An upgraded version of the generator BCVEGPY2.0 for hadronic production of BcBc meson and its excited states

An upgraded version of the package BCVEGPY2.0: [C.-H. Chang, J.-X. Wang, X.-G. Wu, Comput. Phys. Commun. 174 (2006) 241] is presented, which works under LINUX system and is named as BCVEGPY2.1. With the version and a GNU C compiler additionally, users may simulate the BcBc-events in various experimental environments very conveniently. It has been manipulated in better modularity and code reusability (less cross communication among various modules) than BCVEGPY2.0 has. Furthermore, in the upgraded version a special execution is arranged as that the GNU command make compiles a requested code with the help of a master makefile in main code directory, and then builds an executable file with the default name run. Finally, this paper may also be considered as an erratum, i.e., typo errors in BCVEGPY2.0 and corrections accordingly have been listed.New version program (BCVEGPY2.1) summaryTitle of program: BCVEGPY2.1Catalogue identifier: ADTJ_v2_1Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTJ_v2_1Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandReference to original program: BCVEGPY2.0Reference in CPC: Comput. Phys. Commun. 174 (2006) 241Does the new version supersede the old program: NoComputer: Any LINUX based on PC with FORTRAN 77 or FORTRAN 90 and GNU C compiler as wellOperating systems: LINUXProgramming language used: FORTRAN 77/90Memory required to execute with typical data: About 2.0 MBNo. of lines in distributed program, including test data, etc.: 31 521No. of bytes in distributed program, including test data, etc.: 1 310 179Distribution format: tar.gzNature of physical problem:   Hadronic production of BcBc meson itself and its excited statesMethod of solution: The code with option can generate weighted and unweighted events. An interface to PYTHIA is provided to meet the needs of jets hadronization in the production.Restrictions on the complexity of the problem:   The hadronic production of (cb¯)-quarkonium in S-wave and P-wave states via the mechanism of gluon–gluon fusion are given by the so-called ‘complete calculation’ approach.Reasons for new version: Responding to the feedback from users, we rearrange the program in a convenient way and then it can be easily adopted by the users to do the simulations according to their own experimental environment (e.g. detector acceptances and experimental cuts). We have paid many efforts to rearrange the program into several modules with less cross communication among the modules, the main program is slimmed down and all the further actions are decoupled from the main program and can be easily called for various purposes.Typical running time: The typical running time is machine and user-parameters dependent. Typically, for production of the S  -wave (cb¯)-quarkonium, when IDWTUP = 1, it takes about 20 hour on a 1.8 GHz Intel P4-processor machine to generate 1000 events; however, when IDWTUP = 3, to generate 106 events it takes about 40 minutes only. Of the production, the time for the P  -wave (cb¯)-quarkonium will take almost two times longer than that for its S-wave quarkonium.Summary of the changes (improvements):(1) The structure and organization of the program have been changed a lot. The new version package BCVEGPY2.1 has been divided into several modules with less cross communication among the modules (some old version source files are divided into several parts for the purpose). The main program is slimmed down and all the further actions are decoupled from the main program so that they can be easily called for various applications. All of the Fortran codes are organized in the main code directory named as bcvegpy2.1, which contains the main program, all of its prerequisite files and subsidiary ‘folders’ (subdirectory to the main code directory). The method for setting the parameter is the same as that of the previous versions [C.-H. Chang, C. Driouich, P. Eerola, X.-G. Wu, Comput. Phys. Commun. 159 (2004) 192, hep-ph/0309120. [1]], [C.-H. Chang, J.-X. Wang, X.-G. Wu, Comput. Phys. Commun. 174 (2006) 241, hep-ph/0504017. [2]], i.e. the parameters are set in a file named parameter.F. Each subsidiary ‘folders’ contains the necessary files to complete specific tasks accordingly. And there are totally seven modules/‘folders’ in the program:
• The module generate: it is the key module, which contains the files for generating the BcBc events. There are seven source files in this ‘folder’: evntinit.F, colorflow.F, genevnt.F, py6208.F (a nickname of PYTHIA6.208 [T. Sjostrand, Comput. Phys. Commun. 82 (1994) 74. [3]]), totfun.F, outerpdf.F and initmixgrade.F. The function of the module generate is to set the initialize conditions for event simulation; to establish a connection with PYTHIA [T. Sjostrand, Comput. Phys. Commun. 82 (1994) 74. [3]]; to establish a connection to the parton distribution functions (PDFs) that are not included in PYTHIA according to specific need; to record the color flow information of the generated BcBc events and may provide it according to one's need; to calculate the kernel for phase space integration with the help of swave module and pwave module; to do the phase space integration with the help of phase module. A useful trick for generating the mixed type of BcBc events is suggested (three types of mixed events are provided in the generator [C.-H. Chang, J.-X. Wang, X.-G. Wu, Comput. Phys. Commun. 174 (2006) 241, hep-ph/0504017. [2]], e.g. by setting the parameter IMIXTYPE = 2, one can generate the mixed events for the two color-singlet (cb¯)-quarkonium states (cb¯)1(S01) and (cb¯)1(S13)). The file initmixgrade.F is used to initialize the importance sampling function for Monte Carlo simulation, i.e., either by using the importance sampling function given by the current VEGAS running [G.P. Lepage, J. Comp. Phys. 27 (1978) 192. [4]] or by using the existed importance sampling function recorded in an existed grade file in data subdirectory that has already been generated by earlier VEGAS running. Once the importance sampling function has been obtained by VEGAS, it is recorded in a grade file (with suffix.grid) automatically, and can be conveniently used (by initmixgrade.F) for later usage without running VEGAS again. Some more detail on this point will be shown in the following item (2).
