Astrophysics of Galaxies
Tidal Tails of Galactic Open Clusters: A Review of Methods, Evidence, and Sources of Disagreement
Tahereh Ramezani, Johana Balciráková, Prapti Mondal et al. (+3 more)
Tidal tails are a natural consequence of the dynamical
evolution of open clusters in the
Galactic tidal field, but their observational identification is intrinsically difficult because their surface density is low and the
Galactic disc contains a dense and kinematically structured field population. This review paper provides a critical synthesis of the observational and theoretical status of
tidal tails of
Galactic open clusters and, in particular, assesses how membership definitions, data dimensionality, clustering
algorithms, and dynamical assumptions affect reported tail detections. We compare the principal approaches used with
Gaia data, including convergent-point and co-moving selection, density-based clustering, probabilistic membership models, machine-learning methods, and orbit/N-body-based filtering. We compile published measurements for a representative sample of nearby clusters and explicitly distinguish robust detections from candidate or method-dependent extended structures. The literature has progressed from detailed studies of a few nearby clusters to systematic searches involving tens to hundreds of systems. The Hyades remains a
benchmark because independent analyses recover coherent leading and trailing tails, but the extent and membership of the tails depend on the adopted selection. Large
Gaia DR3 studies demonstrate that extended populations are common among nearby and intermediate-age clusters, while also showing that some structures can be produced or exaggerated by projection, field contamination, or the assumptions built into the membership model. Recent homogeneous analyses report tails in most of the nearby clusters in selected samples, but the corresponding catalogues should not be interpreted as equivalent because their completeness, contamination, and physical definitions of a "tail member" differ.
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All authors Tahereh Ramezani, Johana Balciráková, Prapti Mondal, Katerina Neumannova, Ernst Paunzen, Gabriel Szasz
Mesoscale and Nanoscale Physics
Aharonov-Casher-induced electric quadrupole of charge-neutral particles
Hojun Lee, Youngjae Jeon, Suik Cheon et al. (+1 more)
For charged particles, their orbital angular momentum (OAM) in solid have a direct
magnetic manifestation as an orbital magnetization. For charge-neutral particles, however, the physical manifestation of the OAM in solid remains unclear. Here, we show that a charge-neutral particle carrying a
magnetic moment couples to electric-field gradient through the Aharonov-Casher (AC) effect, thereby exhibiting the electric quadrupole in crystalline solids. This AC-induced electric quadrupole (AC-EQ) contains the scalar, toroidal dipole, and reduced quadrupole components, which are conjugate to the divergence, circulation, and shear of the electric field, respectively. As representative examples, we calculate the AC-EQ of
magnons in two
magnetic systems. In
ferromagnetic pyrochlore, Dzyaloshinskii-Moriya interaction (DMI) induces a sizable AC-EQ, whereas in helical Fe langasite the AC-EQ emerges from the helical
spin configuration even in the absence of DMI.
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All authors Hojun Lee, Youngjae Jeon, Suik Cheon, Hyun-Woo Lee
High Energy Physics (Phenomenology)
Polarized observables in $\tau \to VV \nu_{\tau}$ decays
Vindhyawasini Prasad and Hiroyuki Umeeda
We study polarization observables in $\tau^- \to V_1^- V_2^0 \nu_\tau$ decays for $(V_1^-, V_2^0)=(\rho^-, \rho^0), (\rho^-, \omega), (K^{*-}, \rho^0), (K^{*-}, \omega), (\rho^-, \bar{K}^{*0})$ using the helicity formalism within the generalized hidden local
symmetry framework. The predicted branching fractions are comparable with those from the effective
chiral model, but smaller than those from the angular momentum
algebra model. Our results for the longitudinal polarization fractions $f_L$ indicate that nonnegligible corrections to the endpoint limit ($f_L = 1/3$), a consequence of Lorentz
symmetry, are present at the scale of tau mass. Future measurements of $f_L$ at Belle II for $\tau^- \to V_1^- V_2^0 \nu_\tau$ decays will provide crucial information on polarization patterns observed in nonleptonic charm decays.
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General Relativity and Quantum Cosmology
Solid-state gravitational-wave detectors at GHz frequencies: the search for the primordial stochastic GW background and light primordial black hole binaries
Juan Garcia-Bellido
Reheating after inflation is one of the strongest sources of gravitational waves (GW), producing a
stochastic background (SGWB) with a non-thermal spectrum peaked at frequencies of order a few GHz. Detecting it is difficult: experiments based on the inverse Gertsenshtein effect in intense
magnetic fields reach the MHz but not the GHz band, where the typical strain is around $10^{-30}$. The same window contains the coalescence of light
primordial black hole (PBH) binaries, whose merger frequency $f\simeq4.4\ \mathrm{kHz}\,(M_\odot/M)$ falls in the MHz–GHz range for planetary to sub-planetary masses; since such objects are necessarily sub-
solar, their detection would be strong evidence for PBHs as a component of the dark matter. We propose a solid-state detector at GHz frequencies that could integrate over months to years the GW continuously arriving from the Big Bang and search for light PBH binary coalescence. As a concrete realization we consider a modular array of $\sim10^3$ ultra-pure sapphire $(10\ \mathrm{cm})^3$ monocrystals forming a cubic-metre detector read out by cryogenic single-
phonon sensors, whose
segmentation provides thermal isolation, favourable counting statistics and coincidence-based background rejection. We also compare candidate materials, finding diamond superior per unit volume but limited by the unavailability of large single
crystals. Finally, we contrast the two targets. The stationary background is a shot-noise-limited counting problem, best served by a narrow, resonance-enhanced, long-integration search; the loud transient chirp of a nearby merger is better caught by a fast, broad-band search with coincidence tagging. Because the
phonon spectrum is continuous, a modular solid-state array can serve both, by staggering resonant
cells across the band while running a broad-band subset for chirp tracking.
