Tests of models for parton fragmentation in e e annihilation. [29 GeV center-of-mass energy]

Technical Report · Fri Nov 01 04:00:00 EST 1985

DOI:https://doi.org/10.2172/6327329· OSTI ID:6327329

Gary, J W

We examine the distribution of particles in the three jet events of e e annihilation. The data was collected with the PEP-4/Time Projection Chamber detector at 29 GeV center-of-mass energy at PEP. The experimental distributions are compared to the predictions of several fragmentation models which describe the transition of quarks and gluons into hadrons. In particular, our study emphasizes the three fragmentation models which are currently in widest use: the Lund string model, the Webber cluster model and the independent fragmentation model. These three models each possess different Lorentz frame structures for the distribution of hadron sources relative to the overall event c.m. in three jet events. The Lund string and independent fragmentation models are tuned to describe global event properties of our multihadronic annihilation event sample. This tuned Lund string model provides a good description of the distribution of particles between jet axes in three jet events, while the independent fragmentation model does not. We verify that the failure of the independent fragmentation model is not a consequence of parameter tuning or of model variant. The Webber cluster model, which is untuned, does not describe the absolute particle densities between jets but correctly predicts the ratios of those densities, which are less sensitive to the tuning. These results provide evidence that the sources of hadrons are boosted with respect to the overall center-of-mass in three jet events, with components of motion normal to the jet axes. The distribution of particles close to jet axes provides additional support for this conclusion. 94 refs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6327329
• Report Number(s): LBL-20638; ON: DE86005893
• Country of Publication: United States
• Language: English

Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR DISTRIBUTION
ANNIHILATION
BARYONS
BASIC INTERACTIONS
BOSONS
CLUSTER MODEL
COMPOSITE MODELS
DATA
DISTRIBUTION
ELECTROMAGNETIC INTERACTIONS
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
EXPERIMENTAL DATA
EXTENDED PARTICLE MODEL
FERMIONS
FRAGMENTATION
GAS TRACK DETECTORS
GEV RANGE
GEV RANGE 10-100
HADRONS
INFORMATION
INTERACTIONS
JETS
KAONS
LEPTON-LEPTON INTERACTIONS
LINEAR MOMENTUM
LONGITUDINAL MOMENTUM
MASS SPECTRA
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MESONS
MONTE CARLO METHOD
NUCLEAR MODELS
NUCLEONS
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE TRACKS
PARTONS
PATTERN RECOGNITION
PEP STORAGE RINGS
PIONS
POSTULATED PARTICLES
PROJECTION SPARK CHAMBERS
PROTONS
PSEUDOSCALAR MESONS
QUARK MODEL
RADIATION DETECTORS
SPARK CHAMBERS
SPECTRA
STORAGE RINGS
STRANGE PARTICLES
STRING MODELS
THEORETICAL DATA
TRANSVERSE MOMENTUM