Medical Physics
Improving Multi-Delay-ASL through specialized reconstruction
Ingmar Sorgenfrei, Qinyang Shou, Ingrid Barth et al. (+3 more)
Purpose: Although image reconstruction has received relatively little
attention in ASL research to date, it has the potential to address several challenges in ASL. As well as speeding up measurements by increasing undersampling and reducing measurement artifacts, it can improve the signal-to-noise ratio (SNR) of a given data set and the reproducibility of examinations. Methods: This work focuses on extending a dedicated ASL reconstruction approach (ASL-TGV) (Spann et al. (2020)) to multi-delay data and applying it to a high-resolution pCASL test-retest
dataset. To show not only improvement in the Perfusion Weighted Images (PWIs), Cerebral Blood Flow and Arterial Transit Time was estimated and the test-retest reliability was estimated using the within subject Coefficient of Variance (wsCV), the Intraclass Correlation Coefficient (ICC) and Root-Mean-Squared-Error (RMSE). Results: The Perfusion-Weighted-Images reconstructed from highly undersampled single-shot data using ASL-TGV are clearly improved compared to a fully-sampled reference from the same data even after denoising, especially for long PLDs and the outermost slices. SNR calculated in grey and white matter ROIs shows an improvement of 62% and 35% respectively. The CBF maps produced from the ASL-TGV images have an improved test-retest reliability. Conclusion: ASL-TGV, which is now implemented in the Berkeley Advanced Reconstruction Toolbox (BART), can be used with any type of ASL labeling or data acquisition and any existing image post-processing pipeline and can improve SNR for the PWIs and reproducibility of the CBF maps.
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All authors Ingmar Sorgenfrei, Qinyang Shou, Ingrid Barth, Martin Uecker, Danny JJ Wang, Rudolf Stollberger
High Energy Astrophysical Phenomena
Convolutional non-parametric Gamma-Ray Signal and Background Separation
Scarlet Betterman, Emmanuel Moulin and Martin White
In very-high-energy gamma-ray astronomy, signals must be separated from the residual background which arises from misidentified
cosmic-ray
protons. Building on previous work, we introduce an ensemble of variational autoencoders that aims to perform automatic signal-background separation with minimal assumptions that include separability of the spatial and energy distributions in both the signal and background, with no prior specification of the number of components or the point-like/diffuse nature of the signal itself. In addition, we do not assume knowledge of which region of the coordinate space is background-dominated or where the signal is supposed to be located in the field of view. We test the model on an analytic point-source mixture scenario, a realistic simulation of dark matter annihilation in the
Galactic centre, and real observations of the Crab nebula and MSH 15-52 from the public H.E.S.S data release. The model proves capable of completely reconstructing the signal and background at a pixel by pixel level in all scenarios, whilst also denoising the inputs. Stable performance and reasonable error estimates are obtained even for low signal-to-background ratios.
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Soft Condensed Matter
Emergence of Nanoscale Modulation in Liquid Crystals as a Result of Short-Range Order Parameter Condensation
E.I.Kats
The discovery of the twist-bend nematic phase in
liquid crystals composed of bent-core and dimeric molecules has revealed an unexpected mechanism for the spontaneous formation of nanoscale periodic structures in soft condensed matter. Unlike conventional
liquid-crystalline phases, the twist-bend phase exhibits a nanoscale heliconical modulation despite the absence of molecular chirality. In this note, dedicated to the late R. Meyer, we discuss a Landau phenomenological interpretation of this phenomenon. The central idea is that a short-range orientational order parameter undergoes condensation, giving rise to a heliconical structure characterized by a finite wave vector. We emphasize that the conventional nematic order is already long-ranged, whereas the additional order parameter describes local orientational correlations hidden within the nematic state. The resulting phase transition bears a close analogy to the de Gennes theory of the nematic–smectic-A transition. Fluctuation effects are expected to drive the transition weakly first order. The theory also predicts a new Goldstone mode associated with the spontaneously broken continuous
symmetry of the heliconical state
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Earth and Planetary Astrophysics
TS23/McDonald and FIES/NOT strike again. Two new warm Jupiter systems and outer companions in a third
E. Knudstrup, D. Gandolfi, W. D. Cochran et al. (+29 more)
Warm Jupiters (gas
giant planets with orbital periods of P$\sim$8-200 d) are thought to be largely unaffected by the
tidal interactions that can erase information about the dynamical histories of hot Jupiters. Their orbital eccentricities ($e$) and
stellar obliquities are therefore expected to be preserved, making them valuable probes of
giant-
planet formation and migration. Our aim is to identify and characterise transiting warm Jupiters in order to expand the sample of well-characterised systems and enable further studies of
giant-
planet formation and migration. We analyse TESS transit photometry together with ground-based radial velocity measurements and perform a joint fit of the photometric and spectroscopic data from the TS23 and FIES spectrographs to determine the planetary and orbital parameters. We report on the discovery and characterisation of two new, transiting warm Jupiters; TOI-5120 b ($M_p = 1.23\pm0.05$ M$_{\rm Jup}$, $R_p = 0.969\pm0.017$ R$_{\rm Jup}$, $P = 24.91645\pm0.00002$ d, $e = 0.10\pm0.02$) and TOI-5699 b ($M_p = 0.25\pm0.03$ M$_{\rm Jup}$, $R_p = 0.996\pm0.015$ R$_{\rm Jup}$, $P = 22.01850\pm0.00004$ d, $e = 0.30^{+0.09}_{-0.08}$). We also refine the parameters of the known warm Jupiter TOI-2158 b ($M_p = 0.87\pm0.04$ M$_{\rm Jup}$, $R_p = 0.899\pm0.015$ R$_{\rm Jup}$, $P = 8.60079^{+0.00002}_{-0.00001}$ d, $e = 0.028^{+0.013}_{-0.014}$). In addition, we detect an outer planetary companion, TOI-2158 c ($M_p \sin i = 1.62\pm0.13$ M$_{\rm Jup}$, $P = 414.5^{+1.5}_{-1.6}$ d, $e = 0.54\pm0.04$), and identify a long-term radial velocity trend that may indicate another planetary companion on a wide orbit. The diverse architectures of these systems, in particular the presence and absence of outer companions, highlight the range of dynamical pathways leading to warm Jupiters.
