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     *   Minutes of the April 4th meeting   *
     *   of the "Ew paper working group".   *
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Most likely the next electroweak paper
will be splitted into two parts:
 
  1. Asymmetry paper (coordinated by H. Videau)
  2. Cross-sections + SM fits.
 
This will allow us to proceed in a faster way.
If the two documents will be ready at the same time,
they can always be merged at a later stage.
 
 
Both papers will include all of LEP1 data taken
between 1990 and 1995. It has been decided to drop
the 1989 data.
 
ON THE CROSS-SECTION PAPER:
 
It is going to be prepared in a "democratic way" by the
people of the working group. In particular
each section will be responsibility of the person(s) doing
the corresponding analysis.
Since this publication is going to be the final
EW one , at least for what concerns the "standard analyses",
all selections should be explained with some detail (not only
referencing previous publications).
This emplies that the paper will be submitted to Zeit. f. Phys.
 
More important:
THE ANALYSES SHOULD BE HOMOGENEOUS so they should be
repeated if the older cuts and the present ones differ.
 
Using all data, the systematic errors will dominate the
statistical errors for the lepton channels.
THE DIFFERENT CONTRIBUTIONS TO THE SYSTEMATIC ERRORS
SHOULD BE RECONSIDERED IN DETAIL. Some errors that were adeguate
when the statistics was lower are not adeguate now.
 
*everybody should check if the existing MC is sufficient,
especially for off-peak points.
*if the MC will be redone, we have to use the same JULIA
version in data and MC
*do we need reprocessing of the old data?
--> investigate all these points before next meeting.
 
Two run selections exist for 1995: EW(fill 2852<-->3042)
for cross-section measurements and EA for asymmetries.
 
Some specific comments and questions for the different channels:
 
taus: cuts changed from 94 onwards. The previous years should
be analysed in the same way.
There is no obvious way to improve the
systematics.
 
e+e-: UNIBAB replaced BABAMC in 93 --> data
1990-1992 should be reanalysed with UNIBAB.
Should we keep on subtracting the t-channel contribution?
Should we change the angular acceptance cut to reduce the t-channel
contribution? No more studies on this were done after 1990.
 
mu+mu-: reanalyse all data with the same program and
cuts and with MC statistics improved.
Also, what about the systematic error associated to
radiative events (0.15%)? Is this evaluation still correct
if KORL07 is used instead of KORl06?
A program by Martinez, Miquel exists to generate
mumugg events.
 
hadrons: All data have already been analysed in
a homogeneous way with the TPC selection.
The calo selection is homogenous since 1991.
The 1990 selection will be redone.
 
lumi: LCAL measured lumi till sept. 1992.
SICAL:  92 no change
        93 propagate 0.07% correction due to
           new measurement of distance between the
           counters on two sides of the interaction point
        94 finished
        95 bunch train period, results before summer
BHLUMI: a teoretical error of 0.11% can be used in the
        analysis
 
 
Just to be clear: there is no intention to change the
analyses in a radical way, but rather
1. to improve things which can obviously be
   improved (such as, for ex. the MC statistics).
2. to rethink a bit of decisions which were taken at the
   beginning (when we had less data and we knew less)
   and never rediscussed.
3. to treat all data in a homogeneous way .
 
What precisely needs to be done for the various channels
should be established soon and will represent the basis
of a talk that Monica was asked to give at the next
Aleph week (subject: what is still to be done in the
EW sector..)
 
Other, entirely new analyses are of course possible
and welcome. Work in this respect is going on by
Edwige Tournefier and Ioana Videau who are trying
to reanalyse all leptons and aim at reducing
the systematic errors significantly.
Preliminary results are likely to be shown
sometimes in the summer.
 
The ambitious aim is to complete the work
on the cross-sections in time for the
summer conferences, in particular for the ALEPH
week of june 24 (at least the numbers and a draft).
This was considered possible by all the people
present at the meeting with some reservations
from the Bhabha group. Marie-Noelle and Monica
expressed their intention to help with this analysis.
 
The group is going to meet regularly.
Minutes will always be distributed.
 
Next meetings:
April 11th
April 23 15h.