The topological structure of vacuum is the cornerstone of non-Abelian gauge theories describing strong and electroweak interactions within the standard model of particle physics. However, transitions between different topological sectors of the vacuum (believed to be at the origin of the baryon asymmetry of the Universe) have never been observed directly. An experimental observation of such transitions in quantum chromodynamics (QCD) has become possible in heavy-ion collisions, where the chiral magnetic effect converts the chiral asymmetry (generated by topological transitions in hot QCD matter) into an electric current, under the presence of the magnetic field produced by the colliding ions. The Relativistic Heavy Ion Collider programme on heavy-ion collisions such as the zirconium–zirconium and ruthenium–ruthenium isobars thus has the potential to uncover the topological structure of vacuum in a laboratory experiment. This discovery would have far-reaching implications for the understanding of QCD, the origin of the baryon asymmetry in the present-day Universe, and other areas, including condensed matter physics.

真空的拓扑结构是非阿贝尔规范理论的基石，该理论描述了粒子物理学标准模型中的强弱相互作用。但是，从未直接观察到真空的不同拓扑扇区之间的过渡（据信这是宇宙的重子不对称性的起源）。在重离子碰撞中，对量子色动力学（QCD）中此类跃迁的实验观察已成为可能，在这种情况下，手性磁效应将手性不对称性（由热QCD物质中的拓扑跃迁产生）转化为电流。碰撞离子产生的磁场。因此，针对重离子碰撞的相对论重离子对撞机程序，例如锆-锆和钌-钌等压线，有可能在实验室实验中揭示真空的拓扑结构。这一发现对于理解QCD，当今宇宙中重子不对称性的起源以及包括凝聚态物理在内的其他领域将产生深远的影响。