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Nuclear Theory·nucl-th

Thursday·October 8, 2020

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 7 Oct 2020]

    M1 resonance in Pb within the self-consistent phonon-coupling model

    V. Tselyaev · N. Lyutorovich · J. Speth · P.-G. Reinhard

    The main goal of the paper is to investigate theoretically the experimentally observed fragmentation of the isovector resonance in Pb within a self-consistent model based on an energy-density functional (EDF) of the Skyrme type. This fragmentation (spread of the strength) is not reproduced in a conventional one-particle--one-hole () random-phase approximation (RPA) and thus has to be investigated in the framework of more complicated models. However, previously applied models of this type were not self-consistent. In the present work, we use a recently developed renormalized version of the self-consistent time blocking approximation (RenTBA) in which the phonon configurations are included on top of the RPA configurations. We have determined several sets of the parameters of the modified Skyrme EDF fitted within the RenTBA and RPA and have found the necessary condition of producing the fragmentation of the resonance in Pb in our model. We present also the results of the RenTBA and RPA calculations for the first excited states of the natural parity modes in Pb obtained with these modified parametrizations.

    Comments:
    11 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2010.03149 [pdf]
    PRC(2020)·16 citations
  2. 02

    [Submitted on 7 Oct 2020]

    Numerical Simulation of GUE Two-Point Correlation and Cluster Functions

    Adam James Sargeant

    Numerical simulations of the two-point eigenvalue correlation and cluster functions of the Gaussian unitary ensemble (GUE) are carried out directly from their definitions in terms of deltas functions. The simulations are compared with analytical results which follow from three analytical formulas for the two-point GUE cluster function: (i) Wigner's exact formula in terms of Hermite polynomials, (ii) Brezin and Zee's approximate formula which is valid for points with small enough separations and (iii) French, Mello and Pandey's approximate formula which is valid on average for points with large enough separations. It is found that the oscillations present in formulas (i) and (ii) are reproduced by the numerical simulations if the width of the function used to represent the delta function is small enough and that the non-oscillating behaviour of formula (iii) is approached as the width is increased.

    Comments:
    8 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech)
    arXiv:
    2010.03500 [pdf]
    Braz.J.Phys.(2021)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE