Medium-modified Jets and Initial State Fluctuations as Sources of Charge Correlations Measured at RHIC

Abstract

We investigate the contribution of medium-modified jets and initial state fluctuations to the asymmetry in charged particle production with respect to the reaction plane. This asymmetry has been suggested as a compelling signature of the Chiral Magnetic Effect in QCD and make a study of "conventional" scenarios for the creation of such charged particle multiplicity fluctuations a timely endeavor. The different pathlength combinations of jets through the medium in non-central heavy ion collisions result in finite correlations of like and different charged particles emitted in the different hemispheres. Our calculation is based on combining jet events from YaJEM (Yet another Jet Energy Loss Model) and a bulk medium evolution. It is found that the jet production probabilities are too small to observe this effect. The influence of initial state fluctuations on this observable is explored using an event-by-event (3+1)d hybrid approach that is based on UrQMD (Ultra-relativistic Quantum Molecular Dynamics) with an ideal hydrodynamic evolution. In this calculation momentum conservation and elliptic flow are explicitly taken into account. The asymmetries in the initial state are translated to a final state momentum asymmetry by the hydrodynamic flow profile. Dependent on the size of the initial state fluctuations the resulting charged particle asymmetries are in qualitative agreement with the preliminary STAR results. The multi-particle correlation as proposed by the PHENIX collaboration can in principle be used to disentangle the different contributions, however is in practice substantially affected by the procedure to subtract trivial resonance decay contributions.

9 pages, 9 figures, version to be published in PRC, including updated figures and references

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Cited by in corpus (13)

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• Experimental searches for the chiral magnetic effect in heavy-ion collisions
• Constraining the initial state granularity with bulk observables in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV
• Challenges in flow background removal in search for the chiral magnetic effect
• Dynamics of the Chiral Magnetic Effect in a weak magnetic field
• Isolating the chiral magnetic effect from backgrounds by pair invariant mass
• Identified Particle Spectra and Anisotropic Flow in an Event-by-Event Hybrid Approach in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• HIJING can describe the anisotropy-scaled charge-dependent correlations at the Relativistic Heavy Ion Collider
• The Isospin Asymmetry in Anomalous Fluid Dynamics
• Lattice studies of magnetic phenomena in heavy-ion collisions
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• Back-to-back relative-excess observable in search for the chiral magnetic effect