PROGRAM SUMMARY
Title of program:
KoralW, version 1.42
Catalogue identifier:
ADKJ
Ref. in CPC:
119(1999)272
Distribution format: uuencoded compressed tar file
Operating system: UNIX (AIX 4.x,HP-UX 10.x), Linux
High speed store required:
10MK words
Number of lines in distributed program, including test data, etc:
564419
Programming language used: Fortran
Computer: IBM PowerPC M43P240
Other versions of this program:
Cat. Id. Title Ref. in CPC ADCT KORALW 1.02 94(1996)216
Nature of physical problem:
The W-pair production and decay is and will be used as an important data
point for precise tests of the standard electroweak theory at LEP2 and
higher energies. The effects due to background processes, QED
bremsstrahlung and apparatus efficiency have to be subtracted from the
data. The program deals with all e+e- processes leading to 4-fermion
final states accompanied with multiphoton initial-state radiation. It
also includes the effects of the Coulomb correction, 'naive' QCD,
anomalous couplings, quarks hadronization, tau decays and photon
radiation in leptonic decays.
Method of solution
The Monte Carlo methods are used to simulate all 4-fermion final-state
processes in the e+e- collisions in the presence of multiphoton initial-
state radiation. The latter is described in the framework of the YFS
exclusive exponentiation. The W-pair production is included in a
'natural' way as a subset of the Feynman diagrams for the above
processes, but it can also be generated exclusively by switching to the
so-called CC03 process. The Monte Carlo generation is done on an event-
by-event basis, with constant or variable weights, where an event is
represented by flavours and four-momenta of all respective particles -
supplemented with a collection of weights, if the variable weight option
is chosen. After the event generation is completed the program provides
the cross sections together with their statistical errors for all the
processes involved. Any experimental cuts and apparatus efficiencies
may be introduced easily by rejecting some of the generated events.
Restrictions on the complexity of the problem
Only processes with 4-fermion final states are considered. QED
radiative corrections are implemented in terms of multiphoton ISR in the
YFS Monte Carlo framework with the O(alpha**3) LL-type matrix element.
For the CC03 subset of diagrams the Coulomb correction for the
intermediate WW states is also included. The final-state QED radiation
is generated for charged leptons with the help of the program PHOTOS in
the LL approximation (up to two photons). QCD effects are included in
the so-called "naive QCD" approximation. A part of electroweak
corrections is incorporated in the "improved Born approximation"
(through appropriate renormalization scheme). Anomalous triple gauge
boson couplings are implemented only in the CC03 subset of diagrams
(i.e. the W-pair production). Quadruple gauge boson couplings are not
implemented. The tau-decays and quark hadronization are performed,
respectively, with the help of the dedicated packages TAUOLA and JETSET.
Typical running time
On IBM PowerPC M43P240 (266 MHz, 65 CERN units) installation one needs:
(a) 2.5 sec per 1000 constant-weight events and 0.6 sec per 1000
variable-weight events for CC03 matrix element and (b) 12500 sec per
1000 constant-weight events and 6 sec per 1000 variable-weight events
for a complete 4-fermion matrix element (GRACE). These results are for
a default/recommended setting of input parameters but with all decay
libraries switched OFF.