A simultaneous measurement of the strong coupling                              
strength and the QCD colour charges                                            
  
     We performed a simultaneous measurement of the strong coupling strength   
     alpha_s and the colour factors of the underlying gauge group of strong    
     interactions, CF and CA.  The measurement was based on fitting            
     next-to-leading-order perturbative predictions to measured angular        
     correlations of four-jet events, in combination with multi-jet related    
     variables.  Our results are in agreement with SU(3) expectations for CF   
     and CA and with the world average value of alpha_s.                       
  
 Parallel session :3                   
 Plenary  session :11