Intriguing aspects of light baryon resonances

Khemchandani, K. P.*; Martnez Torres, A.*; Kim, S.-H.*; Nam, S.-I.*; 保坂 淳; 永廣 秀子*

EPJ Web of Conferences, 301, p.03001_1 - 03001_10, 2024/08

https://doi.org/10.1051/epjconf/202430103001

3個の軽いクォークからなるバリオン共鳴がバレンスクォーク模型で記述できない例について議論する。

Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer

Kim, G.*; Cho, S.-M.*; Im, S.*; Suh, H.*; 諸岡 聡; 菖蒲 敬久; 兼松 学*; 町田 晃彦*; Bae, S.*

Construction and Building Materials, 411, p.134529_1 - 134529_18, 2024/01

https://doi.org/10.1016/j.conbuildmat.2023.134529

This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.

Exotic properties of and its impact on photoproduction of light hyperons

Khemchandani, K. P.*; Martnez Torres, A.*; Kim, S.-H.*; Nam, S.-I.*; 保坂 淳

Acta Physica Polonica A, 142(3), p.329 - 336, 2022/09

https://doi.org/10.12693/APhysPolA.142.329

In this work, we outline the findings of our recent study of the properties of and its consequential impacts on the cross-sections of the photoproduction of (1405). Further, we discuss the possibility of the existence of an isovector state with a mass similar to (1405), which we refer to as (1400). With the idea of motivating experimental investigations of (1400), we have studied its photo-production process and determined the respective cross-sections and polarization observables. We have studied also the coupling of to (1400) and found that it gives an important contribution to the cross-sections near the threshold. In the process, we have determined the branching ratios of the decay of to the final states involving (1405) and (1400) to be in the range of 6-7 MeV. Our findings can motivate the consideration of alternative processes in partial wave analyses of experimental data when studying the properties of .

Topological Hall effects of magnons in ferrimagnets

仲田 光樹; Kim, S. K.*

Journal of the Physical Society of Japan, 90(8), p.081004_1 - 081004_10, 2021/08

https://doi.org/10.7566/JPSJ.90.081004

マグノンのトポロジカルホール効果について総括する。特に、強磁性絶縁体,反強磁性絶縁体,フェリ磁性絶縁体、それぞれのトポロジカル物性(例:スピンHall効果,スピンNernst効果,熱Hall効果)を解説し、幾何学的位相の観点から統一的な視点を与える。

Effect of the difference in strength of hard and soft components on the synergetic strengthening of layered materials

Kim, J. G.*; Bae, J. W.*; Park, J. M.*; Woo, W.*; Harjo, S.; Lee, S.*; Kim, H. S.*

Metals and Materials International, 27(2), p.376 - 383, 2021/02

https://doi.org/10.1007/s12540-020-00657-1

Heterogeneous structured materials achieve a combination of high strength and extreme ductility due to synergetic strengthening driven by conditions in the interfacial region. Although the origin of synergetic strengthening has been revealed to be strain incompatibility in the interfacial region, the effect of the strength difference between hard and soft phases on strengthening has not been investigated well. In the work reported in the present paper, the effect of the difference in strength of the hard and soft phases on synergetic strengthening was investigated by conducting in situ neutron diffraction tensile tests. As a result, it was determined that the dislocation density in a layered sheet of high Mn (HMn) steel/interstitial free (IF) steel is higher than that in a layered sheet of HMn/low carbon steel. The big difference in mechanical properties between HMn steel and IF steel induces a high stress gradient and results in additional dislocations.

Hexaquark picture for *(2380)

Kim, H.*; Kim, K. S.*; 岡 眞

Physical Review D, 102(7), p.074023_1 - 074023_10, 2020/10

AA2020-0335.pdf:0.31MB

https://doi.org/10.1103/PhysRevD.102.074023

=0, =3のダイバリオン状態の6クォーク(ヘキサクォーク)成分を分析し、質量を求めた。その結果、実験的に報告されている質量をヘキサクォーク構造から矛盾なく説明できることを示した。

Vector and Axial-vector form factors in radiative kaon decay and flavor SU(3) symmetry breaking

Shim, S.-I.*; 保坂 淳; Kim, H.-C.*

Physics Letters B, 795, p.438 - 445, 2019/08

https://doi.org/10.1016/j.physletb.2019.06.046

We study the vector and axial-vector form factors of radiative kaon decay within the framework of the gauged nonlocal effective chiral action from the instanton vacuum, focusing on the effects of flavor SU(3) symmetry breaking. The general tendency of the results are rather similar to those of radiative pion decays: The nonlocal contributions make the results of the vector form factor increased by about 20%, whereas they reduce those of the axial-vector form factor by almost 50%. Suppressing the prefactors consisting of the kaon mass and the pion decay constant, we scrutinize how the kaon form factors undergo changes as the mass of the strange current quark is varied. Those related to the vector and second axial-vector form factors tend to decrease monotonically as the strange quark mass increases, whereas that for the axial-vector form factor decreases. When decay is considered, both the results of the vector and axial-vector form factors at the zero momentum transfer are in good agreement with the experimental data. The results are also compared with those from chiral perturbation theory to order.

neutron diffraction study of phase stress evolution in a ferrous medium-entropy alloy under low-temperature tensile loading

Bae, J. W.*; Kim, J. G.*; Park, J. M.*; Woo, W.*; Harjo, S.; Kim, H. S.*

Scripta Materialia, 165, p.60 - 63, 2019/05

https://doi.org/10.1016/j.scriptamat.2019.02.027

Phase stress evolution of face-centered cubic (FCC) and deformation-induced body-centered cubic (BCC) phases was measured in recently developed ferrous medium-entropy alloy. This was done during tensile deformation at -137C using neutron diffraction measurement for the quantitative interpretation of the role of martensitic transformation on the improved low-temperature tensile properties. The strain-hardening rate curve exhibits two-stage hardening behavior, and the phase stress and stress contribution from the BCC phase increases significantly while that from FCC phase decreases during plastic deformation. This is a direct demonstration that BCC phase contributes significantly to the increase in strength and strain hardening.

photoproduction off the neutron with nucleon resonances

Kim, S.-H.*; Kim, H.-C.

Physics Letters B, 786, p.156 - 164, 2018/11

https://doi.org/10.1016/j.physletb.2018.09.041

We investigate kaon photoproduction off the neutron target, i.e., focusing on the role of nucleon resonances given in the Review of Particle Data Group in the range of MeV. We employ an effective Lagrangian method and a Regge approach. The strong couplings of nucleon resonances with vertices are constrained by quark model predictions. The numerical results of the total and differential cross sections are found to be in qualitative agreement with the recent CLAS and FOREST experimental data. We discuss the effects of the narrow nucleon resonance () on both the total and differential cross sections near the threshold energy. In addition, we present the results of the beam asymmetry as a prediction.

Testing the tetraquark structure for the X resonances in the low-lying region

Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; 慈道 大介*; 岡 眞

European Physical Journal A, 52(7), p.184_1 - 184_8, 2016/07

https://doi.org/10.1140/epja/i2016-16184-0

チャームを含むテトラクォーク状態であるX共鳴に関して、カラースピン相互作用によるスペクトルの分析を行った。スピンが0, 1, 2の状態について超微細構造を計算し、2個のスピン0状態と2個のスピン1状態の固有状態を求めた。X(3872)の質量をインプットとして、他の状態の質量の予言を与え、X(3823), X(3900), X(3940)などの量子状態を決めた。パラメータはすでにDおよびBメソンのスペクトルで決めた値を用い、チャームが隠れたXと無矛盾であることを示した。