Nuclear Theory
Wigner and mirror correlations in nuclear mass predictions with kernel ridge regression
X. H. Wu
Wigner- and mirror-correlated kernel ridge regression (WKRR) and its odd-even extension WKRRoe are developed to improve
nuclear mass predictions. The Wigner and mirror correlations are encoded entirely in the kernel functions without introducing more weight parameters. For experimentally known
nuclear masses, WKRRoe achieves a leave-one-out root-mean-square deviation of 98.0 keV, which falls below the often-quoted 100-keV scale discussed in connection with chaos-related limits. The gain is mainly concentrated in light
nuclei near $N=Z$ and is especially large for mirror pairs. Further tests show that WKRRoe can potentially improve predictions for experimentally unknown
nuclei near $N=Z$, particularly when their mirror partners have already been measured.
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Quantum Physics
Closing a single-copy gap to the Holevo bound with two-copy measurements
Changhao Li
The Holevo Cramér-Rao bound sets the asymptotically attainable precision of
quantum multiparameter estimation, but its attainability with finite
quantum state copies remains unresolved in general. While a gap between the single-copy optimum and the Holevo bound persists at any finite copy number for two-parameter estimation models, the higher-parameter case has remained open. Here we disprove universal finite-copy gap persistence beyond two parameters by constructing a three-parameter rank-two model whose Holevo bound is unattainable with one copy but attained exactly with two. We further prove finite-copy persistence for full-rank models with any number of parameters. We then experimentally implement the two-copy collective measurement for the constructed model using superconducting
qubits. We observe a two-copy estimation error below the single-copy and separate-measurement bounds determined from state
tomography. By introducing controlled depolarization, we show that this precision advantage persists over a finite noise range. Our results connect the attainability of ultimate
quantum precision to the structure of the multiparameter estimation model and the resources available for collective measurements.
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Materials Science
Orientation engineering is a universal strategy for ferroelectric trans-switching
Cameron Scott and Jorge Íñiguez-González
About two decades ago, “strain engineering” emerged as a powerful strategy to tune epitaxial thin films. Here we contend that ”orientation engineering” - that is, controlling the film's growth direction - constitutes a complementary design route that opens unprecedented opportunities and deserves greater
attention. Specifically, we show that orientation engineering can endow standard ferroelectric compounds with exotic and useful behaviors that may be difficult or impossible to obtain otherwise. Critically, we predict it readily enables ”trans-switching,” where polarization components switch perpendicularly to the applied electric field, paving the way for novel 3D device architectures. We also show that, by controlling the electric screening provided by electrodes in contact with the film, ferrielectric behavior can be obtained. Notably, one can even design an operational mode where the switching is, in effect, fully transversal to the applied field. Supported by phenomenological calculations for representative compounds LiNbO$_3$ and BaTiO$_3$, we thus propose orientation engineering as a powerful and general method to unlock unprecedented functionalities in common ferroelectrics.
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Strongly Correlated Electrons
Quantized Hyperfine Field at an Implanted $\mu^+$ Site in PrPb$_3$: Interplay between Localized $f$ Electrons and an Interstitial Charged Particle
T. U. Ito, W. Higemoto, K. Ohishi et al. (+6 more)
The local effect of an interstitial hydrogen-like particle on localized $f$ electrons was studied in PrPb$_3$ by means of $\mu^+$
spin rotation and relaxation. Spontaneous $\mu^+$
spin precession with harmonic frequencies was observed for the first time in $f$ electron compounds. We demonstrate that the signal is derived from a coupling between the $\mu^+$
spin and the hyperfine-enhanced
nuclear spin of nearest neighbor (nn) $^{141}$Pr with Ising-like anisotropy. The signal also suggests a marked suppression of
spin dynamics of the nn $^{141}$Pr in comparison with that of the bulk $^{141}$Pr. These facts strongly indicate modification of the $f$ electronic state due to the interstitial charged particle.
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All authors T. U. Ito, W. Higemoto, K. Ohishi, N. Nishida, R. H. Heffner, Y. Aoki, A. Amato, T. Onimaru, H. S. Suzuki
Cosmology and Nongalactic Astrophysics
Cross-correlating Squared kSZ and HI Intensity Fields: A Map-level ACT–MeerKAT Forecast
Yu-Er Jiang, Yun Liu, Yan Gong et al. (+5 more)
The kinetic Sunyaev–Zel'dovich (kSZ) effect probes the line-of-sight momentum of free electrons, but its blackbody spectrum and velocity-dependent sign make it difficult to isolate and cause conventional cross-correlations with density tracers to vanish. In this work, we investigate the cross-correlation of the squared kSZ field with the projected squared HI intensity field using mock ACT and MeerKAT observations constructed from a Jiutian-1G simulation lightcone. We generate
halo-based kSZ maps and MeerKAT-like HI brightness-temperature cubes over a $13.5^\circ\times13.5^\circ$ field. The simulations incorporate ACT beam smoothing and effective internal-linear-combination noise, together with the frequency-dependent MeerKAT beam, scanning strategy, map-making, and inhomogeneous thermal noise. We analyze signal-only, idealized amplitude-reconstructed, and Wiener-filtered kSZ maps. The resulting squared-field cross-correlations have diagnostic cumulative signal-to-noise ratios of approximately $3$-$4$. Our map-level results demonstrate the detectability of the ${\rm kSZ}^2\times {\rm HI}^2$ correlation in future joint ACT–MeerKAT observations.
