BCVEGPY: an event generator for hadronic production of the Bc meson

Abstract

We have written a Fortran program BCVEGPY, which is an event generator for the hadronic production of the B c meson through the dominant hard subprocess gg→B c(B c ∗)+b+ c ̄ . To achieve a compact program, we have written the amplitude of the subprocess with the particle helicity technique and made it as symmetric as possible, by decomposing the gluon self couplings and then applying the symmetries. To check the program, various cross sections of the subprocess have been computed numerically and compared with those in the literature. BCVEGPY is written in a PYTHIA-compatible format, thus it is easy to implement in PYTHIA. Program summary Title of program: BCVEGPY Version: 1.0 (September, 2003) Catalogue identifier: ADTJ Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADTJ Program obtained from: CPC Program Library, Queen's University of Belfast, N. Ireland. Computer: Any computer with FORTRAN 77 compiler. The program has been tested on HP-SC45 Sigma-X workgroups, Linux PCs and Windows PCs with Visual Fortran. Operating systems: UNIX, Linux and Windows. Programming language used: FORTRAN 77. Memory required to execute with typical data: About 2.0 MB. No. of bytes in distributed program, including test data, etc.: 477630 No. of lines in distributed program, including test data, etc.: 66461 Distribution format: tar gzip file Nature of physical problem: Hadronic production of B c meson. Method of solution: Improved helicity-approach to the amplitude and symmetries of the amplitude itself have been used to compact the program so as to save cpu as possible as one can. The code with option can generate weighted and un-weighted events. For jet hadronization, an interface to PYTHIA is provided. Restrictions on the complexity of the problem: The hadronic production of the B c meson in the S-wave states, i.e. pseudo-scalar state ( 1S 0 ) and vector state ( 3S 1 ) are included by the ‘complete calculation’ approach. The hadronic production of B c meson in P-wave states has not been implemented into the BCVEGPY yet. Typical running time: It depends on which option one chooses to match PYTHIA when generating the B c events. Typically, if IDWTUP=1, then it takes about 20 hour on a 1.8 GHz Intel P4-processor machine to generate 1000 events; however if IDWTUP=3, to generate 10 6 events, it takes about 40 minutes only.