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All authors E. Knudstrup, D. Gandolfi, W. D. Cochran, M. Endl, P. MacQueen, T. Pugh, M. S. Lundkvist, C. M. Persson, A. Stokholm, M. L. Winther, J. R. Larsen, J. L. Rørsted, S. H. Albrecht, K. A. Collins, C. Watkins, B. Edwards, D. R. Ciardi, C. A. Clark, A. S. Polanski, C. Ziegler, C. Briceño, A. W. Mann, M. Everett, S. Howell, B. Safonov, T. Gan, K. Barkaoui, P. Benni, R. P. Schwarz, K. Horne, R. Sefako, D. Muthukrishna
Materials Science
Infrared laser stimulated broadband white emission of transparent Cr:YAG ceramics obtained by solid state reaction sintering
M. Chaika, R. Tomala and W. Strek
In the present work, the Light Induced White Emission (LIWE) was investigated as one of the sources of
laser loss in transparent Cr:YAG ceramics. We have found that transparent Cr:YAG ceramics is capable of generating bright LIWE at excitation powers above a certain threshold. Intensity of LIWE strongly depends on the excitation power and ambient pressure. The host temperature estimated from Cr3+ luminescence was found to be below 600{\deg}C, while the most intense white emission was found between 50-400{\deg}C. The mechanism of the
laser induced white emission was discussed in terms of Intervalence Charge Transfer (IVCT) in chromium mixed valence pair.
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Quantum Physics
Preparation Changes the Cost of Calibration for Quantum Control
Xiu-Hao Deng
Error-correction records can reveal noise yet supply the information needed for control too slowly. In a surface code under Gaussian dephasing, encoded calibration learns a correlation that reverses the preferred control mainly through rare events. A product probe exposes it more often through the same checks, reducing ideal-record sample complexity from inverse-square to inverse-linear in phase variance. Counting both calibration and execution costs, we show that this gain can repay probe overhead and enable protected tasks within budgets that exclude encoded calibration.
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Optics
Laser induced broad band white emission from transparent Cr4+:YAG ceramics: Origin of broadband emission
M. Chaika and W. Strek
Laser-induced white (light) emission was observed from transparent Cr:YAG ceramics irradiated with a focused continuous wave beam of light from an infrared
laser diode. The
laser-induced white emission is detected only on the surface of the sample and is not observed in volume. It is found that the intensity of the emission increases exponentially with the
laser power density above the threshold. The impact of broadband emission on the power of the transmitted
laser beam through the sample was measured. The disappearance of broadband emission due to displacement of the
laser beam or an increase in ambient pressure leads to a decrease in the power of transmitted
laser beam. Origins of the
laser-induced white light emission along with its characteristic features are discussed in terms of multiphoton absorption, intervalence charge transfer and ionic space charge models.
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Soft Condensed Matter
A Bonded-Particle Discrete-Element Model with Self-Gravity for the Collision and Reaccumulation of Rubble-Pile Asteroids: Formulation and Numerical Protocol
Yohann Trivino
I present a discrete-element approach developed to study the collisional and gravitational
evolution of small self-gravitating granular aggregates. Each body is represented as a composite of cohesively bonded spherical grains, so that fragmentation and reaccumulation emerge from the microscopic competition between short-range dissipative contact forces, an irreversible bond-breaking criterion, and pairwise Newtonian self-
gravity summed over every particle pair, including those internal to a single body. A numerical experiment is described: a random-sequential packing procedure that generates two bonded spherical aggregates, a controlled two-body encounter with tunable approach speed and impact parameter, and a systematic parameter sweep designed to map the conditions under which two bodies launched from rest under their mutual
gravity alone either merge into a single remnant or fail to settle after a low-speed encounter. Of the 125 simulated collisions, 56.8% result in the formation of a single residue. The cohesive network remains intact for $\Pi_\sigma\lesssim0.036$, is partially damaged with dispersion determined by the contact damping ratio, and breaks completely for $\Pi_\sigma\approx3.59$
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Materials Science
Thorium-229 as a Phonomagnetometer
Martin Pimon, Andreas Grüneis, Thorsten Schumm et al. (+1 more)
Thorium-229 possesses the only known low-energy
nuclear transition suitable for spectroscopy with narrowband VUV
lasers. While previous experiments have focused on application as a
nuclear clock, this transition also offers a route to high-accuracy magnetometry. Experimental observations of
magnetic fields generated by
phonons carrying angular momentum remain inconclusive, highlighting the need for quantitative tests of the underlying physical mechanisms. In this article, we propose doping thorium-229 into a solid-state host to probe phonomagnetic fields in situ. We identify Na$_2$ThF$_6$, a
chiral stoichiometric thorium compound, as a promising host material and evaluate its spectroscopic sensitivity to
magnetic interactions under two excitation schemes: driving degenerate
phonon modes with a circularly polarized
laser, and applying a temperature gradient. Density functional theory simulations combined with quantitative estimates suggest that the temperature-gradient scheme yields a
magnetic signal that appears too weak to be measurable, while a circularly polarized, high-intensity THz/VUV pump-probe driven phonomagnetic response may approach the shot-noise-limited detection threshold. While experimental challenges remain, the unique suitability of thorium-229 provides a testable pathway toward detecting phonomagnetic fields in a solid-state platform.
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All authors Martin Pimon, Andreas Grüneis, Thorsten Schumm, Kjeld Beeks
Quantum Physics
Room-temperature quantum-sensing molecular crystals grown in minutes
Madhur Parashar, Guangzhao Chen, Emanuel Druga et al. (+3 more)
Quantum sensing increasingly demands materials combining room-temperature optical
spin addressability and coherent control with rapid, accessible fabrication. Yet
semiconductor platforms require costly materials and specialized processing, while molecular systems often depend on bespoke synthesis or involved
crystal growth. Here we apply microspacing in-air sublimation (MAS) to rapidly fabricate
quantum-sensing materials within minutes. Microgram quantities of commercially available precursors crystallize on glass, in air and without
vacuum or inert-gas handling. Monitored in situ, growth yields optically clear, stoichiometric single
crystals of excellent quality, including plates and needles with intrinsic optical waveguiding. Donor-acceptor charge-transfer co-
crystals pairing anthracene or biphenyl with tetracyanobenzene, together with localized-
exciton pentacene:pentacenequinone (P:PQ), exhibit room-temperature optically detected
magnetic resonance (ODMR). Charge-transfer ODMR resonances reach linewidths below $4\mathrm{MHz}$, consistent with motional narrowing of mobile triplet
excitons, while P:PQ supports coherent ensemble
spin control with $T_2=0.56\mu\mathrm{s}$. Functionality across chemically and electronically distinct pairs establishes MAS as an accessible screen for molecular
quantum-sensing materials, connecting molecular
crystal engineering with low-cost, chemically tunable thin triplet-
spin layers and waveguiding sensor geometries for
quantum sensing and microscopy.
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All authors Madhur Parashar, Guangzhao Chen, Emanuel Druga, Liang Z. Tan, Jeffrey Reimer, Ashok Ajoy
Physics and Society
Warned alike, AI agents avoid the less-crowded road while people take it
Takahiro Ezaki, Naoto Imura and Katsuhiro Nishinari
AI
agents built on a few shared models increasingly act for many people. A shared forecast about others can align their choices and change how scarce capacity is allocated. We tested this feedback in a two-road congestion game. Adding one sentence warning that others might follow a routing tip made populations of 50 GPT
agents crowd one road while avoiding the nearly empty alternative. Average travel time rose from 64 to 95 min, although any crowded-road
agent could have saved 69 min by switching alone. The warning discouraged the very move it predicted. The pattern persisted for 100 rounds. Two other model families shifted the same way without locking onto one road. Twelve all-human groups (240 participants) stayed near balance under numerical reports or the tip and warning. In 24 mixed groups with a further 240 participants, imbalance grew with the share of
agents in the registered analysis, while people increasingly took the road the
agents avoided. Collective costs stayed below the allagent reference, but with 15
agents and 5 humans,
agent seats averaged 80 min, compared with 44 min for human seats. Shared forecasts can thus sustain collective inefficiency among similar
agents. A better group average can also hide an unequal burden. Evaluations of AI
agents that share resources should test populations, treat messages as interventions and report who bears the costs.
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Solar and Stellar Astrophysics
Beating and coupling in pulsating stars: A unified Fourier description and observational diagnostics
József M. Benkő and Emese Plachy
Long-term amplitude and phase variations in pulsating
stars produce side peaks or multiplets in the
Fourier spectrum of the light curves around the pulsation frequency and its harmonics. Such structures are often attributed to modulation, although linear beating and the non-linear coupling of close oscillations can also produce similar patterns. We develop a unified analytical
Fourier description of these alternatives and identify observational relations that retain discriminatory power when their frequency patterns overlap. We represent the signal as a dominant, non-sinusoidal oscillation plus one or more secondary oscillations close to it, and analytically derive the frequencies, complex amplitudes, and phases resulting from linear superposition, quadratic and general non-linear coupling. We also illustrate the calculated phenomena using artificial light curves. We implement the resulting tests in a diagnostic tool "freqdiag", which compares modulation with primary–secondary quadratic coupling models anchored to either the higher- or lower-frequency side peak, using the same normalized complex amplitudes, and supplements the fit with hierarchical tests of side-peak amplitude progression. A sinusoidal secondary signal produces only one additional peak in the linear-beating case, whereas a non-sinusoidal secondary signal produces a harmonic sequence, whose separation from the primary harmonics increases with order. Quadratic coupling produces terms $nf_0+lf_B$, but their amplitudes and phases follow shifted-harmonic and combination relations. At general non-linear order, coupling and modulation occupy the same frequency grid. The formalism provides a practical framework for interpreting Blazhko-like RRc
stars, HADS variables, and other pulsating
stars in which modulation and coupling are difficult to separate observationally.
