Phys. Rev. D 76, 012005 (2007) [12 pages]Comparison of particle production in quark and gluon fragmentation at √s∼10 GeVReceived 19 April 2007; published 27 July 2007 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 (ϕ 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-→qq̅ ) 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-→qq̅ γ 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-→qq̅ γ), 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→qq̅ g→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. © 2007 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevD.76.012005
DOI:
10.1103/PhysRevD.76.012005
PACS:
12.38.Aw, 12.38.Qk, 13.60.Hb, 13.87.Fh
|
|
About | Terms and Conditions | Subscriptions | Search | Help
Use of the American Physical Society websites and journals implies that the user has read and agrees to our Terms and Conditions and any applicable Subscription Agreement. Physical Review®, Physical Review Letters®, Reviews of Modern Physics®, and Physical Review Special Topics® are trademarks of the American Physical Society.