Steady electric currents in magnetized QCD and their use for the equation of state

Abstract

In this paper we study the emergence of steady electric currents in QCD as a response to a non-uniform magnetic background using lattice simulations with 2 + 1 quark flavors at the physical point, as well as leading-order chiral perturbation theory. Using these currents, we develop a novel method to determine the leading-order coefficient of the equation of state in a magnetic field expansion: the magnetic susceptibility of the QCD medium. We decompose the current expectation value into valence- and sea-quark contributions and demonstrate that the dominant contribution to the electric current is captured by the valence term alone, allowing for a comparably cheap determination of the susceptibility. Our continuum extrapolated lattice results for the equation of state confirm the findings of some of the existing studies in the literature, namely that the QCD medium behaves diamagnetically at low and paramagnetically at high temperatures.

26 pages, 13 figures

References in corpus (7)

• The QCD equation of state with dynamical quarks
• The QCD equation of state in background magnetic fields
• Chiral Properties of Strong Interactions in a Magnetic Background
• Baryon electric charge correlation as a magnetometer of QCD
• Thermal QCD in a non-uniform magnetic background
• The Chiral Separation Effect from lattice QCD at the physical point
• QCD Thermodynamics and Neutral Pion in a Uniform Magnetic Field: Finite Volume Effects

Cited by in corpus (1)

• Localized Chiral Magnetic Effect in equilibrium QCD