Investigating event-shape methods in the search for the chiral magnetic effect in relativistic heavy ion collisions

Abstract

The Chiral Magnetic Effect (CME) is a phenomenon in which electric charge is separated by a strong magnetic field from local domains of chirality imbalance and parity violation in quantum chromodynamics (QCD). The CME-sensitive observable, charge-dependent three-point azimuthal correlator $\Delta \gamma$, is contaminated by a major physics background proportional to the particle's elliptic flow anisotropy $v_2$. Event-shape engineering (ESE) binning events in dynamical fluctuations of $v_2$ and event-shape selection (ESS) binning events in statistical fluctuations of $v_2$ are two methods to search for the CME by projecting $\Delta \gamma$ to the measured anisotropy $v_2=0$ intercept. We conduct a systematic study of these two methods using physics models as well as toy model simulations. It is observed that the ESE method fulfills the general premise of measuring the CME but is statistically hungry. It is found that the intercept from the ESS method depends on the details of the event content, such as the mixtures of background-contributing sources, because of statistical fluctuations of intertwining variables used in the method, and is thus not practically useful or clean to measure the CME.

24 pages, 8 figures, 14 additional figures in appendix. Version 4: One figure deleted, text modified accordingly. It has been accepted for publication as a Regular Article in Physical Review C

References in corpus (65)

• The Chiral Magnetic Effect
• High-Energy-Physics Event Generation with PYTHIA 6.1
• 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
• 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
• Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR
• Flow Study in Relativistic Nuclear Collisions by Fourier Expansion of Azimuthal Particle Distributions
• HIJING 1.0: A Monte Carlo Program for Parton and Particle Production in High Energy Hadronic and Nuclear Collisions
• Event-by-event generation of electromagnetic fields in heavy-ion collisions
• Chiral Magnetic and Vortical Effects in High-Energy Nuclear Collisions --- A Status Report
• Parity violation in hot QCD: why it can happen, and how to look for it
• Azimuthal Charged-Particle Correlations and Possible Local Strong Parity Violation
• Suppressed pi^0 Production at Large Transverse Momentum in Central Au+Au Collisions at sqrt(s_NN) = 200 GeV
• ZPC 1.0.1: a parton cascade for ultrarelativistic heavy ion collisions
• Identified particle distributions in pp and Au+Au collisions at sqrt{s_NN}=200 GeV
• Possibility of spontaneous parity violation in hot QCD
• Parity violation in hot QCD: how to detect it
• Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions
• System Size, Energy, Pseudorapidity, and Centrality Dependence of Elliptic Flow
• Partonic effects on the elliptic flow at relativistic heavy ion collisions
• Charge separation relative to the reaction plane in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Azimuthally fluctuating magnetic field and its impacts on observables in heavy-ion collisions
• Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC
• Charge conservation in RHIC and contributiuons to local parity violation observables
• Effect of flow fluctuations and nonflow on elliptic flow methods
• Viscous QCD matter in a hybrid hydrodynamic+Boltzmann approach
• Ultra-relativistic nuclear collisions: event shape engineering
• rho^0 Production and Possible Modification in Au+Au and p+p Collisions at sqrt(s_NN) = 200 GeV
• Effects of Cluster Particle Correlations on Local Parity Violation Observables
• Observation of charge-dependent azimuthal correlations in pPb collisions and its implication for the search for the chiral magnetic effect
• Eccentricity fluctuations and elliptic flow at RHIC
• Anomalous Chiral Transport in Heavy Ion Collisions from Anomalous-Viscous Fluid Dynamics
• Azimuthal correlations from transverse momentum conservation and possible local parity violation
• Is the analysis of flow at the CERN SPS reliable?
• Constraints on the chiral magnetic effect using charge-dependent azimuthal correlations in pPb and PbPb collisions at the LHC
• Torqued fireballs in relativistic heavy-ion collisions
• Effects of Momentum Conservation and Flow on Angular Correlations at RHIC
• Resonance decay effects on anisotropy parameters
• Measurement of Charge Multiplicity Asymmetry Correlations in High Energy Nucleus-Nucleus Collisions at 200 GeV
• Experimental searches for the chiral magnetic effect in heavy-ion collisions
• 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
• Measurements of Dielectron Production in Au$+$Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV from the STAR Experiment
• On the Charge Separation Effect in Relativistic Heavy Ion Collisions
• Signatures of Chiral Magnetic Effect in the Collisions of Isobars
• The STAR Event Plane Detector
• Event-plane decorrelation over pseudo-rapidity and its effect on azimuthal anisotropy measurement in relativistic heavy-ion collisions
• Core-corona procedure and microcanonical hadronization to understand strangeness enhancement in proton-proton and heavy ion collisions in the EPOS4 framework
• Varying the chiral magnetic effect relative to flow in a single nucleus-nucleus collision
• Challenges in flow background removal in search for the chiral magnetic effect
• Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model
• Charge-dependent pair correlations relative to a third particle in $p$+Au and $d$+Au collisions at RHIC
• Hadron spectra, flow and correlations in PbPb collisions at the LHC: interplay between soft and hard physics
• Constraining the Chiral Magnetic Effect with charge-dependent azimuthal correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 and 5.02 TeV
• Momentum conservation and correlation analyses in heavy-ion collisions at ultrarelativistic energies
• Estimate of the CME signal in heavy-ion collisions from measurements relative to the participant and spectator flow planes
• Two- and three-particle nonflow contributions to the chiral magnetic effect measurement by spectator and participant planes in relativistic heavy ion collisions
• Search for the Chiral Magnetic Effect in Relativistic Heavy-Ion Collisions
• Non-flow correlations in a cluster model
• Utilization of Event Shape in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
• Event Shape Selection Method in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
• Chiral magnetic effect search in p(d)+Au, Au+Au collisions at RHIC
• Influence of the chiral magnetic effect on particle-pair elliptic anisotropy

Cited by in corpus (1)

• Experimental review on the chiral magnetic effect in relativistic heavy ion collisions