arXiv subjects

Akinobu Doté

Publications and source records attributed to Akinobu Doté.

12 recordsLinked to original sources

arXiv2026

Quadrupole transitions of $^{10}$C and their isospin symmetry with $^{10}$Be

We investigate the structures of $^{10}$C focusing on the quadrupole properties in comparison with the mirror nucleus $^{10}$Be. We describe $^{10}$C and $^{10}$Be in the variation of the multiple bases of the antisymmetrized molecular dynamics (AMD), in which the multiple AMD bases are optimized simultaneously in the total-energy variation. In the monopole transitions, we confirm the isospin symmetry between $^{10}$C and $^{10}$Be by exchanging protons and neutrons. In the quadrupole transitions, most cases show larger values in $^{10}$C than those of $^{10}$Be, except for the transition of $2^+_1\to 0^+_1$. The transition of $2^+_1\to 0^+_1$ shows similar values in the two nuclei in spite of the different proton numbers, which agrees with the experimental situation as an anomaly. This relation comes from the small proton deformation in $^{10}$C due to its subclosed nature and the large proton deformation in $^{10}$Be due to two-$α$ clustering. This property can also be seen in the quadrupole moments of the two nuclei. In the neutron deformations of $^{10}$C and $^{10}$Be, the opposite tendency of protons is confirmed and these results ensure the isospin symmetry between the two nuclei. We also confirm the large quadrupole transitions between the elongated linear-chain states. It would be desirable for future experiments to investigate the present characteristics of the transitions in the two nuclei.

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arXiv2026

Shell and cluster structures in $^{20}$Ne in the variation of multiple bases of the antisymmetrized molecular dynamics

We investigate the structures of $^{20}$Ne in the variation of the multiple bases of the antisymmetrized molecular dynamics (AMD). In this method, the multiple AMD bases are superposed and optimized simultaneously in the total-energy variation. This scheme is beneficial for describing the various configurations in $^{20}$Ne. In the results, we confirm the shell and cluster structures in the $K^π=0^+_{1-4}$ bands, such as the deformed states in the $K^π=0^+_{1,4}$ bands with the $α$ cluster development, and the spherical shell-like states in the $K^π=0^+_2$ band, the latter of which is difficult to describe in the previous AMD calculations imposing the quadrupole deformation. We evaluate the monopole and quadrupole transitions in these states. The negative parity states of $^{20}$Ne with $K^π=0^-$ and $2^-$ are discussed in relation to the shell and cluster structures. As a result, six kinds of the $K^π$ bands in $^{20}$Ne are described comprehensively in the microscopic framework of nuclei.

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arXiv2025

Microscopic study of the asymptotic behavior of the reduced width amplitude in $^7$Li and $^7$Be

We investigate the effects of different basis model spaces on the calculation of reduced width amplitude (RWA) and asymptotic normalization coefficient (ANC) for the $^{7}$Li and $^{7}$Be nuclei. The two-cluster model ($α+t/^3$He) and three-cluster model ($α+d+n/p$) with the generator coordinates method (GCM) are applied to calculate the wave function of $^7$Li and $^7$Be. Specifically, the model space for the three-cluster model is constructed upon a sufficiently broad space of two-cluster configuration bases by further including three-cluster configuration bases. We compare the impact on the results from two basis sets for these added three-cluster bases: one with a compact and one with a broad spatial distribution. The final results reveal that the two-cluster model cannot accurately reproduce the binding energies of $^7$Li and $^7$Be, and tends to overestimate their ANCs. Regarding the calculations with the three-cluster model, while the two basis sets do not give significant differences in energy or energy spectrum, the basis set with a compact model space fails to describe the asymptotic behavior of the RWA adequately. This introduces excessive uncertainty into the ANC calculation. In the end, we conclude that when calculating ANC via a microscopic framework, particular attention must be paid to ensuring sufficient model space, especially for the components describing the breakup channels. This approach provides ANC values for $^7$Li and $^7$Be that agree well with experimental results.