• The module phase: it contains the files for generating the allowed phase-space point and for generating an importance sampling function with VEGAS program [G.P. Lepage, J. Comp. Phys. 27 (1978) 192. [4]]. It contains three source files: phase_gen.F, phase_point.F and vegas.F.
• The module swave: it contains the files for calculating the square of the amplitudes for producing the four color-singlet and color-octet (cb¯)-quarkonium in S  -wave: (cb¯)1(S01), (cb¯)1(S13), (cb¯)8(S01) and (cb¯)8(S13), where the subscripts 1 and 8 stand for color-singlet and color-octet accordingly. Note that in fact the configurations (cb¯)8(S01) and (cb¯)8(S13) play comparatively important role only for the production of the P  -wave excited BcBc states as shown in Ref. [C.-H. Chang, C.-F. Qiao, J.-X. Wang, X.-G. Wu, Phys. Rev. D 71 (2005) 074012. [5]]. It contains five source files: s_bound.F, s_common.F, s_foursets.F, s_free.F and s_samp.F.
• The module pwave: it contains the files for calculating the square of the amplitudes for producing the four color-singlet (cb¯)-quarkonium in P  -wave: (cb¯)1(P11) and (cb¯)1(PJ3) (J=1,2,3J=1,2,3). It contains six source files: p_lorentz.F, p1p1amp.F, pj0amp.F, pj1amp.F, pj2amp.F and p_samp.F.
• The module pybook: it contains the files for initializing the subroutine PYBOOK of PYTHIA to record the events. The user may conveniently switch off this module in the main program to use his/her own way to record the data. It contains five source files: pybookinit.F, uphistrange.F, uppydump.F, uppyfact.F and uppyfill.F.
• The module setparameter: it contains the files for inner use of the parameters (mainly generates some short notations for the parameters) that have been set in parameter.F. It has only two source files: simparameter.F and uperror.F, where uperror.F lists some typical error messages for the cases when the input parameters are out of allowed (reasonable) range.
• The module system: it contains files to open or close the record files and to print out certain running messages at the intermediate steps according to need, which may tell the users at what step the program is running. It contains six source files: upopenfile.F, uplogo.F, vegaslogo.F, updatafile.F, upclosegradefile.F and upclosepyfile.F.Each module is equipped with its own makefile that will be used to make a library of the same name, e.g. the makefile in the ‘folder’ swave/ will be used by the GNU command make to generate a library swave.a. These sub-makefiles are orchestrated by a master makefile in the main code directory. Libraries required for the main program are listed in the LIBS variable of the master makefile and built automatically by invoking the sub-makefiles:LIBS=generate.a swave.a pwave.a phase.a setparameter.a system.a pybook.aLIBS=generate.a swave.a pwave.a phase.a setparameter.a system.a pybook.aIn the way that based on makefile then the make command builds an executable file whose default name is run, the program acquires good modularity and code reusability, and the user can easily make the BCVEGPY generator to suit his/her experimental simulation environment as wish. Namely, to connect this generator with his/her own generator package such as ANTENNA (used by ATLAS group), LHCb (used by LHCB group) and SIMUB (used by CMS group)1only a few pieces of the program need to be changed. By doing this way, the time for compiling the Fortran source files can be saved, because once the source file has been compiled, it does not need to be recompiled again unless some changes have been made. The schematic structure of the program is shown in Fig. 1. Note that in order to let the make command work smoothly, especially, to deal with some preprocessor parameters in the source files, all the suffixes of the source files (with suffix .for) in the original version of BCVEGPY2.0 [C.-H. Chang, J.-X. Wang, X.-G. Wu, Comput. Phys. Commun. 174 (2006) 241, hep-ph/0504017. [2]] are renamed as .F and the suffixes of the original header files (with suffix .f) are renamed as .h.Fig. 1. The schematic structure for the new version of BCVEGPY.Figure optionsDownload as PowerPoint slideprs.rt("abs_1st_end");