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Wednesday 23 September

Strongly Correlated Electrons · Cross-listed from math.NA

Computation of anisotropic singular sums from high-order derivatives of Epstein zeta functions

Andreas A. Buchheit and Jonathan K. Busse

The precise and efficient evaluation of large-scale lattice sums involving power-law kernels is a fundamental computational problem in the simulation of classical and quantum systems with long-range interactions. While methods for spatially isotropic kernels, some based on Epstein zeta functions, have advanced considerably in recent years, the anisotropic case has lagged behind, despite its broad relevance to both fundamental and effective interactions such as the dipole interaction in magnetic materials. In this work, we solve this issue by defining and analyzing anisotropic Epstein zeta functions for which we derive stably computable representations obtained from wave vector derivatives of lattice sums over isotropic interaction kernels. These functions find direct application in the analytical and numerical study of anisotropically interacting lattice systems. Going further, they provide the correction term in an exact equivalence between discrete lattices and their continuous analogs in a recent generalization of the classical Euler-Maclaurin summation formula to lattices and summands involving power-law kernels. Their connection to high-order derivatives of zeta functions can be used to improve convergence rates of numerical algorithms, for instance in micromagnetics, or to provide rapidly convergent expansions suitable for precomputations of generalized zeta functions. We derive a stably computable representation of anisotropic Epstein zeta functions, including the possibility for analytically removing Rayleigh–Wood singularities, and we develop a numerical algorithm for their stable evaluation for any lattice, power-law decay exponent and anisotropy order. We benchmark the algorithm against closed-form identities, direct summation and multi-precision results, obtaining machine precision across various lattices, power-law exponents, and anisotropy orders.
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High Energy Physics (Theory) · Cross-listed from math.DG

Cohomogeneity one solutions of the IIB system

Lorenzo Foscolo and Mario Garcia-Fernandez

The IIB system is a system of PDEs for an SU(3)–structure and a positive function on a 6-manifold. Its solutions describe conformally balanced pluriclosed Hemitian metrics on complex 3-folds with holomorphically trivial canonical line bundle. In particular, solutions of the IIB system are steady solitons for the generalized Ricci-flow and Bismut–Hermitian–Einstein metrics. In this paper we study cohomogeneity one solutions of the IIB system. We construct 1-parameter families (up to scaling symmetries) of complete non-compact non-Kähler solutions on the smoothing of the conifold with controlled geometry at infinity. The generic member of the family is asymptotically conical with tangent cone at infinity the Calabi–Yau cone metric on the conifold. As a limit of the family we recover an explicit solutions known in the physics literature as the Chamseddine–Volkov/Maldacena–Nuñez solution, which has an exotic asymptotic geometry. We show that there are no complete cohomogeneity one solutions on crepant resolutions of the conifold (or its quotient), but we also establish the existence of an analogous 1-parameter family of forward complete solutions defined on exterior domains of the conifold with prescribed incomplete behaviour along the interior boundary and similar asymptotic behaviour at infinity. As a byproduct of these existence results, we produce infinitely many complete non-compact non-Kähler Bismut–Hermitian–Einstein metrics in complex dimension 3 with full holonomy of the Bismut connection, in contrast to the holonomy reduction forced upon compact examples. We also find infinitely many such complete non-compact full-holonomy non-Kähler examples (with at least two ends) in complex dimension 2 by revisiting a construction due to Callan–Harvey–Strominger in the physics literature.
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Soft Condensed Matter · Cross-listed from math.AP

The Naito–Okuda–Ouyang Biconcave Red Blood Cell Profile as a Finite-Energy Unbranched Weak Immersion with Point-Force Residues

Hao Wu

The axisymmetric profile \(\sin\psi(\rho)=c_0\rho\log(\rho/\rho_B)\) introduced by Naito, Okuda, and Ouyang is an exact solution of the unconstrained Helfrich shape equation for every \(\rho>0\), but its mean curvature diverges logarithmically at the dimple center. A covariant local analysis shows that in Cartesian graph coordinates the immersion is nondegenerate and belongs to \(W^{2,p}\) for every finite \(p\); it is \(C^{1,\alpha}\) for every \(\alpha<1\), but neither \(C^{1,1}\) nor \(C^2\). The conformal factor has a finite nonzero limit, so the point has branch multiplicity one and is not a branch point in the sense used in weak-immersion compactness theory. The Helfrich energy is finite, whereas the complete Euler–Lagrange operator carries the distributional residue \(\E_{\CH}=4\pi c_0\delta_p\) under the convention specified below. Hence the profile is a classical solution on the punctured surface and a finite-energy weak immersion, but it is not a free weak critical point of the unforced Canham–Helfrich functional. Stationarity is restored after adding the corresponding point-force potential or under a pinned-point constraint. Area and volume multipliers cannot cancel the Dirac residue. The apparent sign discrepancy between the shape equation used in the original papers and the modern convention is explained by the opposite definition of mean curvature. These results delimit precisely what can and cannot be inferred from modern existence and regularity theorems for Canham–Helfrich minimizers.
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High Energy Astrophysical Phenomena

Study of blazar variability through their flux distribution for CTAO long-term monitoring

