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Nuclear Theory·nucl-th

Wednesday·February 28, 2018

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    [Submitted on 26 Feb 2018]

    Pion and kaon valence-quark quasiparton distributions

    Shu-Sheng Xu🇨🇳 · Lei Chang🇨🇳 · Craig D. Roberts🇺🇸 · Hong-Shi Zong🇨🇳

    Algebraic Ansaetze for the Poincaré-covariant Bethe-Salpeter wave functions of the pion and kaon are used to calculate their light-front wave functions (LFWFs), parton distribution amplitudes (PDAs), quasi-PDAs (qPDAs), valence parton distribution functions (PDFs), and quasi-PDFs (qPDFs). The LFWFs are broad, concave functions; and the scale of flavour-symmetry violation in the kaon is roughly 15%, being set by the ratio of emergent masses in the -and -quark sectors. qPDAs computed with longitudinal momentum GeV provide a semiquantitatively accurate representation of the objective PDA; but even with GeV, they cannot provide information about this amplitude's endpoint behaviour. On the valence-quark domain, similar outcomes characterise qPDFs. In this connection, however, the ratio of kaon-to-pion -quark qPDFs is found to provide a good approximation to the true PDF ratio on , suggesting that with existing resources computations of ratios of quasi-parton-distributions can yield results that support empirical comparison.

    Comments:
    10 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1802.09552 [pdf]
    PRD(2018)·89 citations
  2. 02

    [Submitted on 26 Feb 2018]

    Elliptic flow from Coulomb interaction and low density elastic scattering

    Yuliang Sun🇨🇳 · Qingfeng Li🇨🇳 · Fuqiang Wang🇨🇳

    In high energy heavy ion collisions and interacting cold atom systems, large elliptic flow anisotropies have been observed. For the large opacity () of the latter hydrodynamics is a natural consequence, but for the small opacity () of the former hydrodynamic description is questionable. To shed light onto the situation, we simulate the expansion of a low density Argon ion (or atom) system, initially trapped in an elliptical region, under the Coulomb interaction (or elastic scattering). Significant elliptic anisotropy is found in both cases, and the anisotropy depends on the initial spatial eccentricity and the density of the system. The results may provide insights into the physics of anisotropic flow in high energy heavy ion collisions and its role in the study of quantum chromodynamics.

    Comments:
    5 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1802.09595 [pdf]
    PRC(2018)·0 citations
  3. 03

    [Submitted on 27 Feb 2018]

    Hot and Dense Homogeneous Nucleonic Matter Constrained by Observations, Experiment, and Theory

    Xingfu Du (1) · Andrew W. Steiner (1,2) · Jeremy W. Holt (3) ((1) Tennessee U., (2) Oak Ridge Natl. Lab., (3) Texas A-M, Cyclotron Inst. & Texas A-M)

    We construct a new class of phenomenological equations of state for homogeneous matter for use in simulations of hot and dense matter in local thermodynamic equilibrium. We construct a functional form which respects experimental, observational and theoretical constraints on the nature of matter in various density and temperature regimes. Our equation of state matches (i) the virial coefficients expected from nucleon-nucleon scattering phase shifts, (ii) experimental measurements of nuclear masses and charge radii, (iii) observations of neutron star radii, (iv) theory results on the equation of state of neutron matter near the saturation density, and (v) theory results on the evolution of the EOS at finite temperatures near the saturation density. Our analytical model allows one to compute the variation in the thermodynamic quantities based on the uncertainties in the nature of the nucleon-nucleon interaction. Finally, we perform a correction to ensure the equation of state is causal at all densities, temperatures, and electron fractions.

    Comments:
    16 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    1802.09710 [pdf]
    PRC(2019)·29 citations
  4. 04

    [Submitted on 27 Feb 2018]

    Spin-Isospin Properties of Odd-Odd Nuclei from a Core+ Three-Body Model including Core Excitations

    Futoshi Minato · Yusuke Tanimura

    For odd-odd nuclei, a three-body model assuming two valence particles and an inert core can provide an understanding of pairing correlations in the ground state and spin-isospin excitations. However, since residual core-nucleon interactions can have a significant impact on these quantities, the inclusion of core excitations in the model is essential for useful calculation to be performed. The effect of core excitations must be included in order to gain a detailed understanding of both the ground state and spin-isospin properties of these systems. To this end, we include the vibrational excitation of the core nucleus in our model. We solve the three-body core-nucleon-nucleon problem including core vibrational states to obtain the nuclear ground state as well as spin-isospin excitations. The spin-isospin excitations are examined from the point of view of SU(4) multiplets. By including the effect of core excitation, several experimental quantities of odd-odd nuclei are better described, and the root mean square distances between proton and neutron and that between the center of mass of proton and neutron and core nucleus increase. Large () and (GT) observed for F and Ca were explained in terms of the SU(4) symmetry. The core nucleus is meaningfully broken by the residual core-nucleon interactions, and various quantities concerning spin-isospin excitations as well as the ground state become consistent with experimental data. Including the core excitation in the three-body model is thus important for a more detailed understanding of nuclear structure.

    Comments:
    13 pages, 8 figures, 3 tables
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1802.09991 [pdf]
    EPJA(2020)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE