University of Illinois at Chicago, Chicago, Illinois 60607, USA.
Phys Rev Lett. 2009 Dec 18;103(25):251601. doi: 10.1103/PhysRevLett.103.251601. Epub 2009 Dec 14.
Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au + Au and Cu + Cu collisions at square root of s(NN) = 200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.
同位旋奇域,对应于 QCD 真空的非平凡拓扑解,可能在相对论重离子碰撞中产生。这些域预计会导致夸克沿着系统的轨道动量轴分离电荷。我们研究了一个三粒子方位角相关函数,它是一个 P 偶可观测量,但直接对电荷分离效应敏感。我们使用 STAR 探测器在 Au + Au 和 Cu + Cu 碰撞中,在质心快度附近测量了这个可观测量的带电强子,探测到了与理论的几个预期一致的信号。我们讨论了与宇称破坏无关的其他效应的可能贡献。