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Ishikawa, Takatsugu*; Hosaka, Atsushi; Gubler, P.; Sako, Hiroyuki; Tanida, Kiyoshi; 33 of others*
Proceedings of Science (Internet), 500, p.225_1 - 225_5, 2026/01
from QCD sum rulesSu, N.*; Chen, H.-X.*; Gubler, P.; Hosaka, Atsushi
Proceedings of Science (Internet), 500, p.076_1 - 076_6, 2026/01
Shim, S.-I.*; Hosaka, Atsushi
Proceedings of Science (Internet), 500, p.010_1 - 010_6, 2026/01
no abstracts in English
Fujii, Daisuke; Hosaka, Atsushi*; Iwanaka, Akihiro*; Sakai, Tadakatsu*; Tachibana, Motoi*
Proceedings of Science (Internet), 500, p.135_1 - 135_6, 2026/01
Understanding strongly coupled QCD matter remains challenging due to its non-perturbative nature. We study finite-density, zero-temperature QCD in a two-flavor hard-wall holographic model with nonzero quark mass. The dense phase is obtained by solving the classical equations of motion under a homogeneous ansatz. To relate bulk fields to boundary observables, we perform holographic renormalization and construct the dictionary, emphasizing the essential role of an IR boundary term at the hard-wall cutoff. Within this setup we uncover a baryonic phase with large baryon number density and a strongly suppressed chiral condensate. From these solutions we derive the equation of state and compute neutron-star mass-radius relations, finding stars above two solar masses over a broad parameter range.
Fujii, Daisuke; Kawaguchi, Mamiya*; Tanaka, Mitsuru*
Proceedings of Science (Internet), 500, p.239_1 - 239_6, 2026/01
Elucidating the mechanisms by which quarks and gluons are confined within hadrons is the most fundamental challenge in QCD. To solve this problem, it is important to understand the role of quark and gluon condensation and the associated spontaneous symmetry breaking in making hadrons. Recently, the stress distribution inside the proton has become experimentally measurable. It is extracted from the gravitational form factors that characterize the matrix elements of the energy-momentum tensor for the proton. This stress distribution is the force that confines quarks and gluons inside hadrons, opening the way to approach the above issues from the viewpoint of stress distribution. In this talk, we investigate the contributions of phenomena reflecting chiral and scale symmetry breaking, such as quark and gluon condensation, to the pressure distribution inside the nucleon, and show that these contributions are essential for stabilizing the nucleon.
Catumba, G.*; Hiraguchi, Atsuki; Hou, G. W.-S.*; Jansen, K.*; Kao, Y.-J.*; David Lin, C.-J.*; Ramos, A.*; Sarkar, M.*
Proceedings of Science (Internet), 466, p.145_1 - 145_10, 2025/12
The custodial Two-Higgs-Doublet-Model with SU(2) gauge fields is studied on the lattice. This model has the same global symmetry structure as the Standard Model but the additional Higgs field enlarges the scalar spectrum and opens the possibility for the occurrence of spontaneous symmetry breaking of the global symmetries. Both the spectrum and the running of the gauge coupling of the custodial 2HDM are studied on a line of constant Standard Model physics with cutoff ranging from 300 to 600 GeV. The lower bounds of the realizable masses for the additional BSM scalar states are found to be well bellow the W boson mass. In fact, for the choice of quartic couplings in this work the estimated lower mass for one of the BSM states is found to be about 
0.2 
and independent of the cutoff.
Ueki, Taro
Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025) (Internet), p.2018 - 2027, 2025/04
The criticality analysis of continuously mixed random media is essential to the safe retrieval of fuel debris. Image analysis of an oxide debris mockup reveals that the power spectrum cannot be fully explained by a single factor alone, but instead requires consideration of the complexity of multiple factors. This highlights the need for a randomized function capable of representing complex power spectra. To address this, we developed a new function called the Randomized Fourier Series (RFS), which introduces randomization in amplitude and phase. RFS allows the representation of power spectra with arbitrary shapes, facilitating realistic Monte Carlo (MC) simulations of random continuous material mixtures. For demonstration, taking the Lorentz power spectrum as an example, the spectrum flatness at low wavenumbers is analyzed to understand how the transition to white noise influences the fluctuation in neutron effective multiplication factor across independently generated random media replicas. Numerical results are presented for a mixture of 4 materials, along with the root mean-squared mass deviation over the constituent materials. The MC solver Solomon is employed with a partial volume pairing feature.
Watanabe, Tomoaki; Aizawa, Naoto*; Chiba, Go*; Tada, Kenichi; Yamamoto, Akio*
Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025) (Internet), p.288 - 297, 2025/04
Currently, a major burnup calculation method for the nuclide composition of nuclear fuel conducts neutron transport calculations at each burnup step to account for changes in the neutron spectrum. While this method is highly accurate, the large computational cost of neutron transport calculations can be problematic. Therefore, a fast burnup calculation method based on neutron spectrum reconstruction with the proper orthogonal decomposition (POD) and regression model is investigated. In this method, dimensionality reduction by POD is applied to many neutron fluxes obtained from detailed burnup calculations for various input parameter sets, and regression models are constructed to connect the dimensionality-reduced neutron fluxes and parameters. By substituting arbitrary input parameters to the regression models, the neutron flux is reconstructed and the burnup calculation is performed. This method performs burnup calculations that consider changes in the neutron spectrum based on input conditions without neutron transport calculations. The present method was applied to a PWR UO
fuel pin cell model. The results show the nuclide inventory can be calculated with a prediction accuracy within a few percent. In addition, it is found that the calculation error is dominated by the regression models, which implies the further improvement of the regression models leads to improving the accuracy.
Yang-Mills theory in 
Kitazawa, Masakiyo*; Fujii, Daisuke; Iwanaka, Akihiro*; Suenaga, Daiki*
Proceedings of Science (Internet), 466, p.163_1 - 163_9, 2025/02
We examine the thermal properties and phase transitions of Yang-Mills theory formulated on the spacetime manifold , where two spatial directions are compactified. Using both lattice simulations and an effective model, we study the theory in Euclidean space with anisotropic spatial volumes. Our lattice analysis reveals that significant pressure anisotropy appears only when the compactified spatial dimensions are sufficiently short, in contrast to free scalar theories. Based on these results, we construct an effective theory where two Polyakov loops associated with the compactified directions are treated as dynamical degrees of freedom. This model, tuned to match the lattice thermodynamics, predicts a novel first-order phase transition terminating at critical points. Our findings suggest that the coupling between the two Polyakov loops plays a key role in driving this transition.
Catumba, G.*; Hiraguchi, Atsuki; W.-S. Hou, G.*; Jansen, K.*; Kao, Y.-J.*; David Lin, C.-J.*; Ramos, A.*; Sarkar, M.*
Proceedings of Science (Internet), 453, p.362_1 - 362_7, 2024/11
We study a 3-dimensional SU(2) gauge theory with 4 Higgs fields which transform under the adjoint representation of the gauge group, that has been recently proposed by Sachdev et al. to explain the physics of cuprate superconductors near optimal doping. The symmetric confining phase of the theory corresponds to the usual Fermi-liquid phase while the broken (Higgs) phase is associated with the interesting pseudogap phase of cuprates. We employ the Hybrid Monte-Carlo algorithm to study the phase diagram of the theory. We find the existence of a variety of broken phases in qualitative accordance with earlier mean-field predictions and discuss their role in cuprates. In addition, we investigate the behavior of Polyakov loop to probe the confinement/deconfinement phase transition, and find that the Higgs phase hosts a stable deconfining phase consistent with previous studies.
gauge fieldsCatumba, G.*; Hiraguchi, Atsuki; W.-S. Hou, G.*; Jansen, K.*; Kao, Y.-J.*; David Lin, C.-J.*; Ramos, A.*; Sarkar, M.*
Proceedings of Science (Internet), 453, p.87_1 - 87_9, 2024/11
We study the most general Two Higgs Doublet Model with gauge fields on the lattice. The phase space is probed through the computation of gauge-invariant global observables serving as proxies for order parameters. In each phase, the spectrum of the theory is analysed for different combinations of bare couplings and different symmetry breaking patterns. The scale setting and determination of the running gauge coupling are performed through the Wilson flow computation of the action density.
Tomiya, Akio*; Nagai, Yuki
Proceedings of Science (Internet), 453, p.001_1 - 001_7, 2024/11
Machine learning, deep learning, has been accelerating computational physics, which has been used to simulate systems on a lattice. Equivariance is essential to simulate a physical system because it imposes a strong induction bias for the probability distribution described by a machine learning model. However, imposing symmetry on the model sometimes occur a poor acceptance rate in self-learning Monte-Carlo (SLMC). On the other hand, Attention used in Transformers like GPT realizes a large model capacity. We introduce symmetry equivariant attention to SLMC. To evaluate our architecture, we apply it to our proposed new architecture on a spin-fermion model on a two-dimensional lattice. We find that it overcomes poor acceptance rates for linear models and observe the scaling law of the acceptance rate in machine learning.
Torii, Tatsuo*; Sasaki, Miyuki; Sanada, Yukihisa
Proceedings of 2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor Detectors (IEEE NSS MIC RTSD 2023) (Internet), P. 1, 2023/11
Radiation imaging is useful in various fields where the location of radiation sources needs to be identified. Especially in environments where radiation sources are distributed in three dimensions and difficult to locate, the development of a small imaging sensor that can detect radiation in the 4-
direction will have a significant impact on the progress of work. We have developed a radiation detector with a fractal geometry. This is a unit of tetrahedral radiation sensors, 16 sensors are arranged in a Sierpinski tetrahedron shape, and the space between the sensors is filled with heavy metals. The count rates of the individual sensors make it possible to determine the direction of radiation incidence. Furthermore, since there is no external shielding, the distribution of charged particles, such as beta rays, can also be measured. We have analyzed the response of the Sierpinski radiation detector with respect to the incident direction of gamma and beta rays and compared it with experimental results to understand the sensitivity characteristics.
Kondo, Ryoichi; Nagaya, Yasunobu
Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023) (Internet), 10 Pages, 2023/08
A functional expansion tally (FET) method with numerical basis functions generated by singular value decomposition (SVD) is newly proposed. Traditionally, analytical functions were used for the FET calculations, e.g., Legendre polynomials for a one-dimensional distribution. However, the expansion terms could increase to reconstruct steep or complex distributions with these functions. A basis set that can well represent the target distribution with lower order expansion is desired to achieve high accuracy with the small computational resource. In the present study, a numerical basis set is generated from snapshot data by using SVD. This approach is based on the reduced order modeling (ROM). We applied ROM to the FET method in Monte Carlo calculations. The numerical result showed the applicability of the proposed method, on the other hand, some issues were revealed, e.g., discretization of the snapshot data.
Sugawara, Takanori; Kunieda, Satoshi
Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023) (Internet), 7 Pages, 2023/08
This study investigates the impact of the change from JENDL-4 to JENDL-5 on neutronics analysis of transmutation systems. As the transmutation systems, the following two systems are targeted: JAEA-ADS, a lead-bismuth cooled accelerator-driven system, and MARDS, a molten salt chloride accelerator-driven system. For the JAEA-ADS, the k-eff value increased 189 pcm from JENDL-4 to JENDL-5. It was found that the revisions of various nuclides affected to this difference. For example, the revision of 
N indicated an increase of 200 pcm from the JENDL-4 result. For the MARDS, it was found that the major revision of 
Cl and 
Cl cross sections was the main cause of the k-eff differences. This study confirmed that the difference in the nuclear data libraries still indicated differences in calculation results for the transmutation systems.
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
As
and NaBi, 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.
Rodriguez, D. C.; Koizumi, Mitsuo; Rossi, F.; Takahashi, Tone
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 3 Pages, 2022/12
Nakamura, Tatsuya; To, Kentaro; Koizumi, Tomokatsu; Kiyanagi, Ryoji; Ohara, Takashi; Ebine, Masumi; Sakasai, Kaoru
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 2 Pages, 2022/11
A new thin position-sensitive scintillation neutron detectors have been developed to replace present scintillation detectors in SENJU diffractometer at J-PARC MLF. The SENJU diffractometer originally composed of 37 position-sensitive detectors, where each detector has neutron sensitive area of 256 256 mm with a pixel size of 4 4 mm. To renew some original detectors the new detectors have been developed based on ZnS scintillator and wavelength-shifting fibers technology. The developed replacement detectors were designed with a thin thickness of 12 cm, which is 40% of the original detector. The new detectors have also improved detector performances to the original ones in terms of detection efficiency (60% for 2-A neutrons) and count uniformity (5-8%). The produced six detector modules have been implemented to the beamline after checking their detector performances in the lab.
Rossi, F.; Koizumi, Mitsuo; Rodriguez, D. C.; Takahashi, Tone
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 2 Pages, 2022/11
To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 3 Pages, 2022/11
A real-time data display and storage module was developed for time-of-flight neutron measurement. The module can display real-time experimental data from two-dimensional neutron detector in a two-dimensional image, one-dimensional projection images in X- and Y-axis, and time-of-flight spectra. The module has two modes of operation: standard mode, and simple-display mode. The simple-display mode only displays the experimental results on the monitor and can operate faster than that in the standard mode because the module uses the limited function. Therefore, the simple-display mode is also useful for measurement of high-counting rate neutrons. Operation test using test pulses were performed to confirm the operating speed of the module. The module in standard and simple-display mode could measure the continuous test pulses without counting losses with a frequency of 1.0 and 1.6 MHz, respectively.
