Local CP-violation and electric charge separation by magnetic fields from lattice QCD

Abstract

We study local CP-violation on the lattice by measuring the local correlation between the topological charge density and the electric dipole moment of quarks, induced by a constant external magnetic field. This correlator is found to increase linearly with the external field, with the coefficient of proportionality depending only weakly on temperature. Results are obtained on lattices with various spacings, and are extrapolated to the continuum limit after the renormalization of the observables is carried out. This renormalization utilizes the gradient flow for the quark and gluon fields. Our findings suggest that the strength of local CP-violation in QCD with physical quark masses is about an order of magnitude smaller than a model prediction based on nearly massless quarks in domains of constant gluon backgrounds with topological charge. We also show numerical evidence that the observed local CP-violation correlates with spatially extended electric dipole structures in the QCD vacuum.

19 pages, 7 figures. Additional lattice results about the induced electric dipole structure, extended model description, specified terminology. Version published in JHEP

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• The Chiral Magnetic Effect
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• The Chiral Magnetic Effect and an experimental bound on the late time magnetic field strength
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• Strong-Field Physics in QED and QCD: From Fundamentals to Applications
• Landau levels in QCD
• Collective Modes of Chiral Kinetic Theory in Magnetic Field
• Chiral Magnetic Effect at Weak Coupling with Relaxation Dynamics
• Second Order Transport Coefficient from Chiral Anomaly at Weak Coupling: Diagrammatic Resummation
• Overview of external electromagnetism and rotation in lattice QCD
• Chiral Magnetic Effect in a Lattice Model
• The Chiral Separation Effect from lattice QCD at the physical point
• On the absence of the Chiral Magnetic Effect in equilibrium QCD
• Meson deformation by magnetic fields in lattice QCD
• Elliptic flow due to radiation in heavy-ion collisions
• Chiral magnetohydrodynamics for heavy-ion collisions
• Abelian and non-Abelian Berry curvatures in lattice QCD