A. Mikhno, J. Biteau and J.-P. Lenain on behalf of the CTAO collaboration

The CTAO Key Science Project on Active Galactic Nuclei (AGN) includes a long-term monitoring (LTM) program of blazars. The probability distribution function (PDF) of the flux extracted from unbiased blazar lightcurves can provide important insight into the physical processes taking place in relativistic jets and their connection to observed variability. The aim of this work is to define an optimal observational strategy for the CTAO LTM program using the flux distributions as a quantitative metric. To achieve this goal, we develop a simulation-based analysis framework that enables a systematic comparison of different observational strategies. Light curves were simulated as would be observed with the future CTAO for a representative set of AGN sources, following four different observational strategies within a fixed time budget. For each simulated light curve, different PDF models were fitted and their goodness of fit was evaluated. Based on the best-fit parameters, Monte Carlo simulations were generated to assess the ability of the method to recover the underlying PDF model. Since the true model used to generate the simulated light curves is known, this procedure allows us to quantify the discriminatory power of the algorithm and to identify which observational strategy maximizes model discrimination. Additionally, the algorithm has the potential of discrimination against different models for the flux distributions, such as Gaussian and lognormal. Once validated on simulations, the method is applied to archival lightcurves from existing gamma-ray instruments to extract flux PDFs and study the physical processes driving blazar variability. The analysis framework has been developed and tested on simulated CTAO-like data, showing good stability and robustness. A study to optimize the observing strategy for the CTAO LTM is presented.
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Quantum Physics

Broadband and Large-Multimode Quantum Optical Storage with Rare-Earth Ions in Solids

Yisheng Lei, Senthil Kumar Kuppusamy, Idris Tlemsani et al. (+6 more)

Broadband quantum memory devices are essential elements for future quantum networks. Here we propose a broadband quantum memory scheme called Hole Anti-hole Grating Echo Memory (HAGEM) for rare-earth ions in solids, which can be implemented with most of the present rare-earth ions hosted in various types of solids. Using HAGEM, a quantum memory device with one billion temporal modes per second can be developed with current available technologies. To validate the memory protocol, we conducted some proof-of-concept experiments. We provide a Eu$^\text{{3+}}$ molecular complex with special hyperfine level structures of which the hyperfine level separations are in a specific mathematical correlation that can be obtained by harnessing chemical engineering. Using the proposed memory protocol and material, we experimentally demonstrate a single-mode quantum optical storage efficiency of 14.9% and a memory bandwidth of 200MHz, which can easily be extended to a few GHz. In addition, a multi-mode storage of four temporal modes is achieved with a storage efficiency of 1.3%. Broadband & large-multimode quantum memory device with a long storage time enabled by HAGEM integrating with the current available entangled photon pair source and tunable delay lines, a quantum repeater network with an entanglement distribution rate on the order of 1kHz - 10kHz can be created with a communication distance around 100km. This will greatly facilitate the development of quantum networks in near future.
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All authors Yisheng Lei, Senthil Kumar Kuppusamy, Idris Tlemsani, Suma Al-Hunaishi, Pengrui Jiao, Olaf Fuhr, Mario Ruben, Philippe Goldner, Diana Serrano

Materials Science

Three-photon photoemission on metallic transition metal dichalcogenide NiTe$_{2}$

Cheng-Tien Chiang, Mukesh Singh, Yu-Jhen Chuang et al. (+6 more)

Three-photon photoemission (3PPE) signals on NiTe$_{2}$ are observed for the first time upon ultraviolet excitations. In the energy range beyond two-photon excitations, an energy-momentum dispersive feature is clearly identified with characteristic light polarization dependence. Based on its dispersion, spectral width, as well as intensity as a function of the parallel momentum, this dispersive 3PPE feature could be ascribed to an image potential resonance overlapping with an unoccupied Ni $4s$ -Te $4d$/$5p$ bulk band in accordance with the electronic band structure. Our results underlie higher-order non-linear photoemission on metallic transition metal dichalcogenides and facilitate future ultrafast studies of coherent electron dynamics in anisotropic, two-dimensional systems.
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All authors Cheng-Tien Chiang, Mukesh Singh, Yu-Jhen Chuang, Chia-Nung Kuo, Prabesh Bista, Yu-Chan Lin, Chen-Bin Huang, Ming-Chiang Chung, Chin Shan Lue

Optics

Physical Fidelity of Wave-Based Inverse Problems under Broken Time-Reversal Symmetry

Haiyan Ou, Jiajia Duan, Edmund Y. Lam et al. (+1 more)

Modern coherent imaging commonly treats defocus interference as an undesirable artifact to be suppressed. Here, we show that this interference is instead a deterministic projection shadow associated with broken time-reversal symmetry (TRS) under finite-aperture observation. The resulting non-unitary observation operator imposes irretrievable information loss, making this shadow an unavoidable coherent residual. We demonstrate that suppressing this residual beyond the measurement support can yield physically inconsistent reconstructions by assigning unconstrained components within the null space, thereby disrupting the propagation of the reconstructed complex field. We term this failure mode physical overfitting and introduce the complex-field TRS residual metric, R_TRS(z). By using the measured axial evolution of the projection shadow as a z-resolved physical reference, the metric extends fidelity assessment from two-dimensional (2D) detector-plane agreement to propagation-resolved three-dimensional (3D) complex-field consistency. These results establish a physical constraint on phase-space retrieval and wave-based inverse reconstruction.
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All authors Haiyan Ou, Jiajia Duan, Edmund Y. Lam, Bingzhong Wang

Medical Physics

GenMC: Real-Time Generative Monte Carlo Surrogate for Quantitative Photoacoustic Imaging

Mengjie Shi, Feng He, Tom Vercauteren et al. (+1 more)