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Earth and Planetary Astrophysics
GRACE-DG: A Discontinuous Galerkin Method-Based Code for General Nonlinear Coagulation-Fragmentation Equations
Jing Yang, Zhuo Chen and Xue-Ning Bai
Dust plays a crucial role in protoplanetary disks (PPDs)
evolution and
planet formation, influencing disk dynamics through gas-
dust coupling, regulating disk temperature by dominating continuum opacity, and altering disk ionization fraction by capturing free electrons. In this work, we develop a high-order discontinuous Galerkin (DG) method-based open-source code GRACE-DG to solve the collision-induced coagulation-fragmentation equations. In particular, we have derived a new conservative formulation for the non-linear fragmentation term, which enables the DG method to capture the mass transfer process. The new solver exhibits good convergence in coupled aggregation and breakage simulations, making it highly suitable for future integration into hydrodynamic codes.
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Astrophysics of Galaxies
Adaptive optics imaging of the nuclei of Seyfert 2 galaxies: An unexpectedly high incidence of nuclear stellar rings
Nina Mackensen, Jochen Heidt and Francisco Pozo Nuñez
High-resolution imaging of active
galactic nuclei (AGNs) on subkiloparsec scales is essential for investigating their fueling. Observations in the near-infrared (NIR) are especially valuable as they minimize the absorption by
dust. However, the inferred
nuclear morphology may depend on the method used to analyze the images. We assess whether ground-based adaptive-optics observations of the cores of Seyfert 2
galaxies in the Ks band provide advantages over HST observations at shorter wavelengths (V and H bands). We also investigate whether a dedicated 2D analysis is preferable to a 1D approach. A sample of 18 Seyfert 2
galaxies was observed with the adaptive optics (AO) system in the Ks band at the Large Binocular
Telescope (LBT) and compared to archival HST V- or H-band images. The analysis included a 2D modeling procedure via GALFIT as well as an unsharp masking technique. Results from different filters are consistent, showing no clear advantage of the redder filter. Using both GALFIT and unsharp masking in tandem is preferable, as the two methods provide complementary strengths. We identified
nuclear stellar rings in 8 of the 18
galaxies in our sample (44 +/- 12%). This fraction is significantly higher than reported in previous studies and about a factor of two higher than reported in the most complete atlas of
nuclear rings. The radii, size distribution, and inferred masses of the detected
nuclear rings are similar to those observed in non-active
galaxies. Low-luminosity AGNs appear to have little impact on
nuclear ring formation and
evolution. The high incidence of
nuclear stellar rings in our study is unexpected and warrants further investigation. This could be tested further using the large number of suitable archival HST images available. If confirmed, it would imply that
nuclear stellar rings are considerably more common than previously recognized.
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Soft Condensed Matter
Microscopic constitutive theory of stress overshoot, yielding, and strain hardening in amorphous materials
Ankit Singh, Valeriy V. Ginzburg and Alessio Zaccone
We develop a microscopic constitutive theory for the nonlinear deformation of metallic and
polymer glasses based on nonaffine elasticity coupled to irreversible many-body relaxation. The theory predicts the full stress–strain response, from linear elasticity through stress overshoot and yielding to steady plastic flow. We show that stress overshoot originates from the competition between a nonaffine elastic instability induced by strain-driven loss of mechanical connectivity at the atomic/molecular level, and viscous dissipation associated with structural relaxation. For
polymer glasses, finite chain extensibility naturally accounts for strain hardening at large deformation. The stretched-exponential relaxation exponent is obtained independently from stress or modulus relaxation measurements and provides the primary dynamical input to the theory. Using a small set of physically meaningful parameters, the model quantitatively reproduces experimental stress–strain curves for metallic glasses, polycarbonate, PMMA, and epoxy resins over a broad range of strain rates. These results establish a unified microscopic framework linking relaxation dynamics, yielding, plastic flow, and strain hardening in amorphous solids.
