PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·August 28, 2019

11 papers—3 primary·8 cross-listed

All11Primary3Cross-lists8
  1. 01

    [Submitted on 26 Aug 2019]

    Exact hydrodynamic attractor of an ultrarelativistic gas of hard spheres

    Gabriel S. Denicol🇧🇷 · Jorge Noronha🇺🇸

    We derive the general analytical solution of the viscous hydrodynamic equations for an ultrarelativistic gas of hard spheres undergoing Bjorken expansion, taking into account effects from particle number conservation, and use it to analytically determine its attractor at late times. Differently than all the cases considered before involving rapidly expanding fluids, in this example the gradient expansion converges. We exactly determine the hydrodynamic attractor of this system when its microscopic dynamics is modeled by the Boltzmann equation with a fully nonlinear collision kernel. The exact late time attractor of this system can be reasonably described by hydrodynamics even when the gradients are large.

    Comments:
    7 pages, 2 figures; version accepted for publication in Physical Review Letters
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1908.09957 [pdf]
    PRL(2020)·72 citations
  2. 02

    [Submitted on 27 Aug 2019]

    Back-to-back relative-excess observable in search for the chiral magnetic effect

    Yicheng Feng🇺🇸 · Jie Zhao🇺🇸 · Fuqiang Wang🇺🇸

    The chiral magnetic effect (CME) is extensively studied in heavy-ion collisions at RHIC and LHC. In the commonly used reaction plane (RP) dependent, charge dependent azimuthal correlator (), both the close and back-to-back pairs are included. Many backgrounds contribute to the close pairs (e.g. resonance decays, jet correlations), whereas the back-to-back pairs are relatively free of those backgrounds. In order to reduce those backgrounds, we propose a new observable which only focuses on the back-to-back pairs, namely, the relative back-to-back opposite-sign (OS) over same-sign (SS) pair excess () as a function of the pair azimuthal orientation with respect to the RP (). We use analytical calculations and toy model simulations to demonstrate the sensitivity of to the CME and its insensitivity to backgrounds. With finite CME, the distribution of shows a clear characteristic modulation. Its sensitivity to background is significantly reduced compared to the previous observable. The simulation results are consistent with our analytical calculations. Our studies demonstrate that the observable is sensitive to the CME signal and rather insensitive to the resonance backgrounds.

    Comments:
    6 pages, 4 figures, 1 table
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1908.10210 [pdf]
    PRC(2020)·3 citations
  3. 03

    [Submitted on 27 Aug 2019]

    Influence of the neutron-skin effect on nuclear isobar collisions at RHIC

    Jan Hammelmann🇩🇪 · Alba Soto-Ontoso🇺🇸 · Massimiliano Alvioli🇮🇹 · Hannah Elfner🇩🇪 · Mark Strikman🇺🇸

    The unambiguous observation of a Chiral Magnetic Effect (CME)-driven charge separation is the core aim of the isobar program at RHIC consisting of Zr+Zr and Ru+Ru collisions at GeV. We quantify the role of the spatial distributions of the nucleons in the isobars on both eccentricity and magnetic field strength within a relativistic hadronic transport approach (SMASH, Simulating Many Accelerated Strongly-interacting Hadrons). In particular, we introduce isospin-dependent nucleon-nucleon spatial correlations in the geometric description of both nuclei, deformation for Ru and the so-called neutron skin effect for the neutron-rich isobar i.e. Zr. The main result of this study is a reduction of the magnetic field strength difference between Ru+Ru and Zr+Zr by a factor of 2, from to in peripheral collisions when the neutron-skin effect is included. Further, we find an increase of eccentricity by up to 10 when deformation is taken into account while neither the neutron skin effect nor the nucleon-nucleon correlations result into a significant modification of this observable with respect to the traditional Woods-Saxon modeling. Our results suggest a significantly smaller CME signal to background ratio for the experimental charge separation measurement in peripheral collisions with the isobar systems than previously expected.

    Comments:
    6 pages, 3 figures, v2: bug in the implementation of the deformation has been fixed. Conclusions remain intact
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1908.10231 [pdf]
    PRC(2020)·44 citations

Affiliations

first authorsco-authorsvia INSPIRE