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Journal Articles

Strong decays of singly heavy baryons from a chiral effective theory of diquarks

Kim, Y.*; Oka, Makoto; Suenaga, Daiki*; Suzuki, Kei

Physical Review D, 107(7), p.074015_1 - 074015_15, 2023/04

 Times Cited Count:0

A chiral effective theory of scalar and vector diquarks is formulated, which is based on $$SU(3)_Rtimes SU(3)_L$$ chiral symmetry and includes interactions between scalar and vector diquarks with one or two mesons. We find that the diquark interaction term with two mesons breaks the $$U(1)_A$$ and flavor $$SU(3)$$ symmetries. To determine the coupling constants of the interaction Lagrangians, we investigate one-pion emission decays of singly heavy baryons $$Qqq$$ ($$Q = c$$, $$b$$ and $$q = u$$, $$d$$, $$s$$), where baryons are regarded as diquark-heavy-quark two-body systems. Using this model, we present predictions of the unobserved decay widths of singly heavy baryons. We also study the change of masses and strong decay widths of singly heavy baryons under partial restoration of chiral symmetry.

Journal Articles

Origin of magnetically dead layers in spinel ferrites $$M$$Fe$$_2$$O$$_4$$ grown on Al$$_2$$O$$_3$$; Effects of postdeposition annealing studied by XMCD

Nonaka, Yosuke*; Wakabayashi, Yuki*; Shibata, Goro; Sakamoto, Shoya*; Ikeda, Keisuke*; Chi, Z.*; Wan, Y.*; Suzuki, Masahiro*; Tanaka, Arata*; Tanaka, Masaaki*; et al.

Physical Review Materials (Internet), 7(4), p.044413_1 - 044413_10, 2023/04

 Times Cited Count:0

Journal Articles

Casimir effect for fermions on the lattice

Nakayama, Katsumasa*; Suzuki, Kei

Proceedings of Science (Internet), 430, p.379_1 - 379_9, 2023/04

The conventional Casimir effect has been studied in the continuous spacetime, but to elucidate its counterpart in the lattice space is an important subject. Here, we discuss various types of Casimir effects for quantum fields on the lattice. By using a definition of the Casimir energy on the lattice, we show that the Casimir effect for the Wilson fermion is similar to that for the continuous Dirac fermion. We apply our definition to an effective Hamiltonian describing Dirac semimetals, such as Cd$$_3$$As$$_2$$ and Na$$_3$$Bi, and find an oscillatory behavior of the Casimir energy as a function of film thickness of semimetals. We also study contributions from Landau levels under magnetic fields and the Casimir effect for nonrelativistic particle fields on the lattice.

Journal Articles

Phase diagram of the QCD Kondo effect and inactivation of the magnetic catalysis

Hattori, Koichi*; Suenaga, Daiki*; Suzuki, Kei; Yasui, Shigehiro*

EPJ Web of Conferences, 276, p.01015_1 - 01015_5, 2023/03

We investigate the QCD phase diagram in strong magnetic fields with heavy-quark impurities and determine the ground state within the mean-field analysis. The ground state is characterized by magnitudes of the pairing not only between the light quark and antiquark, i.e., chiral condensate, but also between the light quark and heavy-quark impurity, dubbed the Kondo condensate. We propose signatures of the interplay and/or competition between those two pairing phenomena reflected in the magnitude of the chiral condensate that is saturated with respect to the magnetic-field strength and anomalously increases with increasing temperature.

Journal Articles

Magnonic Casimir effect in ferrimagnets

Nakata, Koki; Suzuki, Kei

Physical Review Letters, 130(9), p.096702_1 - 096702_6, 2023/03

Quantum fluctuations of quantum fields induce a zero-point energy shift under spatial boundary conditions. This quantum phenomenon, called the Casimir effect, has been attracting much attention beyond the hierarchy of energy scales, whereas its application to spintronics has not yet been investigated enough, particularly to ferrimagnetic thin films. Here we fill this gap. Using the lattice field theory, we investigate the Casimir effect induced by quantum fields for magnons and find that the magnonic Casimir effect can arise not only in antiferromagnets but also in ferrimagnets (e.g., YIG). Thus, we pave the way for magnonic Casimir engineering.

Journal Articles

Extraction properties of trivalent rare earth ions from nitric acid using a triamide-amine extractant

Uchino, Seiko*; Narita, Hirokazu*; Kita, Keisuke*; Suzuki, Hideya*; Matsumura, Tatsuro; Naganawa, Hirochika*; Sakaguchi, Koichi*; Oto, Keisuke*

Solvent Extraction Research and Development, Japan, 30(1), p.39 - 46, 2023/00

The extraction of trivalent rare earth ions (RE$$^{3+}$$) from HNO$$_{3}$$ solution using a triamide amine, tris(N,N-di-2-ethylhexyl-ethylamide)amine (DEHTAA), was conducted, and the extraction mechanism was estimated from extraction behavior of HNO$$_{3}$$ and RE$$^{3+}$$ and the relationship between atomic number and extraction percentages (E%) for RE$$^{3+}$$. A DEHTAA molecule dominantly formed a DEHTAA HNO$$_{3}$$ at 1.0 M HNO$$_{3}$$ and a DEHTAA(HNO$$_{3}$$)$$_{2}$$ at 6.0 M HNO$$_{3}$$ in the acid-equilibrated organic phase. This would provide the unique dependence of E% for the light RE$$^{3+}$$ on the HNO$$_{3}$$ concentration, in which the E% value had a minimum and maximum at $$sim$$0.5 M and $$sim$$2 M HNO$$_{3}$$, respectively. The results of the slope analyses for the distribution ratios for RE$$^{3+}$$ suggested that the dominant RE$$^{3+}$$ complex was RE(NO$$_{3}$$)$$_{3}$$DEHTAA(DEHTAA HNO$$_{3}$$) at 1.0 M HNO$$_{3}$$. The E% for RE$$^{3+}$$ decreased from La$$^{3+}$$ to Lu$$^{3+}$$ at 1.0 M HNO$$_{3}$$; on the other hand, those increased from La$$^{3+}$$ to Nd$$^{3+}$$ at 0.25 M and from La$$^{3+}$$ to Sm$$^{3+}$$ and 6.0 M HNO$$_{3}$$.

Journal Articles

A Study on accuracy of analysis of the radiation-induced component in the ESR spectra of teeth

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.

KEK Proceedings 2022-2, p.120 - 125, 2022/11

We investigate the effect of sample's anisotropy and measurement condition to obtain the higher reproducibility for the shape of the ESR spectrum and the intensity of CO$$_{2}^{-}$$ radical.

Journal Articles

Detection limit of electron spin resonance for Japanese deciduous tooth enamel and density separation method for enamel-dentine separation

Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; Sasaki, Keiichi*; et al.

Journal of Radiation Research (Internet), 63(4), p.609 - 614, 2022/07

 Times Cited Count:0 Percentile:0.01(Biology)

Electron spin resonance (ESR) dosimetry is one of the most powerful tools for radiation dose reconstruction. The detection limit of this technique using human teeth is reported to be 56 mGy or 67 mGy; however, the absorbed dose of Fukushima residents after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident was estimated to be lower than this detection limit. Our aim is to assess the absorbed radiation dose of children in Fukushima Prefecture after the accident; therefore, it is important to estimate the detection limit for their teeth. The detection limit for enamel of deciduous teeth of Japanese children separated by the mechanical method is estimated to be 115.0 mGy. The density separation method can effectively separate enamel from third molars of Japanese people. As we have collected thousands of teeth from children in Fukushima, the present technique may be useful to examine their external absorbed dose after the FNPP accident.

Journal Articles

Axial U(1) symmetry at high temperatures in $$N_f=2+1$$ lattice QCD with chiral fermions

Aoki, Sinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kanamori, Issaku*; Kaneko, Takashi*; Nakamura, Yoshifumi*; Rohrhofer, C.*; Suzuki, Kei

Proceedings of Science (Internet), 396, p.332_1 - 332_7, 2022/07

The axial U(1) anomaly in high-temperature QCD plays an important role to understand the phase diagram of QCD. The previous works by JLQCD Collaboration studied high-temperature QCD using 2-flavor dynamical chiral fermions such as the domain-wall fermion and reweighted overlap fermion. We extend our simulations to QCD with 2+1-flavor dynamical quarks, where the masses of the up, down, and strange quarks are near the physical point, and the temperatures are close to or higher than the pseudocritical temperature. In this talk, we will present the results for the Dirac spectrum, topological susceptibility, axial U(1) susceptibility, and hadronic collelators.

Journal Articles

What is chiral susceptibility probing?

