PaperPanorama
FAQ

Nuclear Theory·nucl-th

Thursday·October 31, 2019

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 07

    [Submitted on 25 Oct 2019] (cross-list from hep-ph)

    Hybrid and quark star matter based on a non-perturbative equation of state

    Konstantin Otto🇩🇪 · Micaela Oertel🇫🇷 · Bernd-Jochen Schaefer🇩🇪

    With the recent dawn of the multi-messenger astronomy era a new window has opened to explore the constituents of matter and their interactions under extreme conditions. One of the pending challenges of modern physics is to probe the microscopic equation of state (EoS) of cold and dense matter via macroscopic neutron star observations such as their masses and radii. Still unanswered issues concern the detailed composition of matter in the core of neutron stars at high pressure and the possible presence of e.g. hyperons or quarks. By means of a non-perturbative functional renormalization group approach the influence of quantum and density fluctuations on the quark matter EoS in -equilibrium is investigated within two- and three-flavor quark-meson model truncations and compared to results obtained with common mean-field approximations where important fluctuations are usually ignored. We find that they strongly impact the quark matter EoS.

    Comments:
    15 pages, 7 figures, 2 tables, to be published in PRD
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1910.11929 [pdf]
    PRD(2020)·72 citations
  2. 08

    [Submitted on 30 Oct 2019] (cross-list from physics.hist-ph)

    On the Topic of Emergence from an Effective Field Theory Perspective

    Thomas Luu🇩🇪 · Ulf-G. Meißner🇩🇪

    Effective Field Theories have been used successfully to provide a "bottom-up" description of phenomena whose intrinsic degrees of freedom behave at length scales far different from their effective degrees of freedom. An example is the emergent phenomenon of bound nuclei, whose constituents are neutrons and protons, which in turn are themselves composed of more fundamental particles called quarks and gluons. In going from a fundamental description that utilizes quarks and gluons to an effective field theory description of nuclei, the length scales traversed span at least two orders of magnitude. In this article we provide an Effective Field Theory viewpoint on the topic of emergence, arguing on the side of reductionism and weak emergence. We comment on Anderson's interpretation of constructionism and its connection to strong emergence.

    Comments:
    14 pages, 2 figures
    Subjects:
    History and Philosophy of Physics (physics.hist-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1910.13770 [pdf]
    3 citations
  3. 09

    [Submitted on 30 Oct 2019] (cross-list from hep-lat)

    Role of chiral symmetry in the nucleon excitation spectrum

    Adam Virgili🇦🇺 · Waseem Kamleh🇦🇺 · Derek Leinweber (University of Adelaide)🇦🇺

    The origin of the low-lying nature of the *(1440), or Roper resonance, has been the subject of significant interest for many years, including several investigations using lattice QCD. The majority of lattice studies have not observed a low-lying excited state energy level in the region of the Roper resonance. However, it has been claimed that chiral symmetry could play an important role in our understanding of this resonance. The purpose of this study is to systematically examine the role of chiral symmetry in the low-lying nucleon spectrum by directly comparing the clover and overlap fermion actions. To ensure any differences in results are attributable to the choice of fermion action, simulations are performed on the same set of gauge field configurations at matched pion masses. Correlation matrix techniques are employed to determine the excitation energy of the first positive-parity excited state for each action. The clover and overlap actions show a remarkable level of agreement. We do not find any evidence that fermion action chiral symmetry plays a significant role in understanding the Roper resonance on the lattice.

    Comments:
    8 pages, 4 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1910.13782 [pdf]
    PRD(2020)·11 citations
  4. 10

    [Submitted on 30 Oct 2019] (cross-list from astro-ph.HE)

    On the Deconfinement Phase Transition in Neutron-Star Mergers

    Elias R. Most🇺🇸 · L. Jens Papenfort🇩🇪 · Veronica Dexheimer🇺🇸 · Matthias Hanauske🇩🇪 · Horst Stöcker🇩🇪 · Luciano Rezzolla🇩🇪

    We study in detail the nuclear aspects of a neutron-star merger in which deconfinement to quark matter takes place. For this purpose, we make use of the Chiral Mean Field (CMF) model, an effective relativistic model that includes self-consistent chiral symmetry restoration and deconfinement to quark matter and, for this reason, predicts the existence of different degrees of freedom depending on the local density/chemical potential and temperature. We then use the out-of-chemical-equilibrium finite-temperature CMF equation of state in full general-relativistic simulations to analyze which regions of different QCD phase diagrams are probed and which conditions, such as strangeness and entropy, are generated when a strong first-order phase transition appears. We also investigate the amount of electrons present in different stages of the merger and discuss how far from chemical equilibrium they can be and, finally, draw some comparisons with matter created in supernova explosions and heavy-ion collisions.

    Comments:
    10 pages, 6 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    1910.13893 [pdf]
    EPJA(2020)·126 citations
  5. 11

    [Submitted on 30 Oct 2019] (cross-list from hep-ph)

    Nuclear deformation effects on charge radius measurements of the proton and deuteron

    Yonghui Lin🇨🇳 · Bingsong Zou🇨🇳

    Up to now, all charge radius measurements of the proton and deuteron assumed uniform spheroidal charge distribution. We investigate the nuclear deformation effects on these charge radius measurements by assuming a uniform prolate charge distribution for the proton and deuteron. We solve the energy levels of the corresponding muonic and electric atoms with such deformed nucleus and present how the purely quadruple deformation of proton and deuteron affects their Lamb shifts. The numerical results suggest that the deformation of proton and deuteron leads to that the charge radius extracted from the electronic measurement should be smaller than the corresponding one in the muonic measurement which assumed uniform spheroidal charge distribution. If the central values of newest measurements for the proton are adopted, the proton would have a prolate structure with the 0.91 long axis and 0.73 short axis. Further improved precise charge radius measurements of the proton and deuteron will help us to pin down their shape deformation.

    Comments:
    13pages, 4figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1910.13916 [pdf]
    1 citation

Affiliations

first authorsco-authorsvia INSPIRE