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All authors Yu-Er Jiang, Yun Liu, Yan Gong, Zi-Yan Yuwen, Yin-Zhe Ma, Furen Deng, Xuelei Chen, Qi Guo
Quantum Physics
Exact Trotterization in the Degenerate Quantum Rabi Model
I. Lizuain and A. Rodriguez-Prieto
Digital
quantum simulation of the
quantum Rabi model in the deep strong coupling regime motivates the need for an exact characterization of Trotterization errors, so far known only through qualitative bounds. Here we derive such a characterization in the exactly solvable degenerate limit, valid for arbitrary coupling strength. The first-order Trotter operator admits a closed expression, showing that the generated phase-space trajectory lies exactly on a circle that is rescaled and rigidly rotated with respect to the exact one, rather than merely approximating it. This
geometric renormalization yields a closed form for the state fidelity, structurally identical to the physical survival probability governing revivals in the deep strong coupling regime: both are the same
geometric question – the distinguishability of a displaced Fock state – applied to two different pairs of points in phase space. We further show that this
geometric error is exactly correctable by promoting the Trotter-step coupling to a complex amplitude, at no additional
circuit cost. These results, obtained in the exactly solvable degenerate limit, provide a
benchmark for Trotterization errors in the general Rabi model.
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Instrumentation and Methods for Astrophysics
LUMA: A CNN for Strong Gravitational Lens Searches in Astronomical Imaging
Giovanni Vincenzo Donatiello, Achille A. Nucita, Francesco De Paolis et al. (+2 more)
We present LUMA, a convolutional neural network (CNN) pipeline for the automated detection of strong gravitational lenses in simulated astronomical imaging. The method combines a physically motivated preprocessing stage, which enhances faint arc and ring features, with a compact three-block CNN trained using class reweighting and modern learning-rate scheduling. On simulated data, the model reaches test accuracies of about $96$% and receiver operating characteristic (ROC) area-under-the-curve (AUC) values of $\simeq 0.99$ for the non-trivial classes, while confusion-
matrix analysis shows high completeness and purity for lens candidates. These results demonstrate that relatively lightweight CNN architectures can provide a competitive baseline for strong-lens searches, and they motivate future extensions toward real survey images and
transformer-based models.
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All authors Giovanni Vincenzo Donatiello, Achille A. Nucita, Francesco De Paolis, Antonio Franco, Francesco Strafella
General Relativity and Quantum Cosmology
Holographic dark energy in Einstein-Cartan spin cosmology
Yongjun Yun and Jungjai Lee
We show that, in Einstein-Cartan theory, the torsion scalar modifies the
dust-like equation of state of non-interacting
holographic dark energy with the Hubble radius as the infrared cutoff, enabling late-time
cosmic acceleration within the low-
redshift domain of validity, which is not realized in the corresponding model in general relativity. Using the same
holographic dark energy background, we further derive the torsion-induced modification of the
cosmic distance duality relation, $d_L=d_A(1+z)^2(1+\eta)$. In the late-time universe, the magnitude of the deviation parameter, $|\eta|$, is small but non-vanishing, reflecting the cumulative effect of torsion along the light-propagation path.
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Disordered Systems and Neural Networks
Locking transition in coupled disordered systems
Guy Bunin
When a system of many interacting constituents is extended across space, every region carries the same disordered landscape, and it is unclear whether distant regions settle into the same state. We study copies of the Random Energy Model (REM), sharing one disorder realization, coupled along a chain. A first-order transition separates a phase with short-range correlations, from a locked phase in which the entire chain occupies the lowest-energy state with probability one, even at positive temperature. No intermediate ordering lengths occur. In the Generalized REM the chain locks either to the lowest-energy state or to the lowest free-energy valley.
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High Energy Physics (Phenomenology)
An Operator Analysis of Radiative Muon Decay
Arvind Rajaraman and Chao-Hsiang Sheu
New physics beyond the Standard Model (SM) may induce new four-
fermion interactions. We investigate the sensitivity of radiative
muon decay, $\mu^-\to e^-\bar\nu_e\nu_\mu\gamma$, to such four-
fermion interactions of mass dimension seven and eight. For each operator, we calculate its interference with the SM amplitude and obtain an analytic expression for the decay rate. We apply these to a log-likelihood comparison for a
benchmark sample of $10^5$ events, and find that these operator contributions can be distinguished from the SM prediction at characteristic coefficient magnitudes between $10^{-9}$ and $10^{-8}$.