Aoki, Sinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*; Suzuki, Kei

Proceedings of Science (Internet), 396, p.050_1 - 050_9, 2022/07

In the early days of QCD, the axial $$U(1)$$ anomaly was considered as a trigger for the breaking of the $$SU(2)_Ltimes SU(2)_R$$ symmetry through topological excitations of gluon fields. However, it has been a challenge for lattice QCD to quantify the effect. In this work, we simulate QCD at high temperatures with chiral fermions. The exact chiral symmetry enables us to separate the contribution from the axial $$U(1)$$ breaking from others among the susceptibilities in the scalar and pseudoscalar channels. Our result in two-flavor QCD indicates that the chiral susceptibility, which is conventionally used as a probe for $$SU(2)_Ltimes SU(2)_R$$ breaking, is actually dominated by the axial $$U(1)$$ breaking at temperatures $$Tge 165$$ MeV.

Journal Articles

Heavy-quark spin polarization induced by the Kondo effect in a magnetic field

Suenaga, Daiki*; Araki, Yasufumi; Suzuki, Kei; Yasui, Shigehiro*

Physical Review D, 105(7), p.074028_1 - 074028_19, 2022/04

 Times Cited Count:0 Percentile:0.01(Astronomy & Astrophysics)

We propose a new mechanism of the heavy-quark spin polarization (HQSP) in quark matter induced by the Kondo effect under an external magnetic field. The Kondo effect is caused by a condensate between a heavy and a light quark called the Kondo condensate leading to a mixing of the heavy- and light-quark spins. Thus, the HQSP is driven through the Kondo effect from light quarks coupling with the magnetic field in quark matter. For demonstration, we employ the Nambu-Jona-Lasinio type model under a magnetic field and investigate the HQSP within the linear response theory with vertex corrections required by the $$U(1)_{rm EM}$$ electromagnetic gauge invariance. As a result, we find that the HQSP arises significantly with the appearance of the Kondo effect. Our findings are testable in future sign-problem-free lattice simulations.

Journal Articles

Doubly heavy tetraquarks in a chiral-diquark picture

Kim, Y.*; Oka, Makoto; Suzuki, Kei

Physical Review D, 105(7), p.074021_1 - 074021_17, 2022/04

 Times Cited Count:10 Percentile:94.91(Astronomy & Astrophysics)

Energy spectrum of doubly heavy tetraquarks, $$T_{QQ}$$ ($$QQ bar{q} bar{q}$$ with $$Q = c, b$$ and $$q = u, d, s$$), is studied in the potential chiral-diquark model. Using the chiral effective theory of diquarks and the quark-diquark-based potential model, the $$T_{bb}$$, $$T_{cc}$$, and $$T_{cb}$$ tetraquarks are described as a three-body system composed of two heavy quarks and an antidiquark. We find several $$T_{bb}$$ bound states, while no $$T_{cc}$$ and $$T_{cb}$$ (deep) bound state is seen. We also study the change of the $$T_{QQ}$$ tetraquark masses under restoration of chiral symmetry.

Journal Articles

Construction of machine-learning Zr interatomic potentials for identifying the formation process of c-type dislocation loops

Okita, Taira*; Terayama, Satoshi*; Tsugawa, Kiyoto*; Kobayashi, Keita; Okumura, Masahiko; Itakura, Mitsuhiro; Suzuki, Katsuyuki*

Computational Materials Science, 202, p.110865_1 - 110865_9, 2022/02

 Times Cited Count:5 Percentile:52.96(Materials Science, Multidisciplinary)

Journal Articles

Role of the axial $$U(1)$$ anomaly in the chiral susceptibility of QCD at high temperature

Aoki, Sinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*; Suzuki, Kei

Progress of Theoretical and Experimental Physics (Internet), 2022(2), p.023B05_1 - 023B05_12, 2022/02

 Times Cited Count:4 Percentile:87.23(Physics, Multidisciplinary)

The chiral susceptibility, or the first derivative of the chiral condensate with respect to the quark mass, is often used as a probe for the QCD phase transition since the chiral condensate is an order parameter of $$SU(2)_L times SU(2)_R$$ symmetry breaking. However, the chiral condensate also breaks the axial $$U(1)$$ symmetry, which is usually not studied as it is already broken by the anomaly and apparently has little impact on the transition. We investigate the susceptibilities in the scalar and pseudoscalar channels in order to quantify how much the axial $$U(1)$$ breaking contributes to the chiral phase transition. Employing a chirally symmetric lattice Dirac operator and its eigenmode decomposition, we separate the axial $$U(1)$$ breaking effects from others. Our result in two-flavor QCD indicates that both of the connected and disconnected chiral susceptibilities are dominated by axial $$U(1)$$ breaking at temperatures $$Tgeq 190$$ MeV after the quadratically divergent constant is subtracted.