Photoacoustic (PA) imaging provides molecular and functional information about tissue, such as blood oxygen saturation (sO2), yet its clinical translation is hindered by inaccurate quantification. A major source of error is the spectral colouring effect, in which wavelength-dependent optical attenuation distorts the local optical fluence. Monte Carlo (MC) simulation is the gold standard for modelling light transport, but its computational demand precludes real-time use. Here, GenMC is presented, a deep generative framework based on a conditional generative adversarial network that estimates optical fluence distributions from tissue anatomy and literature-derived optical properties, with anatomical priors obtained from co-registered ultrasound images. Trained on MC-generated synthetic datasets, GenMC produces high-fidelity fluence maps in under 30 ms per frame, a four-orders-of-magnitude speed-up over conventional MC simulation, and reaches peak signal-to-noise ratios of up to 36.24 dB in vivo, outperforming UNet and Pix2Pix baselines. Validation in blood-mimicking phantoms and in 37 human volunteers spanning Fitzpatrick skin types III-V demonstrates improved accuracy, robustness, and physiological consistency of sO2 estimation. By enabling real-time, accurate, and reproducible quantification of tissue oxygenation, GenMC addresses a critical barrier to quantitative PA imaging and offers a general strategy for rapid, high-fidelity approximation of light transport in tissue.
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All authors Mengjie Shi, Feng He, Tom Vercauteren, Wenfeng Xia

Nuclear Theory

Fission Evaluation Tools and Analytics (FETA)

N. Schunck

We present a new Python package called FETA to compute fission observables. In comparison to existing fission event modeling codes on the market, FETA is a modular, flexible, and code-agnostic wrapper around a statistical reaction theory program. In this paper, we report on version 2.0 of FETA, which simulates the prompt decay of the fragments with the LLNL-developed Hauser-Feshbach code YAHFC. We discuss the design philosophy of FETA, present some validation results for the neutron-induced fission of 239Pu, and briefly outline the structure of the package.
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Cosmology and Nongalactic Astrophysics

JWST evidence for a sharp "Cosmic Daybreak" at z = 15

Jiashuo Zhang, Tom Broadhurst, Tzihong Chiueh et al. (+9 more)

Luminous young galaxies have been uncovered with relative ease by JWST, extending to z=14.5, so it is puzzling that deeper spectroscopy of fainter candidates now finds only interlopers. This redshift `ìmpasse" is underscored by the measured stellar ages of these high-z galaxies, which we show converge to zero by z=15, with a marked absence of earlier star-formation. Taken literally, such a late transition from the Dark Ages to luminous galaxies is unlike the gradual Cosmic Dawn of standard LCDM, but does confirm a key prediction of Wave Dark Matter, $\psi$DM, as a Bose-Einstein condensate. The de Broglie wave pressure resists gravity until a substantial Jeans mass of $4\times 10^9M_\odot$ is overcome at z$=$15, corresponding to a light boson $m_\psi=2.2_{-0.3}^{+0.4} \times 10^{-22}$eV, and similar to independent estimates from lensing anomalies and dwarf galaxies. Furthermore, the substantial luminosities of the highest redshift galaxies appear to converge to the initial Jeans scale of $\psi$DM, whereas LCDM predictions extend to lower luminosities and larger ages than observed. These contrasting predictions can be definitively tested as JWST observations accumulate, with diametric implications for Dark Matter as heavy particles beyond the Standard Model or ultra-light bosons motivated by the String Axiverse.
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All authors Jiashuo Zhang, Tom Broadhurst, Tzihong Chiueh, Hsi-Yu Schive, Keiichi Umetsu, Jose M. Diego, Paloma Morilla, Alvaro Pozo, Chian-Chou Chen, Jeremy Lim, Pablo G. Perez-Gonzalez, Rogier Windhorst

Materials Science

Solid-State Dealloying Enables Local Symmetry Breaking in Ternary Intermetallic Thin Films

Mizuki Ohno, Reiley Dorrian, Veronica Show et al. (+2 more)

Metastable quantum materials often occupy narrow composition windows with local symmetries distinct from competing equilibrium structures. These features open pathways for realizing qualitatively new electronic properties within a similar chemical subspace while at the same time complicating their deterministic synthesis. Here we illustrate a post-growth solid-state dealloying process using epitaxial ternary thin films in the La–Ag–Ge chemical space to realize a diffraction-averaged centrosymmetric superconducting structure. The process converts polar $P6_3mc$-LaAgGe into diffraction-averaged centrosymmetric AlB$_2$-type $P6/mmm$ La-Ag-Ge through net Ag loss during annealing at 800–900 $^\circ$C. Atomic-resolution electron microscopy reveals local Ag–Ge displacements of both signs relative to the planar configuration, consistent with local inversion-symmetry-breaking distortions. The converted films exhibit composition-dependent superconductivity with critical temperatures below 1 K and in-plane upper critical fields that exceed the weak-coupling Pauli-field estimate by a factor of approximately 6 in the thinnest superconducting films. These results establish epitaxial solid-state dealloying as a route to phase-selective synthesis of metastable phases, offering control over atomic-scale structural configurations and their interplay with emergent electronic properties.
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All authors Mizuki Ohno, Reiley Dorrian, Veronica Show, Salva Salmani-Rezaie, Joseph Falson

Quantum Physics

Beyond Maximal Entanglement: Exact Resources for Multiparty Encrypted Quantum Cloning

