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Nuclear Theory·nucl-th

Thursday·October 31, 2019

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    [Submitted on 29 Oct 2019]

    Fission in a microscopic framework: from basic science to support for applications

    I. Stetcu · A. Bulgac · S. Jin · K. J. Roche · N. Schunck

    Recent developments, both in theoretical modeling and computational power, have allowed us to make progress on a goal not fully achieved yet in nuclear theory: a microscopic theory of nuclear fission. Even if the complete microscopic description remains a computationally demanding task, the information that can be provided by current calculations can be extremely useful to guide and constrain more phenomenological approaches, which are simpler to implement. First, a microscopic model that describes the real-time dynamics of the fissioning system can justify or rule out some of the approximations. Second, the microscopic approach can be used to obtain trends, e.g., with increasing excitation energy of the fissioning system, or even to compute observables that cannot be otherwise calculated in phenomenological approaches or that can be hindered by the limitations of the method. We briefly present in this contribution the time-dependent superfluid local density approximation (TDSLDA) approach to nuclear fission, approach that has become a very successful theoretical model in many areas of many-body research. The TDSLDA incorporates the effects of the continuum, the dynamics of the pairing field, and the numerical solution is implemented with controlled approximations and negligible numerical corrections. The main part of the current contribution will be dedicated to discussing the method, and recent results concerning the fission dynamics. In addition, we present results on the excitation energy sharing between the fragments, which are in agreement with a qualitative conclusions extracted from a limited number of experimental measurements of properties of prompt neutrons.

    Comments:
    Prepared for the proceedings of the Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays (Theory-5)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1910.13581 [pdf]
    EPJ Web Conf.(2021)·1 citation
  2. 02

    [Submitted on 30 Oct 2019]

    What can we learn from global spin alignment of meson in heavy-ion collisions?

    Xin-Li Sheng🇨🇳 · Lucia Oliva🇩🇪 · Qun Wang🇨🇳

    We propose that a significant positive deviation from 1/3 for the spin density matrix element of the meson may indicate the existence of a mean field of the meson generated in heavy-ion collisions. This explains why STAR preliminary data for the meson's are much larger than 1/3 while the data of and polarization seem not to allow such a significant and positive deviation. The contribution may be from the polarization of the strange quark and antiquark through the field, an effective mode of the gluon field in strong interaction. We show that for the meson is a good analyzer for fields even if they may strongly fluctuate in space-time.

    Comments:
    ReVTex 4, 8 pages, 1 figure. A sign error in the polarization formula for the anti-quark is corrected, related discussions are changed accordingly. The results for the case with the quark polarization along all directions are added as an appendix
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1910.13684 [pdf]
    PRD(2020)·154 citations
  3. 03

    [Submitted on 30 Oct 2019]

    Color transparency of meson produced in the inclusive reaction on nuclei

    Swapan Das🇮🇳

    Color transparency is studied for the meson produced due to large four-momentum transfer in the reaction on nuclei. The variation of the meson color transparency (CT) with the photon virtuality, and kaon momentum is investigated. The calculated results for CT are compared with the data reported from Jefferson Laboratory.

    Comments:
    13 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1910.13685 [pdf]
    PRC(2019)·5 citations
  4. 04

    [Submitted on 30 Oct 2019]

    Hamiltonian flow equations for a Dirac particle in large scalar and vector potentials

    Z. X. Ren · P. W. Zhao

    An efficient solution of the Dirac Hamiltonian flow equations has been proposed through a novel expandsion with the inverse of the Dirac effective mass. The efficiency and accuracy of this new expansion have been demonstrated by reducing a radial Dirac Hamiltonian with large scalar and vector potentials to two nonrelativistic Hamiltonians corresponding to particles and antiparticles, respectively. By solving the two nonrelativistic Hamiltonians, it is found that the exact solutions of the Dirac equation, for both particles and antiparticles, can be reproduced with a high accuracy up to only a few lowest order terms in the expansion. This could help compare and bridge the relativistic and nonrelativistic nuclear energy density functional theories in the future.

    Comments:
    15 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1910.13813 [pdf]
    PRC(2019)·6 citations
  5. 05

    [Submitted on 29 Oct 2019]

    Equivalence of the phenomenological Tsallis distribution to the transverse momentum distribution of -dual statistics

    A.S. Parvan🇷🇺

    In the present work, we have found that the phenomenological Tsallis distribution (which nowadays is largely used to describe the transverse momentum distributions of hadrons measured in collisions at high energies) is consistent with the basis of the statistical mechanics if it belongs to the -dual nonextensive statistics instead of the Tsallis one. We have defined the -dual statistics based on the -dual entropy which was obtained from the Tsallis entropy under the multiplicative transformation of the entropic parameter . We have found that the phenomenological Tsallis distribution is equivalent to the transverse momentum distribution of the -dual statistics in the zeroth term approximation. Since the -dual statistics is properly defined, it provides a correct link between the phenomenological Tsallis distribution and the second law of thermodynamics.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1910.13840 [pdf]
    EPJA(2020)·21 citations
  6. 06

    [Submitted on 30 Oct 2019]

    Signatures of Chiral Magnetic Effect in the Collisions of Isobars

    Shuzhe Shi🇨🇦 · Hui Zhang🇨🇳 · Defu Hou🇨🇳 · Jinfeng Liao🇺🇸

    Quantum anomaly is a fundamental feature of chiral fermions. In chiral materials the microscopic anomaly leads to nontrivial macroscopic transport processes such as the Chiral Magnetic Effect (CME), which has been in the spotlight lately across disciplines of physics. The quark-gluon plasma (QGP) created in relativistic nuclear collisions provides the unique example of a chiral material consisting of intrinsically relativistic chiral fermions. Potential discovery of CME in QGP is of utmost significance, with extensive experimental searches carried out over the past decade. A decisive new collider experiment, dedicated to detecting CME in the collisions of isobars, was performed in 2018 with analysis now underway. In this paper, we develop the state-of-the-art theoretical tool for describing CME phenomenon in these collisions and propose an appropriate isobar subtraction strategy for best background removal. Based on that, we make quantitative predictions for signatures of CME in the collisions of isobars. A new and robust observable that is independent of axial charge uncertainty -- the ratio between isobar-subtracted and correlators, is found to be for event-plane measurement and for reaction-plane measurement.

    Comments:
    7 pages, 4 figures; final published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1910.14010 [pdf]
    PRL(2020)·69 citations

Affiliations

first authorsco-authorsvia INSPIRE