GENXICC: A generator for hadronic production of the double heavy baryons Ξ_cc, Ξ_bc and Ξ_bb

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• 作者：Chao-Hsi Chang ; Jian-Xiong Wang ; Xing-Gang Wu
• 关键词：Event generator ; Hadronic production ; Double-heavy baryon (me=""mml79""> ; none ; color ; black"" href=""/science?_ob=MathURL&_method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml79&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version
• 刊名：Computer Physics Communications
• 出版年：2007
• 出版时间：1 September 2007
• 年：2007
• 卷：177
• 期：5
• 页码：467-478
• 全文大小：970 K

文摘

We write down a generator program for the hadronic production of the double-heavy baryons me=""mml42"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml42&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=c77b2f82352475a73dc03724008d3e21"" title=""Click to view the MathML source"">Ξ_cc, me=""mml43"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml43&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=8a8f5bebcaded5857814698a2cc54dc6"" title=""Click to view the MathML source"">Ξ_bc and me=""mml44"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml44&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=8d846c5a6056214f9323eaef3ffb55aa"" title=""Click to view the MathML source"">Ξ_bb according to relevant publications. We name it as GENXICC and we test it by comparing its numerical results with those in references. It is written in a PYTHIA-compatible format and it can be easily implemented into PYTHIA. GENXICC is also written in modularization manner, with make, a GNU C compiler, one may apply the generator to various situations or experimental environments very conveniently.

Program summary

Program title:GENXICC

Catalogue identifier:ADZJ_v1_0

Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADZJ_v1_0.html

Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland

Licensing provisions:Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html

No. of lines in distributed program, including test data, etc.:99 252

No. of bytes in distributed program, including test data, etc.:1 432 846

Distribution format:tar.gz

Programming language:FORTRAN77/90

Computer:Any LINUX based on PC with FORTRAN77 or FORTRAN90 and GNU C compiler installed

Operating systems:LINUX

RAM:About 2.0 MB

Classification:11.2

Nature of problem:Hadronic production of a double-heavy baryons: me=""mml45"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml45&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=58e0e208f6e809f4d8f9740fc19995a0"" title=""Click to view the MathML source"">Ξ_cc, me=""mml46"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml46&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=d5b5a88c19d703bb7ed3795abc3ad028"" title=""Click to view the MathML source"">Ξ_bc and me=""mml47"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml47&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=8a843d8acbaac081655b2251f6de9bcd"" title=""Click to view the MathML source"">Ξ_bb.

Solution method:The production of the double-heavy baryons is realized by producing a binding double-heavy diquark either me=""mml48"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml48&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=16f722b17c7edc6ddd1df9f3b26c5563"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-N/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=22 width=93> (me=""mml49"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml49&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=6bd6d513b013c81ed94bc6c30556bd85"" title=""Click to view the MathML source"">Q,Q^′=b,c) or me=""mml50"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml50&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=009f5b2ef2675d976452ba6448629d4f"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-1F/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=22 width=93>, which is in color anti-triplet me=""mml51"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml51&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=7cd797647e298ad52e89825fb3078465"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-1V/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=14 width=9> or color sextuplet 6 and in S-wave triplet or singlet configuration, respectively, and then by absorbing a proper light quark non-perturbatively. For the production of the various double-heavy baryons me=""mml52"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml52&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=0de9cc52db59050229ee748a1d82e0d5"" title=""Click to view the MathML source"">Ξ_cc, me=""mml53"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml53&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=6cf879c826a8a6fed2257a0370943de9"" title=""Click to view the MathML source"">Ξ_bcme=""bfn001"">¹ and me=""mml58"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml58&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=effd8c8397118e01671eb3e52d53e73f"" title=""Click to view the MathML source"">Ξ_bb, the ‘gluon–gluon fusion’ mechanism, being the most important, is written precisely in the generator, but two additional mechanisms, i.e. the ‘gluon–charm collision’ and the ‘charm–charm collision’ ones, only for me=""mml59"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml59&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=1328505ebba6c52deac17dac3b479e83"" title=""Click to view the MathML source"">Ξ_cc (me=""mml60"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml60&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=973a8e87c98c65a29b710496f83059fd"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-5B/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=17 width=24> or me=""mml61"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml61&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=c578e1c8cd1093e2684b52a2d1dd5405"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-5R/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=17 width=33>) are written. Furthermore, all the mechanisms are treated consistently within the general-mass flavor-number (GM-VFN) scheme. Specially, to deal with the amplitude and in order to save CPU time as much as possible, the ‘improved helicity-approach’ is applied for the most complicated gluon–gluon fusion mechanism. The code with a proper option can generate weighted and unweighted events accordingly as user's wish. Moreover, an interface to PYTHIA is provided to meet ones' needs to generate the ‘complete events’ of me=""mml62"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml62&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=07032689e7e84ac6921a99fac8133990"" title=""Click to view the MathML source"">Ξ_QQ^′, i.e. to do the ‘showers’ of the partons appearing in the initial and final states of the subprocess, and the hadronization for final obtained ‘showers’, etc.