Pritam Roy and Shashank Gupta

Encrypted quantum cloning distributes an unknown $k$-qubit state among $m$ encrypted clones so that no individual clone reveals the input, yet the state can be recovered from any one clone together with a common quantum key. We ask the inverse question: for a fixed encoding architecture, which multipartite pure states can serve as exact resources for this task? For $m\ge2$, we completely characterize the pure resources compatible with a sector-wise two-Pauli encoder, with necessity holding for arbitrary completely positive trace-preserving (CPTP) recovery maps. For even $m$, exact recovery requires maximal entanglement across the signal–noise cut. For odd $m$, less entanglement can suffice, provided that the surviving signal correlations have the structure selected by the encoder. We further show, without fixing the encoder, that exact recovery from every authorized subsystem already implies perfect concealment of each individual signal and requires at least $(m-1)k$ ebits of signal–noise entanglement. For graph states, the resource classification reduces to an exact condition on the kernel of the signal–noise cut matrix, leading to binary certification and constructive Clifford recovery. We identify rank-deficient graph resources that attain the architecture-independent entanglement bound and prove that the entire Dicke family, including $W$ states, is excluded for every sector-wise two-Pauli encoder. Our results show that encrypted recovery depends not only on how much entanglement a resource contains, but also on how its correlations are organized relative to the encoder.
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Computational Physics

Optimal limits on weak integrability breaking and protected thermal memory near qutrit exchange

Hanbing Liang and Fujun Liu

Although integrability does not universally require a continuous one-site symmetry, we rigorously prove that every jointly analytic, regular Yang-Baxter deformation of the qutrit exchange interaction necessarily retains a nontrivial, analytically varying one-site charge. Breaking this local symmetry imposes a fundamental physical constraint on approximate conservation, governed by the optimal uniform bound $\delta^3 \le C\varepsilon$ that explicitly relates the minimal one-site symmetry defect $\delta$ to the local current-conservation residual $\varepsilon$. While breaking all one-site charges strictly forbids an exact integrable completion, an optimally compensated nearest-neighbor interaction saturates this cubic limit and anomalously extends the guaranteed infinite-temperature energy-current correlation window to order $|\lambda|^{-3}$ in the perturbation strength $\lambda$. Furthermore, we reveal a fundamental resonance obstruction for intrinsic conversion perturbations that strictly prevents any exact first-order repair of a broken one-site charge on any finite ring. Nevertheless, we demonstrate that the complete eight-dimensional charge memory matrix remains thermodynamically protected and approaches the identity for timescales $t=o(|\lambda|^{-3/2})$, a robust feature of the full infinite-temperature dynamics when the thermodynamic limit is taken before weak coupling.
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Quantum Physics

Certifying fermionic Gaussian states (and a little more) with optimal precision dependence

Ninnat Dangniam, Laphas Premcharoen, Metrasit Sripech et al. (+1 more)

Fermionic Gaussian states are the workhorse reference states for qubit-based quantum simulation of fermionic systems, yet existing certification protocols either proceed via fidelity estimation, leading to suboptimal sample complexity in the target precision $\epsilon$, only apply to Haar-typical states, or require adaptive measurements on a large fraction of qubits. We give an adaptive protocol that certifies any $d$-mode pure fermionic Gaussian state using $O(d^2\epsilon^{-1})$ copies, single-qubit measurements with only one qubit measured adaptively per copy, and $O(d^3)$ classical processing time per copy. The $\epsilon^{-1}$ dependence is optimal for the certification problem, even among strategies using entangled measurements. The sample complexity is controlled by the spectral gap of a $d\leftrightarrow d-2$ down-up walk—a Markov chain studied in the theory of high-dimensional expanders, equivalent to a two-site Glauber dynamics in statistical physics—relating certification efficiency to relaxation time to equilibrium. The worst-case bound is tight for this protocol and is attained by physically relevant states, including ground states of the fully dimerized Su-Schrieffer-Heeger (SSH) chain and BCS pair states. In contrast, numerics up to $d=14$ suggest that $O(d \epsilon^{-1})$ copies suffice to certify Haar-typical Gaussian states, a factor of $d$ improvement over the worst-case bound. Finally, because the bound depends only on the target's computational-basis distribution, the protocol extends to efficiently phase-dressed states—states obtained by injecting an efficiently computable diagonal phase to Gaussian states—with the same sample complexity. The class includes a continuous family of four-mode non-Gaussian magic states for matchgate computation.
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All authors Ninnat Dangniam, Laphas Premcharoen, Metrasit Sripech, Thiparat Chotibut

Medical Physics

Non-circular scan trajectories for reducing cone-beam artifacts in Gamma Knife CBCT images: a simulation study

Alexandra Alain-Beaudoin, Håkan Nordström, Luc Beaulieu et al. (+1 more)

Objective. Gamma Knife cone-beam computed tomography (CBCT) images are deteriorated by cone-beam artifacts whose magnitude increases along the superior direction. In this study, a novel scan trajectory compatible with the Gamma Knife CBCT system is optimized to reduce cone-beam artifacts, with the aim to replace the current 200-degree single-arc scan. Approach. Data sampling analysis with tomographic incompleteness maps indicates the level of undersampling across the field of view based on the geometry of the system and of a scan trajectory. Moreover, CBCT simulations are performed from a virtual phantom with disks aligned along the axial direction and from a CT reconstruction of a stereotactic end-to-end validation (STEEV) phantom. CBCT projections are simulated for a given scan trajectory through a polychromatic forward projection model with added noise and scatter, then the CBCT image is reconstructed using an iterative algorithm which minimizes weighted least squares. Main results. Both the incompleteness analysis and the CBCT simulations indicate adding lines to the current single-arc trajectory is more efficient to reduce cone-beam artifacts than adding more arcs, both in terms of number of additional projections and new artifacts. A line-arc-line trajectory with source axial steps of 3.5 mm removes virtually all cone-beam artifacts. The widths of the cone-beam artifacts created by the disks show a positive correlation between the artifact magnitude and the incompleteness value. Significance. A line-arc-line scan trajectory is promising to reduce cone-beam artifacts of the Gamma Knife CBCT images while being a compatible and reasonable trajectory for the current system design.
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All authors Alexandra Alain-Beaudoin, Håkan Nordström, Luc Beaulieu, Joakim da Silva