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Atomic Physics
Rate coefficients for dielectronic recombination of N-like Ne
E.-O. Hanu, M. Lestinsky, E. B. Menz et al. (+16 more)
Dielectronic recombination (DR) for the process Ne$^{3+}$ + e$^{-}$ $\rightarrow$ Ne$^{2+}$ was investigated in a merged-beams arrangement at the heavy-ion storage ring CRYRING@ESR. The energy-dependent DR rate coefficient, $\alpha(E)$ was measured over the electron-ion collision energy range from 0 to 25 eV. The measurements cover the complete set of DR resonance series associated with $2s\to2p$ core excitations. The primary ion beam is estimated to have consisted of $44\%$ of the ions in the ground state, with the remainder distributed among long-lived metastable levels. In addition to the measurements we carried out
quantum mechanical calculations of DR cross sections. The theoretical treatment includes contributions from the ground and excited metastable initial levels, weighted according to the estimated beam composition. From the experimental energy-resolved spectra, we derive a temperature dependent DR
plasma recombination rate coefficient $\alpha_\mathrm{exp}(T)$ (PRRC). In the temperature domain where Ne$^{3+}$ is abundant in collisionally ionized
plasmas, the present results show a good agreement with the present and with previous theoretical predictions. In the low-temperature regime characteristic for photoionized
plasmas, the experimentally derived DR
plasma rate coefficient is slightly larger than the published theoretical ones and does not agree within the experimental uncertainties. Parametrized fits of the experimentally derived DR PRRC are presented in order to facilitate an easy inclusion into astrophysical modelling codes.
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All authors E.-O. Hanu, M. Lestinsky, E. B. Menz, M. Looshorn, Z. Andelkovic, A. Biniskos, C. Brandau, A. Braeuning-Demian, M. R. Fogle, W. Geithner, F. Herfurth, P.-M. Hillenbrand, C. Krantz, R. Schuch, M. Tatsch, G. Vorobyev, S.-X. Wang, T. Stoehlker, S. Schippers
Instrumentation and Detectors
Characterisation of a Thick Pixelated Silicon Detector for Electron Spectroscopy of Neutron Beta Decay
Manuel Lebert, Lilli Löbell, Igor Konorov et al. (+1 more)
Silicon detectors are commonly used for spectroscopy of low-energy particles. For electrons in the 1 MeV range, a rather large thickness of 2mm is required to entirely stop the electrons and commercial options are scarce. With the instrument PERC at the FRM II, we aim to measure beta spectra from polarised and unpolarised
neutrons in order to determine the axial-vector coupling constant, the element $V_\textrm{ud}$ of the Cabibbo-Kobayashi-Maskawa
quark-mixing
matrix, and to search for hypothetical scalar and tensor contributions. We present the characterisation of a commercially available, pixelated detector to assess its suitability to measure the entire electron energy spectrum of free
neutron beta decay.
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All authors Manuel Lebert, Lilli Löbell, Igor Konorov, Bastian Märkisch
High Energy Physics (Theory)
An exact algorithm for U(N) matrix models in the gauge-invariant singlet sector
Enrico M. Brehm and Jean Cazalis
Matrix models appear as fundamental descriptions of M-theory and D-brane dynamics, and via the gauge/
gravity duality their gauge-invariant, or singlet, sector describes the purely gravitational degrees of freedom in the
holographic dual. We present a new exact
algorithm for computing observables of bosonic U(N)
matrix models in the gauge-invariant singlet sector. This sector is spanned by an orthogonal basis of Schur
polynomials (for a single
matrix) and restricted Schur
polynomials (for multiple
matrices), which diagonalizes the free
Hamiltonian and provides a natural truncation of the
Hilbert space by excitation number.
Matrix elements of the interaction
Hamiltonian, or any gauge-invariant observable, are evaluated through a group-theoretic reduction to cosets and double cosets of suitable subgroups of the symmetric group, together with character sums on the symmetric group. The resulting entries are closed-form
polynomials in the gauge-group rank N, assembled from group-theoretic data that are precomputed once and can be reused for any N and any coupling constants. We validate the one-
matrix implementation against the exact mapping to N non-interacting
fermions, demonstrating rapid convergence of the low-lying spectrum with the cutoff. The multi-
matrix extension is outlined; its main bottleneck is the computation of restricted characters of the symmetric group, for which no
algorithm comparable to the Murnaghan–Nakayama rule is currently known. The framework gives direct access to finite-N, finite-coupling dynamics of gauge-invariant states and opens a new computational window on the non-planar regime of
holographic matrix models.
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Quantum Physics
Towards quantum machine learning for assessing the resilience of post-quantum cryptography
Jarosław A. Miszczak
The potential capabilities of
quantum computers motivated the development of cryptographic protocols suitable for securing communication against adversaries with access to large fault-tolerant
quantum computers. However, even though current
quantum computers are limited in terms of size and precision, they can still be useful for finding loopholes and weaknesses in the post-
quantum cryptographic protocols. In this work, we present an attempt to utilize the capabilities of
Quantum Generative
Adversarial Networks (QGANs), one of the promising architectures used in
quantum machine learning, for this purpose. We describe an example application of QGAN architecture for the purpose of loading the probability distribution of the hash-based digital signatures into the
memory of a
quantum computer. Our results confirm that near-term hybrid
quantum-classical methods possess capabilities required for this purpose. The presented approach can be used as a first step in the workflow, enabling the utilization of
quantum computing for attacking post-
quantum cryptographic primitives.
