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Dmitri E. Kharzeev - One of the best experts on this subject based on the ideXlab platform.
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Electric-current susceptibility and the Chiral Magnetic Effect
Nuclear Physics A, 2020Co-Authors: Kenji Fukushima, Dmitri E. Kharzeev, Harmen J WarringaAbstract:We compute the electric-current susceptibility of hot quark-gluon matter in an external Magnetic field B. The difference between the susceptibilities measured in the directions parallel and perpendicular to the Magnetic field is ultraviolet finite and given by [formula here omitted.], where V denotes the volume, T the temperature, Nc the number of colors, and qf the charge of a quark of flavor f. This non-zero susceptibility difference acts as a background to the Chiral Magnetic Effect, i.e. the generation of electric current along the direction of Magnetic field in the presence of topological charge. We propose a description of the Chiral Magnetic Effect that takes into account the fluctuations of electric current quantified by the susceptibility. We find that our results are in agreement with recent lattice QCD calculations. Our approach can be used to model the azimuthal dependence of charge correlations observed in heavy ion collisions
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Giant photocurrent in asymmetric Weyl semimetals from the helical Magnetic Effect
Physical Review B, 2018Co-Authors: Dmitri E. Kharzeev, Yuta Kikuchi, Rene Meyer, Yuya TanizakiAbstract:We propose a new type of photoresponse induced in asymmetric Weyl semimetals in an external Magnetic field. In usual symmetric Weyl semimetals in a Magnetic field, the particles and holes produced by an incident light in different Weyl cones have opposite helicities and hence move in opposite directions, canceling each others's contributions to the photocurrent. However this cancelation does not occur if the Weyl semimetal possesses both a broken particle-hole symmetry and a broken spatial inversion symmetry. We call the resulting generation of photocurrent the helical Magnetic Effect because it is induced by the helicity imbalance in a Magnetic field. We find that due to the large density of states in a Magnetic field, the helical Magnetic Effect induces a remarkable large photocurrent for incident THz frequency light. This suggests a potential application of asymmetric Weyl semimetals for creating THz photosensors.
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Strain-induced chiral Magnetic Effect in Weyl semimetals
Physical Review B, 2016Co-Authors: Alberto Cortijo, Dmitri E. Kharzeev, Karl Landsteiner, María A. H. VozmedianoAbstract:Here, we argue that strain applied to a time-reversal and inversion breaking Weyl semimetal in a Magnetic field can induce an electric current via the chiral Magnetic Effect. A tight-binding model is used to show that strain generically changes the locations in the Brillouin zone but also the energies of the band touching points (tips of the Weyl cones). Since axial charge in a Weyl semimetal can relax via intervalley scattering processes, the induced current will decay with a time scale given by the lifetime of a chiral quasiparticle. Lastly, we estimate the strength and lifetime of the current for typical material parameters and find that it should be experimentally observable.
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Chiral Magnetic Effect in condensed matter systems
Nuclear Physics, 2016Co-Authors: Qiang Li, Dmitri E. KharzeevAbstract:Abstract The chiral Magnetic Effect (CME) is the generation of electrical current induced by chirality imbalance in the presence of Magnetic field. It is a macroscopic manifestation of the quantum chiral anomaly [S. L. Adler. Axial-vector vertex in spinor electrodynamics. Physical Review, 177, 2426 (1969), J. S. Bell and R. Jackiw. A PCAC puzzle: π 0 γ γ in the σ-model. Il Nuovo Cimento A, 60, 47–61 (1969)] in systems possessing charged chiral fermions. In quark-gluon plasma containing nearly massless quarks, the chirality imbalance is sourced by the topological transitions. In condensed matter systems, the chiral quasiparticles emerge in gapless semiconductors with two energy bands having pointlike degeneracies opening the path to the study of chiral anomaly [H. B. Nielsen and M. Ninomiya. The Adler-Bell-Jackiw anomaly and Weyl fermions in a crystal. Physics Letters B, 130, 389–396 (1983)]. Recently, these novel materials – so-called Dirac and Weyl semimetals have been discovered experimentally, are suitable for the investigation of the CME in condensed matter experiments. Here we report on the first experimental observation of the CME in a 3D Dirac semimetal ZrTe5 [Q. Li, D. E. Kharzeev, C. Zhang, Y. Huang, I. Pletikosic, A. V. Fedorov, R. D. Zhong, J. A. Schneeloch, G. D. Gu, and T. Valla. Chiral Magnetic Effect in Z r T e 5 . Nature Physics (2016) doi:10.1038/nphys3648 ].
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Chiral Magnetic Effect in ZrTe5
Nature Physics, 2016Co-Authors: Qiang Li, Dmitri E. Kharzeev, Cheng Zhang, Yuan Huang, Ivo Pletikosic, Alexei V. Fedorov, Ruidan Zhong, J. Schneeloch, Genda Gu, Tonica VallaAbstract:The chiral Magnetic Effect is the generation of an electric current induced by chirality imbalance in the presence of a Magnetic field. It is a macroscopic manifestation of the quantum anomaly1, 2 in relativistic field theory of chiral fermions (massless spin 1/2 particles with a definite projection of spin on momentum)—a remarkable phenomenon arising from a collective motion of particles and antiparticles in the Dirac sea. The recent discovery3, 4, 5, 6 of Dirac semimetals with chiral quasiparticles opens a fascinating possibility to study this phenomenon in condensed matter experiments. Here we report on the measurement of magnetotransport in zirconium pentatelluride, ZrTe5, that provides strong evidence for the chiral Magnetic Effect. Our angle-resolved photoemission spectroscopy experiments show that this material’s electronic structure is consistent with a three-dimensional Dirac semimetal. We observe a large negative magnetoresistance when the Magnetic field is parallel with the current. The measured quadratic field dependence of the magnetoconductance is a clear indication of the chiral Magnetic Effect. The observed phenomenon stems from the Effective transmutation of a Dirac semimetal into a Weyl semimetal induced by parallel electric and Magnetic fields that represent a topologically non-trivial gauge field background. We expect that the chiral Magnetic Effect may emerge in a wide class of materials that are near the transition between the trivial and topological insulators.
Kenji Fukushima - One of the best experts on this subject based on the ideXlab platform.
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Views of the Chiral Magnetic Effect
Lecture Notes in Physics, 2020Co-Authors: Kenji FukushimaAbstract:My personal views of the Chiral Magnetic Effect are presented, which starts with a story about how we came up with the electric-current formula and continues to unsettled subtleties in the formula. There are desirable features in the formula of the Chiral Magnetic Effect but some considerations would lead us to even more questions than elucidations. The interpretation of the produced current is indeed very non-trivial and it involves a lot of confusions that have not been resolved.
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Electric-current susceptibility and the Chiral Magnetic Effect
Nuclear Physics A, 2020Co-Authors: Kenji Fukushima, Dmitri E. Kharzeev, Harmen J WarringaAbstract:We compute the electric-current susceptibility of hot quark-gluon matter in an external Magnetic field B. The difference between the susceptibilities measured in the directions parallel and perpendicular to the Magnetic field is ultraviolet finite and given by [formula here omitted.], where V denotes the volume, T the temperature, Nc the number of colors, and qf the charge of a quark of flavor f. This non-zero susceptibility difference acts as a background to the Chiral Magnetic Effect, i.e. the generation of electric current along the direction of Magnetic field in the presence of topological charge. We propose a description of the Chiral Magnetic Effect that takes into account the fluctuations of electric current quantified by the susceptibility. We find that our results are in agreement with recent lattice QCD calculations. Our approach can be used to model the azimuthal dependence of charge correlations observed in heavy ion collisions
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Mode Decomposed Chiral Magnetic Effect and Rotating Fermions
arXiv: High Energy Physics - Phenomenology, 2020Co-Authors: Kenji Fukushima, Takuya Shimazaki, Lingxiao WangAbstract:We present a novel perspective to characterize the chiral Magnetic and related Effects in terms of angular decomposed modes. We find that the vector current and the chirality density are connected through a surprisingly simple relation for all the modes and any mass, which defines the mode decomposed chiral Magnetic Effect in such a way free from the chiral chemical potential. The mode decomposed formulation is useful also to investigate properties of rotating fermions. For demonstration we give an intuitive account for a nonzero density emerging from a combination of rotation and Magnetic field as well as an approach to the chiral vortical Effect at finite density.
