17th BEW meeting, Tuesday 9 June 1998.
Minutes taken by D. Schlatter
_____________________________________________________________________
Agenda :
1.- BEW
---
o Dilepton Cross Sections and Asymmetries (E. Merle)
o Hadronic Cross Sections (M.-N. Minard)
o Z' Limits (M. Swynghedauw)
o R_b (F. Cerutti)
o R_c (C. Goy)
o Hadronic jet charge asymmetry for b events (S. Gilardoni)
o Contact Terms (F. Teubert)
o Leptoquarks and Squarks (G. Dissertori)
o R parity violating sneutrinos (I. Tomalin)
Minutes of the BEW meeting, June 9th, 1998
=============================================
present: M.N. Minard, E. Merle, D. Schlatter, G. Dissertori,
F.Teubert, C. Goy, I. Tomalin, M. Swynghedauw, F. Cerutti,
J. Coles, P. Morawitz, A. Blondel,S. Gilardoni
Guest: A. Lucotte
Elsa Merle: Dilepton Cross Sections and Asymmetries
----------------------------------------------------
i) Dilepton (ee, mumu, tautau) cross sections and asymmetries
for Ecm 130-183 GeV are final.
(ISR corrections for 161/172 GeV Bhabhas will be redone with
BHWIDE to be consistent)
ii) Results are in good agreement with SM (BHWIDE predictions
will be cross checked)
Writeup will be distributed by Friday (at latest by Monday)
Marie Noelle Minard: Hadronic Cross Sections
---------------------------------------------
i) Inclusive (root(s'/s) > 0.1) and exclusive (root(s'/s)>0.9)
hadronic cross sections for Ecm 130-183 GeV are final.
ii) Systematic studies:
- sys. error on efficiency is from difference between KORALZ
and PYTHIA ( 0.3%)
- data reprocessed with fix for HCAL calibration error
(integer round off)
-> minimal change in energy but some effect in resolution
in forward region.
- poor energy simulation in 1997 MC in forward region
-> no effect on X-section
- jet angles (and inter jet angles) not well simulated,
discrepancy has been reduced with new MC.
MC has been reweighted for efficiency.
iii) Systematic errors have been split into uncorrelated
and year-to-year correlated components.
iv) M(W) world average should be used for predictions
Writeup will be distributed by Friday (at latest by Monday)
Marc Swynghedauw: Z' Limits
----------------------------
i) Z' studies at 183 GeV using mumu, tautau and hadron cross
sections and dilepton asymmetries (dominant).
Showed CL of M(Z') vs THETA (E6 model parameter) using his own
selections.
ii) Limits are around 250 GeV (similar to L3, but much worse than
FNAL limits)
If it should go into the paper, than use standard selections
and all LEP energies (130 -183 GeV) and present next week again
( Writeup needed).
Fabio Cerutti (for Mario Antonelli): R_b
------------------------------------------
i) bb cross section for 130-183 GeV. ( 130/136 Gev from 1995 not
used due to VDET problem) is final.
ii) b-tag is stable during 1997 running periods
Existing note should also quote numbers for systematic studies
(section 2.1)
Corinne Goy: R_c
-----------------
i) cc cross section (almost) final. Systematic errors on
preselection have to be synchronized with Marie Noelle.
Writeup will be available on Thursday
Simone Gilardoni: Hadronic jet charge asymmetry for b events.
-------------------------------------------------------------
i) QFB with jet charge results were presented. Study to optimize
kappa factor with anti WW cuts from W group.
ii) b and udsc sample were overlapping. Should be redone with
one cut, separating the two samples.
If ready by next week (including writeup) it could be used in
the paper.
Usage in contact term fit to be understood.
Frederic Teubert: Contact Terms
--------------------------------
Contact term fits. bb cross section will be used as well.
Some discussion on how to extract limits
a) chi**2(max) - x, x 1 and 4
b) corresponding integration of dchi**2/depsilon
Some preference for a), needs further thoughts.
Guenther Dissertori (for Mario Antonelli): Leptoquarks and Squarks
---------------------------------------------------------------
Showed updated limits for leptoquarks. New result is from fit to
bb cross section, where HERA can't compete.
Ian Tomalin: R parity violating sneutrino search
-------------------------------------------------
Showed first results on sneutrino production limits in RPV SUSY
(s channel and t channel processes).
Results using the cross sections at the fixed Ecm are available
and ready for the paper.
It would be interesting to use the energy spectra to derive limits
(but this may take a couple of months)
Since no overall write-up available yet, Thursday meeting presentation
postponed to ALEPH week.
Therefore all individual write-ups should be available to the BEW group
by Monday at latest!!!
Dieter Schlatter