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Medical Physics · Cross-listed from cs.CV
You Cannot Recover What Was Never Measured: Quantifying the Information Ceiling of Ultra-Low-Field MRI Super-Resolution
Prathamesh Pradeep Khole, Shreya Handa, Utkarsh Gupta et al. (+1 more)
Generative super-resolution models can turn portable 64 mT MRI into images that look like 3T scans, and the field evaluates them with PSNR, SSIM, and pixelwise uncertainty, most often on pairs built by synthetically degrading high-field images. Prior work acknowledges that these models hallucinate and that the problem is ill posed, but to our knowledge no study measures how much information about the individual subject the real low-field scan actually contains. We measure it. Using paired 64 mT and 3T scans of the same subjects from three public
datasets, and a measurement protocol validated on tests whose correct answer is known in advance, we find that, judged over the whole
brain, real 64 mT scans carry structure specific to the individual only down to approximately 3 to 4 mm half-pitch in plane, and coarser still through plane. Standard synthetic degradations preserve subject information roughly 1 mm beyond this ceiling, so models trained and benchmarked on synthetic pairs are evaluated on information that real scanners never record. We then test trained
diffusion models and a publicly released external model on real paired acquisitions; 24 trained runs of five architectures (GAN,
diffusion, and
transformer families) give the coverage of the audit. On every subject where faithfulness can be measured, fine output detail is no more correlated with the subject's own 3T scan than with a stranger's, while sample-variance uncertainty does not distinguish fabricated structure from reconstruction difficulty. Because PSNR and SSIM score resemblance to a reference rather than whether detail belongs to the subject, a
benchmark scored by them cannot tell recovery from fabrication. Code for the measurement protocol will be released so that recoverability claims can be tested for newer models.
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All authors Prathamesh Pradeep Khole, Shreya Handa, Utkarsh Gupta, Razvan Marinescu
Quantum Physics
Ordering controlled by the measurement-feedback interval in quantum Boltzmann samplers
Peng Wang, Yu-Xuan Zhang, Hai-Tao Ding et al. (+1 more)
We show that the measurement–feedback interval alone can induce ordering in a
quantum Boltzmann sampler with fixed programmed couplings and a fixed local dissipative rule. At zero environmental dephasing, repeated projective measurements remove transverse coherence regenerated during relaxation, thereby enhancing the local longitudinal response. We derive the exact finite-interval Markov kernel for successive measurement records and obtain the ordering threshold in the Curie–Weiss limit. For couplings below the
equilibrium Curie–Weiss threshold, shortening the readout interval drives a continuous transition to an ordered stationary state even though the programmed Boltzmann distribution remains disordered. The stationary response and equation of state map exactly onto those of a continuously interacting model with dephasing, while the linear relaxation rates remain distinct at matched static response. Exact finite-size stationary calculations reveal the transition through bimodal magnetization distributions and mean-field critical scaling.
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All authors Peng Wang, Yu-Xuan Zhang, Hai-Tao Ding, Leong-Chuan Kwek
Astrophysics of Galaxies
Morphological Identification of Dynamical Regimes in MHD Turbulence with ScaleAware-JEPA
Mengke Zhao, Guang-Xing Li and Keping Qiu
The morphology of turbulent interstellar gas reflects the coupled action of
turbulence,
magnetic fields, and self-
gravity, but density amplitude alone does not uniquely specify dynamical state. We use ScaleAware-JEPA to learn multiscale structural coordinates from density alone and test whether these learned coordinates organize dynamical states more clearly than density-based conditioning. Clump-like, filament-like, and diffuse-like latent neighborhoods show an ordered progression in turbulent velocity scaling that is not reproduced by density-selected populations. Velocity and
magnetic fields are withheld during training and used afterward as post-training physical diagnostics: MHD states occupy ordered but overlapping regions of the learned representation, and dimensionless dynamical balances vary coherently across the full latent atlas. These results show that a representation learned from density morphology can acquire a geometry that is systematically organized by established MHD diagnostics. Multiscale morphology therefore provides a useful coordinate for dynamical state beyond density amplitude alone.