2609.28232 · 23 Sep · This paper is 18 pages in length, including 7 figures and 1 table. The content of this paper was presented at ESTRO2026, with the reference to the conference abstract as follows: Alain-Beaudoin, A. et al. (2026). Radiother. Oncol., 218, S2059-S2061. The manuscript has been submitted to Physics in Medecine & Biology

Abstract PDF $ALGO ×1$TOMO ×1

Quantum Physics

Distilling Datasets into Shallow Circuits for Quantum Machine Learning

Guang Lin and Qibin Zhao

In quantum machine learning, training a quantum model requires each sample to be prepared as a quantum state by a loading circuit that must be re-executed for every shot at every training step. The total burden therefore scales with both the number of samples and the cost of preparation. Existing approaches reduce the loading cost of individual inputs or distill data and compress their representations before applying a separate quantum encoding. This separation can leave resulting samples costly to prepare or cause additional loss of the information during subsequent compilation into shallow circuits. We propose quantum dataset distillation (QDD), which distills the full dataset directly into a small set of shallow circuits. Each synthetic sample is parameterized as a staircase circuit corresponding to a low-rank tensor network, making the sample and its loading circuit the same object. The circuit parameters are optimized classically with exact gradients using distribution matching under an explicit loading budget, without post-hoc state-preparation synthesis. On MNIST and Fashion-MNIST, only 10 circuits per class ($0.0017\times$ the full dataset size) achieve accuracy comparable to full-data training and outperform selection baselines under matched sample and loading budgets. In finite-shot training, QDD reaches 95% of the full-data accuracy with more than $100\times$ fewer cumulative shots. Additionally, we validate QDD on real quantum hardware, demonstrating its practical deployment potential.
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Mesoscale and Nanoscale Physics

Active control of THz plasmon propagation in a one-dimensional electronic waveguide

Thomas Vasselon, Uzer Ahmad, Clément Geffroy et al. (+14 more)

Quantum nanoelectronics is pushing towards ever higher operating frequencies in order to realise quantum technologies capable of processing information at unprecedented speeds. A particularly promising direction is the development of flying electron qubits, which offer the prospect of quantum operations on picosecond timescales. Achieving in-flight quantum control in this regime would establish a fundamentally new paradigm for studying quantum entanglement and enable a novel form of quantum information processing based on propagating electronic wavepackets. Here we report a first step towards this goal by injecting ultrashort electron wavepackets into an engineered quantum nanoelectronic device. We demonstrate active control over the propagation speed of an electron wavepacket with a temporal duration as short as 4 ps in a quasi-one-dimensional electron waveguide with a length ranging from 10 $\mathrm{\mu}$m to 40 $\mathrm{\mu}$m. This advance provides a key building block for ultrafast quantum operations using flying electrons. Beyond its technological implications, our approach offers a platform for exploring the intrinsic dynamical processes that govern quantum transport and coherence in nanoscale electronic systems.
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All authors Thomas Vasselon, Uzer Ahmad, Clément Geffroy, Lucas Mazzella, Matteo Aluffi, Seddik Ouacel, Jashwanth Shaju, Kevin Bredillet, Nathan Roussel, Jean-François Roux, Pierre-Baptiste Vigneron, Arne Ludwig, Andreas D. Wieck, Matias Urdampilleta, Hermann Sellier, Giorgos Georgiou, Christopher Bäuerle

High Energy Physics (Phenomenology)

Exclusive photoproduction of vector toponium within the color dipole picture

Victor P. Goncalves, Bruno D. Moreira and Haimon Trebien

The exclusive photoproduction of the toponium vector meson ($\psi_t$) is investigated within the color dipole model. The overlap function between the light-cone wave function of the vector toponium state and the photon wave function is estimated using the Boosted Gaussian approach. Considering the dominance of small dipoles, the dipole-proton scattering amplitude is estimated in terms of parton distribution functions, and predictions for the photoproduction cross-section in the energy range of the proposed Large Hadron electron Collider (LHeC) are presented. Moreover, the cross-sections and rapidity distributions for the exclusive $\psi_t$ photoproduction in ultraperipheral proton-proton and proton - nucleus collisions at the Large Hadron Collider (LHC) and Future Circular Collider (FCC) energies are calculated. We find that exclusive $\psi_t$ photoproduction is, in principle, feasible in ultraperipheral $pp$ collisions at the FCC-hh.
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Physics Education

