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Nuclear Theory·nucl-th

Thursday·May 14, 2020

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    From odd-even staggering to the pairing gap in neutron matter

    Georgios Palkanoglou · Fotis K. Diakonos · Alexandros Gezerlis

    The properties of neutron matter are integral to the correct description of neutron stars as well as the description of neutron-rich nuclei. One key property of neutron matter is its superfluid behaviour in a range of densities relevant to the inner crust of neutron stars. This work investigates the finite-size effects in the pairing gap of a pure neutron matter superfluid system at densities found in the inner crust of cold neutron stars. The BCS (Bardeen-Cooper-Schrieffer) treatment of superfluidity gives rise to the mean-field pairing gap while a projection after variation (PBCS Theory) can provide a beyond-mean-field pairing gap through an odd-even staggering formula. While these two pairing gap results should agree in the thermodynamic limit, in this work we demonstrate that this is the case for systems far from the thermodynamic limit as well. This is a first step towards a model-independent extraction of the pairing gap in neutron matter.

    nucl-thcond-mat.quant-gasPRC(2020)·9 citations
  2. 02

    Nonlinear Fokker-Planck Acceleration for Forward-Peaked Transport Problems in Slab Geometry

    J. J. Kuczek · J. K. Patel · R. Vasques

    This paper introduces a nonlinear acceleration technique that accelerates the convergence of solution of transport problems with highly forward-peaked scattering. The technique is similar to a conventional high-order/low-order (HOLO) acceleration scheme. The Fokker-Planck equation, which is an asymptotic limit of the transport equation in highly forward-peaked settings, is modified and used for acceleration; this modified equation preserves the angular flux and moments of the (high order) transport equation. We present numerical results using the Screened Rutherford, Exponential, and Henyey-Greenstein scattering kernels and compare them to established acceleration methods such as diffusion synthetic acceleration (DSA). We observe three to four orders of magnitude speed-up in wall-clock time compared to DSA.

    nucl-thcs.NAmath.NA0 citations
  3. 03

    Coexistence of planar and aplanar rotations in Tl

    J. Peng🇨🇳 · Q. B. Chen🇩🇪

    The chirality suggested for the doublet bands B2 and B2a in Tl in region is reexamined. The potential-energy curves and the configurations together with the deformation parameters are obtained by the constrained covariant density functional theory. The corresponding experimental energy spectra, energy differences between doublet bands, and the available values are investigated by the fully quantal particle rotor model. Analysis on the basis of the angular momentum components, the -plots, and the azimuthal plots suggest a planar rotation interpretation for the bands B2 and B2a. Hence, it coexists with the aplanar rotation in the other doublet bands B4 and B4a in Tl.

    nucl-thnucl-exPLB(2020)·14 citations
  4. 04

    Symmetries Created by Random Interactions- Ultimacy of "More Is Different"

    Takaharu Otsuka · Noritaka Shimizu

    The dominance (preponderance) of the 0+ ground state for random interactions is shown to be a consequence of certain random interactions with chaotic features. These random interactions, called chaotic random interactions, impart a symmetry property to the ground-state wave function: an isotropy under an appropriate transformation, such as zero angular momentum for rotation. Under this mechanism, the ground-state parity and isospin can also be predicted in such a manner that positive parity is favored over negative parity and the isospin T = 0 is favored over higher isospins. As chaotic random interaction is a limit with no particular dynamics at the level of two interacting particles, this realization of isotropic symmetry in the ground state can be considered as the ultimate case of many-body correlations. A possible relation to the isotropy of the early universe is mentioned.

    nucl-thnucl-exquant-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE