Cluster and toroidal aspects of isoscalar dipole excitations in ${}^{12}$C

Abstract

We investigated cluster and toroidal aspects of isoscalar dipole excitations in ${}^{12}$C based on the shifted basis antisymmetrized molecular dynamics combined with the generator coordinate method, which can describes 1p-1h excitations and $3\alpha$ dynamics. In the $E=10-15$ MeV region, we found two low-energy dipole modes separating from the giant dipole resonance. One is the developed $3\alpha$-cluster state and the other is the toroidal dipole mode. The cluster state is characterized by the large amplitude cluster motion beyond the 1p-1h model space, whereas the toroidal dipole mode is predominantly described by 1p-1h excitations on the ground state. The low-energy dipole states are remarkably excited by the toroidal dipole operator, which can measure the nuclear vorticity. For compressive dipole transition strengths, a major part is distributed in the $30-50$ MeV region for the giant dipole resonance, and 5\% of the total energy weighted sum exist in the $E<20$ MeV region.

arXiv comment9 pages, 7 figures

References in corpus (17)

• Exotic modes of excitation in atomic nuclei far from stability
• Structure of Light Unstable Nuclei Studied with Antisymmetrized Molecular Dynamics
• Structure of ground and excited states of ${}^{12}$C
• Variation after Angular Momentum Projection for the Study of Excited States Based on Antisymmetrized Molecular Dynamics
• Structure of Excited States of 10Be studied with Antisymmetrized Molecular Dynamics
• Toroidal dipole resonances in the relativistic random phase approximation
• Isoscalar monopole excitations in ${}^{16}$O: $\alpha$-cluster states at low energy and mean-field-type states at higher energy
• On the toroidal nature of the low-energy E1 mode
• Isoscalar dipole transition as a probe for asymmetric clustering
• General Treatment of Vortical, Toroidal, and Compression Modes
• Cluster states and monopole transitions in ${}^{16}$O
• Isoscalar monopole and dipole excitations of cluster states and giant resonances in ${}^{12}$C
• Isoscalar dipole coherence at low energies and forbidden E1 strength
• Toroidal resonance: relation to pygmy mode, vortical properties and anomalous deformation splitting
• Isovector and isoscalar dipole excitations in ${}^9$Be and ${}^{10}$Be studied with antisymmetrized molecular dynamics
• Toroidal, compressive, and $E1$ properties of low-energy dipole modes in ${}^{10}$Be
• Structure and decay of the pygmy dipole resonance in 26Ne

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• Isoscalar monopole and dipole transitions in ${}^{24}$Mg, ${}^{26}$Mg and ${}^{28}$Si
• Individual dipole toroidal states: main features and search in (e,e') reaction
• Cluster correlation and nuclear vorticity in low-lying $1^{-}$ states of ${}^{24}$Mg
• Low-energy dipole excitation modes in ${}^{10}$Be
• Low-energy dipole excitations in ${}^{20}$O with antisymmetrized molecular dynamics