Cheng-Li Wu

A systematic study of superheavy nuclei for Z = 114 and beyond using the relativistic mean field approach

Abstract We have studied the structural properties of even-even, neutron deficient, Z = 114–126, superheavy nuclei in the mass region A ∼ 270–320, using an axially deformed relativistic mean field model. The calculations are performed with three parameter sets (NL1, TM1 and NL-SH), in order to see the dependence of the structural properties on the force used. The calculated ground state shapes are found to be parameter dependent. For some parameter sets, many of the nuclei are degenerate in their ground state configuration. Special attention is given to the investigation of the magic structures (spherical shell closures) in the superheavy region. We find that some known magic numbers are absent and new closed shells are predicted. Large shell gaps appear at Z = 80, 92, (114), 120 and 138, N = 138, (164), (172), 184, (198), (228) and 258, irrespective of the parameter sets used. The numbers in parenthesis are those which correspond to relatively smaller gaps. The existence of new magic numbers in the valley of superheavy elements is discussed. It is suggested that nuclei around Z = 114 and N = 164 ∼ 172 could be considered as candidates for the next search of superheavy nuclei. The existence of superheavy islands around Z = 120 and N = 172 or N = 184 double shell closure is also discussed.

SU(4) model of high-temperature superconductivity and antiferromagnetism

We present an SU(4) model of high-temperature superconductivity having many similarities to dynamical symmetries known to play an important role in microscopic nuclear structure physics and in elementary particle physics. Analytical solutions in three dynamical symmetry limits of this model are found: an SO(4) limit associated with antiferromagnetic order; an

The fermion dynamical symmetry model

\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}\mathrm{SO}(3)

Two-quasiparticle K-isomeric states in strongly deformed neutron-rich Nd and Sm isotopes: a projected shell-model analysis

limit that may be interpreted as a d-wave pairing condensate; and an SO(5) limit that may be interpreted as a doorway state between the antiferromagnetic order and the superconducting order. The model suggests a phase diagram in qualitative agreement with that observed in the cuprate superconductors. The relationship between the present model and the SO(5) unification of superconductivity and antiferromagnetic order proposed by Zhang is discussed.

SO(5) as a Critical Dynamical Symmetry in the SU(4) Model of High-Temperature Superconductivity

The bulk of contemporary research in nuclear structure physics deals with nuclei that are at least moderately collective in their low-lying states.These are usually well removed from closed shells and constitute a difficult theoretical problem. The most successful descriptions of such nuclei have neglected the many-body nature of the problem, replacing it instead with some form of single-particle field, often deformed, always violating fundamental symmetries that must be restored through projection. Such approaches allow calculations that otherwise would have been impossible, and have been central to the rapid advance in quantitative descriptions of nuclear structure.

An algebraic fermion description of band termination and loss of collectivity in heavy nuclei

Motivated by recent spectroscopy data from fission experiments, we apply the projected shell model to study systematically the structure of strongly deformed, neutron-rich, even–even Nd and Sm isotopes with neutron number from 94 to 100. We perform calculations for rotational bands up to spin I = 20 and analyze the band structure of low-lying states with quasiparticle excitations, with emphasis given to rotational bands based on various negative-parity two-quasiparticle (2-qp) isomers. Experimentally known isomers in these isotopes are described well. The calculations further predict proton 2-qp bands based on a 5− and a 7− isomer and neutron 2-qp bands based on a 4− and an 8− isomer. The properties for the yrast line are discussed, and quantities to test the predictions are suggested for future experiment.

Theoretical Constraints for Observation of Superdeformed Bands in the Mass-60 Region

An SU(4) model of high-temperature superconductivity and antiferromagnetism has recently been proposed. The SO(5) group employed by Zhang [Science 275, 1089 (1997)] is embedded in this SU(4) as a subgroup, suggesting a connection between our SU(4) model and the Zhang SO(5) model. In order to understand the relationship between the the two models, we have used generalized coherent states to analyze the nature of the SO(5) subgroup. By constructing coherent-state energy surfaces, we demonstrate explicitly that the

Z = 110–111 elements and the stability of heavy and superheavy elements

\mathrm{SU}(4)\ensuremath{\supset}\mathrm{SO}(5)

Strong anisotropy of cuprate pseudogap correlations: implications for Fermi arcs and Fermi pockets

symmetry can be interpreted as a critical dynamical symmetry interpolating between superconducting and antiferromagnetic phases, and that this critical dynamical symmetry has many similarities to critical dynamical symmetries identified previously in other fields of physics. More generally, we demonstrate with this example that the mathematical techniques associated with generalized coherent states may have powerful applications in condensed-matter physics because they provide a clear connection between microscopic many-body theories and their broken-symmetry approximate solutions. In addition, these methods may be interpreted as defining the most general Bogoliubov transformation subject to a Lie group symmetry constraint, thus providing a mathematical connection between algebraic formulations and the language of quasiparticle theory. Finally, we suggest that the identification of the SO(5) symmetry as a critical dynamical symmetry implies deep algebraic connections between high-temperature superconductors and seemingly unrelated phenomena in other field of physics.

Temperature-dependent gap equations and their solutions in the SU(4) model of high-temperature superconductivity

Abstract An algebraic fermion model is used to interpret the loss of E2 collectivity observed in two- and four-quasiparticle aligned bands, and the termination of collective bands at high spins in rare-earth nuclei. Both can be understood as a systematic consequence of finite angular momentum content in a coherent SU3 core.