Comparison of three-jet and radiative two-jet events in electron-positron annihilation at 29 GeV

Technical Report · Sat Nov 01 04:00:00 EST 1986

DOI:https://doi.org/10.2172/5707921· OSTI ID:5707921

Sheldon, P D

By comparing 3-jet (e/sup +/e/sup -/ ..-->.. q anti q g) and radiative 2-jet (e/sup +/e/sup -/ ..-->.. q anti q ..gamma..) events from electron-positron annihilation, we have studied the local and global effects of the presence of a hard bremsstrahlung gluon in hadronic events. Detector and event selection efficiencies and biases affect these two kinds of events almost equally because they have very similar kinematics and topologies. Accurate comparisons of q anti q g and q anti q ..gamma.. events can therefore be made. Globally, we observe a depletion of hadrons in q anti q g events relative to q anti q ..gamma.. events on the opposite side of the event plane from the gluon, in the angular region between the q and anti q jets. This depletion is shown to be in agreement with the predictions of Quantum Chromodynamics (QCD). The existence of this effect demonstrates that the presence of a gluon significantly alters the color forces and hence the fragmentation process in hadronic events. We also use these q anti q ..gamma.. and q anti q g events to compare low energy (4.5 GeV) gluon and quark jets. Our data indicate that gluon jets have softer x/sub p/ distributions than quark jets, while the transverse momentum distributions of these two types of jets are identical within our errors. Although we are unable to determine if the multiplicities of gluon (n/sub /) and quark (n/sub q/) jets are different, the ratio n/sub g//n/sub q/ = 9/4 predicted asymptotically in QCD would not be consistent with our data.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5707921
• Report Number(s): LBL-22525; ON: DE88003190
• Country of Publication: United States
• Language: English

Related Subjects

645101 -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
645102* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Weak Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANNIHILATION
BASIC INTERACTIONS
COMPOSITE MODELS
DATA
ELECTROMAGNETIC INTERACTIONS
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY SPECTRA
EXPERIMENTAL DATA
EXTENDED PARTICLE MODEL
FIELD THEORIES
FRAGMENTATION
GLUONS
INFORMATION
INTERACTIONS
JETS
LEPTON-LEPTON INTERACTIONS
LINEAR MOMENTUM
MASSLESS PARTICLES
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MONTE CARLO METHOD
MULTIPLE PRODUCTION
MULTIPLICITY
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PRODUCTION
PEP STORAGE RINGS
PHOTONS
POSTULATED PARTICLES
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK MODEL
QUARKS
RADIATION DETECTORS
SHOWER COUNTERS
SPECTRA
STORAGE RINGS
STRING MODELS
TRANSVERSE MOMENTUM