The effects of topological charge change in heavy ion collisions: “Event by event P and CP violation”

By D. Kharzeev, Larry McLerran, Harmen J. Warringa. 2007

1,581 citations recorded by the source corpus.

Abstract Quantum chromodynamics (QCD) contains field configurations which can be characterized by a topological invariant, the winding number Q w . Configurations with non-zero Q w break the charge-parity ( CP ) symmetry of QCD. We consider a novel mechanism by which these configurations can separate charge in the presence of a background magnetic field—the “chiral magnetic effect”. We argue that sufficiently large magnetic fields are created in heavy ion collisions so that the chiral magnetic effect causes preferential emission of charged particles along the direction of angular momentum. Since separation of charge is CP -odd, any observation of the chiral magnetic effect could provide a clear demonstration of the topological nature of the QCD vacuum. We give an estimate of the effect and conclude that it might be observed experimentally.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/c34d6f5eb7b02314c03e39d681b0022ee4aafbfa

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In Nuclear and High Energy Physics

1. K. Landsteiner
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3. C. Fischer
4. S. Gubser
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6. Zoltán Fodor
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8. V. Koch

Citations in the corpus

• The QCD phase diagram for external magnetic fields (2011, background): “For noncentral heavy ion collisions, an exciting consequence of the interplay between the strong magnetic field and the nontrivial topological structure of the quark-gluon plasma is the so-called chiral magnetic effect [4, 5].”
• Thermodynamics and instabilities of a strongly coupled anisotropic plasma (2011, background): “It has been suggested that ‘bubbles’ or regions with a spacetime-dependent theta-angle, θ(t, x), may be formed in heavy ion collisions [52, 53, 54, 55, 56, 57].”
• Properties of hot and dense matter from relativistic heavy ion collisions (2015, background): “Topological charge fluctuations in the initial state of a heavy ion collision, combined with the magnetic field generated by the highly charged ions, can manifest themselves in electric charge fluctuations in the final state [232].”
• Charged magnetic brane solutions in AdS5 and the fate of the third law of thermodynamics (2009, background): “This is the chiral magnetic current [13, 14, 15]: in the presence of a nonzero anomaly coefficient k and a chemical potential, a current is induced parallel to the applied magnetic field.”
• Anomalous transport of Weyl fermions in Weyl semimetals (2013, background): “It is however still an open question if they really lead to observable effects in heavy ion collisions, such as charge separation [23], a chiral magnetic wave [59, 60] or enhanced production of high spin baryons [61].”
• Parity-violating hydrodynamics in 2 + 1 dimensions (2011, methodology): “Parity-violating transport effects were also studied in 3+1 dimensions with QCD applications in mind: using field theory techniques [24–28], in the context of hydrodynamics [29–32], and in parallel using the AdS/CFT correspondence along with hydrodynamics [33–41].”