The extremely large electromagnetic fields generated in heavy-ion collisions provide access to novel observables that are expected to constrain various key transport properties of the quark-gluon plasma and could help solve one of the outstanding puzzles in QCD: the strong CP problem. In this review we present a brief overview of the theoretical and experimental characterization of these electromagnetic fields. After reviewing the current state, emphasizing one of the observables — the charge-dependent flow — we discuss the various discrepancies between the measurements and theoretical predictions. Finally, to help resolve the discrepancies, we suggest new measurements and theoretical ideas.

中文翻译：

---

电荷相关流动作为重离子碰撞中强电磁场的证据

重离子碰撞中产生的极大电磁场提供了获得新的可观测数据的途径，这些数据有望限制夸克-胶子等离子体的各种关键传输特性，并有助于解决 QCD 中的一个突出难题：强 CP 问题。在这篇综述中，我们简要概述了这些电磁场的理论和实验特性。在回顾了当前状态之后，强调了其中一个可观察的——电荷相关的流动——我们讨论了测量和理论预测之间的各种差异。最后，为了帮助解决这些差异，我们提出了新的测量方法和理论思想。