Restrictions:In GENXICC, the approach to the hadronic production in terms of a ‘complete me=""mml63"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml63&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=d4dfebf56927cae7b835bc4468e18812"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-6H/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=19 width=19> calculation’ via the production of a binding diquark state either me=""mml64"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml64&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=81a768bb04ae3339339b71f9b68c2d65"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-6X/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=20 width=78> or me=""mml65"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml65&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=01e12a4414292bf9ffd4fabb8037bf8a"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-79/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=18 width=78> (me=""mml66"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml66&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=abb30767f29f4c66e881a9152162ac7d"" title=""Click to view the MathML source"">Q=c,b) for me=""mml67"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml67&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=175993d0471f0bcf845908ab60ea4b32"" title=""Click to view the MathML source"">Ξ_cc and me=""mml68"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml68&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=1346fcf660d3f4c339d9c5e540d4d417"" title=""Click to view the MathML source"">Ξ_bb production, and via that of a binding diquark state of me=""mml69"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml69&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=e894bc3a1a2de5c4d4616152d685cd9a"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-8W/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=20 width=67> or me=""mml70"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml70&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=87f831d2bca3d9c3b47564ae60ff6285"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-98/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=20 width=67> or me=""mml71"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml71&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=8aa3502106555b5df0ede7842b6cff2d"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-9N/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=18 width=67> or me=""mml72"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml72&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=cbdd69683eae36b620015384c26f72df"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-B2/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=18 width=67> for me=""mml73"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml73&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=b48ea43ae143ff0ff2be5a18a94f95ee"" title=""Click to view the MathML source"">Ξ_bc is available, but the contributions from the other higher Fock states of the diquark states are not involved. Considering the needs of comparisons and applications in most cases, three mechanisms and their consistent summation for the hadronic production of me=""mml74"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml74&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=b2de230f6fd7329041e4e85b6f6ac434"" title=""Click to view the MathML source"">Ξ_cc are available. But for most purposes and applications to the baryons me=""mml75"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml75&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=b961951d88f510f202690d51f9d0f9f9"" title=""Click to view the MathML source"">Ξ_bb and me=""mml76"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml76&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=d85a324684e9bd74f315eca5b5c2f34d"" title=""Click to view the MathML source"">Ξ_bc, which contain b-quark(s) (much heavier than c-quark), only the ‘gluon–gluon fusion’ mechanism for the production is accurate enough, therefore, here only the ‘gluon–gluon fusion’ mechanism is available. Moreover, since the polarization of the double-heavy baryons is also strongly effected by hadronization of the double-heavy diquark produced via the mechanisms considered here, so in the present generator only the unpolarized production for the baryons are available.

Running time:It depends on which option one chooses to match PYTHIA when generating the events and also on which mechanism is chosen for generating the events. Typically, for the most complicated case via gluon–gluon mechanism to generate the mixed events via the intermediate diquark in me=""mml77"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml77&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=1e470fe7a4521d55664401041ea0ad3b"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-CW/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=20 width=66> and me=""mml78"">method=retrieve&_udi=B6TJ5-4NWWWJ1-1&_mathId=mml78&_user=10&_cdi=5301&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=ef474220b83caf6041ee9c6107422380"">mg src=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ5-4NWWWJ1-1-D8/0?wchp=dGLbVtb-zSkWb"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=18 width=66> states, then on a 1.8 GHz Intel P4-processor PC-machine, if taking IDWTUP=1 for PYTHIA option (the meaning will be explained later on), it takes about 20 hours to generate 1000 events, whereas, if IDWTUP=3 (the meaning will be explained later on), it takes only about 40 minutes to generate 10⁶ events.