Charge-dependent flow as evidence of strong electromagnetic fields in heavy-ion collisions

TL;DR

This paper reviews how strong electromagnetic fields in heavy-ion collisions influence charge-dependent flow, offering insights into quark-gluon plasma properties and addressing discrepancies between experiments and theory.

Contribution

It provides a comprehensive overview of electromagnetic field effects in heavy-ion collisions, highlighting charge-dependent flow as a key observable and proposing new directions to resolve existing discrepancies.

Findings

Charge-dependent flow observed experimentally.

Discrepancies between measurements and theoretical models.

Suggestions for new measurements and theoretical approaches.

Abstract

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, emphasising 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.