Interplay Between Quark-Antiquark and Diquark Condensates in Vacuum in a Two-Flavor Nambu-Jona-Lasinio Model  

作　　者：ZHOU Bang-Rong 

机构地区：[1]College of Physical Sciences, Graduate School of the Chinese Academy of Sciences, Beijing 100049, China [2]CCAST （World Laboratory） P.O. Box 8730, Beijing 100080, China

出　　处：《Communications in Theoretical Physics》2007年第1期95-101,共7页理论物理通讯（英文版）

基　　金：The project supported by National Natural Science Foundation of China under Grant No, 10475113

摘　　要：By means of a relativistic effective potential, we analytically research competition between the quark- antiquark condensates （qq） and the diquark condensates （qq） in vacuum in ground state of a two-flavor Nambu Jona Lasinio （NJL） model and obtain the Gs-Hs phase diagram, where Gs and Hs are the respective four-fermion coupling constants in scalar quark-antiquark channel and scalar color anti-triplet diquark channel. The results show that, in the chiral limit, there is only the pure （qq） phase when Gs/Hs 〉 2/3, and as Gs/Hs decreases to 2/3 〉 Gs/Hs ≥ 0 one will first have a coexistence phase of the condensates （qq） and （qq） and then a pure （qq） phase. In non-zero bare quark mass case, the critical value of Gs/Hs at which the pure （qq） phase will transfer to the coexistence phase of the condensates （qq） and （qq） will be less than 2/3. Our theoretical results, combined with present phenomenological fact that there is no diquark condensates in the vacuum of QCD, will also impose a real restriction to any given two-flavor NJL model which is intended to simulate QCD, i.e. in such model the resulting sma/lest ratio Gs/Hs after the Fierz transformations in the Hartree approximation must be larger than 2/3. A few phenomenological QCD-like NJL models are checked and analyzed.

关 键 词：Nambu-Jona-Lasinio model quark-antiquark condensates diquark condensates effective potential chiral symmetry breaking color-superconductivity 

分 类 号：O572.243[理学—粒子物理与原子核物理]