Introduction

The following samples have been generated in the context of the WW '01 Cetraro Workshop, to aid the understanding of systematics and correlations between the four LEP experiments.

FATMEN= - jetset reference sample

FATMEN= - SK1 colour reconnection sample

FATMEN= - Herwig fragmented sample

An older set of samples also exist these were generated for the crete '99 workshop.

The 1M (eventually) events per sample are generated with KORALW version 1.21, CC03 diagrams Mw=80.35 and ECM= 188.6 Gev. The cross-section from the generator is 16.5626 +- 0.0106 pb.

80.35 GeV is the mass in the fixed width parametrisation, the equivalent running width mass is 27MeV higher (YB vol. 1 p153) MWFIX = MWRUN -27 MeV

The same generator (i.e. four -fermion) level events have been used in production of all three samples.

The events were generated and fragmented by ALEPH. They were processed through DELSIM and DELANA.

Sample Details

Aleph tunings are used for every configuration :

Jref = Jetset 7.4 ( slightly modified version by Aleph )

AC0 = Ariadne 4.10 + Jetset 7.4 (as above) , No Color reco ( Aleph specific tuning)

AC2 = Ariadne 4.10 + Jetset 7.4 (as above) , AR2 for hadronics, AR1 for semileptonics ( Aleph specific tuning)

HC0 = Herwig 6.1, no Color reco ( Aleph specific tuning)

HC1 = Herwig 6.1, 11% Color reco ( Aleph specific tuning)

JSKI = Jetset 7.4 (as above) with reco code from Sjostrand page, 1000 integration points ( same tuning as Jref)

PBA = Pythia 6.1 ( model BE32 exists only there ) , BE effects between all pairs of identical particles ( Aleph global tuning on udsc)

PBI = Pythia 6.1 ( model BE32 exists only there ) , BE effects between all pairs of identical particles from the same W only (tuning as PBA)

PBB = Pythia 6.1 ( model BE32 exists only there ) , BE effects between all pairs of identical particles from different Ws only (tuning as PBA)

The original run and event numbers can be retrieved as follows by SKELANA users from +CDE, PSCLUJ.

PP(NP,1) - original run number at generator stage

PP(NP,2) - original event number at generator stage

The SKI colour reconnection string overlap has been saved to the DST and can be retrieved as:

PP(NP,3) - is this event colour reconnected ? (0.0 or 1.0)

PP(NP,4) - If colour reconnected, this is the string overlap

For Ariadne CR the meaning is :

PP(NP,3) - total number of reco, ie MHAR(135) for experts

PP(NP,4) - float(total number of reco in same string), ie MHAR(136)

This allows selection of more or less reconnected events,

The SK authors recommended mechanism is described here.

       PREC=1.-EXP(-PARA*RECO)

RECO is the string overlap number you read for each event from the DST

PARA is an arbitrary parameter that determines how much colour reconnection you want. Plots should be made as a function of PARA.

The standard PARA value at 189 GeV according to Sjostrand is 0.65 - this gives equivalent fraction of reconnected events to the SK2, SK2' models.

       IF (PREC.GE.RANDM) take this event from CR sample

       IF (PREC.LT.RANDM) take this event from standard JETSET sample

RANDM is a random number uniformly distributed in the range 0 to 1, generated separately for each event.

Chris Parkes, February '02