Experimental searches for the chiral magnetic effect in heavy-ion collisions

Abstract

The chiral magnetic effect (CME) in quantum chromodynamics (QCD) refers to a charge separation (an electric current) of chirality imbalanced quarks generated along an external strong magnetic field. The chirality imbalance results from interactions of quarks, under the approximate chiral symmetry restoration, with metastable local domains of gluon fields of non-zero topological charges out of QCD vacuum fluctuations. Those local domains violate the $\mathcal{P}$ and $\mathcal{C}\mathcal{P}$ invariance, potentially offering a solution to the strong $\mathcal{C}\mathcal{P}$ problem in explaining the magnitude of the matter-antimatter asymmetry in today's universe. Relativistic heavy-ion collisions, with the likely creation of the high energy density quark-gluon plasma and restoration of the approximate chiral symmetry, and the possibly long-lived strong magnetic field, provide a unique opportunity to detect the CME. Early measurements of the CME-induced charge separation in heavy-ion collisions are dominated by physics backgrounds. Major efforts have been devoted to eliminate or reduce those backgrounds. We review those efforts, with a somewhat historical perspective, and focus on the recent innovative experimental undertakings in the search for the CME in heavy-ion collisions.

arXiv commentInvited review by Progress in Particle and Nuclear Physics, 57 pages, 33 figures

References in corpus (137)