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Quantum Physics
Daming Li
We simulate three-
flavor neutrino oscillations on two-
qubit quantum circuits. The
flavor space is embedded as $\ket{00}=\nu_e$, $\ket{01}=\nu_\mu$, $\ket{10}=\nu_\tau$ with the $\ket{11}$ channel kept inert, and the input mixing parameters (NuFIT~5.3, normal ordering, with SK-atm) follow the global fit. We verify three physical settings against analytic or exact references:
vacuum propagation, reproduced by a mass-eigenstate phase
circuit to $\sim 10^{-16}$; constant-density Mikheev–Smirnov–Wolfenstein (MSW) matter effects, showing resonant
flavor conversion when the matter potential $A$ crosses $\Delta m^2_{31}$; and varying-density (
supernova shock-shell) propagation by slicing plus second-order Suzuki–Trotter splitting, with per-slice Trotter error $\sim 10^{-6}$ and total accuracy $\sim 10^{-4}$ against the continuous profile. We report a Suzuki–Trotter precision–resource calibration varying order, step number, and
matrix/probability error. It delimits brute-force Trotterization on
solar baselines: we quantify both standard alternatives, coherence averaging and adiabatic MSW. We also compute
quantum-information diagnostics from the same model parameters, namely mode
entanglement and the CP asymmetry. Finally, we extend the framework to open
quantum systems via a Lindblad master equation with dephasing and absorptive channels. These results provide a reproducible link between low-energy oscillation observables and
quantum-information measures.
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Quantum Physics
From Received Power to Certified Secret Keys: A General Method for Bridging Classical FSO Link Budgets and Decoy-State QKD
Hasan Abbas Al-Mohammed
Received optical power determines
photon arrival flux, but
photon arrival flux does not certify a
quantum key. This paper gives a deployment-independent interface from a classical free-space optical (FSO) link budget to phase-randomized weak coherent pulse BB84, decoy-state estimation, and composable finite-key postprocessing. The channel interface separates
geometric collection, atmospheric extinction, residual pointing, and detector efficiency, and states when common
geometric and pointing expressions are approximations. The finite-key output follows the decoy-state analysis of Lim et al., with key- and test-basis counts estimated separately and an infinite-decoy asymptotic reference. The numerical study covers a five-level attenuation sweep, basis- and
vacuum-probability sensitivities, a conditional Chernoff comparison, and integer-count Monte Carlo. For $3.33 \times 10^8$ emitted pulses, the Hoeffding-based predicted one-kilobit-per-second distance limits are 2.727, 1.883, 1.472, 1.236, and 0.962 km from very clear to dense-fog parameterizations. These are conditional performance predictions, not experimental security certificates. Satellite, drone, high-altitude-platform, terrestrial, and train links enter through the same interface but require their own propagation, acquisition, and device inputs. The framework integrates established security tools into an engineering procedure without claiming a new security proof or a universal range.
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Strongly Correlated Electrons
Systematic Evolution of Magnetic Anisotropy and Crystal-electric-field Ground States in SmTr2Ge2
Ryuji Higashinaka, Kokoro Higo, Tatsuma D. Matsuda et al. (+1 more)
We investigated the
crystal-electric-field (CEF) states in SmTr2Ge2 (Tr= Co-Cu and Ag) with the ThCr2Si2-type structure by magnetization and specific heat measurements. The
magnetic anisotropy evolves systematically with Tr, changing from an easy ab plane for Tr = Co and Ni to an easy c axis for Tr = Cu and Ag. Combined analyses of the low-temperature susceptibility and
magnetic entropy indicate a level crossing of the CEF ground state between Ni and Cu, together with a systematic
evolution of the first excited CEF energy. The
evolution of the
magnetic properties correlates with changes in local structural parameters, providing an experimental basis for discussing how the ligand environment around the Sm ion is related to the 4f electronic state.
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All authors Ryuji Higashinaka, Kokoro Higo, Tatsuma D. Matsuda, Yuji Aoki
Chemical Physics
Observing Phase Space Evolution During Unimolecular Decay
Abhirami Vijayakumar, Raidel Martin Barrios, Meenu Upadhyay et al. (+4 more)
Direct time-resolved observation of large amplitude dynamics during ground state statistical unimolecular decay remains an experimental challenge. Here, an experimental Time-Resolved Coulomb Explosion Imaging (TR-CEI) study (J. Chem. Phys. 151, 174301, 2019) of the canonical unimolecular reaction NO$_2$ $\rightarrow$ NO($^2\Pi, v=0, J)$ + O($^3P_j$) at threshold dissociation energies is modeled and analyzed. Quasi-classical trajectory (QCT) simulations on an accurate and validated ground state potential energy surface (PES), with energy and angular momentum constraints from known product state distributions, are used to characterize the dissociation dynamics. TR-CEI projects suddenly, via ultrafast Strong Field Ionization (SFI), the evolving neutral ground state wavepacket onto the repulsive doubly charged cationic state which then impulsively fragments into the NO$^{+}$ + O$^{+}$ ion pair. Within the Coulomb
recoil approximation, which applies at longer NO–O (Jacobi) separations, the ion pair CEI-energy is inversely proportional to the scalar distance between the neutral ground state NO and O moieties at the moment of SFI, thus providing a direct measure of the evolving average NO–O distance during unimolecular decay. Results from QCT simulations agree favourably with the TR-CEI measurements. Phase space
evolution, recurrence time distributions and Lyapunov exponent analysis are presented which support the conclusion that TR-CEI directly observes phase space
evolution during unimolecular decay. For the present system, the time scale for the phase space distribution to achieve statisticality is estimated to be 2 to 3 ps.
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All authors Abhirami Vijayakumar, Raidel Martin Barrios, Meenu Upadhyay, JingChun Wang, Andre Staudte, Albert Stolow, Markus Meuwly
Materials Science
Universal Drift Correction for Multidimensional Scanning Microscopy
Sangjoon Lee, William Millsaps, Dasol Yoon et al. (+7 more)
In scanning microscopy, drift causes the specimen to be sampled at positions displaced from the nominal probe positions. This displacement alters the spatial assignment of the recorded signals and biases quantitative measurements across two-dimensional imaging, channel-resolved spectroscopic mapping, and scan-position-resolved diffraction analysis. Here, we extend orthogonal-scan drift correction from 2D images to spectrum images and diffraction
datasets. We demonstrate how to recover probe positions using either differently oriented multidimensional scans or structural reference images. The recovered positions are used either to resample the multidimensional data onto a regular grid or to assign each recorded signal to its corrected coordinate. Our method combines affine and non-rigid correction, requires no prior structural model, and is implemented as open-source, GPU-accelerated software that reduces processing times by two to three orders of magnitude, enabling routine and automated drift correction for quantitative multidimensional microscopy.
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All authors Sangjoon Lee, William Millsaps, Dasol Yoon, Caitlyn Obrero, Guoliang Hu, Corrie Barnes, Cedric Lim, Andrew Barnum, Arthur R. C. McCray, Colin Ophus
Quantum Physics
Classification of Generalised Triorthogonal Codes through Length 54
Adam Wills, Shubham P. Jain and Shraddha Singh
Magic state
distillation is a widely considered primitive in fault-tolerant
quantum computation for the preparation of high-fidelity non-Clifford resources. The most commonly considered class of such protocols are generalised triorthogonal codes; these distil $n$ noisy input $\mathrm{T}$ states into purified third-level diagonal magic states. Extensive prior work has searched this space of protocols, often using heuristic methods that do not guarantee optimality. Existing classification work is limited to protocols distilling $k$ output $\mathrm{T}$ states with $n+k\leq 38$ (Nezami and Haah, Phys. Rev. A 106, 012437 (2022)). In this work, we significantly expand this classification to all protocols with lengths $n\leq 54$. We restrict to distance $d\geq 3$ to keep the classification to a sensible size, and because efficient searches are well understood at distance $2$ (Singh et al., arXiv:2606.28518). Moreover, our results are complementary to synthillation (Campbell and Howard, Phys. Rev. A 95, 022316 (2017)), which can distil third-level states from $\mathrm{T}$ states, but only at distance $2$. Under optimality in terms of input count, space footprint, and distance for a given output, we find $74$ optimal generalised triorthogonal protocols in our range, $65$ of which are new to the literature. To achieve our classification, we extend the classification of unital triorthogonal spaces of Nezami and Haah from length $38$ to $54$ using a directional derivative method. Using these as the stabiliser spaces, we add logical rows that satisfy the triorthogonality constraints to create full protocols.
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Mathematical Physics · Cross-listed from math.AP
On the Cauchy problem for the Tzitzéica equation: Soliton resolution conjecture and asymptotic analysis
Shou-Fu Tian and Jia-Fu Tong
We prove the
soliton resolution
conjecture for the Tzitzéica equation, which is an important integrable model arising in affine differential geometry and characterizing proper affine spheres. Recently, Huang, Wang and Zhu (Math. Ann. 395, 18 (2026)) reported the long-time asymptotic result for the Tzitzéica equation with purely continuous spectrum. Inspired by their work, we carry out a full asymptotic analysis of the Tzitzéica equation. Compared with the previous work, by developing the $\bar{\partial}$-nonlinear steepest descent method, we reveal that the solutions of the Tzitzéica equation exhibits three different asymptotic regions depending on $\xi:=x/t$. For the region $\xi\in(-\infty,-1]\cup[1,\infty)$, where there are no stationary phase points, we rigorously prove that the solution satisfies $u(x,t)=O_\xi(t^{-1})$ for $\xi\ge1$ and $u(x,t)=2\pi i+O_\xi(t^{-1})$ for $\xi\le-1$. In the region $\xi\in(-1,1)$, the phase function $\theta(z)$ has two stationary phase points. The corresponding asymptotic approximations can be characterized with an $N$-
soliton solution as well as an interaction term between
soliton solutions and the dispersion term with a residual error of order $O(t^{-3/4+b_K})$ with $0\le b_K<1/4$. In the transition regions $\{(x,t):1-\varepsilon<|\xi|<1\}$, the corresponding asymptotic approximation can be characterized by the dispersion term with a residual error of order $O(t^{-3/4+b_\varepsilon})$ where $0\le b_\varepsilon<1/4$. Our results provide a rigorous analysis of the long-time asymptotic behavior of solutions of the Tzitzéica equation in different regions and confirm the
soliton resolution
conjecture for the Tzitzéica equation.
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Materials Science
Rare-earth Bilayer Triangular Lattice as a Platform for Tunable Ground States and Field-induced Magnetic Phases
Jianqiao Wang, Fangli Li, Yangyang Yu et al. (+4 more)
Rare-earth
bilayer triangular
lattice (TL) antiferromagnets provide a versatile platform for realizing diverse
magnetic states by combining
geometric frustration, interlayer coupling, and strong single-ion anisotropy. Here, we report a family of R2O2Se (R = Sm, Eu, Tb-Lu; ROSe) single
crystals featuring
bilayer equilateral TLs.
