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[Licence| Download | New Version Template] adzj_v2_0.tar.gz(1435 Kbytes)
Manuscript Title: GENXICC2.0: An Upgraded Version of the Generator for Hadronic Production of Double Heavy Baryons Ξcc, Ξbc and Ξbb
Authors: Chao-Hsi Chang, Jian-Xiong Wang, Xing-Gang Wu
Program title: GENXICC2.0
Catalogue identifier: ADZJ_v2_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 181(2010)1144
Programming language: Fortran 77/90.
Computer: Any LINUX based on PC with FORTRAN 77 or FORTRAN 90 and GNU C compiler as well.
Operating system: Linux.
RAM: About 2.0 MByte
Keywords: Event generator, Hadronic production, double heavy baryons.
Classification: 11.2.

Does the new version supersede the previous version?: No

Nature of problem:
Hadronic production of double heavy baryons Ξcc, Ξbc and Ξbb

Solution method:
The code is based on NRQCD framework. With proper options, it can generate weighted and un-weighted events of hadronic double heavy baryon production. When the hadronizations of the produced jets and double heavy diquark are taken into account in the production, the upgraded version with proper interface to PYTHIA can generate full events.

Reasons for new version:
Responding to the feedback from users[1], we improve the generator mainly by carefully completing the 'final nonperturbative process' i.e. the formulation of the double heavy baryon from relevant intermediate diquark. In the present version, the information for fragmentation about momentum-flow and the color-flow, that is necessary for PYTHIA to generate full events, is retained although reasonable approximations are made. In comparison with the original version, the upgraded one can implement it in PYTHIA properly to do the full event simulation of the double heavy baryon production.

Summary of revisions:
  1. We try to explain the treatment of the momentum distribution of the process more clearly than the original version, and show how the final baryon is generated through the typical intermediate diquark precisely.
  2. We present color flow of the involved processes precisely and the corresponding changes for the program are made.
  3. The corresponding changes of the program are explained in the paper.

The color flow, particularly, in the piece of code programming of the fragmentation from the produced colorful double heavy diquark into a relevant double heavy baryon, is treated carefully so as to implement it in PYTHIA properly.

Running time:
It depends on which option is chosen to configure PYTHIA when generating full events and also on which mechanism is chosen to generate the events. Typically, for the most complicated case with gluon-gluon fusion mechanism to generate the mixed events via the intermediate diquark in (cc)[3S1] 3 and (cc)[1S0]6 states, under the option, IDWTUP=1, to generate 1000 events, takes about 20 hours on a 1.8 GHz Intel P4-processor machine, whereas under the option, IDWTUP=3, even to generate 106 events takes about 40 minutes on the same machine.

[1] Private communications with Braden Keim Abbott and Richard J. Van Kooten (D0 Collaboration).