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arXiv2018

Fully coupled-channel study of $K^-pp$ resonance in a chiral SU(3)-based $K^{bar}N$ potential

Nuclear system with antikaons, so-called kaonic nuclei, has been a longstanding issue in strange nuclear physics and hadron physics, because they might have exotic nature; In particular, they could be a doorway to the dense matter due to the strong attraction between antikaon and nucleon. Among kaonic nuclei, the three-body system composed of two protons and a single $K^-$ meson, $K^-pp$, is the most essential. In this article, we will report on the recent situation of $K^-pp$ studies in both theoretical and experimental sides. Afterwards, we will explain our latest study of the $K^-pp$ with a fully coupled-channel complex scaling method (Full ccCSM) using a chiral SU(3)-based $\bar{K}N$(-$πY$) potential. In Full ccCSM, the $K^-pp$ is completely treated as a resonant state of a $\bar{K}NN$-$πΣN$-$πΛN$ coupled-channel system. The energy dependence involved in the chiral potential is handled with a self-consistent calculation in which two extreme ansatzes are examined: field picture and particle picture. With our chiral SU(3)-based potential constrained by the precise data of kaonic hydrogen atom (SIDDHARTA experiment), the $K^-pp$ resonance is obtained as a shallowly bound state measured from the $\bar{K}NN$ threshold with a narrow width, if the field picture is employed in the calculation: the binding energy is $14-28$ MeV and half value of the mesonic decay width are $8-15$ MeV. On the other hand, if the particle picture is employed, it is found that the binding energy could be as large as about 50 MeV, even though such a chiral potential is used. Based on these results of Full ccCSM calculation, we have discussed on the possibility for kaonic nuclei to form a dense matter and on the latest experimental result reported by J-PARC E15 collaboration.

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arXiv2018

Fully coupled-channel study of $K^-pp$ resonance in a chiral SU(3)-based $\bar{K}N$ potential

We have investigated the most essential kaonic nucleus "$K^-pp$" as a resonant state of the $\bar{K}NN$-$πΣN$-$πΛN$ coupled channel system using a chiral SU(3)-based $\bar{K}N$ potential. We treat the "$K^-pp$" resonance adequately with a fully coupled-channel complex scaling method (full ccCSM). Self-consistency needs to be considered for the energy dependence of the chiral SU(3)-based potential. In the present study, we propose a simple prescription for the treatment of self-consistency, considering the {\it averaged threshold} and {\it averaged binding energy of mesons}. With this prescription, we have successfully found the self-consistent solutions of the "$K^-pp$" three-body resonance. The results indicate that the "$K^-pp$" system is bound rather shallowly. In particular, when the potential parameters are constrained with the latest $\bar{K}N$ scattering length, the binding energy and half of the mesonic decay width are obtained as $14-50$ MeV and $8-19$ MeV, respectively.

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arXiv2017

Fully coupled-channel complex scaling method for the $K^-pp$ system

We have developed a fully coupled-channel complex scaling method (ccCSM) for the study of the most essential kaonic nucleus, $``K^-pp,"$ which is a resonant state of a $\bar{K}NN$-$πΣN$-$πΛN$ coupled-channel system based on a theoretical viewpoint. By employing the ccCSM and imposing the correct boundary condition of resonance, the coupled-channel problem is completely solved using a phenomenological energy-independent potential. As a result of the ccCSM calculation of $``K^-pp,"$ in which all three channels are treated explicitly, we have obtained three-body resonance as a Gamow state. The resonance pole indicates that the binding energy of $``K^-pp"$ and the half value of its mesonic decay width are 51 MeV and 16 MeV, respectively. In the analysis of the resonant wave function obtained using the ccCSM, we clarify the spatial configuration and channel compositions of $``K^-pp."$ Compared with past studies of single-channel calculations based on effective $\bar{K}N$ potentials, the current study provides a guideline for the determination of the $\bar{K}N$ energy to be used in effective potentials.

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arXiv2015

Investigation of $K^{bar}NN$ resonances with a coupled-channel Complex Scaling Method + Feshbach projection

We have investigated a prototype of kaonic nuclei, "$K^-pp$", with a coupled-channel Complex Scaling Method (ccCSM). Combining the ccCSM with Feshbach projection method, we can handle a coupled-channel problem effectively as a single-channel problem. By using an energy-dependent chiral SU(3)-based $\bar{K}N$ potential, the $K^-pp$ ($J^π=0^-$ and $T=1/2$) is obtained to be shallowly bound with the binding energy of 20-30 MeV. The mesonic decay width depends on the interaction parameters and ansatz; the decay width is ranging from 20 to 65 MeV. In case of $J^π=1^-$ state, no three-body $\bar{K}NN$ resonant states are found.

