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Nuclear Theory·nucl-th

Friday·May 14, 2021

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    [Submitted on 12 May 2021] (cross-list from hep-ph)

    Is the Chiral Magnetic Effect fast enough?

    Jewel K. Ghosh🇧🇩 · Sebastian Grieninger🇪🇸 · Karl Landsteiner🇪🇸 · Sergio Morales-Tejera🇪🇸

    It depends: While we find within holography that the lifetime of the magnetic field for collider energies like the ones achieved at RHIC is long enough to build up the chiral magnetic current, the lifetime of the magnetic field at LHC seems to be too short. We study the real time evolution of the chiral magnetic effect out-of-equilibrium in strongly coupled holographic gauge theories. We consider the backreaction of the magnetic field onto the geometry and monitor pressure and chiral magnetic current. Our findings show that generically at small magnetic field the pressure builds up faster than the chiral magnetic current whereas at strong magnetic field the opposite is true. At large charge we also find that equilibration is delayed significantly due to long lived oscillations. We also match the parameters of our model to QCD parameters and draw lessons of possible relevance to the realization of the chiral magnetic effect in heavy ion collisions. In particular, we find an equilibration time of about fm/c in presence of the chiral anomaly for plasma temperatures of order MeV.

    Comments:
    v2 matches version published in PRD; 11 pages + appendix, 9 + 3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2105.05855 [pdf]
    PRD(2021)·26 citations
  2. 04

    [Submitted on 13 May 2021] (cross-list from hep-ph)

    Far-from-equilibrium hydrodynamic simulations of ultrarelativistic nuclear collisions

    Mike McNelis🇺🇸

    We develop a far-from-equilibrium hydrodynamic model to evolve ultrarelativistic heavy-ion collisions in event-by-event simulations. Anisotropic hydrodynamics is designed to better handle the strong and highly anisotropic expansion during the early stages of the collision. The large gradients cause conventional second-order viscous hydrodynamic approaches to break down at early times. Anisotropic hydrodynamics evolves the large pressure anisotropies present in the quark-gluon plasma non-perturbatively, which prevents negative longitudinal pressures from developing even under extreme conditions. This increased stability allows us to start anisotropic hydrodynamics already at a very early longitudinal proper time to evolve the pre-hydrodynamic stage. In current pre-hydrodynamic models, the equation of state is not consistent with the QCD equation of state used in the subsequent fluid dynamic stage. Since our approach avoids this inconsistency, we are able to achieve a smooth transition to non-conformal viscous hydrodynamics as the gradients decrease over time. For our first phenomenological application, we apply our new simulation to model fluctuating Pb+Pb collisions at LHC energies ( TeV) and find that our preliminary calculations for the hadronic observables are in excellent agreement with the experimental data.

    Comments:
    PhD thesis, 332 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2105.06007 [pdf]
    3 citations
  3. 05

    [Submitted on 13 May 2021] (cross-list from nucl-ex)

    Investigation of Experimental Observables in Search of the Chiral Magnetic Effect in Heavy-ion Collisions in the STAR experiment

    Subikash Choudhury🇨🇳 · Xin Dong🇺🇸 · Jim Drachenberg🇺🇸 · James Dunlop🇺🇸 · ShinIchi Esumi🇯🇵 · Yicheng Feng🇺🇸 · Evan Finch🇺🇸 · Yu Hu🇨🇳 · Jiangyong Jia🇺🇸 · Jerome Lauret🇺🇸 · Wei Li🇺🇸 · Jinfeng Liao🇺🇸 and 18 other authors

    The chiral magnetic effect (CME) is a novel transport phenomenon, arising from the interplay between quantum anomalies and strong magnetic fields in chiral systems. In high-energy nuclear collisions, the CME may survive the expansion of the quark-gluon plasma fireball and be detected in experiments. Over the past decade, the experimental searches for the CME have aroused extensive interest at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The main goal of this article is to investigate three pertinent experimental approaches: the correlator, the correlator and the signed balance functions. We will exploit both simple Monte Carlo simulations and a realistic event generator (EBE-AVFD) to verify the equivalence in the kernel-component observables among these methods and to ascertain their sensitivities to the CME signal for the isobaric collisions at RHIC.

    Comments:
    18 pages, 8 figures, 2 tables. Extended the discussion on R observable with the consideration of multiplicity fluctuation as used in practice
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2105.06044 [pdf]
    CPC(2022)·47 citations
  4. 06

    [Submitted on 13 May 2021] (cross-list from hep-ph)

    Understanding partonic energy loss from measured light charged particles and jets in PbPb collisions at LHC energies

    Prashant Shukla🇮🇳 · Kapil Saraswat🇮🇳

    We perform a comprehensive study of partonic energy loss reflected in the nuclear modification factors of charged particles and jets measured in PbPb collisions at = 2.76 and 5.02 TeV in wide transverse momentum () and centrality range. The distributions in pp collisions are fitted with a modified power law and the nuclear modification factor in PbPb collisions can be obtained using effective shift () in the spectrum measured at different centralities. Driven by physics consideration, the functional form of energy loss given by can be assumed as power law with different power indices in three different regions. The power indices and the boundaries of three regions are obtained by fitting the measured nuclear modification factor as a function of in all collision centralities simultaneously. The energy loss in different collisions centralities are described in terms of fractional power of number of participants. It is demanded that the power law functions in three regions and their derivatives are continuous at the boundaries. The for light charged particles is found to increase linearly with in low region below GeV/ and approaches a constant value in high region above GeV/ with an intermediate power law connecting the two regions. The method is also used for jets and it is found that for jets, the increases approximately linearly even at very high .

    Comments:
    19 pages, 14 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2105.06364 [pdf]
    J.Phys.G(2020)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE