Tuesday 18th May 1999
                                                Ian Tomalin

                MINUTES OF THE 31st BEW MEETING
               =================================

Agenda
------
    I.Tomalin: "SM predictions newest ZFITTER version",
               "Effect of Afb theory error on contact term limits",
           and "Using d(sigma)/d(|cos(theta)|) of qq in graviton search".
                                                                     
 P.-F. Giraud: R_b in Z0 calibration data                            

       C. Goy: Heavy flavour progress report                   

      E.Merle: First look at 1999 dileptons

 M.-N. Minard: "First look at 1999 hadronic events",
          and  "Polar angle systematic in Bhahbas",


I.Tomalin: SM predictions newest ZFITTER version
-------------------------------------------------
  v5.15 and v6.04 agree to better than 1% if ISR/FSR interference
is switched off. However, there was a bug in the interference for
qq in v5.15 which caused it to be X3 too large.

I.Tomalin: Effect of Afb theory error on contact term limits
-------------------------------------------------------------
  Theory error on Afb and experimental systematic error on Afb 
included in contact term fits. Limits get worse for qq and Bhabha 
channels by about 10%. Also, all new physics limit programs tidied up 
to ease maintenance.

I.Tomalin: Using d(sigma)/d(|cos(theta)|) of qq in graviton search
-------------------------------------------------------------------
  d(sigma)/d(|cos(theta)|)(qqbar) is 4th order polynomial in presence
of gravity. Adding it to graviton fit improves slightly sensitivity
of hadronic events, but combined limit from all channels is still
dominated by the Bhahbas.

P.-F. Giraud: R_b in Z0 calibration data                            
-----------------------------------------
  R_b measured with QIPBTAG event tag in Z0 calibration data.
Results very similar in 96, 97, 98. R_b too high for small and
intermediate cut values.
  Applying the Higgs group track smearing routine makes R_b too
low at small cut values.

C. Goy: Heavy flavour progress report                   
--------------------------------------
  Since winter conf.:
     i) BTRK card removed from QIPBTAG (bug)
    ii) udsc efficiency of QIPBTAG studied with WW semileptonic events.
        Is higher in data than in MC in barrel region of detector.
   iii) QIPBTAG selects 4% fewer tracks in data than MC,
          so delete excess tracks in MC.
    iv) B decay mult. is 5.49 in MC and 4.96 in data, so 
          delete excess tracks from B decay in MC.

   => R_b = 0.17 +- 0.012 at LEP2 
   => But at LEP1, measured R_b rises dramatically with QIPBTAG
      cut.

     v) R_c analysis simplified: 12 NN variables -> 9.

E.Merle: First look at 1999 dileptons
--------------------------------------
  Results for all channels. e.g.
     16 exclusive dimuons => sigma = 3.7+-0.9 pb  (SM=2.6)
    321 e+e- events       => sigma = 86.5+-4.8 pb  (SM=?)

  Z return peak is missing for dimuons (statistics ?)

M.-N. Minard: First look at 1999 hadronic events
-------------------------------------------------
  Exclusive qq: sigma 23.9 +- 2.4 pb  (SM=18.6)
  Inclusive qq: sigma 107  +- 5   pb  (SM=93)

Inclusive cross section is high (calibration in forward region bad ?).
For Thrust < 0.75, data/MC events = 20/13 => No WW missing !

M.-N. Minard: Polar angle systematic in Bhahbas
------------------------------------------------
  Polar angle measured by FRFT 0 agrees well with that from FRFT 2.
Both disagree with ECAL by a few mrads.