Magnetic susceptibility and specific-heat measurements reveal predominantly
antiferromagnetic (AFM) interactions and diverse
magnetic ground states across the series, including successive AFM transitions in TbOSe and single AFM transitions in SmOSe, DyOSe, HoOSe, and YbOSe. Notably, DyOSe and HoOSe exhibit pronounced 1/2 magnetization plateau-like features for fields along the c-axis, revealing field-induced
magnetic states. In HoOSe, complementary thermodynamic and magnetization measurements resolve three critical fields and a rich field-temperature phase diagram containing five distinct
magnetic phases. These results establish rare-earth
bilayer TLs as a chemically tunable materials platform for accessing novel
quantum spin states through the interplay of
lattice geometry, single-ion anisotropy, and competing
magnetic interactions.
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All authors Jianqiao Wang, Fangli Li, Yangyang Yu, Quan Xiao, Zhibin Qiu, Liusuo Wu, Shu Guo
Materials Science
Energetically Driven Structure Matching for Autonomous Total X-ray Scattering Experiments
Emil J. P. Frost, Martin A. Karlsen, Jonas H. Jensen et al. (+6 more)
The emergence of autonomous laboratories motivates rapid conversion of experimental data into reliable atomistic models on time-scales compatible with closed-loop optimization. Here we develop an energetically driven structure matching framework for analysis during ongoing total X-ray scattering experiments. Using data from gold nanoparticles, we match against idealized spherical, octahedral, decahedral, and icosahedral geometries, their machine-learned interatomic potential (MLIP)-relaxed structures, and molecular dynamics (MD) ensembles. Idealized models are fast to generate but can misassign morphology and systematically underestimate size by neglecting surface relaxation, strain, and thermal disorder. MLIP relaxation markedly improves both, while MD ensemble averaging agrees best with experiment. We therefore introduce a hierarchical workflow combining rapid idealized screening with targeted MLIP and MD refinement of top candidates, delivering improved structural feedback without interrupting autonomous operation. This framework provides a route towards autonomous campaigns in which the target structure itself can be updated in response to the evolving energy landscape of structures compatible with the experimental data.
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All authors Emil J. P. Frost, Martin A. Karlsen, Jonas H. Jensen, Rodrigo Moreno, Jørn Lambertsen, Jonathan Quinson, Andy S. Anker, Alexander Bagger, Tejs Vegge
High Energy Physics (Experiment)
Strangeness Production at GlueX
Hao Li
The GlueX experiment at Jefferson Lab is well suited for exclusive studies of strangeness production, combining a linearly polarized
photon beam at $8.0 < E_\gamma < 8.8$ GeV with a large-acceptance detector that reconstructs weakly decaying hyperons. We outline a research program built on three aspects: (i) spectroscopy of strange
mesons, where many excited $K^*$ states remain unestablished and crypto-exotic strange hybrids must be identified from combined spectrum and decay information, anchored by the $K^*(892)$ as a standard candle; (ii)
spin dynamics, where the first precise measurements of the complete
spin-density
matrix elements in the photoproduced $K^*(892)\Lambda$ system beyond the Schilling formalism constrain the $t$-channel strange production mechanism; and (iii) hadronization, probed through the newly published $p\bar{p}$, $\Lambda\bar{\Lambda}$, and $p\bar{\Lambda}$ photoproduction cross sections and emerging $\Lambda\bar{\Lambda}$
spin-correlation measurements. We place these efforts in the context of the broader GlueX strangeness program and give an outlook toward the high-statistics GlueX-II era.
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Materials Science
When Is Molecular-Dynamics-Predicted Ionic Conductivity Reliable in Solid Electrolytes?
Yiwei You, Shaofei Chen, Zhifeng Wu et al. (+4 more)
Molecular dynamics is widely used to predict ionic conductivity in solid electrolytes, but the reliability of these predictions is often difficult to assess. Our analysis identifies finite trajectory length, limited
cell size, and insufficient sampling as intrinsic limitations of finite atomistic ion-transport calculations. Cubic Li7La3Zr2O12 is used as a representative solid electrolyte to quantify their consequences. These limitations can remain hidden behind apparently linear mean-squared displacements and well-behaved Arrhenius relations, leading to inaccurate diffusivities, activation energies, and extrapolated ionic conductivities. Such inaccuracies can misrank candidate solid electrolytes and consequently misdirect computational screening and experimental validation. Here, we establish the local mean-squared-displacement exponent, {\alpha}(t), as a quantitative reliability criterion that links dynamical convergence to errors in diffusivity and Nernst-Einstein ionic conductivity. The criterion further determines the minimum trajectory length required to achieve a prescribed accuracy as a function of temperature. Independent replicas reduce statistical uncertainty, while selective single-axis expansion mitigates finite-size effects. By establishing when simulated ionic conductivity is quantitatively trustworthy, this approach enables more reliable materials ranking and more efficient use of computational and experimental resources, thereby accelerating the development of high-performance solid electrolytes for solid-state batteries.
