Joachim Meyer
 
 
                  MINUTES OF THE BEW MEETING  12/07/00
                 =======================================

 
  1. Z' Limits (G. Quast)
    =====================
 
   Guenter gave updated information on recent fits searching
   for a Z'. 
   The data used are 
       185 x-sextion and Asym. measurements from LEP1  and
        48 measurements at LEP2 up to 202 GeV
        R_b measurements are included  
 
   Including LEP1 data gives more sensitive limits. 
 
   Using the correct 95% one-sided CL for a one-sided distribution
   (delta Chisq = 3.84) gives new limits which are substantially
    improved w.r.t. previous ones :
       
           Model       M_Z' limit (GeV)
          E6(chi)        680
          E6(psi)        410          
          E6(eta)        350
          E6(I)          510
          LRsym          600
   
   Details of this analysis con be found in :
   ALEPH 2000-057 PHYSIC (PHYSICs) 2000-019



   2. 2000 Data analysis  : Dileptons (I. De Bonis)
     ==============================================
 
    Isabelle presented the dileptonresults corresponding 
    to 
        E = 204.9  GeV  with 61.54 pb-1
        E = 206.7  GeV  with 31.15 pb-1
    
    MC used : 204 and 206 (202 for gamma/gamma backgr)
 
    Results were presented for 
       - exclusive analysis 
           (sqrt(s'/s) > 0.1 for mumu and tautau
            -0.9 < cos Th* < 0.9  for ee 
       - inclusive analysis 
           (sqrt(s'/s) > 0.9 for mumu and tautau
            -0.9 < cos Th* < 0.7  for ee 
       - both energies 
 
  all error statistically only

  mu mu : 
  -----
     E = 204.9  incl.  sigma = 6.07+-0.4  sigma_SM = 5.98
                excl.  sigma = 1.91+-0.2  sigma_SM = 2.24 
                        A_fb = 0.57+-0.07
 
     E = 206.7  incl.  sigma = 5.48+-0.55  sigma_SM = 5.86
                excl.  sigma = 2.04+-0.28  sigma_SM = 2.19 
                        A_fb = 0.60+-0.10  A_fb_SM  = 0.54 
  
     Distributions in sqrt(s'/s), M_mumu and cos Th* look ok 
 
 
  tau tau : 
  ---------
     E = 204.9  incl.  sigma = 6.07+-0.5 
                excl.  sigma = 2.30+-0.3  sigma_SM = 2.32 
                        A_fb = 0.576+-0.09
 
     E = 206.7  incl.  sigma = 5.89+-0.7  
                excl.  sigma = 1.99+-0.4  sigma_SM = 2.27 
                        A_fb = 0.526+-0.14  A_fb_SM  = 0.54 
  
     Distributions in sqrt(s'/s), M_mumu and cos Th* look ok 

 
    e+ e- : 
  --------
     E = 204.9  incl.  sigma = 75.5+- 1.4  sigma_SM = 74.4
                excl.  sigma = 15.03+-0.58 sigma_SM = 15.2
             
 
     E = 206.7  incl.  sigma = 73.7+- 1.9  sigma_SM = 74.5
                excl.  sigma = 14.8+-0.8  sigma_SM = 15.3 
        
     Distributions in M_ee and cos Th* look ok, apart from 
     a systematic undershoot of the data at backward Th* for
     206.7 GeV. 

 
   3. 2000 Data analysis  : Dijets (M.-N. Minard)
     ==============================================
 
    Marie-Noelle presented the equivalent results for 
    difermion hadronic final states.
 
    All distributions shown 
       - M_vis
       - cos TH_jet
       - E_gamma
       - TH_gamma
       - sqrt(s'/s)
       - Thrust
       - Cos TH_thrust
    agree for both energies well with SM-expectation
 
   cross sections :
      204.9   incl :  sigma = 78.47 +- 1.24  
              excl :  sigma = 15.98 +- 0.55  Sigma_SM = 15.76
 
      206.7   incl :  sigma = 80.81 +- 1.81  
              excl :  sigma = 16.27 +- 0.79  Sigma_SM = 15.38
 

     4. A.O.B.
 
       M.-N. Minard will present the new results and also
       the combined LEP results at the 'ALEPH-Thursday-Meeting'
       on 18/7/00.