Determination of the Charge of Electron Using Faraday's Law of Electrolysis

Vladimir Ya. Kezerashvili and Roman Ya. Kezerashvili

We propose a simple experiment for measuring the charge of the electron based on Faraday's law of electrolysis, assuming the known value of Avogadro's number. The experimental setup consists of electrolytic cells connected in series, so that the same electric current passes through each electrolyte. By measuring the mass deposited at the electrodes and relating it to the total electric charge transferred through the electrolyte using Faraday's law, the charge of the electron can be determined. The experiment requires only standard laboratory equipment, and its performance and analysis are within the skills and knowledge of most students taking algebra-based general physics courses. It is therefore particularly suitable for instructional laboratories in high schools and two- and four-year colleges. We demonstrate that students can obtain a reasonable value for the charge of the electron from simple measurements, providing a direct experimental connection between Faraday's law, Avogadro's number, and the electron charge.
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High Energy Physics (Phenomenology)

Solar capture and annihilation of fermionic and scalar dark matter motivated by the LUX-ZEPLIN high-recoil candidate

Antonio Capolupo, Gabriele Pisacane and Raoul Serao

Motivated by the LUX-ZEPLIN high-energy nuclear-recoil candidate, we ask whether solar evolution can distinguish dark-matter models that are degenerate in their leading xenon recoil response. We compare a split fermionic electroweak doublet with a specified inert scalar doublet, matching their masses, excitation energy, coherent transition interaction, and leading elastic nuclear response. This matching fixes the same direct-detection signal and the same optically thin first-capture source in the Sun, while leaving post-capture dynamics model dependent. We follow finite-temperature capture, orbital evolution, scattering, excited-state decay, escape, thermal entry, and annihilation. The different excited-state lifetimes generate distinct capture histories, but, for the specified cooling interaction, both retained populations thermalize and reach capture–annihilation equilibrium, yielding only a modest difference in their late annihilation rates. We also derive an analytic protected-capture criterion and test the result against shared halo, solar-composition, and nuclear-response variations. Although the total annihilation rates remain similar, model-dependent gauge-boson branching fractions and polarizations produce distinct neutrino spectra at production. A source-level comparison with published IceCube templates shows that the nominal partial $WW$ sources exceed the corresponding pure-$WW$ template limits, without constituting a detector-level exclusion or model discrimination. Solar evolution therefore provides a complementary probe of particle-model differences hidden by a matched xenon signal.
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High Energy Astrophysical Phenomena

4U 1624-490 as a possible intermediate-mass X-ray binary: constraints from XRISM and NuSTAR spectroscopy

R. Iaria, A. Anitra, T. Di Salvo et al. (+7 more)

High-inclination dipping neutron-star X-ray binaries provide a direct view of accretion-flow structure because the line of sight intercepts ionised plasma above the disc. We analyse two XRISM/Resolve observations of 4U 1624$-$490 with simultaneous NuSTAR coverage, dividing the data into seven orbital-phase intervals. Phase-resolved fits include neutral partial covering, a photoionised absorber, thermal Comptonisation, and ionised disc reflection. Fe XXV and Fe XXVI absorption are detected over most of the orbit. The absorber column density, ionisation state, covering fraction, and projected velocity vary with orbital phase and the lines are systematically blueshifted, with line-of-sight velocities of about $85$-$440\ {\rm km\,s^{-1}}$. Absorption-only models leave broad Fe-K residuals, while ionised reflection improves the fits. The velocity modulation has a semi-amplitude $K=210\pm14\ {\rm km\,s^{-1}}$ and, if interpreted as orbital motion, implies a mass function $f(M)=0.83\pm0.17\,M_\odot$. Residual structure in the blue wing of Fe XXVI suggests additional kinematic complexity near the dip, but the modulation remains consistent when the two dip-adjacent measurements are excluded. If the absorber traces the neutron-star orbital motion, the inferred donor mass is $M_2=2.66\pm0.32\,M_\odot$, compatible with a Roche-lobe-filling B9 V-B9.5 V star. Under this interpretation, 4U 1624$-$490 may be an intermediate-mass rather than a classical low-mass X-ray binary. (Abridged abstract)
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All authors R. Iaria, A. Anitra, T. Di Salvo, A. Sanna, F. Barra, L. Burderi, C. Maraventano, S. Caserta, W. Leone, C. Miceli

Materials Science

Disentangling spin polarization from driven circular ionic motion in EuTiO$_3$

Clifford J. Allington, Matthew J. Lutz, Enoch Ho et al. (+30 more)

Coherently driven circular ionic motion has been reported to produce large helicity-dependent optical responses attributed to transient magnetization. However, the microscopic nature and magnitude of this phenomenon, sometimes referred to as dynamical multiferroicity, remain strongly debated. Here, we directly study the connection between ionic circulation induced by a high-field circular terahertz (THz) drive and its effect on the spin system of EuTiO$_3$ using X-rays. This material exhibits an optical response consistent with the putative magnetic signal observed in related non-magnetic materials. Furthermore, the presence of Eu$^{2+}$ ions enables the use of X-ray magnetic circular dichroism (XMCD) to test for the creation of transient spin polarization. Simultaneously, ultrafast X-ray diffraction (XRD) measures the circular ionic motion from which we determine the mechanical angular momentum. We find a classical ionic contribution of $3\times10^{-8}~\mu_B$ from XRD and upper limits of $0.03~\mu_B$ and $0.11~\mu_B$ from the sensitivity of XMCD at the europium $M_5$ and $L_2$ edges, probing the $4f$ and $5d$ shells of Eu$^{2+}$, respectively. These observations show that large-amplitude circular ionic motion in this system is not accompanied by a detectable spin polarization despite the clear signature in the optical data, with the XMCD upper bounds and classical contribution differing by many orders of magnitude.
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All authors Clifford J. Allington, Matthew J. Lutz, Enoch Ho, Fabian Graf, Martina Basini, Hiroki Ueda, Michael Grimes, Alexander B. Elliott, Megan F. Biggs, Ravi Finn, Shih-Wen Huang, Merideth A. Henstridge, Matthias C. Hoffmann, Takahiro Sato, Roberto Alonso-Mori, Diling Zhu, Quynh L. Nguyen, Vincent Esposito, Jeffrey T. Babicz Jr., Elizabeth Skoropata, Biaolong Liu, Eugenio Paris, Arnau Romaguera Camps, Elia Razzoli, Roman Mankowsky, Flavio Capotondi, Nicolas Jaouen, Daniele Pergolesi, Milan Radovic, Matteo Savoini, Steven L. Johnson, Jeremy A. Johnson, Urs Staub

