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Nuclear Theory·nucl-th

Wednesday·October 30, 2019

15 papers—7 primary·8 cross-listed

All15Primary7Cross-lists8
  1. 01

    [Submitted on 28 Oct 2019]

    The Skinny on Bulk Viscosity and Cavitation in Heavy Ion Collisions

    M. Byres🇺🇸 · S.H. Lim🇰🇷 · C. McGinn🇺🇸 · J. Ouellette🇺🇸 · J.L. Nagle🇺🇸

    Relativistic heavy ion collisions generate nuclear-sized droplets of quark-gluon plasma (QGP) that exhibit nearly inviscid hydrodynamic expansion. Smaller collision systems such as p+Au, d+Au, and He+Au at the Relativistic Heavy Ion Collider, as well as p+Pb and high-multiplicity p+p at the Large Hadron Collider may create even smaller droplets of QGP. If so, the standard time evolution paradigm of heavy ion collisions may be extended to these smaller systems. These small systems present a unique opportunity to examine pre-hydrodynamic physics and extract properties of the QGP, such as the bulk viscosity, where the short lifetimes of the small droplets makes them more sensitive to these contributions. Here we focus on the influence of bulk viscosity, its temperature dependence, and cavitation effects on the dynamics in small and large systems using the publicly available hydrodynamic codes SONIC and MUSIC. We also compare pre-hydrodynamic physics in different frameworks including AdS/CFT strong coupling, IP-GLASMA weak coupling, and free streaming or no coupling.

    Comments:
    8 pages, 5 figures, submitted for publication
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1910.12930 [pdf]
    PRC(2020)·20 citations
  2. 02

    [Submitted on 28 Oct 2019]

    Role of U(1) breaking term in dynamical chiral symmetry breaking of chiral effective theories

    Shinnosuke Kono (1,2)🇯🇵 · Daisuke Jido (2,1)🇯🇵 · Yoshiki Kuroda (3)🇯🇵 · Masayasu Harada (3) ((1) Tokyo Metropolitan University, (2) Tokyo Institute of Technology, (3) Nagoya University)🇯🇵

    The spontaneous breaking of chiral symmetry is examined by chiral effective theories, such as the linear sigma model and the Nambu Jona-Lasinio (NJL) model. Indicating that sufficiently large contribution of the UA(1) anomaly can break chiral symmetry spontaneously, we discuss such anomaly driven symmetry breaking and its implication. We derive a mass relation among the SU(3) flavor singlet mesons, eta0 and sigma0, in the linear sigma model to be satisfied for the anomaly driven symmetry breaking in the chiral limit, and find that it is also supported in the NJL model. With the explicit breaking of chiral symmetry, we find that the chiral effective models reproducing the observed physical quantities suggest that the sigma0 meson regarded as the quantum fluctuation of the chiral condensate should have a mass smaller than an order of 800 MeV when the anomaly driven symmetry breaking takes place.

    Comments:
    22 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1910.12982 [pdf]
    PTEP(2021)·10 citations
  3. 03

    [Submitted on 28 Oct 2019]

    Convenient location of a near-threshold proton-emitting resonance in B

    J. Okołowicz🇵🇱 · M. Płoszajczak🇫🇷 · W. Nazarewicz🇺🇸

    The presence of cluster-like narrow resonances in the vicinity of reaction/decay thresholds is a ubiquitous phenomenon with profound consequences. We argue that the continuum coupling, present in the open quantum system description of the atomic nucleus, can profoundly impact the nature of near-threshold states. In this Letter, we discuss the structure of the recently observed near-threshold resonance in B, whose very existence explains the puzzling beta-delayed proton emission of the neutron-rich Be.

    Comments:
    4 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1910.12984 [pdf]
    PRL(2020)·44 citations
  4. 04

    [Submitted on 28 Oct 2019]

    Parametric correlations in energy density functionals

    A. Taninah🇺🇸 · S. E. Agbemava🇺🇸 · A. V. Afanasjev🇺🇸 · P. Ring🇩🇪

    Parametric correlations are studied in several classes of covariant density functional theories (CDFTs) using a statistical analysis in a large parameter hyperspace. In the present manuscript, we investigate such correlations for two specific types of models, namely, for models with density dependent meson exchange and for point coupling models. Combined with the results obtained previously in Ref. [1] for a non-linear meson exchange model, these results indicate that parametric correlations exist in all major classes of CDFTs when the functionals are fitted to the ground state properties of finite nuclei and to nuclear matter properties. In particular, for the density dependence in the isoscalar channel only one parameter is really independent. Accounting for these facts potentially allows one to reduce the number of free parameters considerably.

