arXiv subjects

Y. Kanada-En'yo

Publications and source records attributed to Y. Kanada-En'yo.

35 records · Page 2Linked to original sources

arXiv2005

$^{16}$C inelastic scattering studied with microscopic coupled-channels method

In order to test the $^{16}$C internal wave function, we perform microscopic coupled-channels (MCC) calculations of the $^{16}$C($0_1^+ \to 2_1^+$) inelastic scattering by $^{208}$Pb target at $E/A$=52.7 MeV using the antisymmetrized molecular dynamics (AMD) wave functions of $^{16}$C, and compare the calculated differential cross sections with the measured ones. The MCC calculations with AMD wave functions reproduce the experimental data fairly well, although they slightly underestimate the magnitude of the cross sections. The absolute magnitude of calculated differential cross sections is found to be sensitive to the neutron excitation strength. We prove that the MCC method is a useful tool to connect the inelastic scattering data with the internal wave functions.

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arXiv2005

Prediction of Narrow $J^π=1/2^+$, $3/2^+$, and $3/2^-$ states of $Θ_+$ in a Quark model with Antisymmetrized Molecular Dynamics

The exotic baryon $Θ^+(uudd\bar{s})$ is studied with microscopic calculations in a quark model by using a method of antisymmetrized molecular dynamics. We predict that the lowest even state is $J^π=1/2^+(I=0)$ or $J^π=3/2^+(I=0)$, and the lowest odd state is $J^π=3/2^-(I=1)$. They nearly degenerate in the $uudd\bar{s}$ system. We discuss $K^+n$ decay widths and estimate them to be $Γ< 7$ for the $J^π=\{1/2^+,3/2^+\}$, and $Γ<1$ MeV for the $J^π=3/2^-$ state.

hep-ph↗

arXiv2004

Narrow Pentaquark States in a Quark Model with Antisymmetrized Molecular Dynamics

The exotic baryon $Θ^+(uudd\bar{s})$ is studied with microscopic calculations in a quark model by using a method of antisymmetrized molecular dynamics(AMD). We predict narrow states, $J^π=1/2^+(I=0)$, $J^π=3/2^+(I=0)$, and $J^π=3/2^-(I=1)$, which nearly degenerate in a low-energy region of the $uudd\bar{s}$ system. We discuss $NK$ decay widths and estimate them to be $Γ< 7$ for the $J^π=\{1/2^+,3/2^+\}$, and $Γ<1$ MeV for the $J^π=3/2^-$ state.

hep-ph↗

arXiv2004

Cluster structure in stable and unstable nuclei

Cluster structure in stable and unstable nuclei has been studied. We report recent developments of theoretical studies on cluster aspect, which is essential for structure study of light unstable nuclei. We discuss negative parity bands in even-even Be and Ne isotopes and show the importance of cluster aspect. Three-body cluster structure and cluster crystallization are also introduced. It was found that the coexistence of cluster and mean-field aspect brings a variety of structures to unstable nuclei.

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arXiv2004

Deformation of C isotopes

Systematic analysis of the deformations of proton and neutron densities in even-even C isotopes was done based on the method of antisymmetrized molecular dynamics. The $E2$ transition strength was discussed in relation to the deformation. We analyze the $B(E2;2^+_1\to 0^+_1)$ in $^{16}$C, which has been recently measured to be abnormally small. The results suggest the difference of the deformations between proton and neutron densities in the neutron-rich C isotopes. It was found that stable proton structure in C isotopes plays an important role in the enhancement the neutron skin structure as well as in the systematics of $B(E2)$ in the neutron-rich C.

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arXiv2003

Clustering in stable and unstable nuclei in $p$-shell and $sd$-shell regions

According to microscopic calculations with antisymmetrized molecular dynamics, we studied cluster features in stable and unstable nuclei. A variety of structure was found in stable and unstable nuclei in the $p$-shell and $sd$-shell regions. The structure of excited states of $^{12}$Be was investigated, while in $sd$-shell nuclei we focused on molecular states and deformed states. The deformed states in $^{28}$Si and $^{40}$Ca were discussed in connection with the high-lying molecular states. Appealing molecular states in $^{36}$Ar and $^{24}$Mg were suggested. The results signified that both clustering of nucleons and mean-field formation are essential features in $sd$-shell nuclei as well as $p$-shell nuclei.

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arXiv2003

New effective nuclear forces with a finite-range three-body term and their application to AMD+GCM calculations

We propose new effective inter-nucleon forces with a finite-range three-body operator. The proposed forces are suitable for describing the nuclear structure properties over a wide mass number region, including the saturation point of nuclear matter. The forces are applied to microscopic calculations of $Z=N$ ($A\le 40$) nuclei and O isotopes with a method of antisymmetrized molecular dynamics. We present the characteristics of the forces and discuss the importance of the finite-range three-body term.

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arXiv2002

Shape coexistence in N=14 isotones: 19B, 24Ne and 28Si

Shape coexistence problems in N=14 isotones are studied with a microscopic method of antisymmetrized molecular dynamics. The present calculations reproduce features of deformation in 28Si, and predict possible shape coexistence of neutron density in neutron-rich nuclei(19B and 24Ne). We also systematically study the structures of the ground and excited states, and the molecular resonances of 28Si. Besides the shape coexistence in the low-energy region, the results indicate the high-lying levels with $α$-cluster and 12C+16O molecular structures in 28Si, which are consistent with the observed spin-assigned resonances. The resonance states above the threshold energies are connected with the low-lying deformed states from a view point of molecular excitation by discussing inter-cluster wave functions.