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Chiral Magnetic Effect and the QCD Phase Transitions
2011Co-Authors: Kenji FukushimaAbstract:We summarize the idea of the chiral Magnetic Effect and the observables relevant to the heavy‐ion collision experiment which could be affected by QCD phase transitions.
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Dielectric correction to the chiral Magnetic Effect
Physical Review D, 2010Co-Authors: Kenji Fukushima, Marco RuggieriAbstract:We derive an electric current density j{sub em} in the presence of a Magnetic field B and a chiral chemical potential {mu}{sub 5}. We show that j{sub em} has, not only the anomaly-induced term {proportional_to}{mu}{sub 5}B (i.e. chiral Magnetic Effect), but also a nonanomalous correction which comes from interaction Effects and is expressed in terms of the susceptibility. We find the correction characteristically dependent on the number of quark flavors. The numerically estimated correction turns out to be a minor Effect on heavy-ion collisions but can be tested by the lattice-QCD simulation.
Harmen J Warringa - One of the best experts on this subject based on the ideXlab platform.
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Electric-current susceptibility and the Chiral Magnetic Effect
Nuclear Physics A, 2020Co-Authors: Kenji Fukushima, Dmitri E. Kharzeev, Harmen J WarringaAbstract:We compute the electric-current susceptibility of hot quark-gluon matter in an external Magnetic field B. The difference between the susceptibilities measured in the directions parallel and perpendicular to the Magnetic field is ultraviolet finite and given by [formula here omitted.], where V denotes the volume, T the temperature, Nc the number of colors, and qf the charge of a quark of flavor f. This non-zero susceptibility difference acts as a background to the Chiral Magnetic Effect, i.e. the generation of electric current along the direction of Magnetic field in the presence of topological charge. We propose a description of the Chiral Magnetic Effect that takes into account the fluctuations of electric current quantified by the susceptibility. We find that our results are in agreement with recent lattice QCD calculations. Our approach can be used to model the azimuthal dependence of charge correlations observed in heavy ion collisions
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Dynamics of the Chiral Magnetic Effect in a weak Magnetic field
Physical Review D, 2012Co-Authors: Harmen J WarringaAbstract:We investigate the real-time dynamics of the chiral Magnetic Effect in quantum electrodynamics (QED) and quantum chromodynamics (QCD). We consider a field configuration of parallel (chromo)electric and (chromo)Magnetic fields with a weak perpendicular electroMagnetic Magnetic field. The chiral Magnetic Effect induces an electroMagnetic current along this perpendicular Magnetic field, which we will compute using linear response theory. We discuss specific results for a homogeneous sudden switch-on and a pulsed (chromo)electric field in a static and homogeneous (chromo)Magnetic field. Our methodology can be easily extended to more general situations. The results are useful for investigating the chiral Magnetic Effect with heavy ion collisions and with lasers that create strong electroMagnetic fields. As a side result we obtain the rate of chirality production for massive fermions in parallel electric and Magnetic fields that are static and homogeneous.
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Real-time dynamics of the chiral Magnetic Effect.
Physical Review Letters, 2010Co-Authors: Kenji Fukushima, Dmitri E. Kharzeev, Harmen J WarringaAbstract:In quantum chromodynamics, a gauge field configuration with nonzero topological charge generates a difference between the number of left- and right-handed quarks. When a (electroMagnetic) Magnetic field is added to this configuration, an electroMagnetic current is induced along the Magnetic field; this is called the chiral Magnetic Effect. We compute this current in the presence of a color-flux tube possessing topological charge, with a Magnetic field applied perpendicular to it. We argue that this situation is realized at the early stage of relativistic heavy-ion collisions.