    Comments:
    8 pages, 4 figures and supplemental material in suppl.pdf, Physics Letters B in press
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1910.13007 [pdf]
    PLB(2020)·78 citations
  5. 05

    [Submitted on 29 Oct 2019]

    QCD phase diagram in chiral imbalance with self-consistent mean field approximation

    Li-Kang Yang🇨🇳 · Xiaofeng Luo🇨🇳 · Hong-Shi Zong🇨🇳

    We employ a new self-consistent mean field approximation of NJL model, which introduces a free parameter ( reflects the weight of different interaction channels), to study the effects of the chiral chemical potential on QCD phase structure, especially the location of the QCD critical end point (CEP). We find that, at a high temperature, the critical temperature of QCD phase transition smoothly increases with at the beginning, and then decreases rapidly. At low temperature and high baryon density region, the increase of the chiral chemical potential will reduce the critical chemical potential of phase transition. The temperature of the CEP shows a non-monotonic dependence on the chiral chemical potential with a long plateau around the maximum. At , we found that the CEP will disappear when the value is larger than 0.71 and will reappear when the increases. This study is important for exploring the QCD phase structure and the location of CEP in chiral imbalanced systems.

    Comments:
    6 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1910.13185 [pdf]
    PRD(2019)·28 citations
  6. 06

    [Submitted on 29 Oct 2019]

    Role of the symmetry energy and the neutron-matter stiffness on the tidal deformability of a neutron star with unified equations of state

    Loic Perot🇧🇪 · Nicolas Chamel🇧🇪 · Aurélien Sourie🇧🇪

    The role of the symmetry energy and the neutron-matter stiffness on the tidal deformability of a cold nonaccreted neutron star is studied using a set of unified equations of state. Based on the nuclear energy-density functional theory, these equations of state provide a thermodynamically consistent treatment of all regions of the star and were calculated using functionals that were precision fitted to experimental and theoretical nuclear data. Predictions are compared to constraints inferred from the recent detection of the gravitational-wave signal GW170817 from a binary neutron-star merger and from observations of the electromagnetic counterparts.

    Comments:
    26 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    1910.13202 [pdf]
    PRC(2019)·44 citations
  7. 07

    [Submitted on 29 Oct 2019]

    Spectroscopy of short-lived radioactive molecules: A sensitive laboratory for new physics

    R.F. Garcia Ruiz🇨🇭 · R. Berger🇩🇪 · J. Billowes🇩🇪 · C.L. Binnersley🇧🇪 · M.L. Bissell🇩🇪 · A.A. Breier🇬🇧 · A.J. Brinson🇬🇧 · K. Chrysalidis🇬🇧 · T. Cocolios🇺🇸 · B. Cooper🇨🇭 · K.T. Flanagan🇧🇪 · T.F. Giesen🇬🇧 and 15 other authors

    The study of molecular systems provides exceptional opportunities for the exploration of the fundamental laws of nature and for the search for physics beyond the Standard Model of particle physics. Measurements of molecules composed of naturally occurring nuclei have provided the most stringent upper bounds to the electron electric dipole moment to date, and offer a route to investigate the violation of fundamental symmetries with unprecedented sensitivity. Radioactive molecules - where one or more of their atoms possesses a radioactive nucleus - can contain heavy and deformed nuclei, offering superior sensitivity for EDM measurements as well as for other symmetry-violating effects. Radium monofluoride, RaF, is of particular interest as it is predicted to have an appropriate electronic structure for direct laser cooling. Furthermore, some Ra isotopes are known to be octupole deformed, thereby resulting in a large enhancement of their symmetry-violating nuclear moments. Until now,however, no experimental measurements of RaF have been performed, and their study is impeded by major experimental challenges, as no stable isotopes of radium exist. Here, we present a novel experimental approach to study short-lived radioactive molecules using the highly sensitive collinear resonance ionisation method. With this technique we have measured, for the first time, the energetically low-lying electronic states for each of the isotopically pure RaF molecules at the ISOLDE-CERN. Our results provide strong evidence of the existence of a suitable laser-cooling scheme for these molecules and constitute a pivotal step towards high-precision studies in these systems. Our findings open up new opportunities in the synthesis, manipulation and study of short-lived radioactive molecules, which will have a direct impact in many-body physics, astrophysics, nuclear structure, and fundamental physics research.

    Comments:
    Submitted
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1910.13416 [pdf]
    Nature(2020)·98 citations

Affiliations

first authorsco-authorsvia INSPIRE