Symmetry Breaking in the Strong Interaction – The Chiral Magnetic Effect  

强相互作用中的对称性破缺—手征磁效应

作　　者：WANG Fuqiang 王福强(湖州师范学院理学院,浙江湖州313000)

机构地区：[1]School of Science,Huzhou University,Huzhou 313000,Zhejiang,China

出　　处：《原子核物理评论》2024年第1期1-10,共10页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(12035006,12075085);科技部资助项目(2020YFE020200)。

摘　　要：The chiral magnetic effect (CME) refers to a charge separation along a strong magnetic field due to an imbalanced chirality of quarks from interactions with the vacuum topological gluon field. This chiral anomaly is a fundamental property of quantum chromodynamics (QCD) and, therefore, an observation of the CME would have far-reaching impact on our understanding of QCD and Nature. The measurements of the CME-sensitive azimuthal correlator Δγ observable in heavy-ion collisions are contaminated by a major background induced by elliptic flow anisotropy. Several novel approaches have been carried out, including a dedicated isobar collision program, to address this flow-induced background. Further background effects, arising from nonflow correlations, have been studied. While the isobar data are consistent with zero CME signal with an upper limit of 10% of the measured Δγ, the Au+Au midcentral data suggest a positive CME signal on the order of 10% of the measured Δγ with a significance of ~2 standard deviations. Future increased statistics and improved detector capability should yield a firm conclusion on the existence (or the lack) of the CME in relativistic heavy-ion collisions.手征磁效应(CME)指夸克—真空拓扑胶子场相互作用导致手征不平衡而引起沿强磁场方向的电荷分离。这种手征反常是量子色动力学(QCD)的基本性质,因此对CME的观测将对我们理解QCD和大自然产生深远影响。在重离子碰撞中的对CME敏感的方位角关联Δγ的测量结果受到各向异性椭圆流引起的背景污染。现已通过几种新颖方法,包括专门的同质异位素核碰撞运行项目,来解决椭圆流引起的背景问题,并研究了由非流关联引起的进一步背景效应。虽然同质异位素核碰撞结果与零CME信号一致(上限为Δγ测量值的10%),但中间中心度Au+Au数据表明Δγ测量值中可能有10%的CME信号(大概2个标准差的显着性)。未来增加的数据统计量以及改进的探测器功能应该会得出相对论重离子碰撞中CME存在或不存在的明确结论。

关 键 词：chiral magnetic effect charge separation Δγcorrelator flow-induced background nonflow 

分 类 号：O571.3[理学—粒子物理与原子核物理]