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lattice QCD with chiral fermionsAoki, Shinya*; 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.
Aoki, Shinya*; 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 
anomaly was considered as a trigger for the breaking of the 
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 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 breaking, is actually dominated by the axial breaking at temperatures 
MeV.
anomaly in the chiral susceptibility of QCD at high temperatureAoki, Shinya*; 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：8 Percentile：82.94(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 
symmetry breaking. However, the chiral condensate also breaks the axial 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 breaking contributes to the chiral phase transition. Employing a chirally symmetric lattice Dirac operator and its eigenmode decomposition, we separate the axial breaking effects from others. Our result in two-flavor QCD indicates that both of the connected and disconnected chiral susceptibilities are dominated by axial breaking at temperatures 
MeV after the quadratically divergent constant is subtracted.
anomaly at high temperature with lattice chiral fermionsAoki, Shinya*; Aoki, Yasumichi*; Cossu, G.*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kaneko, Takashi*; Rohrhofer, C.*; Suzuki, Kei
Physical Review D, 103(7), p.074506_1 - 074506_18, 2021/04
Times Cited Count：14 Percentile：73.22(Astronomy & Astrophysics)We investigate the axial anomaly of two-flavor QCD at temperatures 190-330 MeV. In order to preserve precise chiral symmetry on the lattice, we employ the M
bius domain-wall fermion action as well as overlap fermion action implemented with a stochastic reweighting technique. Compared to our previous studies, we reduce the lattice spacing to 0.07 fm, simulate larger multiple volumes to estimate finite size effect, and take more than four quark mass points, including one below physical point to investigate the chiral limit. We measure the topological susceptibility, axial susceptibility, and examine the degeneracy of partners in meson/baryon correlators. All the data above the critical temperature indicate that the axial violation is consistent with zero within statistical errors. The quark mass dependence suggests disappearance of the anomaly at a rate comparable to that of the symmetry breaking.
lattice QCDSuzuki, Kei; Aoki, Shinya*; Aoki, Yasumichi*; Cossu, G.*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*
Proceedings of Science (Internet), 363, p.178_1 - 178_7, 2020/08
We investigate the high-temperature phase of QCD using lattice QCD simulations with dynamical Mbius domain-wall fermions. On generated configurations, we study the axial symmetry, overlap-Dirac spectra, screening masses from mesonic correlators, and topological susceptibility. We find that some of the observables are quite sensitive to lattice artifacts due to a small violation of the chiral symmetry. For those observables, we reweight the Mbius domain-wall fermion determinant by that of the overlap fermion. We also check the volume dependence of observables. Our data near the chiral limit indicates a strong suppression of the axial anomaly at temperatures 
220 MeV.
Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Suzuki, Kazuhiro; Endo, Shinya; Obata, Hiroki; Kurishita, Hiroaki*; Watanabe, Ryuzo*; Kawai, Masayoshi*; Yong, D.*
no journal, ,
no abstracts in English
Abe, Hitoshi; Masaki, Tomoo; Watanabe, Koji; Suzuki, Shinya; Tashiro, Shinsuke; Amano, Yuki; Yamane, Yuichi; Yoshida, Kazuo; Uchiyama, Gunzo; Ueda, Yoshinori*; et al.
no journal, ,
The release and transport characteristics of radioactive materials under the boiling and desiccating accident of the high active liquid waste in a reprocessing plant have been studied. Ruthenium is one of the important nuclides for evaluating public dose from the volatile viewpoint. By using apparatus which can control the experimental condition of temperature and atmosphere composition in the gas phase, the transport characteristics data of RuO
which is chemical form of Ru with volatility was acquired. As the results, it was found that RuO would transport in the gas phase without thermal decomposition and deposition onto the inner wall of glass under the experimental condition with nitric acid vapor.
Amano, Yuki; Watanabe, Koji; Suzuki, Shinya; Tashiro, Shinsuke; Yamane, Yuichi; Abe, Hitoshi; Yoshida, Kazuo; Uchiyama, Gunzo
no journal, ,
no abstracts in English
Saito, Shigeru; Kikuchi, Kenji*; Suzuki, Kazuhiro; Hatakeyama, Yuichi; Endo, Shinya; Suzuki, Miho; Okubo, Nariaki; Kondo, Keietsu
no journal, ,
The world's first megawatt-class lead-bismuth target, MEGAPIE (MEGAwatt Pilot Experiment), was dismantled and post irradiation examination (PIE) samples were prepared at PSI hot-lab. The samples were shipped to each institutions including JAEA. The samples were cut from the beam window (BW, T91) and the flow guide tube (FGT, SS316L). And all samples are prepared without LBE. The irradiation conditions of the specimens irradiated at SINQ target were as follows: proton energy was 580 MeV, irradiation temperatures were ranged from 251 to 341
C, and displacement damage levels were ranged from 0.16 to 1.57 dpa. PIE including SP (small punch) and three point bending tests were performed. SP tests were executed for T91 and SS316L specimens at R.T. in air condition. Specimen size for SP test with 2.4 mm steel-ball is 8 mm 
8 mm 0.5 mm. T91 specimens were cut from the Spitze (triangle) sample and polished to thickness of 0.5 mm. The OM/SP specimens of SS316L were polished to thickness of 0.5 mm. Three point bending tests were executed for SS316L specimens at R.T. in air condition. The bend bar specimens of SS316L without notch were employed. Results of the SP tests and three point bending tests on the irradiated specimens will be presented at the workshop. Cross sectional observation on the Spitze sample and microstructural observation by TEM will be also reported.
Saito, Shigeru; Okubo, Nariaki; Endo, Shinya; Suzuki, Kazuhiro; Hatakeyama, Yuichi; Kikuchi, Kenji*
no journal, ,
To evaluate the lifetime of the beam window of an accelerator-driven transmutation system (ADS) and spallation neutron source, material irradiation programs, the STIP (SINQ target irradiation program, SINQ; Swiss spallation neutron source) and MEGAPIE (MEGAwatt Pilot Experiment), have been executed. Part of the specimens were transported to JAEA and post irradiation examination (PIE) of the specimens was carried out. In this presentation, in addition to representative results of the PIE, our experience and knowledge of irradiation experiments and PIE processes will be introduced. These information will be useful for high energy particle irradiation experiments and PIE planed under the frame work of RaDIATE.
Kimuro, Shingo; Suzuki, Shinya*; Tachi, Yukio
no journal, ,
lattice QCD with chiral fermionsAoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kanamori, Issaku*; Kaneko, Takashi*; Nakamura, Yoshifumi*; Rohrhofer, C.*; Suzuki, Kei; Ward, D.*
no journal, ,
Quantum chromodynamics (QCD) is the fundamental theory describing the dynamics of quarks and gluons. The axial U(1) symmetry in QCD is broken at low temperatures by the effect of quantum anomaly, and it is important for understanding the phase structure of QCD to investigate what happens to this symmetry in the high-temperature regime of QCD. In this study, we simulate a high-temperature regime of 2+1 flavor QCD using dynamical chiral fermions such as the domain-wall fermions and the overlap fermions (obtained by the reweighting method). Here, for up- and down-quark masses, we investigate masses heavier than the physical point, near the physical point, and lighter than the physical point. For temperatures, we investigate the near-pseudo-critical temperature and slightly lower and higher temperature regions. For physical quantities, we report results and discussion on the behavior of the Dirac spectrum, axial U(1) susceptibility, topological susceptibility, and hadronic correlation functions.
lattice QCD at high temperaturesAoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kanamori, Issaku*; Kaneko, Takashi*; Nakamura, Yoshifumi*; Rohrhofer, C.*; Suzuki, Kei; Ward, D.*
no journal, ,
no abstracts in English