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All authors Yiwei You, Shaofei Chen, Zhifeng Wu, Pushun Lu, Eric Jianfeng Cheng, Songyan Chen, Shunqing Wu
Computational Physics
$U(1)$ Gauge-Equivariant Representation Learning of Bloch States
Chengyan Zhang, Xian Xu, Bowen Hou et al. (+1 more)
Representation learning, or featurization, of mean-field Bloch states provides an important route for incorporating electronic information into machine-learning models of first-principles condensed-phase systems. A challenge in representing Bloch states is the gauge redundancy of each state. In this work, we propose to address this issue by explicitly incorporating gauge equivariance in the machine-learning framework. We develop a $U(1)$-equivariant autoencoder that compresses the plane-wave-basis Bloch states obtained from density functional theory into a low-dimensional latent representation. We achieve an average overlap of 0.970 between original wavefunctions and the reconstructions from a 64-dimensional latent space using a
dataset of two-dimensional
insulators. We further show that $U(1)$ equivariance endows the latent space with physically meaningful structures, including smoothness and topological information. Finally, we present a proof-of-principle application in which the latent representations are used to predict the off-diagonal elements of the $GW$ self energy
matrix, and demonstrate the importance of enforcing gauge equivariance in the prediction.
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All authors Chengyan Zhang, Xian Xu, Bowen Hou, Diana Y. Qiu
Nuclear Theory
A Quantization-Constrained Parameter Method for Studying $\alpha$ and Cluster Decay
Nguyen Thi Huyen Nga, Le Hoang Chien, Nguyen Tri Toan Phuc et al. (+1 more)
We propose a Quantization-Constrained Parameter Method (QCPM) for determining the Woods-Saxon (WS) potential depth $V_0$ and diffuseness $a$ in studies of $\alpha$ and cluster decay half-lives. In this approach, the parameters are derived analytically by imposing the Bohr–Sommerfeld (BS) quantization condition, thereby eliminating the need for parameter fitting. The calculated diffuseness values exhibit a strong dependence on
nuclear shell structure. The reliability of the QCPM-derived WS potential is validated through optical model analyses of elastic $\alpha$ scattering data. The resulting $\alpha$ and cluster decay half-lives show good agreement with experimental values. Our results highlight the significant role of daughter-
nucleus deformation in improving the consistency between theoretical predictions and experimental data. In addition, we introduce a modified Woods–Saxon (mWS) potential that effectively approximates the surface behavior of folding potentials incorporating the
nuclear medium effect. This modification leads to closer agreement with the measured half-lives. Free of adjustable parameters such as $V_0$ and $a$, the QCPM enhances the predictive power of phenomenological potentials for $\alpha$ and cluster decay studies.
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All authors Nguyen Thi Huyen Nga, Le Hoang Chien, Nguyen Tri Toan Phuc, Chau Van Tao
Solar and Stellar Astrophysics
Near-infrared spectra of chemically peculiar stars and applications to kilonova spectra
Nanae Domoto, Masaomi Tanaka, Wako Aoki et al. (+11 more)
Kilonova spectra provide information on rapid
neutron-capture nucleosynthesis in
neutron star mergers. However, it remains challenging to identify individual elements in kilonova spectra, primarily due to incomplete atomic data for heavy elements at near-infrared wavelengths. Recent work demonstrated that spectra of chemically peculiar
stars offer excellent laboratory for studying kilonova spectra. In this paper, to expand our understanding of strong transitions of heavy elements at near-infrared wavelengths, we present high-resolution near-infrared spectra of 14 chemically peculiar
stars covering a range of effective temperatures, surface gravities, and abundance patterns, obtained with Subaru/IRD. The Sr II, Ce III, and Gd III lines, previously suggested to be among the strongest transitions, are detected in the spectra of most of our targets, confirming their intrinsic importance. In addition, Eu II and Nd III lines are detected in several
stars. By comparing observed equivalent widths and abundance ratios, we show that under a highly heavy-element-enriched abundance pattern, Eu II and Nd III lines may contribute to kilonova spectral features comparably to Sr II. Importantly, we find no unidentified lines systematically stronger than these transitions despite the larger
stellar sample. These results further support the primary importance of the Sr II and Ce III transitions and provide new insights into the potential contribution of Eu II and Nd III.
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All authors Nanae Domoto, Masaomi Tanaka, Wako Aoki, Salma Rahmouni, Tomoyuki Kudo, Hiroki Harakawa, Teruyuki Hirano, Takayuki Kotani, Takashi Kurokawa, Masayuki Kuzuhara, Jun Nishikawa, Takuma Serizawa, Motohide Tamura, Akitoshi Ueda
Astrophysics of Galaxies
KBSS-InCLOSE II: First Detailed Insights on the Inner CGM of Low-Mass $z\sim2.3$ Galaxies
Evan Haze Nunez-Cravin, Charles C. Steidel, Gwen C. Rudie et al. (+7 more)
We present results from an extension to the Keck Baryonic Structure Survey (KBSS) that focuses on the Inner Circumgalactic Medium (CGM) of QSO Line Of Sight Emitting
galaxies at z$\sim$2.3 (InCLOSE). We analyze two low-mass
galaxies $\log{(\rm{M_*} / \rm{M_\odot})} \leq 9$ that are within small a projected distance of a QSO $D_{\rm tran} \leq 50~{\rm kpc}$ ($D_{\rm tran} /R_{\rm vir} \leq 0.75$). One
galaxy is detected as a bright Lyman- Emitter with Keck/KCWI (confirmed with follow-up Keck/MOSFIRE spectra), and the other as a serendipitous line emitter with Keck/MOSFIRE. Both
galaxies have nebular and morphological properties consistent with those of typical low-mass z$\sim$2.3
star-forming
galaxies. Analysis of their CGM absorption as seen with Keck/HIRES spectra of the background QSOs shows no detections of low-ionization metal absorption (low-ions; e.g., Si II), ubiquitous detections of intermediate- (e.g., C IV) and high-ions (O VI), kinematically complex absorption ($\geq$7 components per
galaxy halo) spread over $|\Delta v|\pm 150~{\rm km~s^{-1}}$, and no unambiguously unbound gas is detected in either
galaxy halo. We analyze the thermal properties of a subset of CGM components, finding that the majority (6/10) have temperatures consistent with heating from the metagalactic UV background ($\log{(T/\rm{K})_{\mathrm{med}}}=4.0$) while the remainder possess short-lived, intermediate temperature gas that would require additional heating or rapid replenishment ($4.6 \leq \log{(T/\rm{K})} \leq 5.1$), the internal energy of these absorbers are dominated by thermal broadening, their internal (turbulent) velocities are all subsonic, while their motions through the
halo are likely supersonic. These results hint that the z2.3 CGM changes with
stellar mass in terms of kinematic complexity and unbound gas fraction, while thermal properties remain similar.
