Energy dependence of the chiral magnetic effect in expanding holographic plasma

Abstract

Based on a holographic far-from-equilibrium calculation of the chiral magnetic effect (CME) in an expanding quark gluon plasma, we study collisions at various energies. We compute the time evolution of the CME current in the presence of a time-dependent axial charge density and subject to a time-dependent magnetic field. The plasma expansion leads to a dilution of the CME current. We study distinct combinations of how the initial magnetic field and initial axial charge behave with changing initial energy as proposed in previous literature. Most scenarios we consider lead to an increasing time-integrated CME current, when increasing the initial energy. This would make it more likely to observe the CME at higher collision energies. CONTENTS I. Introduction 1 II. Holographic Model 3 A. Gravitational theory 3 B. Metric and gauge field ansatz 3 C. Energy-momentum tensor and currents of the dual boundary field theory 5 D. Preparation of initial conditions 6 E. Remarks on the holographic model construction 7 III. Results: CME current & pressure anisotropies 8 A.