Comparison of Particle Production in Quark and Gluon Fragmentation at sqrt s ~ 10 GeV

R. A. Briere

Published 2007-04-20Version 1

Using data collected with the CLEO III detector at the Cornell Electron Storage Ring, we study the inclusive production of baryons/antibaryons (p, /) and mesons (phi and f_2(1270)) in gluon-fragmentation and quark-fragmentation processes. We first corroborate previous per-event total particle yields in Upsilon(1S)->ggg compared with nearby continuum (e+e- -> qqbar) indicating greater (x2) per-event yields of baryons in 3-gluon fragmentation. We find similar results when we extend that comparison to include the Upsilon(2S) and Upsilon(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 Upsilon(1S)->gggamma with that in e+e- -> qqbar 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 both gluon and quark fragmentation. In the photon-tagged analysis (U(1S)->gggamma compared to e+e- -> qqbar+gamma), we find almost no enhancement for protons (1.2+/-0.1), but a significant enhancement (1.9+/-0.3) for /\'s. Overall, per-event baryon production in radiative two-gluon fragmentation is somewhat smaller than that observed in three-gluon decays of the Upsilon(1S). Our results for baryon production are inconsistent with the predictions of the JETSET (7.3) fragmentation model.