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All authors Evan Haze Nunez-Cravin, Charles C. Steidel, Gwen C. Rudie, Evan N. Kirby, Charis M. Hall, Nikolaus Z. Prusinski, Zhuyun Zhuang, Yuanze Ding, Alice E. Shapley, Ryan F. Trainor
Earth and Planetary Astrophysics
On the Compositions of Interstellar Objects
Matthew J. Hopkins, Michele T. Bannister, Bertram Bitsch et al. (+2 more)
As physical samples of distant planetary systems, the compositions of interstellar objects (ISOs) should correlate with the properties of their diverse parent
stars. We combine a chemical partition model with a sample of
stellar elemental abundances from APOGEE DR17 to predict the abundances of commonly-observed cometary volatiles in ISOs. We find that the compositions of ISOs vary significantly between different
stars. In particular, we predict a strong correlation between an ISO's ammonia abundance and its parent
star's
metallicity: high-
metallicity stars will create ISOs rich in ammonia. This suggests the production rates of NH$_3$'s photolytic daughter products are an ideal observational tracer for the origins of ISOs. We infer that 2I/Borisov formed around a
star of near-
solar metallicity ($-0.4\lesssim[\mathrm{Fe}/\mathrm{H}]\lesssim0.3$), and corroborate the velocity- and isotope-based inferences that 3I/ATLAS formed around a lower-
metallicity star ($-0.8\lesssim[\mathrm{Fe}/\mathrm{H}]\lesssim0.0$). The production rates of 2I and 3I imply both only contain hypervolatiles such as CO and N$_2$ that are trapped in other less-volatile ices, similar to typical
Solar System comets. Despite this, we argue that true hypervolatile-ice-rich ISOs may exist; they would exhibit high CO and N$_2$ production rate ratios, possibly similar to those of C/2016 R2 (PanSTARRS). Our predictions provide context for future ISO discoveries, opening a path to link the properties of their origin systems to observable production rates.
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All authors Matthew J. Hopkins, Michele T. Bannister, Bertram Bitsch, Chris Lintott, John C. Forbes
Materials Science
Engineering Ferromagnetism in Wide Bandgap w-AlN for Spintronic Applications: Insights from DFT Calculations
Chinnappan Ravi
Spintronics drives the search for functional materials, pursuing room-temperature dilute
magnetic semiconductors to realize practical, energy-efficient devices. This paper presents a theoretical investigation into the
magnetic properties of w-AlN doped with Cr, Ru, and Rh atoms, using
spin-polarized density functional theory calculations with supercell models. Calculations of point-defect formation energies as a function of the
Fermi level predict that Cr4+, Ru4+, and Rh3+ are the most favorable charge states substituting Al in w-AlN. With these preferred charge states, Cr-doped AlN is stable in the
ferromagnetic state, preferable for spintronic devices, across a wide concentration range (1.85 to 16.67% of Al). Conversely, Ru- and Rh-doped AlN are unstable in the
ferromagnetic state relative to the
antiferromagnetic state. Further investigation into the electronic density of states reveals a fascinating
evolution: for Cr concentrations below 5.56%, the
Fermi level resides within the band gap directly above the valence band maximum, keeping the system insulating. It transitions to a high-
spin half-metallic state between 7.40% and 12.96%, and finally transforms into a normal metal at 16.67% Cr. This behavior is absent in the DOS of the
antiferromagnetic model of Ru- and Rh-doped systems, where insulating and metallic behaviors instead appear non-sequentially with varying concentrations.
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Materials Science
The conductance filtration: sink-relative persistence and exact edge sensitivity for heat transport in particle-filled composites
Daisuke Yasufuku
We formulate the thermal conductance $g_e$ of a particle pair as three branch types – contact, near-contact and bond – within a single construction, and we introduce the filtration that takes this $g_e$ as its axis (the conductance filtration) together with persistence taken relative to the sink boundary. We then show that the dissipation share is exactly the logarithmic sensitivity of the effective conductance, and that a finite change of a single edge is predicted exactly in closed form. The allocation of the dissipation among branch types, and the idealisation ratio of each mechanism (interface,
matrix and particle), are thereby obtained as diagnostic quantities on one and the same graph representation.
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