Polyakov-loop拓展的夸克介子模型中的Roberge-Weiss相变研究  

Roberge-Weiss Transition in the Polyakov-loop Extended Quark-meson Model

作　　者：张啟玥 张昭 ZHANG Qiyue;ZHANG Zhao(School of Mathematics and Physics,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学数理学院,北京102206

出　　处：《原子核物理评论》2020年第3期713-719,共7页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11875127,11275069)。

摘　　要：Z_(3)-QCD是具有严格中心对称性的类QCD理论,研究其在特殊条件下的性质有助于理解QCD退禁闭相变。本文应用三种味道的Polyakov-loop拓展的夸克介子模型作为Z_(3)-QCD的低能有效理论,研究了不同中心对称性破缺模式下的Roberge-Weiss(RW)相变。为保证RW周期性,本文采用味道依赖的虚化学势(μu,μd,μs)=iT(θ2Cπ/3,θ,θ+2Cπ/3),其中0≤C≤1。传统的和夸克反馈效应改进的两种不同Polyakov-loop势被分别用于相应的计算。研究表明,当N_(f)=3,C≠1时,RW相变出现在θ=π/3(mod2π/3)处,其强度随C值的减小而加强;当C=1,N_(f)=2+1时,RW相变位置出现反常,变为θ=2π/3(mod 2π/3);而当C=1,N_(f)=1+2时,RW相变点又返回θ=π/3 (mod 2π/3)。上述几种情形的RW相变端点均为三相点。研究发现,夸克反馈效应使得RW相变强度减弱,退禁闭相变温度变低,但并未改变前述的定性结论。Z_(3)-QCD is a QCD-like theory with strict center symmetry.We use the Polyakov-loop extended quark meson model(PQM) as a low-energy effective theory of Z_(3)-QCD to study the RW transitions in different center symmetry breaking patterns.The flavor-dependent imaginary chemical potentials,namely(μu,μd,μs)=iT(θ-2 Cπ/3,θ,θ+2 Cπ/3) are adopted,which guarantees the RW periodicity.The traditional and quark improved Polyakov-loop potentials are used,respectively.For N_(f)=3 with C≠1,the RW transition occurs at θ=π/3(mod 27 r/3),which gets stronger when C declines from one to zero.When C=1,the RW transition happens atθ=2π/3(mod 2π/3) for N_(f)=2+1,but θ=π/3(mod 2π/3) for N_(f)=1+2.We find that all RW transition endpoints are triple points when C=1.We confirm that the RW transition becomes weaker and the deconfinement temperature gets lower when taking into account the quark back-reaction effect.However,the modification of the gluon sector due to the quark effect does not change the main conclusions mentioned above.

关 键 词：PQM模型 夸克反馈作用 RW相变 退禁闭相变 

分 类 号：O572.24[理学—粒子物理与原子核物理]