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Nuclear Theory·nucl-th

Wednesday·August 4, 2021

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    Spin-polarized phases of superfluids in neutron stars

    Takeshi Mizushima · Shigehiro Yasui · Daisuke Inotani · Muneto Nitta

    The interior of a neutron star is expected to be occupied by a neutron superfluid, which is the condensate of spin-triplet -wave Cooper pairs of neutrons with total angular momentum . Here we investigate the thermodynamic stability of superfluids in a neutron-star interior under a strong magnetic field. Using the theory incorporating the finite size correction of neutron Fermi surface, we show that the spin-polarized phases of superfluids, the magnetized biaxial nematic phase and the ferromagnetic phase, appear in high temperatures and high magnetic fields. These phases were missed in the previous studies using the quasiclassical approximation in which dispersions of neutrons are linearized around the Fermi surface. In particular, the ferromagnetic phase, which is the condensation of Cooper-paired neutrons with fully polarized spins, appears between the normal phase and the biaxial nematic phase and enlarge the thermodynamic stability of superfluids under strong magnetic fields. Furthermore, we present the augmented Ginzburg-Landau theory that incorporates the thermodynamic stability of spin-polarized superfluid phases.

    nucl-thcond-mat.supr-conPRC(2021)·12 citations
  2. 02

    Collective states of even-even nuclei in gamma-rigid quadrupole Hamiltonian with Minimal Length under the sextic potential

    A. El Batoul · M. Oulne · I.Tagdamte

    In the present paper, we study the collective states of even even nuclei in gamma rigid mode within the sextic potential and the Minimal Length (ML) formalism in Bohr Mottelson model. The eigenvalues problem for this latter is solved by means conjointly of Quasi-Exact Solvability (QES) and a Quantum Perturbation Method (QPM). Numerical calculations are performed for 35 nuclei:(98 108)Ru, (100 102)Mo, (116 130)Xe, (180 196)Pt, (172)Os, (146 150)Nd, (132 134)Ce, (154)Gd, (156)Dy and (150 152)Sm. Through this study, it appears that our elaborated model leads to an improved agreement of the theoretical results with the corresponding experimental data by reducing the rms with a rate going up to 63% for some nuclei. This comes out from the fact that we have combined the sextic potential, which is a very useful phenomenological potential, with the formalism of the ML which is based on the generalized uncertainty principle and which is in turn a quantum concept widely used in quantum physics. Besides, we investigate the effect of ML on energy ratios, transition rates, moments of inertia and a shape phase transition for the most numerous isotopic chains, namely Ru, Xe, Nd and Pt.

    nucl-thJ.Phys.G(2021)·5 citations
  3. 03

    Pion photoproduction in chiral perturbation theory with explicit treatment of the resonance

    N. Rijneveen🇩🇪 · A. M. Gasparyan🇩🇪 · H. Krebs🇩🇪 · E. Epelbaum🇩🇪

    We study the reaction of pion photoproduction on the nucleon in the framework of chiral perturbation theory with explicit degrees of freedom. In the covariant approach, we give results up to order in the small scale expansion scheme. Furthermore, we provide -less and -full results obtained in the heavy-baryon scheme to analyze the differences to the covariant approach. Low energy constants are fitted to multipole amplitudes using theoretical truncation errors estimated by a Bayesian approach. We also compare our findings to data of neutral pion production cross sections and polarization asymmetries. The description of the reaction is clearly improved by the explicit treatment of the resonance.

    nucl-thhep-phPRC(2022)·12 citations
  4. 04

    Antiproton-deuteron hydrogenic states in optical models

    Rimantas Lazauskas · Jaume Carbonell

    By solving the Faddeev equations for the p̄pn system, we compute the antiproton-deuteron level shifts and widths for the lowest hydrogenic states as well as the corresponding p̄d scattering lengths and volumes. The p̄d annihilation densities are obtained and compared to the nuclear density of deuterium. The validity of the Trueman relation for composite particles is studied. The strong part of N̄N interaction is described by two different optical models, including the p̄p-n̄n coupling and n-p mass difference, while for NN several realistic interactions are used.

    nucl-thhep-phPLB(2021)·14 citations
  5. 05

    Structural properties of nuclei with semi-magic number N(Z)=40

    R. Sharma · A. Jain · M. Kaushik · S. K. Jain · G. Saxena

    Various ground state properties are explored for full isotonic(isotopic) chain of neutron number N(proton number Z)40 using different families of Relativistic Mean-Field theory. Several properties such as nucleon separation energies, pairing energies, deformation, radii and nucleon density distributions are evaluated and compared with the experimental data as well as those from other microscopic and macroscopic models. N40 isotonic chain presents ample of support for the neutron magicity and articulates double magicity in recently discovered Ca and Ni. Our results are in close conformity with recently measured value of charge radius of Ni [S. Kaufmann \textit{et al.}, Phys. Rev. Lett. 124, 132502 (2020)] which supports the N40 magicity. Contrarily, Zr isotopes (Z40) display variety of shapes leading to the phenomenon of shape transitions and shape co-existence. The role of 3s state, which leads to central depletion if unoccupied, is also investigated. S and Zr are found to be doubly bubble nuclei.

    nucl-thIJMPE(2021)·4 citations

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