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  • 1. Glowacz, S.
    et al.
    Satula, Wojtek
    KTH, Superseded Departments, Physics.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Cranking in isospace2004In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 19, no 1, p. 33-44Article in journal (Refereed)
    Abstract [en]

    The response of isovector and isoscalar pair fields to generalized rotation in isospace is studied. Analytical expressions for constant gap solutions for different limiting cases of the model are derived. In particular, the connections between gauge angles among pairing gaps and the position of the iso-cranking axis are investigated in N = Z nuclei. The two domains of collective and noncollective rotation in space are generalized to isospace. The amplitudes for pair-transfer of T = 0 and T = 1 pairs are calculated. It is shown that the structure of the T = 0 state in odd-odd nuclei prevents any enhancement of pair transfer also in the presence of strong isoscalar pairing correlations. The energy differences of the T = 0 and T = 1 excitations in odd-odd nuclei are qualitatively reproduced by Total-Routhian-Surface calculations.

  • 2. Rafalski, M.
    et al.
    Satula, Wojtek
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Mass number dependence of the Skyrme-force-induced nuclear symmetry energy2006In: International Journal of Modern Physics E, ISSN 0218-3013, Vol. 15, no 2, p. 484-489Article in journal (Refereed)
    Abstract [en]

    The global mass dependence of the nuclear symmetry energy a(sym)(A) and its two basic ingredients due to the mean-level spacing epsilon(A) and effective strength of the isovector mean-potential K(A) is studied within the Skyrme-Hartree-Fock model. In particular, our study determines the ratio of the surface-to-volume contributions to a(sym)(A) to be r(S/V) similar to 1.6 and reveals that after removing momentum-dependent effects by rescaling epsilon and kappa with isoscalar and isovector effective masses, respectively, one obtains epsilon(star) approximate to kappa(star).

  • 3.
    Satula, Wojciech
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Rafalski, Michal
    Global properties of the Skyrme-force-induced nuclear symmetry energy2006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 74, no 1, p. 011301-Article in journal (Refereed)
    Abstract [en]

    A novel concept for the nuclear symmetry energy (NSE) is corroborated by large scale calculations. The paper firmly demonstrates that within the local density approximation, the value of the NSE coefficient, a(sym)(A), depends on two basic ingredients: the mean-level spacing, epsilon(A), and the effective strength of the isovector mean-potential, kappa(A). Surprisingly, our results reveal that these two basic ingredients of a(sym) are almost equal after rescaling them linearly by the isoscalar and the isovector effective masses, respectively. This result points towards a hidden and hitherto unresolved fundamental property of the effective nuclear interaction. In addition, our analysis yields naturally the ratio of the surface-to-volume contributions to a(sym) with a value of similar to 1.6, consistent with hydrodynamical estimates for the static dipole polarizability as well as the neutron-skin. Although the present study is restricted to energy density functionals obtained from Skyrme forces the method is general and can easily be applied to more general local energy density functionals and nonnuclear bifermionic systems.

  • 4.
    Satula, Wojtek
    et al.
    KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Dobaczewski, J.
    Nazarewicz, W.
    Rafalski, M.
    Isospin Mixing in Nuclei around N similar or equal to Z and the Superallowed beta-decay2011In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 42, no 3-4, p. 415-425Article in journal (Refereed)
    Abstract [en]

    Theoretical approaches that use one-body densities as dynamical variables, such as Hartree-Fock or the density functional theory (DFT), break isospin symmetry both explicitly, by virtue of charge-dependent interactions, and spontaneously. To restore the spontaneously broken isospin symmetry, we implemented the isospin-projection scheme on top of the Skyrme-DFT approach. This development allows for consistent treatment of isospin mixing in both ground and exited nuclear states. In this study, we apply this method to evaluate the isospin impurities in ground states of even-even and odd-odd N similar or equal to Z nuclei. By including simultaneous isospin and angular-momentum projection, we compute the isospin-breaking corrections to the 0(+) -> 0(+) superallowed beta-decay.

  • 5.
    Satula, Wojtek
    et al.
    KTH, Superseded Departments, Physics.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Comments on the nuclear symmetry energy2003In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 572, no 3-4, p. 152-158Article in journal (Refereed)
    Abstract [en]

    According to standard textbooks, the nuclear symmetry energy originates from the kinetic energy and the interaction itself. We argue that this view requires certain modifications and propose a different scenario. We ascribe the physical origin of the kinetic term to the discreteness of fermionic levels of, in principle arbitrary binary fermionic systems, and relate its mean value directly to the average level density. Physically it connects this part also to the isoscalar interaction which, at least in self-bound systems- like atomic nuclei, decides upon the spatial dimensions of the system. For the general case of binary fermionic systems possible external confining potentials as well as specific boundary conditions will contribute to this part. The reliability of this concept is verified using self-consistent Skyrme-Hartree-Fock calculations.

  • 6.
    Satula, Wojtek
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    Mean-field description of high-spin states2005In: Reports on progress in physics (Print), ISSN 0034-4885, E-ISSN 1361-6633, Vol. 68, no 1, p. 131-200Article, review/survey (Refereed)
    Abstract [en]

    Recent high-spin observations reveal entirely new modes of collective rotational motion and the existence of novel symmetries and spontaneous symmetry breaking phenomena, uncovering hitherto unexploited coupling schemes of intrinsic and collective degrees of freedom. It continues to stimulate the theoretical progress in the field, which clearly turns towards a microscopic description based on self-consistent approaches using either an effective non-relativistic Hamiltonian or an effective relativistic Lagrangian. New coupling schemes call not only for symmetry unrestricted mean-field theories, but also for extensions going beyond the mean-field. The progress in the development of these theoretical methods is discussed in this review.

  • 7.
    Satula, Wojtek
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Rafalski, M.
    Cranking in isospace - Applications to neutron-proton pairing and the nuclear symmetry energy2005In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 25, no SUPPL. 1, p. 559-562Article in journal (Refereed)
    Abstract [en]

    Isoscalar pairing interaction and nuclear symmetry energy are investigated by means of the iso-cranking technique. Iso-cranking represents the lowest order approximation to isospin projection after variation. Due to its internal simplicity, it offers a very intuitive understanding of the structure of the nuclear symmetry energy as well as the response of the isoscalar and isovector pairing versus isospin.

  • 8.
    Satula, Wojtek
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Zalewski, M.
    Contradicting effective mass scalings in the single-particle spectra calculated using the Skyrme energy density functional method2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 78, no 1, p. 011302-Article in journal (Refereed)
    Abstract [en]

    The problem of the effective mass scaling in the single-particle (s.p.) spectra calculated within the Skyrme energy density functional (EDF) method is studied. It is demonstrated that for specific pairs of orbitals like 1d(3/2)-1f(7/2) the commonly anticipated isoscalar effective mass (m*) scaling of the s.p. level splittings is almost canceled by an implicit m* scaling present in the two-body spin-orbit (SO) strength. On the other hand, the nu f(7/2)-nu f(5/2) SO splitting depends solely on the SO strength. Hence, two conflicting scaling properties appear to be at work in standard Skyrme EDF, making the theory internally inconsistent with respect to s.p. energies. It is argued that this unphysical property is, to a large extent, a consequence of the strategies and data sets used to fit these functionals. The inclusion of certain s.p. spin-orbit splittings to fit the two-body spin-orbit and the tensor interaction strengths reinstates the conventional m* scaling and improves the performance of the Skyrme EDF.

  • 9.
    Satula, Wojtek
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Zdunczuk, H.
    Using high-spin data to constrain spin-orbit term and spin-fields of Skyrme forces - The need to unify the tune-odd part of the local energy density functional2005In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 25, no Suppl. 1, p. 551-552Article in journal (Refereed)
    Abstract [en]

    A method to study spin-fields and the spin-orbit potential within the local energy density approach is presented. The concept utilizes the intrinsic simplicity of terminating states in order to constrain certain parameters of the local nuclear energy functional. In particular, constraints on the isoscalar Landau parameter go and the strength of the spin-orbit potential are thoroughly discussed.

  • 10.
    Satula, Wojtek
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Zalewski, M.
    Dobaczewski, J.
    Olbratowski, P.
    Rafalski, M.
    Werner, T. R.
    Wyss, Ramon A.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    GLOBAL NUCLEAR STRUCTURE ASPECTS OF TENSOR INTERACTION2009In: International Journal of Modern Physics E, ISSN 0218-3013, Vol. 18, no 4, p. 808-815Article in journal (Refereed)
    Abstract [en]

    A direct fit of the isoscalar spin-orbit and both isoscalar and isovector tensor coupling constants to the f(5/2) - f(7/2) SO splittings in Ca-40, Ni-56, and Ca-48 requires (i) a significant reduction of the standard isoscalar spin-orbit strength and (ii) strong attractive tensor coupling constants. The aim of this paper is to address the consequences of these strong attractive tensor and weak spin-orbit fields on total binding energies, two-neutron separation energies and nuclear deformability.

  • 11.
    Wyss, Ramon
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Davies, Paul John
    Satula, Wojtek
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wadsworth, Robert
    Contrasting behavior in the rotational structure of the T-z=1/2 nuclei Kr-73 and Rb-75: A possible fingerprint of T=0 neutron-proton pairing correlations2007In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 76, no 1, p. 011301-Article in journal (Refereed)
    Abstract [en]

    Three different rotational bands have been observed to high spin in Rb-75 using Gammasphere. The structures are similar, but not identical to those found in the neighboring T-z=1/2 nucleus Kr-73. Conventional total Routhian surface (TRS) calculations with T=1 pairing are able to reproduce the rotational bands in Rb-75 with extreme accuracy, but they completely fail in reproducing the spectra and decay pattern of the negative parity bands in Kr-73. Simple qualitative arguments are put forward to show that the decay pattern observed in the negative parity bands in Kr-73 can be accounted for by means of T=0 pair correlations. To further corroborate this scenario, deformation, and pairing self-consistent TRS calculations, including schematic T=1 and T=0 pairing, are performed for the first time indicating the onset of dynamical T=0 pair-correlations at high angular momenta.

  • 12. Zalewski, M.
    et al.
    Olbratowski, P.
    Rafalski, M.
    Satula, Wojtek
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Werner, T. R.
    Wyss, Ramon A.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Global nuclear structure effects of the tensor interaction2009In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 80, no 6, p. 064307-Article in journal (Refereed)
    Abstract [en]

    A direct fit of the isoscalar spin-orbit (SO) and both isoscalar and isovector tensor coupling constants to the f(5/2)-f(7/2) SO splittings in Ca-40, Ni-56, and Ca-48 nuclei requires a drastic reduction of the isoscalar SO strength and strong attractive tensor coupling constants. The aim of this work is to address further consequences of these strong attractive tensor and weak SO fields on binding energies, nuclear deformability, and high-spin states. In particular, the contribution to the nuclear binding energy from the tensor field shows a generic magic structure with tensorial magic numbers N(Z)=14,32,56, or 90, corresponding to the maximum spin asymmetries in 1d(5/2), 1f(7/2)circle plus 2p(3/2), 1g(9/2)circle plus 2d(5/2), and 1h(11/2)circle plus 2f(7/2) single-particle configurations, respectively, and that these numbers are smeared out by pairing correlations and deformation effects. The consequences of strong attractive tensor fields and weak SO interaction for nuclear stability at the drip lines are also examined, particularly those close to the tensorial doubly magic nuclei. The possibility of an entirely new tensor-force-driven deformation effect is discussed.

  • 13. Zalewski, M.
    et al.
    Satula, Wojtek
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Dobaczewski, J.
    Olbratowski, P.
    Rafalski, M.
    Werner, T. R.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Shell structure fingerprints of tensor interaction2009In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 42, no 3, p. 577-581Article in journal (Refereed)
    Abstract [en]

    We address the consequences of strong tensor terms in the local energy density functional, resulting from fits to the f(5/2)-f(7/2) splittings in Ca-40, Ca-48, and Ni-56. In this study, we focus on the tensor contribution to the nuclear binding energy. In particular, we show that it exhibits an interesting topological feature closely resembling that of the shell correction. We demonstrate that in the extreme single-particle scenario at spherical shape, the tensor contribution shows tensorial magic numbers equal to N(Z) = 14, 32, 56, and 90, and that this structure is smeared out due to configuration mixing caused by pairing correlations and migration of proton/neutron sub-shells with neutron/proton shell filling. Based on a specific Skyrme-type functional SLy4(T), we show that the proton tensorial magic numbers shift with increasing neutron excess to Z = 14, 28, and 50.

  • 14. Zdunczuk, H.
    et al.
    Satula, Wojtek
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Probing spin fields and spin-orbit term of the local nuclear energy functional at band termination2005In: International Journal of Modern Physics E, ISSN 0218-3013, Vol. 14, no 3, p. 451-456Article in journal (Refereed)
    Abstract [en]

    A systematic study of the terminating states in A similar to 50 mass region using the self-consistent Skyrme-Hartree-Fock model is presented. The objective is to use the intrinsic simplicity of the terminating states to constrain certain parameters of the local nuclear energy functional. In particular, the work focuses on the spin fields and the spin-orbit term and constrain the appropriate Landau parameters and the strength of the spin-orbit potential.

  • 15. Zdunczuk, H.
    et al.
    Satula, Wojtek
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Probing the nuclear energy functional at band termination2005In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 71, no 2, p. 024305-Article in journal (Refereed)
    Abstract [en]

    A systematic study of terminating states in the Asimilar to50 mass region using the self-consistent Skyrme-Hartree-Fock model is presented. The objective of this study is to demonstrate that the terminating states, due to their intrinsic simplicity, offer unique and so far unexplored opportunities to study different aspects of the effective NN interaction or nuclear local energy density functional. In particular, we show that the agreement of the calculations to the data depends on the spin fields and the spin-orbit term which, in turn, allows us to constrain the appropriate Landau parameters and the strength of the spin-orbit potential. The present study reveals that the structure and energy of terminating states can be used as a tool to differentiate among the many Skyrme force parametrizations.

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