Mesoscale and Nanoscale Physics

Local time-reversal-invariant topological markers in two dimensions

Thomas Klein Kvorning, Miguel F. Martínez and Julia D. Hannukainen

Local topological markers provide a real-space characterization of topological phases and are suited to noncrystalline models. We derive a local topological marker, the Chern-Simons descendant marker, for characterizing the topology of two-dimensional time-reversal-invariant near-Gaussian states from the one-particle density matrix \(\rho\). We construct an auxiliary three-dimensional state characterized by the local Chern-Simons marker, and use dimensional reduction to obtain the Chern-Simons descendant marker for the original two-dimensional state. This derivation introduces a local Hermitian involution \(S\) that is odd under time reversal. When \([S,\rho]=0\), the local Chern-Simons descendant marker reduces to half the difference of the local Chern markers in the \(S=\pm1\) sectors. Constructing an \(S\) that commutes exactly with \(\rho\) generally requires fine-tuning, but this is not needed—the local Chern-Simon marker remains well defined whenever \(\Gamma=\{\rho,S\}-S\) has a spectral gap around zero, even when \([S,\rho]\neq0\). This leaves the practical problem of identifying a suitable \(S\) for a given state, which, importantly, is straightforward even when spin is not a candidate. We show this by considering both strong Rashba and Dresselhaus spin-orbit coupling, for which knowledge of the physical origin of the state reduces the general problem of choosing $S$ to a one-parameter family \(S(\theta)\). We evaluate the optimal angle $\theta$ maximizing the spectral gap of $\Gamma$ analytically assuming translation invariance, and find that the gap of $\Gamma$ remains open for a broad range of angles around the optimum. The same value of \(\theta\) remains valid in disordered systems, providing an easy way to obtain choice of \(S\) for evaluating the local Chern-Simons descendant marker of the state.
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High Energy Physics (Theory)

Geometries of Quantum Field Theories

Masahito Yamazaki

This is an English translation of a book originally published in Japanese by Saiensu-sha in 2015. The book is an introduction to the 3d-3d correspondence, the relation between 3d $\mathcal{N}=2$ supersymmetric gauge theories and the geometry of 3-manifolds, which arises from the compactification of the 6d $\mathcal{N}=(2,0)$ theory. The presentation is bottom-up rather than top-down: instead of starting from the 6d theory, we begin by asking what a quantum field theory is, and let the geometry emerge on its own. Along the way we discuss renormalization and low-energy effective theories, gauging as an operation which glues field theories together, the resulting $Sp(2n, \mathbb{Z})$-action on 3d theories, 3d $\mathcal{N}=2$ supersymmetric theories and their dualities, the squashed three-sphere partition function and supersymmetric localization, duality domain walls of 4d $\mathcal{N}=2$ theories, quantum Teichmuller theory, complex Chern-Simons theory and the quantization of the moduli space of flat $SL(2, \mathbb{C})$-connections on 3-manifolds, with quantum dilogarithm functions as a recurring thread. The emphasis throughout is on geometric and algebraic structures which are invisible in a single field theory, and appear only in the theory space of quantum field theories. Appendices summarize supersymmetry in various dimensions, classical and quantum dilogarithm functions, and cluster algebras. Exercises with difficulty ratings are included in each chapter.
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Instrumentation and Detectors

Study of the properties of sustainable materials for shielding against ionizing radiations

Julien Faivre

The SuShi project aims at determining how sustainable materials can be used to shield against ionizing radiations. This contribution presents a comparison of the effect of concrete and rammed raw earth on photons. For energies around the MeV, where interactions by Compton scattering dominate, changes in the material composition have virtually no effect. The density difference results in 20% more thickness needed for earth to achieve the same flux attenuation as concrete. The same value is found for higher energies, where photons produce electromagnetic showers. Below 0.1 MeV, material composition and earth moisture content matter but the attenuation is much larger.
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Plasma Physics

Alfvénic high-frequency oscillations at the pedestal of JET plasmas

Leonor Roque, Paulo Rodrigues, Emilia R. Solano et al. (+2 more)