• Weyl and Dirac Semimetals in Three Dimensional Solids
• Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
• Discovery of a Weyl Fermion Semimetal and Topological Fermi Arcs
• Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
• Quark Gluon Plasma an Color Glass Condensate at RHIC? The perspective from the BRAHMS experiment
• The PHOBOS Perspective on Discoveries at RHIC
• The Chiral Magnetic Effect
• The effects of topological charge change in heavy ion collisions: "Event by event P and CP violation"
• A Multi-Phase Transport Model for Relativistic Heavy Ion Collisions
• An Improved Experimental Limit on the Electric Dipole Moment of the Neutron
• Collective flow and viscosity in relativistic heavy-ion collisions
• Methods for analyzing anisotropic flow in relativistic nuclear collisions
• Estimate of the magnetic field strength in heavy-ion collisions
• Leptogenesis
• Observation of the chiral magnetic effect in ZrTe5
• Flow Study in Relativistic Nuclear Collisions by Fourier Expansion of Azimuthal Particle Distributions
• Global $\Lambda$ hyperon polarization in nuclear collisions: evidence for the most vortical fluid
• Event-by-event generation of electromagnetic fields in heavy-ion collisions
• Chiral Magnetic and Vortical Effects in High-Energy Nuclear Collisions --- A Status Report
• Experimental Searches for the Axion and Axion-like Particles
• The origin of the matter-antimatter asymmetry
• Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals
• Parity violation in hot QCD: why it can happen, and how to look for it
• Charge separation induced by P-odd bubbles in QCD matter
• The Chiral Magnetic Effect and Anomaly-Induced Transport
• Event-by-event fluctuations of magnetic and electric fields in heavy ion collisions
• A Revised Experimental Upper Limit on the Electric Dipole Moment of the Neutron
• First Results from Pb+Pb collisions at the LHC
• Matter and Antimatter in the Universe
• Flow analysis from multiparticle azimuthal correlations
• Angular momentum conservation in heavy ion collisions at very high energy
• Anomalous Axion Interactions and Topological Currents in Dense Matter
• Physics of Strongly coupled Quark-Gluon Plasma
• Chiral Magnetic Wave
• Possibility of spontaneous parity violation in hot QCD
• Parity violation in hot QCD: how to detect it
• Axions as Dark Matter Particles
• System Size, Energy, Pseudorapidity, and Centrality Dependence of Elliptic Flow
• Comments About the Electromagnetic Field in Heavy-Ion Collisions
• Chiral Magnetic conductivity
• Partonic effects on the elliptic flow at relativistic heavy ion collisions
• Electromagnetic fields and anomalous transports in heavy-ion collisions --- A pedagogical review
• Magnetohydrodynamics, charged currents and directed flow in heavy ion collisions
• Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field and feed-down
• Small System Collectivity in Relativistic Hadron and Nuclear Collisions
• Charge separation relative to the reaction plane in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Chiral magnetic wave at finite baryon density and the electric quadrupole moment of quark-gluon plasma in heavy ion collisions
• Generic framework for anisotropic flow analyses with multi-particle azimuthal correlations
• Novel Collective Phenomena in High-Energy Proton-Proton and Proton-Nucleus Collisions
• Topologically induced local P and CP violation in QCD x QED
• Azimuthally fluctuating magnetic field and its impacts on observables in heavy-ion collisions
• Directed Flow of Charm Quarks as a Witness of the Initial Strong Magnetic Field in Ultra-Relativistic Heavy Ion Collisions
• Vortical fluid and $\Lambda$ spin correlations in high-energy heavy-ion collisions
• Charge conservation in RHIC and contributiuons to local parity violation observables
• Conformal hydrodynamics in Minkowski and de Sitter spacetimes
• Probing vorticity structure in heavy-ion collisions by local $\Lambda$ polarization
• Ultra-relativistic nuclear collisions: event shape engineering
• Observation of charge-dependent azimuthal correlations in pPb collisions and its implication for the search for the chiral magnetic effect
• Anisotropic parton escape is the dominant source of azimuthal anisotropy in transport models
• Anisotropic parton escape is the dominant source of azimuthal anisotropy in transport models
• Synchrotron radiation by fast fermions in heavy-ion collisions
• Anomalous Chiral Transport in Heavy Ion Collisions from Anomalous-Viscous Fluid Dynamics
• Azimuthal correlations from transverse momentum conservation and possible local parity violation
• Charge-dependent Flow Induced by Magnetic and Electric Fields in Heavy Ion Collisions
• Observation of charge asymmetry dependence of pion elliptic flow and the possible chiral magnetic wave in heavy-ion collisions
• Is the analysis of flow at the CERN SPS reliable?
• Electric Charge Separation in Strong Transient Magnetic Fields
• Constraints on the chiral magnetic effect using charge-dependent azimuthal correlations in pPb and PbPb collisions at the LHC
• Effects of Momentum Conservation and Flow on Angular Correlations at RHIC
• Pionic Measures of Parity and CP Violation in High Energy Nuclear Collisions
• Charge-Dependent Correlations in Relativistic Heavy Ion Collisions and the Chiral Magnetic Effect
• Measurement of Charge Multiplicity Asymmetry Correlations in High Energy Nucleus-Nucleus Collisions at 200 GeV
• Low-$p_T$ $e^{+}{e}^{-}$ pair production in Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U$+$U collisions at $\sqrt{s_{NN}}$ = 193 GeV at STAR
• Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76$ TeV