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arXiv2002

Exotic shapes in Ca-40 and Ar-36 studied with Antisymmetrized Molecular Dynamics

The structures of the ground and excited states of sd-shell nuclei: Ca-40 and Ar-36 were studied with a method of antisymmetrized molecular dynamics. Recently observed rotational bands were described with deformed intrinsic states which are dominated by excited configurations such as 4p-4h, 8p-8h and 4p-8h states. The results showed the coexistence of various kinds of exotic shapes with oblate, prolate and large prolate deformatios in the low-energy region of Ca-40. Possible cluster aspects in heavy sd-shell nuclei were implied in these exotic shapes.

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arXiv2002

Exotic clusters in the excited states of Be-12, Be-14 and B-15

The excited states of Be-12, Be-14 and B-15 were studied by an antisymmetrized molecular dynamics method. The theoretical results reproduced the energy levels of recently measured excited states of Be-12, and also predicted rotational bands with innovative clustering structures in Be-12, Be-14 and B-15. Clustering states with new exotic clusters (He-6, He-8 and Li-9) were theoretically suggested. One new aspect in very neutron-rich nuclei is a 6-nucleon correlation among 4 neutrons and 2 protons, which plays an important role in the formation of He-6 clusters during clustering: 8He + 6He of Be-14 and 9Li+6He of B-15.

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arXiv2002

Structures and Transitions in Light Unstable Nuclei

We study the structures of the unstable Be isotopes with the theoretical method of antisymmetrized molecular dynamics. It is found that various structures of the excited states appear in the low-energy region of neutron-rich Be nuclei. Focusing on the 2$α$ clustering, we analyze the intrinsic structures with the help of the experimental data of Gamow-Teller transitions.

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arXiv2002

Structure of excited states of Be-11 studied with Antisymmetrized Molecular Dynamics

The structures of the ground and excited states of Be-11 were studied with a microscopic method of antisymmetrized molecular dynamics. The theoretical results reproduce the abnormal parity of the ground state and predict various kinds of excited states. We suggest a new negative-parity band with a well-developed clustering structure which reaches high-spin states. Focusing on a $2α$ clustering structure, we investigated structure of the ground and excited states. We point out that molecular orbits play important roles for the intruder ground state and the low-lying $2\hbar ω$ states. The features of the breaking of $α$ clusters were also studied with the help of data for Gamow-Teller transitions.

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arXiv2002

Variation after Angular Momentum Projection for the Study of Excited States Based on Antisymmetrized Molecular Dynamics

In order to study the structure of excited states we perform a variational calculation after spin parity projection (VAP) within the framework of Antisymmetrized Molecular Dynamics (AMD). The framework is proven to be a new powerful approach for the study of the various structures of excited states because it is free from model assumptions such as inert cores, existence of clusters, and the axial symmetry. By using finite range interactions with a density dependent term we reproduce well all the energy levels below 15 MeV in $^{12}$C. This is the first theoretical model that reproduces many $E2$ transition rates and $β$ decays to $^{12}$C successfully.

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arXiv2002

Molecular Structure with Exotic Clusters in light Neutron-rich Nuclei

The excited states of Be-12, Be-14 and B-15 have been studied with a method of antisymmetrized molecular dynamics. In the predicted excited states we find novel molecule-like structures with very exotic clusters such as 6He+8He in Be-14 and 6He+9Li in B-15. The origin of the He-6 cluster development in the very neutron-rich nuclei is understood by the new-type correlation among 4 neutrons and 2 protons. In this paper we also present our recent challenge to study $sd$-shell nuclei. Shape coexistence problems in Ar-36 and Ca-40 are discussed.

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arXiv2001

Structure of Light Unstable Nuclei Studied with Antisymmetrized Molecular Dynamics

Structures of light unstable nuclei, Li, Be, B, and C isotopes are systematically studied with a microscopic method of antisymmetrized molecular dynamics. The theoretical method is found to be very useful to study ground and excited states of various nuclei covering unstable nuclei. The calculations succeed to reproduce many experimental data for nuclear structures; energies, radii, magnetic dipole moments, electric quadrupole moments, transition strength. In the theoretical results it is found that various exotic phenomena in unstable nuclei such as molecular-like structures, neutron skin, and large deformations may appear in unstabel nuclei. We investigate the structure change with the increase of neutron number and with the increase of the excitation energies, and find the drastic changes between shell-model-like structures and clustering structures. The mechanism of clustering developments in unstable nuclei are discussed.

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arXiv1999

Structure of Excited States of 10Be studied with Antisymmetrized Molecular Dynamics

We study structure of excited states of 10Be with the method of variation after spin parity projection in the framework of antisymmetrized molecular dynamics. Present calculations describe many excited states and reproduce the experimental data of E2 and E1 transitions and the new data of the $β$ transition strength successfully. We make systematic discussions on the molecule-like structures of light unstable nuclei and the important role of the valence neutrons based on the results obtained with the framework which is free from such model assumptions as the existence of inert cores and clusters.

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arXiv1997

AMD + HF model and its application to Be isotopes

In order to study light unstable nuclei systematically, we propose a new method ''AMD + Hartree-Fock''. This method introduces the concept of the single particle orbits into the usual AMD. Applying AMD + HF to Be isotopes, it is found that the calculated lowest intrinsic states with plus and minus parities have rather good correspondence with the explanation by the two-center shell model. In addition, by active use of the single particle orbits extracted from AMD wave function, we construct the first excited 0^+ state of $^{10}$Be. The obtained state appears in the vicinity of the lowest 1^- state. This result is consistent with the experimental data.

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