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arXiv2015

Application of a coupled-channel Complex Scaling Method with Feshbach projection to the $K^-pp$ system

Kaonic nuclei (nuclear system with anti-kaons) have been an interesting subject in hadron and strange nuclear physics, because the strong attraction between anti-kaon and nucleon might bring exotic properties to that system. In this article, we investigate $K^-pp$ as a prototype of kaonic nuclei. Here, $K^-pp$ is a three-body resonant state in the $\bar{K}NN$-$πYN$ coupled channels. ($Y$=$Λ$, $Σ$) To treat resonant states in a coupled-channel system properly, we propose newly a coupled-channel complex scaling method combined with the Feshbach projection (ccCSM+Feshbach method). In this method, the Feshbach projection is realized with help of so-called the extended closure relation held in the complex scaling method, and a complicated coupled-channel problem is reduced to a simple single-channel problem which one can treat easily. First, we confirm that the ccCSM+Feshbach method completely reproduces results of a full coupled-channel calculation in case of two-body $\bar{K}N$-$πY$ system. We then proceed to study of three-body $\bar{K}NN$-$πYN$ system, and successfully find solutions of the $K^-pp$ resonance by imposing self-consistency for the complex $\bar{K}N$ energy. Obtained binding energy of $K^-pp$ is well converged around 27 MeV, with an energy-dependent $\bar{K}N$(-$πY$) potential based on the chiral SU(3) theory, independently of ansatz for the self-consistency. This binding energy is small as ones reported in earlier studies based on chiral models. The decay width of $K^-pp$ strongly depends on the ansatz. We calculate also the correlation density of $NN$ and $\bar{K}N$ pairs by using the obtained complex-scaled wave function of the $K^-pp$ resonance. Effect of the repulsive core of $NN$ potential and survival of $Λ^*$ resonance are confirmed.

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arXiv2011

Modification of triaxial deformation and change of spectrum in $^{25}_{\ Λ}$Mg caused by $Λ$ hyperon

The positive-parity states of $^{25}_{\ Λ}$Mg with a $Λ$ hyperon in $s$ orbit were studied with the antisymmetrized molecular dynamics for hypernuclei. We discuss two bands of $^{25}_{\ Λ}$Mg corresponding to the $K^π=0^+$ and $2^+$ bands of $^{24}$Mg. It is found that the energy of the $K^π= 2^+ \otimes Λ_s$ band is shifted up by about 200 keV compared to $^{24}$Mg. This is because the $Λ$ hyperon in $s$ orbit reduces the quadrupole deformation of the $K^π= 0^+ \otimes Λ_s$ band, while it does not change the deformation of the $K^π= 2^+ \otimes Λ_s$ band significantly.

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arXiv2008

Chiral SU(3) dynamics and the quasibound K^-pp cluster

The prototype of a Kbar nuclear cluster, K^-pp, has been investigated using effective KbarN potentials based on chiral SU(3) dynamics. Variational calculation shows a bound state solution with shallow binding energy B(K^-pp)=20 \pm 3 MeV and broad mesonic decay width Γ(KbarNN -> πY N)=40 - 70 MeV. The KbarN(I=0) pair in the K^-pp system exhibits a similar structure as the Λ(1405). We have also estimated the dispersive correction, p-wave KbarN interaction, and two-nucleon absorption width.

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arXiv2008

Variational calculation of the ppK^- system based on chiral SU(3) dynamics

The ppK^- system, as a prototype for possible quasibound Kbar nuclei,is investigated using a variational approach. Several versions of energy dependent effective KbarN interactions derived from chiral SU(3) dynamics are employed as input, together with a realistic NN potential (Av18). Taking into account theoretical uncertainties in the extrapolations below the KbarN threshold, we find that the antikaonic dibaryon ppK^- is NOT deeply bound. With the driving s-wave KbarN interaction the resulting total binding energy is B(ppK^-) = 20 $\pm$ 3 MeV and the mesonic decay width involving KbarN -> πY is expected to be in the range 40 - 70 MeV. Properties of this quasibound ppK^- system (such as density distributions of nucleons and antikaon) are discussed. The Λ(1405), as an I=0 quasi-bound state of Kbar and a nucleon, appears to survive in the ppK^- cluster. Estimates are given for the influence of p-wave KbarN interactions and for the width from two-nucleon absorption (KbarNN -> YN) processes. With inclusionof these effects and dispersive corrections from absorption, the ppK^- binding energy is expected to be in the range 20 - 40 MeV, while the total decay width can reach 100 MeV but with large theoretical uncertainties.

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arXiv2008

$K^-pp$ system with chiral SU(3) effective interaction

The $K^-pp$ system is investigated using a variational approach with realistic two-body interactions: the Argonne v18 $NN$ potential and an energy dependent $\bar{K}N$ effective interaction derived from chiral SU(3) coupled-channel dynamics. Uncertainties in subthreshold extrapolations of the $\bar{K}N$ interaction are considered. A weakly bound $K^-pp$ state is found, with a binding energy $B = (19\pm 3)$ MeV substantially smaller than suggested in previous calculations. The decay width $Γ(K^-pp\to πΣN)$ is estimated to range between about 40 and 70 MeV.

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