PROGRAM SUMMARY
Title of program:
QCDINS 2.0
Catalogue identifier:
ADMI
Ref. in CPC:
132(2000)267
Distribution format: tar gzip file
Operating system: Linux 2.0.X, HP-UX 10.2
High speed store required:
2.6MK words
Number of lines in distributed program, including test data, etc:
33308
Keywords:
QCD, Instanton, Deep-inelastic scattering, Monte Carlo simulation,
Elementary particle physics.
Programming language used: Fortran
Computer:
HP 9000/735 (99 MHz) .
CPC Program Library subprograms used:
Cat. Id. Title Ref. in CPC ACBY HERWIG 67(1992)465 ACTU PYTHIA 5.7 AND JETSET 7.4 82(1994)74
Nature of physical problem:
Instantons are a basic aspect of Quantum Chromodynamics. Being
non-perturbative fluctuations of the gauge fields, they induce hard
processes absent in conventional perturbation theory. Deep-inelastic
lepton-nucleon scattering at HERA offers a unique possible discovery
window for such processes induced by QCD-instantons through their
characteristic final-state signature and a sizable rate, calculable
within instanton-perturbation theory. An experimental discovery of such
a novel, non-perturbative mainifestation of non-abelian gauge theories
would be of fundamental significance. However, instanton-induced events
are expected to make up only a small fraction of all deep-inelastic
events. Therefore, a detailed knowledge of the resulting hadronic final
state, along with a multi-observable analysis of experimental data by
means of Monte Carlo techniques, is necessary.
Method of solution:
The QCDINS package is degigned as an "add-on" hard process generator
interfaced to the general hadronic event simulation package HERWIG. It
incorporates the theoretically predicted production rate for
instanton-induced events as well as the essential characteristics that
have been derived theoretically for the partonic final state of
instanton-induced processes: notably, the flavour democratic and
isotropic production of the partonic final state, energy weight factors
different for gluons and quarks, and a high average multiplicity O(10)
of produced partons with a Poisson distribution of the gluon
multiplicity. While the subsequent perturbative evolution of the
generated partons is always handled by the HERWIG package, the final
hadronization step may optionally be performed also by means of the
general hadronic event simulation package JETSET.
Restrictions:
The default values of the implemented kinematical cuts represent the
state of the art limits for the reliability of the generated
instanton-induced event rate and event topology.
Typical running time:
10 - 100 events per second for a PC with Pentium CPU, depending on its
clock frequency. On a HP 9000/735 (99 MHz) workstation, 6 events per
second are generated.
Unusual features:
The program needs HERWIG version 5.9. The CPC Library version is 5.1
[1]. The HERWIG library may be downloaded from the homepage
http://hepwww.rl.ac.uk/theory/seymour/herwig/.
References:
[1] G. Marchesini et al., Comput. Phys. Commun. 67 (1992) 465.