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Electric-current Susceptibility and the Chiral Magnetic Effect
Nuclear Physics, 2010Co-Authors: Kenji Fukushima, Dmitri E. Kharzeev, Harmen J WarringaAbstract:Abstract We compute the electric-current susceptibility χ of hot quark–gluon matter in an external Magnetic field B . The difference between the susceptibilities measured in the directions parallel and perpendicular to the Magnetic field is ultraviolet-finite and given by χ ∥ − χ ⊥ = V T N c ∑ f q f 2 | q f B | / ( 2 π 2 ) , where V denotes the volume, T the temperature, N c the number of colors, and q f the charge of a quark of flavor f . This non-zero susceptibility difference acts as a background to the Chiral Magnetic Effect, i.e. the generation of electric current along the direction of Magnetic field in the presence of topological charge. We propose a description of the Chiral Magnetic Effect that takes into account the fluctuations of electric current quantified by the susceptibility. We find that our results are in agreement with recent lattice QCD calculations. Our approach can be used to model the azimuthal dependence of charge correlations observed in heavy ion collisions.
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chiral Magnetic Effect
Physical Review D, 2008Co-Authors: Kenji Fukushima, Dmitri E. Kharzeev, Harmen J WarringaAbstract:Topological charge changing transitions can induce chirality in the quark-gluon plasma by the axial anomaly. We study the equilibrium response of the quark-gluon plasma in such a situation to an external Magnetic field. To mimic the Effect of the topological charge changing transitions we will introduce a chiral chemical potential. We will show that an electroMagnetic current is generated along the Magnetic field. This is the chiral Magnetic Effect. We compute the magnitude of this current as a function of Magnetic field, chirality, temperature, and baryon chemical potential.
M. I. Polikarpov - One of the best experts on this subject based on the ideXlab platform.
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Axial Magnetic Effect in two-color quenched lattice QCD
Epj Web of Conferences, 2015Co-Authors: Victor Braguta, Maxim Chernodub, Karl Landsteiner, Alexander Molochkov, M. I. PolikarpovAbstract:The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) Magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the Effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.
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Temperature dependence of the axial Magnetic Effect in two-color quenched QCD
Physical Review D, 2014Co-Authors: Victor Braguta, Maxim Chernodub, Karl Landsteiner, Alexander Molochkov, M. I. PolikarpovAbstract:The Axial Magnetic Effect is the generation of an equilibrium dissipationless energy flow of chiral fermions in the direction of the axial (chiral) Magnetic field. At finite temperature the dissipationless energy transfer may be realized in the absence of any chemical potentials. We numerically study the temperature behavior of the Axial Magnetic Effect in quenched SU(2) lattice gauge theory. We show that in the confinement (hadron) phase the Effect is absent. In the deconfinement transition region the conductivity quickly increases, reaching the asymptotic $T^2$ behavior in a deep deconfinement (plasma) phase. Apart from an overall proportionality factor, our results qualitatively agree with theoretical predictions for the behavior of the energy flow as a function of temperature and strength of the axial Magnetic field.
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Numerical evidence of the axial Magnetic Effect
Physical Review D, 2013Co-Authors: Victor Braguta, Maxim Chernodub, Karl Landsteiner, M. I. Polikarpov, M. V. UlybyshevAbstract:The axial Magnetic field, which couples to left- and right-handed fermions with opposite signs, may generate an equilibrium dissipationless energy flow of fermions in the direction of the field even in the presence of interactions. We report on numerical observation of this axial Magnetic Effect in quenched SU(2) lattice gauge theory. We find that in the deconfinement (plasma) phase the energy flow grows linearly with the increase of the strength of the axial Magnetic field. In the confinement (hadron) phase the axial Magnetic Effect is absent. Our study indirectly confirms the existence of the chiral vortical Effect since both these Effects have the same physical origin related to the presence of the gravitational anomaly.