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Astrophysics of Galaxies
The different methods to calculate cluster membership probabilities
Tahereh Ramezani, Prapti Mondal, Katerina Neumannova et al. (+3 more)
Reliable membership determination is a fundamental step in the study of
star clusters. With the advent of $Gaia$ astrometry, a wide range of statistical and machine-learning techniques has been developed to assign membership probabilities. However, the current situation of membership lists is very unsatisfactory. This review summarises the main methodologies, compares their strengths and limitations, and discusses future directions. The aim is to provide a comprehensive overview and to lead to a more efficient and reliable approach for the forthcoming $Gaia$ DR4. Basically, we know of spatial, classical kinematic, and photometric methods, as well as maximum likelihood and
Bayesian statistical methods, and machine learning and clustering
algorithms. These different methods come with many modifications and flavours. We assessed all the advantages and disadvantages of the known methods to determine cluster membership probabilities. Although nowadays most methods are based on poor statistical numerics, the more robust
algorithms should still be taken into account. It is important to apply and compare several methods. The next step must be to define a list of standard
star clusters to test and verify all known methods. The list must cover the complete grid of cluster parameters (age, distance, reddening, and
metallicity) and total masses.
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All authors Tahereh Ramezani, Prapti Mondal, Katerina Neumannova, Ernst Paunzen, Johana Supikova, Gabriel Szasz
Solar and Stellar Astrophysics
Multi-height Diagnosis of MHD Wave Periods and their Propagation in Solar Plages Using IRIS Observations
Gayathri Hegde and Pradeep Kayshap
This work aims to investigate magnetohydrodynamic (MHD) waves in
solar plages at five distinct heights, spanning from photosphere to the upper chromosphere, using spectroscopic observations provided by Interface Region Imaging Spectrograph (IRIS). The dominant period is found to not change within the plages, while, in pores, the dominant period decreases linearly from 4.20 to 3.20 minutes from the photosphere to the upper chromosphere. Furthermore, in the
solar plages, cross-wavelet analysis reveals that periods from 2.0 to 6.0 minutes propagate till the upper chromosphere from the photosphere. The periods beyond 6 minutes have a zero/constant phase difference in the photosphere and in the middle chromosphere. Thus, the 6.0-minute period would be considered the cutoff period at these heights. Next, the propagation speeds of MHD waves above
solar plages are estimated in the photosphere and chromosphere. Within the limit of uncertainties, the propagation speed in
solar plage is close to the sound speed; hence, the waves are slow magnetoacoustic in nature. Lastly, with the help of phase difference analysis, we found that formation heights of Mg ii k2r and Mg ii k3 are underestimated in
solar plage, while the formation height of Mn i is overestimated. In case of pores, the formation heights of Mg ii k2r, Mg ii k3, and Mn i are overestimated. Interestingly, in the quiet-Sun (QS), the formation heights of Mn i and Fe i are nearly the same, and also the formation height of Mg ii k3 is similar to the formation height of Mg ii k2r. In conclusion, some important findings are reported in this work, namely, (1) dominant periods at five different heights between the photosphere and chromosphere, (2) estimation of cutoff periods in the photosphere, middle chromosphere, and the upper chromosphere in the plages, and (3) variations in the formation heights of these spectral lines in pore, plage, and QS.
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Quantum Physics
Machine learning development for quantum computing and neutrino physics
Annalisa De Lorenzis
This thesis investigates the application of machine-learning methods in the context of
quantum computing and
neutrino physics, with particular emphasis on the construction of effective representations for complex, high-dimensional data. The first part of the work is devoted to
Quantum Extreme Learning Machines (QELMs), a hybrid
quantum–classical framework in which classical data are encoded into
quantum states and processed through fixed
quantum dynamics, while learning is performed by a classical readout layer. Within this framework, we analyze the role of encoding strategies, feature-reduction methods,
Hamiltonian structure, and measurement, with particular focus on the relationship between
quantum dynamics, expressivity,
entanglement, and classical simulability. The second part of the thesis concerns the application of deep learning to the analysis of images produced by water Cherenkov detectors in
neutrino physics. Convolutional architectures, including residual networks, are developed for the classification of complex events in realistic simulated
datasets, showing that such models can effectively extract relevant information from detector data. Taken together, these results highlight the potential of machine learning, in both its classical and
quantum forms, as a powerful framework for the analysis of complex data in fundamental physics, while also outlining relevant challenges and directions for future research.
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Physics and Society · Cross-listed from cs.MA
Social Simulations: from Agent-Based Modeling to Digital Twins
Erica Cau, Andrea Failla, Valentina Pansanella et al. (+1 more)
This book chapter covers the
evolution of social simulation from classical
agent-based models, in which
agents interact according to explicitly defined behavioral rules, to AI-enhanced simulations based on Large
Language Models and, ultimately, Social Digital Twins: high-fidelity, data-driven representations of real-world socio-technical systems. Along this trajectory, we discuss the main methodological foundations, applications, advantages, and limitations of each paradigm, highlighting the progressive shift from abstract models designed to investigate general social mechanisms toward increasingly realistic computational representations of specific social systems.
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All authors Erica Cau, Andrea Failla, Valentina Pansanella, Giulio Rossetti
Fluid Dynamics
Drawing with water waves
Taiga Kanehira, James Steer, Laura-Beth Jordan et al. (+4 more)
The deterministic reproduction of complex 3D wave fields remains a significant challenge in ocean engineering. This study proposes a novel methodology for drawing arbitrary 2D curves and 3D volumetric shapes on a water surface using transient multi-directional focused waves. To overcome the limitations of conventional discrete-point focusing methods, our framework integrates Bézier curve parametrisation, equal arc-length sampling, and an Iterative Amplitude Correction (IAC)
algorithm. This effectively mitigates wave height overshoot and enables precise spatial superposition of spectral components. The method's effectiveness was validated through linear wave theory and Smoothed Particle Hydrodynamics (SPH) simulations, successfully reproducing 2D characters and a 3D human face. Physical experiments in the FloWave circular wave basin further demonstrated target shape generation, such as a 2D
star and 3D pyramid. Although further integration of nonlinear wave theories is necessary for high-amplitude accuracy, this technique establishes a deterministic methodology for creating arbitrary 2D and 3D surface geometries. It represents a significant advantage in wave field control for ocean engineering applications.
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All authors Taiga Kanehira, James Steer, Laura-Beth Jordan, Shaun Fraser, Thomas Davey, Hidemi Mutsuda, Samuel Draycott
Nuclear Experiment
Nuclear Charge Radius of $^9$Be from Muonic Atom Spectroscopy Using a Microcalorimeter
Ofir Eizenberg, Shikha Rathi, Andreas Abeln et al. (+34 more)
The $2p\to1s$ transition energy in muonic $^9$Be was measured using a metallic
magnetic calorimeter, resulting in $E_{2p\to 1s}=33\,391.48(34)\,$eV. The result is 30 times more precise than the previous best measurement and enables the extraction of the corresponding
nuclear charge radius $r_c($$^9$Be$)=2.5506(51)\,$fm. It is $2.4$ times more precise than the commonly used value based on electron scattering and differs from it by $2.3$ times the combined uncertainties. This measurement represents the first determination of a
nuclear charge radius using muonic x-ray spectroscopy with microcalorimeters.
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All authors Ofir Eizenberg, Shikha Rathi, Andreas Abeln, Sonia Bacca, Gonçalo Baptista, Nir Barnea, Noam Burger, Thomas Elias Cocolios, Marie Deseyn, Tim Egert, Christian Enss, Andreas Fleischmann, Loredana Gastaldo, César Godinho, Nitzan Goldberg, Michael Heines, Daniel Hengstler, Paul Indelicato, Weiguang Jiang, Klaus Kirch, Andreas Knecht, Daniel Kreuzberger, Jorge Machado, Ulf-G. Meißner, Ben Ohayon, Nancy Paul, Randolf Pohl, Tim Redelbach, Michael Roosa, Katharina von Schoeler, Quentin Senetaire, Shihang Shen, Daniel Unger, Stergiani Marina Vogiatzi, Johanna Walch, Frederik Wauters, Aziza Zendour
Materials Science · Cross-listed from cs.LG
Microstructure-Conditioned Surrogate Models for Graded Multiscale Optimization of Mycelium Composites
J. Storm, I.B.C.M. Rocha, S. Schyck et al. (+2 more)
Emerging sustainable materials increasingly rely on engineered hierarchy and microstructure to achieve control of their properties and mechanical behavior. Optimizing these materials with controllable microstructures requires efficient multiscale simulations. Data-driven surrogate models for the microscale can accelerate multiscale simulations, but require large amounts of data even for a fixed microstructure. When a range of microstructures is considered, as is the case in multiscale optimization, even more data is needed to train a surrogate. To overcome this challenge, we condition a hybrid physics-data surrogate on microstructural variables using a hypernetwork. This approach enables accurate predictions of multiscale mechanical behavior for a mycelium-woodchip composite material, even when trained on small
datasets. The conditioned surrogate makes multiscale simulations of functionally graded structures tractable, and we validate it against a full FE^2 simulation. We optimize a graded multiscale disk, and reduce the peak stress by 43% compared to one with a random microstructure. Then, we go one step further, conditioning the network directly on manufacturing variables that can have a complex influence on the microstructure. This is a practical route to engineer the microscale for desired macroscale behavior. This contribution highlights the benefits of microarchitectured structures and demonstrates how conditioned surrogate models enable their multiscale optimization, which will accelerate the development and design of future sustainable materials and structures.
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All authors J. Storm, I.B.C.M. Rocha, S. Schyck, K. Masania, F.P. van der Meer
High Energy Astrophysical Phenomena
Towards a joint X-ray and gamma-ray analysis of Pulsar Wind Nebulae with Gammapy
Katharina Egg and Alison M. W. Mitchell
For detailed studies of
Pulsar Wind Nebulae (PWNe), objects that show
photon emission across the entire electromagnetic spectrum, multiwavelength analyses are crucial. The comparison of especially X-ray and gamma-ray emission and their angular sizes can help us to constrain the properties of PWNe, such as their particle transport mechanism or their potential for the acceleration of hadronic particles. In this vein, we are working towards a joint analysis of eROSITA X-ray data and H.E.S.S. gamma-ray data. To enable this, eROSITA data is adapted into the framework of Gammapy, a Python package for gamma-ray analysis through a multi-step process of adapting the formats of not only the
photon event list, but also all X-ray response functions, into open data formats compatible with Gammapy. This is accomplished using newly developed Python converter functions. In this contribution we present the first eROSITA maps of the PWN MSH 15-52 in Gammapy, compared to the associated H.E.S.S. emission.
