双重味重子Xicc强产生机制的研究

*,吴兴刚,重庆大学物理系,高能物理分会第八届全国会员代表大会暨学术年会,双重味重子,Xicc,强产生机制的研究,近期完成与双重味,Xicc,重子有关的工作,In collaboration with,Prof.Z.X,.Zhang,J.X.Wang,C.F.,Qiao,J.P.Ma,Progress Basis:BCVEGPY(,V1.0,V 2.0WIN,V2.1LINUX,V3.0?,),1),Comput.Phys.Commun.,177,467-478(2007),2),Comput.Phys.Commun.181,1144-1149(2010),=,GENXICC,=,Theoretical Prediction,=,1),Phys.Rev.D,73,094022(2006),2),J.Phys.G,34,845(2007),B.K.Abbott,R.J.Van,Kooten,-D0,报告主要内容,3,.Prospects,1.,Background,2.Xicc Generator GENXICC,Basic,Properties(V1.0),New Improvements(V2.0),Results for Hadronic Production of Xicc at LHC,1.,Background,Phys.Lett.B628:18-24,2005,.,SELEX,07,年结果仍然没有确定结论,因此理论上仔细研究产生及衰变过程是完全必须的,Xicc,强产生机制,(production of,diquark,pair first and then,diquark,fragment into baryon with 100%efficiency),(GM-VFN),1),gluon-gluon fusion mechanism,2),gluon-charm collision mechanism,3),charm-charm collision mechanism,-the above is for extrinsic charm-,4),Intrinsic charms contribution(model dependent),Similar to Bc case,1980:BHPS-model,DGLAP,J.Pumplin,CTEQ,PRD73,114015(2006),Intrinsic Charm model,2.Xicc Generator GENXICC,该过程硬散射振幅的计算与,Bc,介子类似，最大区别在于颜色因子的不同。将颜色因子提出之后，所有图形的处理（拆分，组成，分类）完全一致。,改进后的螺旋度振幅方法：能有效处理有质量夸克线及改进数值处理方式,类比,程序化简核心思想,通过图形的拆分找到所有费曼图中最基本的架构,=,基本,QED,图,=,最大程度合并同类项,振幅做数值,=Helicity Amplitude Approach,验证程序正确性,规范不变性（胶子极化矢量换成胶子动量；因为振幅解析公式有很大差别，因此需编写两个振幅程序）,数值结果与选用的参考动量无关,Nine basic QED-like diagrams,Gluon-gluon fusion,基本图形的选取主要根据过程所具有的对称性,QED,结构简单,Decompose,Decompose,Decompose,K1,k2,交换,Decompose,关键：,QCD,图拆分成,QED,形式图,最基本顶点为例,QED,图对应基本费米子线,七个基本,QED,费曼图,两个基本关系,最后由其中两重夸克投影响到强子态上,就得到完整的振幅表达式,Xicc,与,Bc,的不同之处及其处理,颜色因子,核心是如何与原有,BCVEGPY,程序联系,Y,New GRADE,I=NEV,PYDUMP(),BEGIN,VEGASOPEN,IT=0；IT=IT+1,IGRADE=1,Read existed GRADE,N,NUM=NUMBER,NUM=0；NUM=NUM+1,I=0；I=I+1,PYEVNT,PYFILL(),END,CALL PHPOINT(),CALL AMP2UP(),CALL PHPOINT(),CALL AMP2UP(),N,Y,N,Y,EVNTINIT，PYINIT，UPINIT,Y,Y,N,N,IT(3s1),Results for Xicc,Xibc and Xibb Production,程序正确性检验,LHC,TEVATRON,can not see the difference between the cases of with or with intrinsic charm,Due to its high efficiency,GENXICC,together with BCVEGPY shall be very useful for MC simulation and also for theoretical studies.More applications shall be available.,The coming LHC experiment shall provide a better platform to check all the,theoretical predications and to learn the,Xicc,Xibc,Xibb,properties in more detail.This generator is now used by D0 group.,Together with the decay channel calculation,we can obtain a full estimation of Xicc,and hence have a better comparison with SELEX experiment.,4.Prospects,Thanks!,