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We study the orbital magnetic susceptibility of tilted massless Dirac fermions in two dimensions. It is well-known that the type-I massless Dirac fermions exhibit divergingly-large diamagnetic susceptibility, whereas less is known about the types II and III cases. We first clarify that the orbital magnetic susceptibility is vanishing for the types II and III in the continuum model. We then compare the three types of Dirac fermions for the lattice models. We employ three tight-binding models with different numbers of Dirac points, all of which are two-band models defined on a square lattice. For all three models, we find that the type-I Dirac fermions show the divergingly-large orbital diamagnetic susceptibility, whereas the type-II Dirac fermions exhibit non-diverging paramagnetic susceptibility. The type-III Dirac fermions exhibit diamagnetism but its susceptibility is small compared with the type-I case., Comment: 11 pages, 7 figures

Theoretical quest of flat-band tight-binding models usually relies on lattice structures on which electrons reside. Typical examples of candidate lattice structures include the Lieb-type lattices and the line graphs. Meanwhile, there can be accidental flat-band systems that belong to neither of such typical classes and deriving flat-band energies and wave functions for such systems is not straightforward. In this work, we investigate the characteristic band structure for the tight-binding model on a network composed of pentagonal rings, which is inspired by the theoretically-predicted carbon-based material. Although the lattice does not belong to conventional classes of flat band models, the exact flat bands appear only for fine-tuned parameters. We analytically derive the exact eigenenergies and eigenstates of the flat bands. By using the analytic form of the Bloch wave function, we construct the corresponding Wannier function and reveal its characteristic real-space profile. We also find that, even away from the exact flat-band limits, the nearly flat band exists near the Fermi level for the half-filled systems, which indicates that the present system will be a suitable platform for questing flat-band-induced correlated electron physics if it is realized in the real material., Comment: 8 pages, 4 figures

We present TelEdge, a novel method of remote haptic communication using electrical stimulation through the edges of the smartphone. The aim of this study is to explore communications that can be created by adding touch sensing and haptic feedback using the electrical edge display to conventional audio-visual functionality. We conducted monitoring observations and interviews during a video call between two people, presenting interactive haptic feedback., Comment: Part of proceedings of 6th International Conference AsiaHaptics 2024

Tracing sensation plays an important role in discriminating friction and texture of objects. We have been studying a method of presenting the tracing sensation by contacting the center of a rotating disk with the fingertip. Although this method can reduce the size and complexity of the presentation device compared to conventional methods, it has the problem of fixed sensation. In this study, we examined a method to dynamically modulate the roughness sensation by devising the surface shape of the disk. We designed two types of disks: slit disks and milling disks. Experiments revealed that the perceived roughness of these disks can be changed by altering the rotation speed and direction., Comment: Part of proceedings of 6th International Conference AsiaHaptics 2024

Kinesthetic illusion can present a sense of movement without actual physical movement of the body, but it often lacks a sense of agency over the movement. Therefore, we focused on the sensation of walking induced by the kinesthetic illusion and hypothesized that incorporating coordinated arm swing movements as actual actions could enhance the sense of agency over the kinesthetic illusion. In this study, we implemented a system that switches the vibrations of the thighs and ankles back and forth based on arm swing movements and investigated whether the sense of agency over the walking sensation induced by the kinesthetic illusion changes with or without arm swing movements. The results suggest a tendency for the sense of agency to be enhanced when arm swing movements are combined., Comment: Part of proceedings of 6th International Conference AsiaHaptics 2024

Although 3D object editing has the potential to significantly influence various industries, recent research in 3D generation and editing has primarily focused on converting text and images into 3D models, often overlooking the need for fine-grained control over the editing of existing 3D objects. This paper introduces a framework that employs a pre-trained regressor, enabling continuous, precise, attribute-specific modifications to both the stylistic and geometric attributes of vehicle 3D models. Our method not only preserves the inherent identity of vehicle 3D objects, but also supports multi-attribute editing, allowing for extensive customization without compromising the model's structural integrity. Experimental results demonstrate the efficacy of our approach in achieving detailed edits on various vehicle 3D models., Comment: 18 pages, 12 figures

We identify Narain conformal field theories (CFTs) that correspond to code lattices for quantum error-correcting codes (QECC) over integers of cyclotomic fields $Q(\zeta_p)$ $(\zeta_p=e^{\frac{2\pi i}p})$ for general prime $p\geq 3$. This code-lattice construction is a generalization of more familiar ones such as Construction A${}_C$ for ternary codes and (after the generalization stated below) Construction A for binary codes, containing them as special cases. This code-lattice construction is redescribed in terms of root and weight lattices of Lie algebras, which allows to construct lattices for codes over rings $Z_q$ with non-prime $q$. Corresponding Narain CFTs are found for codes embedded into quotient rings of root and weight lattices of $ADE$ series, except $E_8$ and $D_k$ with $k$ even. In a sense, this provides a unified description of the relationship between various QECCs over $F_p$ (or $Z_q$) and Narain CFTs. A further extension on constructing the $E_8$ lattice from codes over the Mordell-Weil groups of extremal rational elliptic surfaces is also briefly discussed., Comment: 16 pages. Version 2: References are made to some literature. A discussion of codes over the Mordell-Weil groups of extremal rational elliptic surfaces is included

Chiral symmetry plays an essential role in condensed matter physics. In tight-binding models, it is often attributed to bipartite lattice structures, and its typical consequence is the ``particle-hole symmetric" band structures, that is, the positive and negative eigenenergies appear in a pairwise manner. In this work, we address the chiral symmetry for non-bipartite lattice models with flat bands. Our argument relies on what we call the molecular-orbital representation, by which we can guarantee the existence of the flat band. We show that the chiral symmetry is preserved for the non-flat bands when the molecular orbitals are normalized and divided into two sets within which they are non-overlapping. The chiral operator is constructed by the same molecular orbitals as the Hamiltonian. This results in the characteristic relation between the chiral operator and the Hamiltonian, which we call the Pythagoras relation. We present the examples of such models, i.e., the kagome lattice and its one-dimensional analog, and address the characteristics originating from the chiral symmetry, such as the emergence of the topological edge modes. We also show an example where the numbers of molecular orbitals in each set are different from each other, resulting in multiple flat bands with different energies., Comment: 11 pages, 6 figures

We investigate the geometrical structure of multiply enhanced codimension-two singularities in the $SU(5)$ model of six-dimensional F-theory, where the rank of the singularity increases by two or more. We perform blow-up processes for the enhancement $SU(5)\rightarrow G'$, where $G'=E_6$, $E_7$ or $E_8$, to examine whether a sufficient set of exceptional curves emerge that can explain the charged matter generation predicted from anomaly cancelation. We first apply one of the six Esole-Yau small resolutions to the multiply enhanced singularities, but it turns out that the proper transform of the threefold equation does not reflect changes in the singularity or how the generic codimension-two singularities gather there. We then use a(n) (apparently) different way of small resolutions than Esole-Yau to find that, except for the cases of $G'= E_6$ and special cases of $E_7$, either (1) the resolution only yields exceptional curves that are insufficient to cancel the anomaly, or (2) there arises a type of singularity that is neither a conifold nor a generalized conifold singularity. Finally, we revisit the Esole-Yau small resolution and show that the change of the way of small resolutions amounts to simply exchanging the proper transform and the constraint condition, and under this exchange the two ways of small resolutions are completely equivalent., Comment: 43 pages, 7 figures

Recent advances in deep learning have enabled the generation of realistic data by training generative models on large datasets of text, images, and audio. While these models have demonstrated exceptional performance in generating novel and plausible data, it remains an open question whether they can effectively accelerate scientific discovery through the data generation and drive significant advancements across various scientific fields. In particular, the discovery of new inorganic materials with promising properties poses a critical challenge, both scientifically and for industrial applications. However, unlike textual or image data, materials, or more specifically crystal structures, consist of multiple types of variables - including lattice vectors, atom positions, and atomic species. This complexity in data give rise to a variety of approaches for representing and generating such data. Consequently, the design choices of generative models for crystal structures remain an open question. In this study, we explore a new type of diffusion model for the generative inverse design of crystal structures, with a backbone based on a Transformer architecture. We demonstrate our models are superior to previous methods in their versatility for generating crystal structures with desired properties. Furthermore, our empirical results suggest that the optimal conditioning methods vary depending on the dataset.

We prove that two formulas of the orbital magnetic susceptibility, namely, Koshino-Ando's formula and G\'{o}mez-Santos and Stauber's formula, are equivalent for the tight-binding models. The difference between these two formulas can be written in a form containing the surface terms arising from the momentum-space integration, and we show that the surface terms are exactly vanishing although the primitive functions are seemingly non-periodic with respect to the translation by the reciprocal lattice vector., Comment: 2 pages

Nilpotent Lie groups with left-invariant metrics provide non-trivial examples of Ricci solitons. One typical example is given by the class of two-step nilpotent Lie algebras obtained from simple directed graphs. In this paper, however, we focus on the use of quivers to construct nilpotent Lie algebras. A quiver is a directed graph that allows loops and multiple arrows between two vertices. Utilizing the concept of paths within quivers, we introduce a method for constructing nilpotent Lie algebras from finite quivers without cycles. We prove that for all these Lie algebras, the corresponding simply-connected nilpotent Lie groups admit left-invariant Ricci solitons. The method we introduce constructs a broad family of Ricci soliton nilmanifolds with arbitrarily high degrees of nilpotency., Comment: 15pages, 9figures

Crystal Orbital Overlap Population (COOP) is one of the effective tools for chemical-bonding analysis, and thus it has been utilized in the materials development and characterization. In this study, we developed a code to perform the COOP-based chemical-bonding analysis based on the wavefunction obtained from a first principles all-electron calculation with numeric atom-centered orbitals. The chemical-bonding analysis using the developed code was demonstrated for F2 and Si. Furthermore, we applied the method to analyze the chemical-bonding changes associated with a Li intercalation in three representative layered materials: graphite, MoS2, and ZrNCl, because of their great industrial importance, particularly for the applications in battery and superconducting materials. The COOP analysis provided some insights for understanding the intercalation mechanism and the stability of the intercalated materials from a chemical-bonding viewpoint.

The L3 Collaboration reported data on 2-jet and 3-jet Bose--Einstein correlations (BECs) with the results obtained through the $\tau$-model in 2011. In this study, we analyze these correlations using the conventional formula with the Gaussian long-range correlation (${\rm CF_I\times LRC_{(Gauss)}}$). The estimated ranges of interactions for 2-jet and 3-jet, $R_{\rm 2-jet}$ and $R_{\rm 3-jet}$, are almost the same magnitude as those by $\tau$-model: $R_{\rm 2-jet}=0.83\pm 0.05$ (stat) fm and $R_{\rm 3-jet}=1.09\pm 0.04$ (stat) fm. The anticorrelation in BEC (less than 1.0) observed by the L3 Collaboration is related to the partially negative density profile ($\rho_{\rm \tau, BE}(\xi)$ in $\xi$ space) in the $\tau$-model and the ${\rm LRC_{(Gauss)}}=1/(1+\alpha e^{-\beta Q^2})$ in ${\rm CF_I\times LRC_{(Gauss)}}$, respectively. Remarkably, the probability $P_{\tau}(\xi)$ calculated from the Levy canonical form exhibits partially negative behavior.

A Model capable of handling various elemental species and substances is essential for discovering new materials in the vast phase and compound space. Message-passing neural networks (MPNNs) are promising as such models, in which various vector operations model the atomic interaction with its neighbors. However, conventional MPNNs tend to overlook the importance of physicochemical information for each node atom, relying solely on the geometric features of the material graph. We propose the new three-body MPNN architecture with a message-passing layer that utilizes optimized basis functions based on the electronic structure of the node elemental species. This enables conveying the message that includes physical information and better represents the interaction for each elemental species. Inspired by the LCAO (linear combination of atomic orbitals) method, a classical method for calculating the orbital interactions, the linear combination of atomic basis constructed based on the wave function of hydrogen-like atoms is used for the present message-passing. Our model achieved higher prediction accuracy with smaller parameters than the state-of-the-art models on the challenging crystalline dataset containing many elemental species, including heavy elements. Ablation studies have also shown that the proposed method is effective in improving accuracy. Our implementation is available online., Comment: 11 pages, 2 figures

To understand physical properties of the interstellar medium (ISM) on various scales, we investigate it at parsec resolution on the kiloparsec scale. Here, we report on the sub-kpc scale Gas Density Histogram (GDH) of the Milky Way. The GDH is a density probability distribution function (PDF) of the gas volume density. Using this method, we are free from an identification of individual molecular clouds and their spatial structures. We use survey data of $^{12}$CO and $^{13}$CO ($J$=1-0) emission in the Galactic plane ($l = 10^{\circ}$-$50^{\circ}$) obtained as a part of the FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45m telescope (FUGIN). We make a GDH for every channel map of $2^{\circ} \times 2^{\circ}$ area, including the blank sky component, and without setting cloud boundaries. This is a different approach from previous works for molecular clouds. The GDH fits well to a single or double log-normal distribution, which we name the low-density log-normal (L-LN) and high-density log-normal (H-LN) components, respectively. The multi-log-normal components suggest that the L-LN and H-LN components originate from two different stages of structure formation in the ISM. Moreover, we find that both the volume ratios of H-LN components to total ($f_{\mathrm{H}}$) and the width of the L-LN along the gas density axis ($\sigma_{\rm{L}}$) show coherent structure in the Galactic-plane longitude-velocity diagram. It is possible that these GDH parameters are related to strong galactic shocks and other weak shocks in the Milky Way.

Rydberg atoms in optical lattices and tweezers is now a well established platform for simulating quantum spin systems. However, the role of the atoms' spatial wavefunction has not been examined in detail experimentally. Here, we show a strong spin-motion coupling emerging from the large variation of the interaction potential over the wavefunction spread. We observe its clear signature on the ultrafast many-body nanosecond-dynamics of atoms excited to a Rydberg $S$ state, using picosecond pulses, from an unity-filling atomic Mott-insulator. We also propose a novel approach to tune arbitrarily the strength of the spin-motion coupling relative to the motional energy scale set by trapping potentials. Our work provides a new direction for exploring the dynamics of strongly-correlated quantum systems by adding the motional degree of freedom to the Rydberg simulation toolbox., Comment: v2: revised version accepted in PRL