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Nuclear Theory·nucl-th

Wednesday·February 10, 2016

8 papers—5 primary·3 cross-listed

All8Primary5Cross-lists3
  1. 01

    [Submitted on 8 Feb 2016]

    Electrocouplings in Dyson-Schwinger Equations

    Jorge Segovia🇩🇪

    A symmetry preserving framework for the study of continuum Quantum Chromodynamics (QCD) is obtained from a truncated solution of the QCD equations of motion or QCD's Dyson-Schwinger equations (DSEs). A nonperturbative solution of the DSEs enables the study of, e.g., hadrons as composites of dressed-quarks and dressed-gluons, the phenomena of confinement and dynamical chiral symmetry breaking (DCSB), and therefrom an articulation of any connection between them. It is within this context that we present a unified study of Nucleon, Delta and Roper elastic and transition electromagnetic form factors, and compare predictions made using a framework built upon a Faddeev equation kernel and interaction vertices that possess QCD-like momentum dependence with results obtained using a symmetry-preserving treatment of a vectorvector contact-interaction. The comparison emphasises that experiment is sensitive to the momentum dependence of the running coupling and masses in QCD and highlights that the key to describing hadron properties is a veracious expression of dynamical chiral symmetry breaking in the bound-state problem.

    Comments:
    8 pages, 14 figures. Contribution to the proceedings of the ECT* Workshop: "Nucleon Resonances: From Photoproduction to High Photon Virtualities". October 12-16, 2015. Trento, Italy. arXiv admin note: substantial text overlap with arXiv:1601.00973
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1602.02768 [pdf]
    Few Body Syst.(2016)·5 citations
  2. 02

    [Submitted on 8 Feb 2016]

    Mode-coupling effects in anisotropic flow in heavy-ion collisions

    Jing Qian (Ohio State and Harbin Institute of Technology)🇨🇳 · Ulrich W. Heinz (Ohio State)🇺🇸 · Jia Liu (Ohio State)🇺🇸

    Higher-order anisotropic flows in heavy-ion collisions are affected by nonlinear mode coupling effects. It has been suggested that the associated nonlinear hydrodynamic response coefficients probe the transport properties and are largely insensitive to the spectrum of initial density fluctuations of the medium created in these collisions. To test this suggestion, we explore nonlinear mode coupling effects in event-by-event viscous fluid dynamics, using two different models for the fluctuating initial density profiles, and compare the nonlinear coupling coefficients between the initial eccentricity vectors before hydrodynamic expansion and the final flow vectors after the expansion. For several mode coupling coefficients we find significant sensitivity to the initial fluctuation spectrum. They all exhibit strong sensitivity to the specific shear viscosity at freeze-out, but only weak dependence on the shear viscosity during hydrodynamic evolution.

    Comments:
    13 pages, 9 figures. Significantly rewritten, especially Section III, due to error in Eq. (9) of v1 (now Eq. (11)). Main conclusions unchanged. This version to appear in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1602.02813 [pdf]
    PRC(2016)·87 citations
  3. 03

    [Submitted on 9 Feb 2016]

    Effect of Pauli principle on the deformed QRPA calculations and its consequence in the -decay calculations of deformed even-even nuclei

    Dong-Liang Fang

    In this work, we take into consideration of Pauli Exclusion Principle(PEP) in the quasi-particle random phase approximation (QRPA) calculations for the deformed systems by replacing the traditional Quasi-Boson Approximation(QBA) with the renormalized one. With this new formalism, the parametrization of QRPA calculations has been changed and the collapse of QRPA solutions could be avoid for realistic values. We further find that the necessity of renormalization parameter of particle-particle residual interaction in QRPA calculations is due to the exclusion of PEP. So with the inclusion of PEP, we could easily extend the deformed QRPA calculations to the less explored region where lack of experimental data prevent effective parametrization of for QRPA methods. With this theoretical improvement, we give predictions of weak decay rates for even-even isotopes in the rare earth region and the results are then compared with existing calculations.

    Comments:
    8 Pages, 4 Figures, Accepted by PRC
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.02833 [pdf]
    PRC(2016)·5 citations
  4. 04

    [Submitted on 9 Feb 2016]

    The impact of the off-diagonal cross-shell interaction on C

    Cenxi Yuan

    The shell-model investigation is performed to show the impact on the structure of C contributed by the off-diagonal cross-shell interaction, V, which represents the mixing between the and configurations in the model space. Observed levels of the positive states in C can be nicely described in or a larger model space through the well defined Hamiltonians, YSOX and WBP, with a reduction on the strength of the V interaction in the latter. The observed B(GT) values for C can be generally described by YSOX, while WBP and their modifications on the V interaction fail for some values. Further investigation shows the effect of such interaction on the configuration mixing and occupancy. The present work shows examples on how the off-diagonal cross-shell interaction strongly drives the nuclear structure.

    Comments:
    will be appear in Chinese Physics C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.02957 [pdf]
    CPC(2017)·22 citations
  5. 05

    [Submitted on 9 Feb 2016]

    Efficacy of the SU(3) scheme for ab initio large-scale calculations beyond the lightest nuclei

    T. Dytrych · P. Maris · K. D. Launey · J. P. Draayer · J. P. Vary · D. Langr · E. Saule · M. A. Caprio · U. Catalyurek · M. Sosonkina

    We report on the computational characteristics of ab initio nuclear structure calculations in a symmetry-adapted no-core shell model (SA-NCSM) framework. We examine the computational complexity of the current implementation of the SA-NCSM approach, dubbed LSU3shell, by analyzing ab initio results for 6Li and 12C in large harmonic oscillator model spaces and SU(3)-selected subspaces. We demonstrate LSU3shell's strong-scaling properties achieved with highly-parallel methods for computing the many-body matrix elements. Results compare favorably with complete model space calculations and significant memory savings are achieved in physically important applications. In particular, a well-chosen symmetry-adapted basis affords memory savings in calculations of states with a fixed total angular momentum in large model spaces while exactly preserving translational invariance.

    Comments:
    11 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.02965 [pdf]
    Comput.Phys.Commun.(2016)·43 citations

Affiliations

first authorsco-authorsvia INSPIRE