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Strongly Correlated Electrons
Magnetic quadrupole current generation and accumulation in noncentrosymmetric systems
Yuuga Takasu and Satoru Hayami
Magnetization control via
magnetic octupole injection has recently been proposed for a new class of centrosymmetric antiferromagnets, namely $d$-wave altermagnets, where the
magnetic octupole is the lowest-rank
magnetic multipole allowed by
symmetry and serves as an alternative carrier to
spin injection. In contrast, in noncentrosymmetric antiferromagnets, the
magnetic quadrupole (MQ) constitutes the lowest-rank
symmetry-allowed
magnetic multipole, suggesting that MQ currents can provide an efficient route toward magnetization control through MQ injection. Here, we establish the
symmetry conditions for MQ-current generation by constructing the multipole representation of the MQ conductivity tensor and show that MQ currents are generically allowed in noncentrosymmetric crystallographic point groups. As a representative example, we demonstrate MQ-current generation in the linear-response regime associated with
symmetry lowering from the centrosymmetric point group ($mmm$) to its noncentrosymmetric subgroup ($mm2$). Furthermore, we reveal MQ accumulation near sample edges, analogous to
spin accumulation induced by the
spin Hall effect. This edge accumulation provides direct evidence of MQ-current generation and constitutes a key prerequisite for realizing MQ injection and MQ-based magnetization control in noncentrosymmetric antiferromagnets.
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Strongly Correlated Electrons
Stoner transitions beyond mean-field in two-dimensional electronic systems: a diagrammatic Monte Carlo study
Yueh-Chen Lee, Nikolay V. Prokof'ev and Andrey V. Chubukov
Stoner instabilities for
fermions with repulsive interaction have been well studied within the mean-field (ladder) approximation. In this study, we consider two-dimensional electronic systems with one or two valleys and discuss a Stoner transition beyond the ladder approximation. At weak coupling, the corrections to the ladder approximation come predominantly from the renormalization of the particle-hole vertex in the particle-particle channel, and the lowest-order corrections are logarithmically singular in the low-density limit. To investigate the problem beyond the lowest order, we apply the diagrammatic Monte Carlo
algorithm and treat ladder and non-ladder renormalizations on equal footing. We find that in a one-valley system, a Stoner transition to a ferromagnetism occurs at low density only if there is a cutoff on the momentum transfer carried by the interaction. In a two-valley system, the restriction is less severe. Here we find either a direct Stoner transition into a
spin- and valley-polarized state, or a set of two Stoner transitions via an intermediate valley-polarized state. The pathway is controlled by the anisotropy of the fermionic dispersion.
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High Energy Physics (Theory)
Deriving the $\text{AdS}_3\times\text{S}^3\times \text{T}^4$ Quantum Spectral Curve I: Y-system and discontinuity relations
Andrea Cavaglià, Davide Polvara, Nicolò Primi et al. (+2 more)
The mirror Thermodynamic Bethe Ansatz (TBA) describes the spectrum of $\text{AdS}_3\times\text{S}^3\times \text{T}^4$ superstrings supported by a mixture of Ramond-Ramond (RR) and Neveu-Schwarz-Neveu-Schwarz (NSNS) flux. In recent years, a
conjecture was put forward regarding the
Quantum Spectral Curve (QSC) formulation in the Ramond-Ramond case. In this paper, we initiate the derivation of the Ramond-Ramond QSC from the mirror TBA equations. We describe the Y-system underlying the TBA and its discontinuity relations for pure-RR backgrounds. This provides the foundation for the derivation of the T-system and the
Quantum Spectral Curve, which will be presented in a follow-up paper.
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All authors Andrea Cavaglià, Davide Polvara, Nicolò Primi, Alessandro Sfondrini, Roberto Tateo
Plasma Physics
Dual-pulse micronozzle acceleration of sub-GeV-class protons
D. Pan and M. Murakami
We propose a dual-pulse micronozzle acceleration scheme that enables phase-locked acceleration of
laser-driven
protons, mitigating the trade-off between maximum
proton energy and
laser-to-
proton conversion efficiency. A delay-tuned synchronization window injects a compact
proton front generated by a shaping prepulse into a quasistatic axial electric field driven by a delayed main pulse in a micronozzle cavity. Phase locking preserves the relative phase between the
proton bunch and the accelerating field, suppresses thermal debunching, and prolongs the acceleration stage. At main-pulse intensities of order 10^21 W/cm^2, sub-GeV
proton cutoff energies are obtained with a total
laser-to-
proton conversion efficiency of about 20%. The efficiency for
protons above 100 MeV exceeds about 13%, indicating preferential energy loading into a compact
proton population. Simulations with an unconfined dual-pulse hydrogen rod show that the improvement results from temporal synchronization and
geometric confinement, which sustain a long-lived axial accelerating channel. An analytical synchronization model agrees with the simulations. Three-dimensional particle-in-
cell simulations confirm that phase locking and spectral hardening are preserved in slit-nozzle geometries, with cutoff energies about 60% higher than those of an unconfined hydrogen rod. These results establish phase-locked acceleration as a practical design principle for compact, high-yield sub-GeV
proton drivers for secondary-particle applications.
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Instrumentation and Methods for Astrophysics
Proof of concept of heterodyne interferometry at 10.6 um using photonic correlation
Tituan Allain, Jean-Philippe Berger, Guillaume Bourdarot et al. (+2 more)
The task of imaging complex
dust environments such as the inner astronomical units of a
planet-forming disks requires dedicated mid-infrared (MIR) interferometric facilities with kilometric baselines and a large number of
telescopes. Extrapolating technologies from current facilities is not straightforward. We aim to demonstrate the feasibility of using MIR heterodyne interferometry with a photonic correlation approach to recombine MIR signals from distant
telescopes. We want to determine the current technological limits of such systems are. We developed a laboratory demonstration bench that can correlate MIR signals at 10 um with a photonic correlator. The photonic correlator uses commercially available telecom components at 1.5 um to transport and correlate heterodyne signals that could go up to 10 GHz in bandwidth, directly extendable to 40 GHz. We used the demonstration bench to study the noise levels and detection limits of a heterodyne interferometer with a photonic correlation. We confirm the correlation exhibited by wideband MIR signals with the photonic correlator, along with a characterization of the performance of the system and analyzed the noise levels. We show that the photonic correlator does not limit the detection and that it can be used to compensate for free-space delays at 10 um with a fiber delay at 1.5 um. With our current sub-optimal commercial infrared (IR) detectors, we have derived a detection limit of 130 Jy that is coherent flux for 8 m class
telescopes with 1 h of incoherent integration. We discuss the possibility of lowering the detection limit down to typical T-Tauri
stars (approximately 1 Jy) using new detectors and coherent integration based upon local oscillator synchronization with telecom fiber links.
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All authors Tituan Allain, Jean-Philippe Berger, Guillaume Bourdarot, Carlo Sirtori, Hugues Guillet De Chatellus
High Energy Physics (Theory)
A de Sitter Anti-Scrambling Algebra
Wentao Cui and David K. Kolchmeyer
We study the
algebra of observables of a semiclassical observer in de Sitter space. When operators are time-evolved by a scrambling time, out-of-time-ordered correlation functions (OTOCs) receive corrections due to shockwave scattering near the cosmological horizon. When the observer's clock is treated classically, we show that the time advance effect implies the breakdown of the KMS condition for
vacuum correlators of matter operators. When the observer's clock is quantized, this implies that the Hartle-Hawking state is not a trace on the resulting crossed-product
algebra. We
conjecture that the observer's
algebra has a trivial commutant. When the time separation between operators exceeds the scrambling time, the OTOC decays to zero and a free product
algebra emerges. We illustrate this using classical solutions of de Sitter JT
gravity with shocks. We comment on how our results pose a challenge for observer-centric static patch holography.
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Superconductivity
Direct observation of photon-induced vortices in superconducting films
Takeshi Jodoi, Fuminori Hirayama, Tetsuya Tsuruta et al. (+2 more)
Nucleation of
vortex-antivortex pairs (VAPs) is believed to play a central role in the
photon detection mechanism of superconducting detectors; however, their direct dynamic observation has remained challenging. Here, we report the direct observation of
photon-induced VAP dynamics in a current-carrying
superconductor as quantized voltage signals following
photon absorption. The observed signals are interpreted as discrete phase-slip events, where each
vortex traversal induces a 2-pi phase change of the superconducting order parameter, resulting in a quantized voltage pulse whose time integral is given by the
magnetic flux
quantum. We analyze the resulting quantized signals as a function of bias current, base temperature, and input
photon-number states, and find that the number of VAPs generated per absorbed
photon becomes effectively stabilized under specific conditions. Under these conditions, we demonstrate
photon-number-resolving capability by directly counting phase-slip-induced voltage quanta. Our results reveal a detection mechanism governed by phase dynamics rather than conventional resistive transitions. We further show that
photon-number resolution emerges when the fluctuation of
photon-induced
vortex-antivortex pair generation becomes statistically suppressed. These findings establish a new route toward
photon-number-resolving detection based on phase-slip counting and open opportunities for high-speed superconducting detectors for
quantum optics and photonic
quantum technologies.
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All authors Takeshi Jodoi, Fuminori Hirayama, Tetsuya Tsuruta, Takahiro Kikuchi, Daiji Fukuda
Materials Science
Role of small-radius and high-electronegativity A-Site dopants in enhancing proton transport and stability of perovskite electrolytes
Hang Ma, Ying Liang and Tianxing Ma
The practical application of BaCeO$_3$-based electrolytes is limited by their poor chemical stability in
proton-conducting solid
oxide fuel
cells. Commonly employed B-site doping strategies typically improve
proton transport with limited improvement in stability. Recent experiments show that A-site Ca doping can simultaneously enhance both properties. Here, through first-principles calculations and mechanistic analysis of Ca-doped BaCeO$_3$, we identify the synergistic roles of small-radius, high-electronegativity A-site dopants in governing
proton transport and chemical stability in perovskite electrolytes. We show that the higher electronegativity of A-site dopant weakens the A-O ionic bonding, facilitating oxygen-vacancy formation and enhancing
proton uptake by increasing the basicity. This weakened A-O interaction also suppresses the formation of
impurity phases and reduces the adsorption strength of acidic gases such as CO$_2$ and SO$_2$. The
lattice contraction induced by the smaller ionic radius improves thermal stability and can enhance
proton diffusion in systems where
proton transfer is the rate-limiting step. Furthermore, we find that Ca surface segregation can mitigate grain-boundary resistance effects. Our results demonstrate the advantages of A-site Ca doping in Ba-based electrolytes, clarify the mechanisms by which small-radius, high-electronegativity dopants influence
proton transport and chemical stability, and provide guidance for the design of high-performance
proton-conducting electrolytes.
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Physics and Society
Calming traffic in unsignalized bidirectional streets by introducing one-lane bottlenecks
Victor L. Knoop and Carlos F. Daganzo
A common strategy to calm traffic in an unsignalized, bidirectional street consists in narrowing the street to a single lane at one or more locations. These locations become bottlenecks. Two policies are commonly used there: first-in-first-out (FIFO), and directional priority (DP), which means one of the directions has priority. This paper examines the performance of these two policies on streets with one or more bottlenecks. Two measures of performance are considered: the expected delay (evaluated for typical situations with low demand) and the system capacity. The latter is defined as the pair of flows (d1, d2) that depart the street in the two opposite directions when the system is oversaturated with queues. For a street with a single bottleneck, the capacity under both FIFO and DP is not unique: In both cases, the values of (d1, d2) form a continuous decreasing curve. As expected, we find that arrival flow pairs (a1, a2) below this curve can get through the system without generating queues. Those above cannot. For a single bottleneck it is shown that FIFO yields lower expected delay than DP under low demand. For high demand, DP's capacity exceeds FIFO's when the flows are balanced, but are lower otherwise. For multiple bottlenecks, the expected total delay on the street under low demand is that of a single bottleneck multiplied by the number of bottlenecks. The multi-bottleneck capacity under FIFO turns out to be the same as for a single bottleneck. For DP, traffic near capacity is complex. Capacity points turn out to be numerous and disjointed. Formulas are derived for their values. Higher capacities are typically obtained for longer streets. Curiously, these capacity points are often above the capacity curve of a street with a single FIFO or DP bottleneck, indicating that an extra bottleneck can increase capacity.
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Quantum Physics
Effects of coherent and incoherent measurement imperfections on multipartite quantum nonlocality and quantum key distribution
Qiong Wang, Wen-Long Qiao, Qing Chen et al. (+1 more)
Multipartite Bell nonlocality is a central resource for device-independent
quantum information protocols, but its practical certification is inevitably affected by imperfect measurements. We analyze how coherent angular misalignment and incoherent outcome flipping affect Bell-value degradation and nonlocality thresholds in $n$-partite GHZ states based on the Mermin, Svetlichny, and Mermin–Ardehali–Belinskii–Klyshko (MABK) inequalities. Coherent misalignment produces periodic angular violation windows whose individual widths shrink with the number of parties. In contrast, incoherent outcome flipping yields a single critical outcome-flipping probability, which increases with $n$ for MABK and the odd-$n$ Mermin inequalities, but decreases with $n$ for the Svetlichny inequality. Connecting the degraded Bell values to asymptotic Devetak–Winter key-rate bounds under a convex-combination attack model shows that secret-key generation imposes stricter constraints on measurement imperfections than nonlocality certification. These results provide quantitative
benchmarks for robust multipartite nonlocality certification and key-rate estimation under measurement imperfections.
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All authors Qiong Wang, Wen-Long Qiao, Qing Chen, Liu-Jun Wang
Quantum Physics
The potential of quantum computers for Particle Image Velocimetry
Philipp Pfeffer, Theo Käufer, Julia Ingelmann et al. (+2 more)
Particle Image Velocimetry (PIV) is the
prime image-processing technique to measure and visualize velocity fields of laminar and turbulent flows. The velocity field vectors are obtained with sub-pixelaccuracy by analyzing cross-correlations, empowered by Fast
Fourier Transforms (FFT). Here, we present a
quantum algorithm with multidimensional
quantum Fourier Transforms, termed
Quantum-based PIV (QuPIV), to replace the classical computation of up to millions of velocity vectors. Our end-to-end
quantum algorithm includes a novel state preparation, modified amplitude amplification, and the output extraction. We enhance amplitude amplification by a contracted ground-state projector, which allows a significant reduction of the number of gates in the
quantum circuit. We justify the end-to-end capability with numerical studies on all stages of the
algorithm on both synthetic and experimental data.
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All authors Philipp Pfeffer, Theo Käufer, Julia Ingelmann, Christian Cierpka, Jörg Schumacher