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Chiral Magnetic Effect in SU(2) lattice gluodynamics at zero temperature
Jetp Letters, 2009Co-Authors: Pavel Buividovich, M. I. Polikarpov, E. V. Lushchevskaya, Maxim ChernodubAbstract:The chiral Magnetic Effect is the appearance of a quark electric current along a Magnetic-field direction in topologically nontrivial gauge fields. There is evidence that this Effect is observed in collisions between heavy ions at the RHIC collider. The features of the chiral Magnetic Effect in SU(2) lattice gluodynamics at zero temperature have been investigated. It has been found that the electric current increases in the Magnetic-field direction owing to quantum fluctuations of gluon fields. Fluctuations of the local charge density and chirality also increase with the Magnetic field strength, which is a signature of the chiral Magnetic Effect.
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Numerical evidence of chiral Magnetic Effect in lattice gauge theory
Physical Review D, 2009Co-Authors: Pavel Buividovich, Maxim Chernodub, E. V. Luschevskaya, M. I. PolikarpovAbstract:The chiral Magnetic Effect is the generation of electric current of quarks along an external Magnetic field in the background of topologically nontrivial gluon fields. There is recent evidence that this Effect is observed by the STAR Collaboration in heavy-ion collisions at the Relativistic Heavy Ion Collider. In our paper we study qualitative signatures of the chiral Magnetic Effect using quenched lattice simulations. We find indications that the electric current is indeed enhanced in the direction of the Magnetic field both in equilibrium configurations of the quantum gluon fields and in a smooth gluon background with nonzero topological charge. In the confinement phase the Magnetic field enhances the local fluctuations of both the electric charge and chiral charge densities. In the deconfinement phase the Effects of the Magnetic field become smaller, possibly due to thermal screening. Using a simple model of a fireball we obtain a good agreement between our data and experimental results of STAR Collaboration.
Jinfeng Liao - One of the best experts on this subject based on the ideXlab platform.
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Charge-Dependent Correlations in Relativistic Heavy Ion Collisions and the Chiral Magnetic Effect
Lecture Notes in Physics, 2020Co-Authors: Adam Bzdak, Volker Koch, Jinfeng LiaoAbstract:We provide a phenomenological analysis of present experimental searches for local parity violation manifested through the Chiral Magnetic Effect. We introduce and discuss the relevant correlation functions used for the measurements. Our analysis of the available data from both RHIC and LHC shows that the present experimental evidence for the Chiral Magnetic Effect is rather ambiguous. We further discuss in some detail various background contributions due to conventional physics, which need to be understood quantitatively in order to draw a definitive conclusion about the existence of local parity violation in heavy ion collisions.
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Chiral Magnetic Effect in Isobar Collisions from Stochastic Hydrodynamics.
arXiv: Nuclear Theory, 2020Co-Authors: Gui-rong Liang, Jinfeng Liao, Miao LiAbstract:We study chiral Magnetic Effect in collisions of AuAu, RuRu and ZrZr at s = 200GeV. The axial charge evolution is modeled with stochastic hydrodynamics and geometrical quantities are calculated with Monte Carlo Glauber model. By adjusting the relaxation time of Magnetic field, we find our results in good agreement with background subtracted data for AuAu collisions at the same energy. We also make prediction for RuRu and ZrZr collisions. We find a weak centrality dependence of initial chiral imbalance, which implies the centrality dependence of chiral Magnetic Effect signal comes mainly from those of Magnetic field and volume factor. Our results also show an unexpected dependence on system size: while the system of AuAu has larger chiral imbalance and Magnetic field, it turns out to have smaller signal for chiral Magnetic Effect due to the larger volume suppression factor.
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Chiral Magnetic Effect in Heavy Ion Collisions
Nuclear Physics, 2016Co-Authors: Jinfeng LiaoAbstract:Abstract The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. It is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong Magnetic fields | B → | ∼ m π 2 are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. In this contribution we give a brief overview on the status of such efforts.
