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Nuclear Theory·nucl-th

Friday·February 28, 2020

11 papers—5 primary·6 cross-listed

All11Primary5Cross-lists6
  1. 01

    [Submitted on 26 Feb 2020]

    Local spin polarizations in relativistic heavy ion collisions

    Shuai Y. F. Liu🇨🇳 · Yifeng Sun🇮🇹 · Che Ming Ko🇺🇸

    Based on a generalized side-jump formalism for massless chiral fermions, which naturally takes into account the spin-orbit coupling in the scattering of two chiral fermions and the chiral vortical effect in a rotating chiral fermion matter, we have developed a covariant and total angular momentum conserved chiral transport model to study both the global and local polarizations of this matter. For a system of massless quarks of random spin orientations and finite vorticity in a box, we have demonstrated that the model can exactly conserve the total angular momentum of the system and dynamically generate the quark spin polarization expected from a thermally equilibrated quark matter. Using this model to study the spin polarization in relativistic heavy-ion collision, we have found that the local quark spin polarizations depend strongly on the reference frame where they are evaluated as a result of the nontrivial axial charge distribution caused by the chiral vortical effect. We have further shown that because of the anomalous orbital or side-jump contribution to the quark spin polarization, the local quark polarizations calculated in the medium rest frame are qualitatively consistent with the local polarizations of Lambda hyperons measured in experiments.

    Comments:
    4 pages, 2 figures, Proceedings for Quark Matter 2019
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2002.11752 [pdf]
    NPA(2021)·3 citations
  2. 02

    [Submitted on 27 Feb 2020]

    Extremely large matter radii in Ca isotopes and the breathing mode states of Ca

    Syed Afsar Abbas · Anisul Ain Usmani · Usuf Rahaman

    Through inelastic scattering cross section measurements for Ca on a carbon target at 280 MeV/nucleon recently, Tanaka {\it et al.} [ arXiv:1911.05262 [nucl-ex]], in a very significant experiment, have demonstrated large swelling of doubly magic Ca core in calcium isotopes beyond N=28. The matter radii observed in these experiments, are surprisingly much larger than the corresponding, already amazingly large charge radii of the same calcium isotopes, by Garcia {\it et al.} [Nat. Phys. 12 (2016) 594]. Here we propose a novel solution, wherein the breathing mode states of Ca, provide a global and consistent solution of this matter radii conundrum.

    Comments:
    5 pages
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2002.12002 [pdf]
    0 citations
  3. 03

    [Submitted on 26 Feb 2020]

    Estimations of Cross-Sections for Photonuclear Reaction on Calcium Isotopes by Artificial Neural Networks

    S. Akkoyun · H. Kaya

    The nuclear reaction induced by photon is one of the important tools in the investigation of atomic nuclei. In the reaction, a target material is bombarded by photons with high-energies in the range of gamma-ray energy range. In the bombarding process, the photons can statistically be absorbed by a nucleus in the target material. Then the excited nucleus can decay by emitting proton, neutron, alpha and light particles or photons. By performing photonuclear reaction on the target, it can be easily investigated low-lying excited states of the nuclei. In the present work, ({\gamma}, n) photonuclear reaction cross-sections on different calcium isotopes have been estimated by using artificial neural network method. The method is a mathematical model that mimics the brain functionality of the creatures. The correlation coefficient values of the method for both training and test phases being 0.99 indicate that the method is very suitable for this purpose.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2002.12166 [pdf]
    0 citations
  4. 04

    [Submitted on 27 Feb 2020]

    Hydrodynamic response to jets with a source based on causal diffusion

    Y. Tachibana🇺🇸 · A. Angerami · S. A. Bass · S. Cao · Y. Chen · J. Coleman · L. Cunqueiro · T. Dai · L. Du · R. Ehlers · H. Elfner · D. Everett and 38 other authors

    We study the medium response to jet evolution in the quark-gluon plasma within the JETSCAPE framework. Recoil partons' medium response in the weakly coupled description is implemented in the multi-stage jet energy-loss model in the framework. As a further extension, the hydrodynamic description is rearranged to include in-medium jet transport based on a strong-coupling picture. To interface hydrodynamics with jet energy-loss models, the hydrodynamic source term is modeled by a causal formulation employing the relativistic diffusion equation. The jet shape and fragmentation function are studied via realistic simulations with weakly coupled recoils. We also demonstrate modifications in the medium caused by the hydrodynamic response.

    Comments:
    4 pages, 2 figures, contribution to the Quark Matter 2019 proceedings
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2002.12250 [pdf]
    NPA(2021)·21 citations
  5. 05

    [Submitted on 27 Feb 2020]

    Improved description of light nuclei through chiral effective field theory at leading order

    M. Sanchez Sanchez🇫🇷 · N. A. Smirnova🇫🇷 · A. M. Shirokov🇺🇸 · P. Maris🇺🇸 · J. P. Vary🇺🇸

    We propose an arrangement of the most commonly invoked version of the two-nucleon chiral potential such that the low-lying amplitude zero of the 1S0 partial wave is captured at leading order of the effective expansion. Adopting other partial waves from the LENPIC interaction, we show how this modification yields an improved description of ground-state energies and point-proton radii of three test nuclei.

    Comments:
    10 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2002.12258 [pdf]
    PRC(2020)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE