao, M. Artuso, S. Blusk, J. Butt, J. Li, N. Menaa, G. C. Moneti, R. Mountain, S. Nisar, K. Randrianarivony, R. Sia, T. Skwarnicki, S. Stone, J. C. Wang, K. Zhang, G. Bonvicini, D. Cinabro, M. Dubrovin, A. Lincoln, D. M. Asner, K. W. Edwards

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18 Scopus citations


Using e+e-→hadrons data collected with the CLEO-III detector at the Cornell Electron Storage Ring, we study the inclusive production of baryons/antibaryons (p,Λ) and mesons ( and f2(1270)) in gluon-fragmentation and quark-fragmentation processes. We first corroborate previous per-event total particle yields in Υ(1S)→ggg compared with nearby continuum (e+e-→qq̄) indicating greater (∼×2) per-event yields of baryons in 3-gluon fragmentation. We find similar results when we extend that comparison to include the Υ(2S) and Υ(3S) resonances. With higher statistics, we now also probe the momentum dependence of these per-event particle yields. Next, we compare particle production in the photon-tagged process Υ(1S)→ggγ with that in e+e-→qq̄γ events, to allow comparison of two-parton with three-parton particle-specific fragmentation. For each particle, we determine the "enhancement" ratio, defined as the ratio of particle yields per gluon-fragmentation event compared to quark-fragmentation event. Thus defined, an enhancement of 1.0 implies equal per-event production in gluon and quark fragmentation. In the photon-tagged analysis (Υ(1S)→ggγ compared to e+e-→qq̄γ), we find almost no enhancement for protons (∼1.2±0.1), but a significant enhancement (∼1.9±0.3) for Λ's. This small measured proton enhancement rate is supported by a study of baryon production in χb2→gg→p+X relative to χb1→qq̄g→p+X. Overall, per-event baryon production in radiative two-gluon fragmentation is somewhat smaller than that observed in three-gluon decays of the Υ(1S). Our results for baryon production are inconsistent with the predictions of the JETSET (7.3) fragmentation model.

Original languageEnglish (US)
Article number012005
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number1
StatePublished - Jul 27 2007

Bibliographical note

Funding Information:
W. Cai appreciates the assistance from Keonwook Kang and Seunghwa Ryu in constructing the case studies and acknowledges support by NSF grant CMS-0547681, AFOSR grant FA9550-07-1-0464, and the Army High Performance Computing Research Center at Stanford. J. Li acknowledges support by NSF grant CMMI-0728069 and DMR-1008104, MRSEC grant DMR-0520020, and AFOSR grant FA9550-08-1-0325.


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