Journal Articles

Development of dose estimation method using wild animal teeth for low dose exposure

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.

KEK Proceedings 2021-2, p.91 - 96, 2021/12

We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.

Journal Articles

Kondo effect with Wilson fermions

Ishikawa, Tsutomu*; Nakayama, Katsumasa*; Suzuki, Kei

Physical Review D, 104(9), p.094515_1 - 094515_11, 2021/11

 Times Cited Count:1 Percentile:15.91(Astronomy & Astrophysics)

We investigate the Kondo effect with Wilson fermions. This is based on a mean-field approach for the chiral Gross-Neveu model including four-point interactions between a light Wilson fermion and a heavy fermion. For massless Wilson fermions, we demonstrate the appearance of the Kondo effect. We point out that there is a coexistence phase with both the light-fermion scalar condensate and Kondo condensate, and the critical chemical potentials of the scalar condensate are shifted by the Kondo effect. For negative-mass Wilson fermions, we find that the Kondo effect is favored near the parameter region realizing the Aoki phase. Our findings will be useful for understanding the roles of heavy impurities in Dirac semimetals, topological insulators, and lattice simulations.

Journal Articles

Heavy baryon spectrum with chiral multiplets of scalar and vector diquarks

Kim, Y.*; Liu, Y.-R.*; Oka, Makoto; Suzuki, Kei

Physical Review D, 104(5), p.054012_1 - 054012_18, 2021/09

 Times Cited Count:6 Percentile:58.46(Astronomy & Astrophysics)

Chiral effective theory of scalar and vector diquarks is formulated according to the linear sigma model. The main application is to describe the ground and excited states of singly heavy baryons with a charm or bottom quark. Applying the potential quark model between the diquark and the heavy quark ($$Q=c, b$$), we construct a heavy-quark-diquark model. The spectra of the positive- and negative-parity states of $$Lambda_Q$$, $$Sigma_Q$$, $$Xi^{(')}_Q$$ and $$Omega_Q$$ are obtained. The masses and interaction parameters of the effective theory are fixed partly from the lattice QCD data and also from fitting low-lying heavy baryon masses. We find that the negative parity excited states of $$Xi_Q$$ (flavor $$bar{bf 3}$$) are different from those of $$Lambda_Q$$, because of the inverse hierarchy of the pseudoscalar diquark. On the other hand, $$Sigma_Q, Xi'_Q$$ and $$Omega_Q$$ (flavor $${bf 6}$$) baryons have similar spectra. We compare our results of the heavy-quark-diquark model with experimental data as well as the quark model.

Journal Articles

Survival probabilities of charmonia as a clue to measure transient magnetic fields

Iwasaki, Sachio*; Jido, Daisuke*; Oka, Makoto; Suzuki, Kei

Physics Letters B, 820, p.136498_1 - 136498_6, 2021/09

 Times Cited Count:0 Percentile:0.02(Astronomy & Astrophysics)

We investigate time evolution of $$S$$-wave charmonium populations under a time-dependent homogeneous magnetic field and evaluate survival probabilities of the low-lying charmonia to the goal of estimating the magnetic field strength at heavy-ion collisions. Our approach implements mixing between different spin eigenstates and transitions to radially excited states. We show that the survival probabilities can change even by an extremely short magnetic field. Furthermore, we find that the survival probabilities depend on the initial spin states. We propose the sum of the survival probabilities over spin partners as an observable insensitive to the initial states. We also find that the sum can be approximately given as a function of $$sigma B_0^2$$ with a duration time $$sigma$$ and the maximum strength of the magnetic field $$B_0$$.

Journal Articles

Rapid analysis of $$^{90}$$Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometry

Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.

Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08

 Times Cited Count:2 Percentile:38.85(Chemistry, Analytical)

Rapid analysis of $$^{90}$$Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of $$^{90}$$Sr in small bone and tooth samples derived from terrestrial animals.

Journal Articles

Fundamental study on scheduling of inspection process for fast reactor plants

Suzuki, Masaaki*; Ito, Mari*; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru

2020 9th International Congress on Advanced Applied Informatics (IIAI-AAI 2020), p.797 - 801, 2021/07

435 (Records 1-20 displayed on this page)