• Quantifying Chiral Magnetic Effect from Anomalous-Viscous Fluid Dynamics
• Initial value problem for magnetic field in heavy ion collisions
• Importance of isobar density distributions on the chiral magnetic effect search
• Normal ground state of dense relativistic matter in a magnetic field
• Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collisions
• Anomalous centrality variation of minijet angular correlations in Au-Au collisions at 62 and 200 GeV from STAR
• Anomalous Hydrodynamics
• Effects of final state interactions on charge separation in relativistic heavy ion collisions
• Search for Chiral Magnetic Effects in High-Energy Nuclear Collisions
• Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions
• Directed flow of charged particles at mid-rapidity relative to the spectator plane in Pb-Pb collisions at $\sqrt{s_\rm{NN}}$=2.76 TeV
• On the Charge Separation Effect in Relativistic Heavy Ion Collisions
• A new method for the experimental study of topological effects in the quark-gluon plasma
• Multi-particle and charge-dependent azimuthal correlations in heavy-ion collisions at the Relativistic Heavy-Ion Collider
• A New Correlator to Detect and Characterize the Chiral Magnetic Effect
• $\Lambda$ and $\bar{\Lambda }$ spin interaction with meson fields generated by the baryon current in high energy nuclear collisions
• Charge-dependent flow and the search for the Chiral Magnetic Wave in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Acoplanarity of Lepton Pair to Probe the Electromagnetic Property of Quark Matter
• Nearly isentropic flow at sizeable $\eta /s$
• The Chiral Magnetic Effect and an experimental bound on the late time magnetic field strength
• Charge Fluctuations from the Chiral Magnetic Effect in Nuclear Collisions
• Collective flow without hydrodynamics: simulation results for relativistic ion collisions
• Azimuthal Anisotropies at High Momentum from Purely Non-Hydrodynamic Transport
• Hydrodynamics with chiral anomaly and charge separation in relativistic heavy ion collisions
• Contributions to the event-by-event charge asymmetry dependence for the elliptic flow of pi^{+} and pi^{-} in heavy-ion collisions
• Chiral kinetic approach to the chiral magnetic effect in isobaric collisions
• Anomalous transport model study of chiral magnetic effects in heavy ion collisions
• Multi-phase transport model predictions of isobaric collisions with nuclear structures from density functional theory
• Elliptic flow difference of charged pions in heavy-ion collisions
• Isolating the chiral magnetic effect from backgrounds by pair invariant mass
• Elliptic Anisotropy $v_2$ May Be Dominated by Particle Escape instead of Hydrodynamic Flow
• Study of chiral vortical and magnetic effects in the anomalous transport model
• Investigating different $\Lambda$ and $\bar{\Lambda }$ polarizations in relativistic heavy-ion collisions
• Separation of flow from chiral magnetic effect in U+U collisions using spectator asymmetry
• To CME or not to CME? Implications of p+Pb measurements of the chiral magnetic effect in heavy ion collisions
• Conductivities of magnetic quark-gluon plasma at strong coupling
• Anomaly-induced dynamical refringence in strong-field QED
• Charge-dependent directed flow in Cu+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• Event-shape-engineering study of charge separation in heavy-ion collisions
• Flow harmonics $v_n$ at finite density
• Chiral magnetic currents with QGP medium response in heavy ion collisions at RHIC and LHC energies
• Origin of the mass splitting of azimuthal anisotropies in a multi-phase transport model
• Search for the Chiral Magnetic Effect in Relativistic Heavy-Ion Collisions
• A Centrality Detector Concept
• Examination of the observability of a chiral magnetically-driven charge-separation difference in collisions of the ${}_{44}^{96}\mathrm{Ru}+{}_{44}^{96}\mathrm{Ru}$ and ${}_{40}^{96}\mathrm{Zr}+{}_{40}^{96}\mathrm{Zr}$ isobars at energies available at RHIC
• Charge separation with fluctuating domains in relativistic heavy-ion collisions
• Event-by-event background in estimates of the chiral magnetic effect
• Nuclear Zemach Moments and Finite-Size Corrections to Allowed Beta Decay
• Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR
• Medium-modified Jets and Initial State Fluctuations as Sources of Charge Correlations Measured at RHIC
• Disentangling flow and signals of Chiral Magnetic Effect in U+U, Au+Au and p+Au collisions
• Responses of the chiral-magnetic-effect-sensitive sine observable to resonance backgrounds in heavy-ion collisions
• Isolation of Flow and Nonflow Correlations by Two- and Four-Particle Cumulant Measurements of Azimuthal Harmonics in $\sqrt{s_{{}_{\mathrm{NN}}}}=$ 200 GeV Au+Au Collisions
• Nonflow "factorization" and a novel method to disentangle anisotropic flow and nonflow
• Investigating Local Parity Violation in Heavy-Ion Collisions Using Lambda Helicity
• Elliptic flow of thermal dileptons in event-by-event hydrodynamic simulation
• Glauber-based evaluations of the odd moments of the initial eccentricity relative to the even order participant planes
• The effect of the fluctuating proton size on the study of chiral magnetic effect in proton-nucleus collisions
• Aspects of the pseudo Chiral Magnetic Effect in 2D Weyl-Dirac Matter
• Chiral magnetic effect in isobaric collisions
• A novel invariant mass method to isolate resonance backgrounds from the chiral magnetic effect
• Chiral magnetic effect search in p(d)+Au, Au+Au collisions at RHIC
• Re-examining the premise of isobaric collisions and a novel method to measure the chiral magnetic effect