Long-lived ($\sim 10$ s) high-frequency oscillations (HFOs, $50-450$ kHz) near the plasma edge have been reported and experimentally described in L-H transition studies at JET and AUG. In this work, we show that these HFOs are a general phenomenon observed in various plasma scenarios and compositions (H$^1$, D, D-He$^3$, D-T) under different heating schemes, including pure Ohmic, ICRH and NBI. We demonstrate that dominant axisymmetric ($n=0$) HFOs are Global Alfvén eigenmodes (GAEs) tied to the shear-Alfvén continuum (SAC) minima arising at the plasma edge due to the sharp decrease of the density and increase of the safety factor. This hypothesis is corroborated by the remarkable agreement found between the measured frequencies of HFOs and the SAC minima computed by the ideal MHD code CSMISH for a comprehensive set of JET pulses. This result, along with the fact that HFOs are observed over long time windows and across a variety of plasma scenarios, makes them convenient MHD constraints for accurate equilibrium reconstruction near the edge. In view of this pragmatic application, we derive a first-order analytic expression for the two lowest coupled branches of the $n=0$ SAC, disclosing their dependence (and, consequently, that of the HFOs) on the plasma density, safety factor, and elongation profiles. In addition, we discuss the nature of $n\neq 0$ HFOs observed along with the dominant $n=0$ HFOs.
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All authors Leonor Roque, Paulo Rodrigues, Emilia R. Solano, JET contributors, The Eurofusion Tokamak Exploitation Team

High Energy Astrophysical Phenomena

Radio component of the multi-messenger emission from the anticipated T Coronae Borealis outburst

O. Petruk, T. Kuzyo, S. Orlando et al. (+4 more)

T Coronae Borealis is the nearest symbiotic recurrent nova and is expected to undergo a new eruption soon, offering a rare opportunity to study shock evolution and particle acceleration. We predict radio emission from the outburst and assess how radio observations can constrain the circumbinary medium (CBM) and cosmic-ray acceleration. We post-process three-dimensional (3D) hydrodynamic nova simulations with a multi-zone model for particle acceleration and radio emission, computing thermal free-free and non-thermal synchrotron radiation, including the Razin effect and free-free and synchrotron self-absorption for different CBM configurations. Early radio morphology should not be interpreted directly as the intrinsic shock geometry, because free-free absorption selectively obscures regions of the 3D emitting volume. The intrinsic radio emission is dominated by synchrotron radiation from electrons accelerated at the forward shock, with unabsorbed fluxes reaching 100-1000 Jy at GHz frequencies during the first day. Dense ejecta and shocked CBM material strongly absorb the emission, reducing the observable flux by several orders of magnitude. The source becomes largely transparent at GHz frequencies within about one month. Radio emission remains predominantly non-thermal during the first year, while thermal emission becomes important only for dense equatorial enhancements. The radio spectral index evolves from positive values caused by absorption to the optically thin synchrotron value of about 0.5 after several weeks. A short-lived polarized signal may arise during the first few days if the red giant's magnetic field contributes to the cosmic-ray-generated field. Early multi-frequency radio monitoring and polarimetry of the forthcoming T CrB eruption will probe density structure and magnetic field, testing particle acceleration in symbiotic recurrent novae.
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All authors O. Petruk, T. Kuzyo, S. Orlando, L. Chomiuk, F. Bocchino, M. Miceli, V. Beshley

Soft Condensed Matter

State-Resolved Integral of First-Passage Times for Multi-Site Polymer Adsorption

Yifan Huang and Qiyun Tang

Understanding the interfacial structure of multi-site polymer adsorption is critical for the rational design of functional nanomaterials. However, the distribution of chains attached via one, two, or more anchor points has remained inaccessible to experiments and conventional simulations. Experiments typically measure ensemble averages such as total adsorbed mass, while molecular dynamics simulations are limited to timescales far shorter than the relevant adsorption processes. To address this challenge, we introduce the State-Resolved Integral of First-Passage Times (SR-IFS) method. This approach decouples fast intra-layer conformational adjustments from the slow kinetics of external chain exchange, enabling quantitative prediction of the time-dependent distribution of attachment states ($p_1$, $p_2$, $p_3$) within a multi-site adsorbed layer. Using 3-arm star-like polymers as a model system, we show that the interfacial state distribution evolves from an initial prevalence of three-point attachments to a more heterogeneous mixture over long time scales, and that the equilibrium distribution can be systematically tuned by adjusting the monomer binding energy. The SR-IFS method provides access to this state-resolved information, offering a connection between microscopic kinetics and macroscopic interfacial properties.
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Chemical Physics

From $\langle n \rangle$ to $n$: Separating multi-particle dynamics by intensity cycling

Pavel Malý, František Trojánek, Petr Malý et al. (+1 more)

We address the interpretation of transient spectroscopy signals proportional to average excitation number in terms of discrete number of excitations. Building on our recent intensity cycling approach, we derive a general scheme to isolate multi-particle dynamics from any transient signal under minimal assumptions. The key result is a general formula expressing the extracted nonlinear signal terms by multi-excitation propagators. We demonstrate the approach on exciton transport and annihilation in organic nanoparticles, and carrier recombination in silicon nanocrystals.
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All authors Pavel Malý, František Trojánek, Petr Malý, Jérémie Léonard

Quantum Gases

Quantum dynamics of spinful impurity in ideal Bose gas

O. Hryhorchak and V. Pastukhov

We discuss the quench dynamics of an isolated system composed of a single spinful impurity in the transverse Rabi field and bath of non-interacting three- and two-dimensional bosons. Specifically, we consider the evolution of bosons and a spin-$\frac{1}{2}$ particle, initially prepared in a Bose-Einstein condensate state and a magnetic ground state, respectively, with the spin-dependent contact boson-impurity interaction switched on. Applying an original mean-field-like approximation, which naturally reflects the statistical effects of the bosonic bath, we calculate time-dependent components of the average impurity spin and the overlap of the wave function between initial and arbitrary time moments. A key prediction is a substantial speed-up in the decoherence (thermalization) dynamics of the spin degree of freedom compared to results obtained with the Chevy-like ansatz.
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