Cover Story (Issue 9, 2026): Charge Separation Measurements in Au+Au collisions at 
= 7.7-200 GeV in Search of the Chiral Magnetic Effect
Author: Dmitri Kharzeev (Distinguished Professor, Stony Brook University, United States)
The search for the chiral magnetic effect (CME) has been one of the central goals of relativistic heavy-ion physics for more than two decades. The CME offers a unique opportunity to directly probe the topological structure of the QCD vacuum through macroscopic transport phenomena in the quark-gluon plasma. Because the expected signal is quite small and accompanied by substantial background correlations, establishing convincing experimental evidence has required sustained advances in detector capabilities, high statistics, and novel analysis techniques. The new STAR measurements represent an important milestone in this long-standing effort. By introducing an innovative event-shape selection method that suppresses flow-related backgrounds, the collaboration isolates a residual charge-separation signal that emerges most clearly at intermediate RHIC beam energies, where theoretical expectations predict favorable conditions for observing the CME.
Beyond the immediate implications for heavy-ion physics, these results reinforce the broader importance of quantum anomalies and topological phenomena in strongly interacting matter. The chiral magnetic effect links fundamental aspects of quantum field theory − including the axial anomaly, topology, and chirality − to experimentally observable transport phenomena, creating deep connections with condensed matter systems such as Dirac and Weyl semimetals, as well as with astrophysics and cosmology. While additional experimental confirmation and theoretical refinement will continue to strengthen the case, the present STAR results provide the strongest evidence to date that observation of
anomalous chiral transport driven by QCD topology may indeed be possible in relativistic nuclear collisions. They mark a significant step toward revealing one of the most remarkable manifestations of quantum anomalies in Nature.
[1] The STAR Collaboration, Chin. Phys. C 50, 094006 (2026)
