The data recorded at the peak of the Z⁰ boson resonance with large statistics are of primary importance for studies of QCD. Some observables with particular perturbative properties  are used for determinations of alpha_s. Event-shapes in general serve as control variables for the tuning of QCD event generators, event shape mean values are particulary well suited for the energy evolution and inclusive charged particle distribution are analysed in the frame of MLLA calculations.  New variables have been proposed for tests of 4-jet calculations at NLO.
Here a consistent measurement of a large variety of variables is presented. High quality data from the runs in 1994 and 1995 have been re-analysed,  1.1 million events were selected and the variables have been measured with Energy Flow Objects (both charged tracks and neutral calorimeter clusters).

The measurements of event-shape variables presentedted here superseede results given in a previous publication

General explanation of the plots 

Each differential measurement is shown as a plot in eps format and compared to various Monte Carlo prediction.
Non-QCD experts may find this  explanation   useful.

Definition of the variables 

Find out how the variables are precisely defined. A definition is given in [postscript]  format or [PDF] .

• Thrust  [table][plot]
• Thrust Major  [table][plot]
• Thrust  Minor (log(T_Mi)) [table][plot]
• Oblateness  [table][plot]
• Heavy jet mass squared [table][plot]
• Light jet mass squared [table][plot]
• Jet mass difference (M_H - M_L) [table][plot]
• Sphericity  [table][plot]
• Aplanarity  [table][plot]
• -log(y2) Durham scheme [table][plot]
• -log(y3) Durham scheme [table][plot]
• -log(y4) Durham scheme [table][plot]
• -log(y5) Durham scheme [table][plot]
• -log(y6) Durham scheme [table][plot]
• Wide jet broadening [table][plot]
• Total jet broadening [table][plot]
• Narrow jet broadening [table][plot]
• C-parameter  [table] [plot]
• D-parameter  [table] [plot]

Energy-Energy correlation and asymmetry at Q=91.2 GeV 

• Energy-Energy correlation (EEC)  [table] [plot]
• Energy-Energy correlation asymmetry (AEC)  [table] [plot]

Single inclusive jet mass and jet broadening at Q=91.2 GeV 
 

• Single inclusive jet mass (M_S)  [table][plot]
• Single inclusive jet broadening (B_S) [table][plot]

4-jet observables Minor and D-parameter for different y_cut at Q=91.2 GeV 

• Thrust  Minor (log(T_Mi) y_cut > 0.1) [table][plot]
• Thrust  Minor (log(T_Mi) y_cut > 0.05) [table][plot]
• Thrust  Minor (log(T_Mi) y_cut > 0.025) [table][plot]
• D-parameter (y_cut > 0.1)   [table] [plot]
• D-parameter (y_cut > 0.05)   [table] [plot]
• D-parameter (y_cut > 0.025)   [table] [plot]

n-jet rates (Durham) as function of y_cut at Q=91.2 GeV 

• 1-jet rate  [table] [plot]
• 2-jet rate  [table] [plot]
• 3-jet rate  [table] [plot]
• 4-jet rate  [table] [plot]
• 5-jet rate  [table] [plot]
• 6-jet rate  [table] [plot]

mean values and second moments of event-shape variables at Q=91.2 GeV 

• mean values [html] [asci]
• second moments [html] [asci]

Inclusive charged particle momentum spectrum at  Q=91.2 GeV 

• Inclusive distribution of  xi = -log(x_p)   [table] [plot]

 

• Jet resolution parameters  -log(y₂) to -log(y₅)   [plot]
• n-jet fractions  1-jet to 6-jet   [plot]
• D-parameter for different y_cut  from 0.025  to 0.1  [plot]
• Thrust Minor (log(T_Mi)) for different y_cut from 0.025  to 0.1  [plot]