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Nuclear Theory·nucl-th

Tuesday·May 26, 2020

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 24 May 2020]

    Power-law intensity distribution in -decay cascades -- Nuclear Structure as a Scale-Free Random Network

    Keisuke Fujii · Julian C. Berengut

    By modeling the transition paths of the nuclear -decay cascade using a scale-free random network, we uncover a universal power-law distribution of -ray intensity , with the -ray intensity of each transition. This property is consistently observed for all datasets with a sufficient number of -ray intensity entries in the National Nuclear Data Center database, regardless of the reaction type or nuclei involved. In addition, we perform numerical simulations which support the model's predictions of level population density.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2005.11844 [pdf]
    PRL(2021)·2 citations
  2. 02

    [Submitted on 25 May 2020]

    Effective field theory for deformed odd-mass nuclei

    T. Papenbrock · H. A. Weidenmüller

    We develop an effective field theory (EFT) for deformed odd-mass nuclei. These are described as an axially symmetric core to which a nucleon is coupled. In the coordinate system fixed to the core the nucleon is subject to an axially symmetric potential. Power counting is based on the separation of scales between low-lying rotations and higher-lying states of the core. In leading order, core and nucleon are coupled by universal derivative terms. These comprise a covariant derivative and gauge potentials which account for Coriolis forces and relate to Berry-phase phenomena. At leading order, the EFT combines the particle-rotor and Nilsson models. We work out the EFT up to next-to-leading order and illustrate the results in Pu and Os. At leading order, odd-mass nuclei with rotational band heads that are close in energy and differ by one unit of angular momentum are triaxially deformed. For band heads that are well separated in energy, triaxiality becomes a subleading effect. The EFT developed in this paper presents a model-independent approach to the particle-rotor system that is capable of systematic improvement.

    Comments:
    24 pages, 6 figures; discussion amplified in several places and one figure added; accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2005.11865 [pdf]
    PRC(2020)·15 citations
  3. 03

    [Submitted on 25 May 2020]

    Finite size effect on Dissociation and Diffusion of chiral partners in Nambu-Jona-Lasinio model

    Paramita Deb🇮🇳 · Sabyasachi Ghosh🇮🇳 · Jai Prakash🇮🇳 · Santosh Kumar Das🇮🇳 · Raghava Varma🇮🇳

    Along with masses of pion and sigma meson modes, their dissociation into quark medium provide a detail spectral structures of the chiral partners. Present article has studied a finite size effect on that detail structure of chiral partners by using the framework of Nambu-Jona-Lasinio model. Through this dissociation mechanism, their diffusions and conductions are also studied. The masses, widths, diffusion coefficients, conductivities of chiral partners are merged at different temperatures in restore phase of chiral symmetry, but merging points of all are shifted in lower temperature, when one introduce finite size effect into the picture. The strengths of diffusions and conductions are also reduced due to finite size consideration.

    Comments:
    8 pages and 9 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2005.12037 [pdf]
    CPC(2022)·5 citations
  4. 04

    [Submitted on 25 May 2020]

    Scattering Observables from One- and Two-Body Densities: Formalism and Application to He Scattering

    Harald W. Griesshammer (George Washington U.) · Judith A. McGovern (U. of Manchester) · Andreas Nogga (FZ Jülich) · Daniel R. Phillips (Ohio U.)

    We introduce the transition-density formalism, an efficient and general method for calculating the interaction of external probes with light nuclei. One- and two-body transition densities that encode the nuclear structure of the target are evaluated once and stored. They are then convoluted with an interaction kernel to produce amplitudes, and hence observables. By choosing different kernels, the same densities can be used for any reaction in which a probe interacts perturbatively with the target. The method therefore exploits the factorisation between nuclear structure and interaction kernel that occurs in such processes. We study in detail the convergence in the number of partial waves for matrix elements relevant in elastic Compton scattering on He. The results are fully consistent with our previous calculations in Chiral Effective Field Theory. But the new approach is markedly more computationally efficient, which facilitates the inclusion of more partial-wave channels in the calculation. We also discuss the usefulness of the transition-density method for other nuclei and reactions. Calculations of elastic Compton scattering on heavier targets like He are straightforward extensions of this study, since the same interaction kernels are used. And the generality of the formalism means that our He densities can be used to evaluate any He elastic-scattering observable with contributions from one- and two-body operators. They are available at https://datapub.fz-juelich.de/anogga.

    Comments:
    44 pages LaTeX2e (pdflatex) including 4 figures as .pdf files using includegraphics. Improved proofs of symmetry relations and clarifications. Final version with minor changes and updates to reverences is text-identical with journal publication but more readable layout
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2005.12207 [pdf]
    Few Body Syst.(2020)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE