A. Repko

Nuclear vorticity in isoscalarE1modes: Skyrme-random-phase approximation analysis

Two basic concepts of nuclear vorticity, hydrodynamical (HD) and Rawenthall-Wambach (RW), are critically inspected. As a test case, we consider the interplay of irrotational and vortical motion in isoscalar electric dipole E1(T=0) modes in Pb, namely the toroidal and compression modes. The modes are described in a self-consistent random-phase-approximation (RPA) with the Skyrme force SLy6. They are examined in terms of strength functions, transition densities, current fields, and formfactors. It is shown that the RW conception (suggesting the upper component of the nuclear current as the vorticity indicator) is not robust. The HD vorticity is not easily applicable either because the definition of a velocity field is too involved in nuclear systems. Instead, the vorticity is better characterized by the toroidal strength which closely corresponds to HD treatment and is approximately decoupled from the continuity equation.

Toroidal resonance: Relation to pygmy mode, vortical properties, and anomalous deformation splitting

We review a recent progress in investigation of the isoscalar toroidal dipole resonance (TDR). A possible relation of the TDR and low-energy dipole excitations (also called a pygmy resonance) is analyzed. It is shown that the dipole strength in the pygmy region can be understood as a local manifestation of the collective vortical toroidalmotion at the nuclear surface. Application of the TDR as a measure of the nuclear dipole vorticity is discussed. An anomalous splitting of the TDR in deformed nuclei is inspected.

Skyrme random-phase-approximation description of lowest K π = 2 γ + states in axially deformed nuclei

The lowest quadrupole

E1 STRENGTH IN LIGHT NUCLEI: SKYRME RPA ANALYSIS

\ensuremath{\gamma}

Deformation-induced splitting of the isoscalar E0 giant resonance: Skyrme random-phase-approximation analysis

-vibrational

Deformation effects in Giant Monopole Resonance

{K}^{\ensuremath{\pi}}={2}^{+}

Toroidal nature of the low-energy

states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies

E1

{E}_{\ensuremath{\gamma}}

mode

and reduced transition probabilities

Individual low-energy E1 toroidal and compression states in light nuclei: deformation effect, spectroscopy and interpretation.

B(E2)