Cited by in corpus (76)

• Properties of the QCD Matter -- An Experimental Review of Selected Results from RHIC BES Program
• Anomalous chiral transports and spin polarization in heavy-ion collisions
• Chiral magnetic effect reveals the topology of gauge fields in heavy-ion collisions
• Exploring QCD matter in extreme conditions with Machine Learning
• Azimuthal Angular Asymmetry of Soft Gluon Radiation in Jet Production
• Foundations and Applications of Quantum Kinetic Theory
• Spin polarization dynamics in the Gubser-expanding background
• Signatures of Chiral Magnetic Effect in the Collisions of Isobars
• Mapping the Electromagnetic Fields of Heavy-Ion Collisions with the Breit-Wheeler Process
• Strong-Field Physics in QED and QCD: From Fundamentals to Applications
• Anisotropic electrical conductivity of magnetized hot quark matter
• Charge-dependent pair correlations relative to a third particle in $p$+Au and $d$+Au collisions at RHIC
• Implications of the isobar run results for chiral magnetic effect in heavy ion collisions
• Probing nuclear structure with mean transverse momentum in relativistic isobar collisions
• Causality and stability in relativistic viscous non-resistive magneto-fluid dynamics
• Global polarization effect and spin-orbit coupling in strong interaction
• A stable and causal model of magnetohydrodynamics
• Momentum Anisotropy of Leptons from Two Photon Processes in Heavy Ion Collisions
• Chiral Magnetic Effect in Heavy Ion Collisions: The Present and Future
• Two- and three-particle nonflow contributions to the chiral magnetic effect measurement by spectator and participant planes in relativistic heavy ion collisions
• Kinetic theory with spin: From massive to massless fermions
• Deconfinement and chiral phase transitions in quark matter with a strong electric field
• Electromagnetic fields in ultra-peripheral relativistic heavy-ion collisions
• Chirality Production with Mass Effects-Schwinger Pair Production and the Axial Ward Identity
• Effect of magnetic field on the charge and thermal transport properties of hot and dense QCD matter
• Lepton pair photoproduction in peripheral relativistic heavy-ion collisions
• Dynamically assisted Schwinger mechanism and chirality production in parallel electromagnetic field
• Charge diffusion in relativistic resistive second-order dissipative magnetohydrodynamics
• Revisit the Chiral Magnetic Effect Expectation in Isobaric Collisions at the Relativistic Heavy Ion Collider
• Search for the chiral magnetic effect in collisions between two isobars with deformed and neutron-rich nuclear structures
• Search for the Chiral Magnetic Effect in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=27$ GeV with the STAR forward Event Plane Detectors
• Utilization of Event Shape in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
• Numerical Study of the Chiral Separation Effect in Two-Color QCD at Finite Density
• Pair invariant mass to isolate background in the search for the chiral magnetic effect in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$= 200 GeV
• Charge-dependent directed flows in heavy-ion collisions by Boltzmann-Maxwell equations
• Effects of the quark anomalous magnetic moment in the chiral symmetry restoration: magnetic catalysis and inverse magnetic catalysis
• Anomalous magnetohydrodynamics with temperature-dependent electric conductivity and application to the global polarization
• Global constraint on the magnitude of anomalous chiral effects in heavy-ion collisions
• HIJING can describe the anisotropy-scaled charge-dependent correlations at the Relativistic Heavy Ion Collider
• Relativistic resistive magneto-hydrodynamics code for high-energy heavy-ion collisions
• Systematic study of the Chiral Magnetic Effect with the AVFD model at LHC energies
• Causality violation and the speed of sound of hot and dense quark matter in the Nambu--Jona-Lasinio model
• Interpreting the charge-dependent flow and constraining the chiral magnetic wave with event shape engineering
• Out of equilibrium chiral magnetic effect and momentum relaxation in holography
• Impact of nuclear structure on the CME background in ${}_{44}^{96}$Ru + ${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr + ${}_{40}^{96}$Zr collisions at $\sqrt{s_{NN}}$ = 7.7 $\sim$ 200 GeV from a multiphase transport model
• Photoproduction of $e^{+}{e}^{-}$ in peripheral isobar collisions
• Quantum version of transport coefficients in Nambu--Jona-Lasinio model at finite temperature and strong magnetic field
• Charge-dependent transverse momentum and its impact on the search for the chiral magnetic wave
• Search for CME in U+U and Au+Au collisions in STAR with different approaches of handling backgrounds
• Charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a multiphase transport model
• Critical temperature of deconfinement in a constrained space using a bag model at vanishing baryon density
• Predictions for production of ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}^3\overline{\mathrm{H}}$ in isobaric ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV
• Spin-orbital magnetic response of relativistic fermions with band hybridization
• Collective dynamics of polarized spin-half fermions in relativistic heavy-ion collisions
• Review of nonflow estimation methods and uncertainties in relativistic heavy-ion collisions
• Dynamic scale anomalous transport in QCD with electromagnetic background
• Shear viscosity coefficient of magnetized QCD medium near chiral phase transition
• The BEST framework for the search for the QCD critical point and the chiral magnetic effect
• Magnetic field effects in peripheral heavy-ion collisions around 1 GeV/nucleon
• Collective Excitation in High-Energy Nuclear Collisions -- In Memory of Professor Lianshou Liu
• Difference between signal and background of the chiral magnetic effect relative to spectator and participant planes in isobar collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV
• Event-by-event correlations between $\Lambda$ ($\bar{\Lambda }$) hyperon global polarization and handedness with charged hadron azimuthal separation in Au+Au collisions at $\sqrt{s_{\text{NN}}}=27\text{ GeV}$ from STAR
• Chiral anomaly in a (1+1)-dimensional Floquet system under high-frequency electric fields
• Chirality imbalance and chiral magnetic effect under a parallel electromagnetic field
• Experimental review on the chiral magnetic effect in relativistic heavy ion collisions
• Sliding Dumbbell Method to search for the CME in heavy ion collisions
• Investigating event-shape methods in the search for the chiral magnetic effect in relativistic heavy ion collisions
• Magnetic helicity in plasma of chiral fermions electroweakly interacting with inhomogeneous matter
• Influence of the chiral magnetic effect on particle-pair elliptic anisotropy
• Chirality and Magnetic Field
• Investigation of Experimental Observables in Search of the Chiral Magnetic Effect in Heavy-ion Collisions in the STAR experiment
• Turning up and down strong magnetic fields in relativistic nuclear collisions
• Back-to-back relative-excess observable in search for the chiral magnetic effect
• Magnetic helicity in rotating neutron stars
• Optimal Observables for the Chiral Magnetic Effect from Machine Learning
• Helicity conservation in perfect electromagnetic and chiral fluids