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Fluid Dynamics
Radial flow of an Oldroyd-B fluid: theoretical and simulation results in the ultra-dilute limit
Ron Lottem and Evgeniy Boyko
Pressure-driven radial flows of viscoelastic fluids are common in various industrial applications, such as injection molding and extrusion. It is well known that viscoelastic rheology can significantly impact the hydrodynamic features of non-Newtonian flows. However, these hydrodynamic features remain not fully understood compared to those observed in Newtonian flows. We analyze the pressure-driven radial flow of an Oldroyd-B fluid between parallel plates and present a theoretical framework together with finite-element numerical simulations for determining the flow rate-pressure drop relation. Unlike previous theoretical studies restricted to the weakly viscoelastic limit of low Deborah ($De$) numbers, we apply lubrication theory and consider the ultra-dilute limit, which allows us to study viscoelastic radial flows at order-one Deborah numbers. Using the one-way coupling between the Newtonian velocity profile and elastic stresses, we derive closed-form expressions for the conformation tensor and pressure drop in the ultra-dilute limit. We show that the pressure drop monotonically increases with $De$, identify the physical mechanisms governing this increase, and delineate the range of validity of the ultra-dilute approximation. We further reveal that the low-$De$ asymptotic analysis of the pressure drop may fail to accurately capture finite-element simulation results, even at low Deborah numbers, owing to its inability to satisfy the inlet elastic stresses. In contrast, our theoretical predictions based on the ultra-dilute limit are in excellent agreement with the finite-element simulation results, enabling us to elucidate the pressure drop behavior for order-one Deborah numbers.
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High Energy Physics (Phenomenology)
Does the High Energy LUX-ZEPLIN Event Suggest Hyperfine Atomic Dark Matter?
Prolay Chanda, Bhaskar Das and Sagnik Mukherjee
The LUX-ZEPLIN (LZ) Collaboration has reported a
nuclear-
recoil candidate at $248\pm23~({\rm stat})\pm23~({\rm sys})~{\rm keV}$ in an extended high energy search window. We investigate whether this event can arise from the hyperfine excitation of hydrogen-like atomic dark matter. For a TeV-scale dark atom, a hyperfine splitting near $340~{\rm keV}$ places xenon scattering close to the observed value by naturally selecting the high-velocity tail of the
Galactic halo while suppressing the leading low-energy elastic response. The resulting endothermic kinematics predict a pronounced target hierarchy: the
benchmark transition is inaccessible on Ar and Ge, lies close to threshold on Xe, and remains open on heavier targets such as W, which is specific to our model parameters. Because xenon probes the extreme high-speed tail, the signal exhibits a large annual modulation and a strong dependence on the assumed
halo distribution. We also examine how the infall of the Large Magellanic Cloud enhances the high-speed tail of the Milky Way's local dark matter distribution, extending the kinematic reach to larger hyperfine splittings.
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Astrophysics of Galaxies
Dynamical friction vs. subhalo heating in Cold Dark Matter haloes
Jorge Peñarrubia, Pierfrancesco Di Cintio, Eduardo Vitral et al. (+1 more)
The orbital
evolution of massive
stellar systems embedded in dark matter
haloes is governed by competing processes. Dynamical friction removes orbital energy, whereas fluctuations in the gravitational field generated by dark matter subhaloes inject energy through
stochastic heating. We investigate the balance between these two mechanisms using analytical arguments and numerical experiments. We show that, for a given host
halo and subhalo population, there exists a critical mass $M_{\rm crit}$ at which heating and friction balance. Clusters with masses $M_{\rm cl}>M_{\rm crit}$ lose orbital energy and sink towards the centre of the
halo, whereas those with $M_{\rm cl}<M_{\rm crit}$ gain energy and expand outwards. At $M_{\rm cl}\simeq M_{\rm crit}$, the two processes balance, leading to a cluster population that, on average, neither sinks nor expands within the host
halo. In CDM
haloes, the critical mass is primarily controlled by the upper end of the subhalo mass function. Since massive subhaloes are intrinsically rare, the balance between heating and friction shows substantial
halo-to-
halo scatter. For dark matter
haloes in the mass range associated with
dwarf spheroidal
galaxies (dSphs), we find $M_{\rm crit}\gtrsim 10^5M_\odot$, comparable to the masses of globular clusters in the Fornax dSph.
Stochastic heating by dark substructure may therefore significantly delay the orbital decay of globular clusters and help alleviate the Fornax timing problem.
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All authors Jorge Peñarrubia, Pierfrancesco Di Cintio, Eduardo Vitral, Matthew G. Walker
Mathematical Physics
Analysis of Delay Differential Equations Using the Offset Linear Canonical Transform
Gita Rani Mahato and Manab Kundu
Motivated by the work of Ohira and the advantages of the offset linear canonical transform (OLCT) over the
Fourier transform (FT), this paper proposes an OLCT based framework for solving a class of delay differential equations. By exploiting the operational properties of the OLCT, the original delay differ- ential equation is transformed into a Volterra-type delay integral equation in the transform domain and solved numerically using Brunners method of steps . An explicit analytical solution is derived for a special case to investigate the effect of the delay parameter. A unified transform-domain formulation is also established by relating the proposed OLCT approach to its
Fourier transform counterpart. Numerical and graphical results demonstrate the accuracy and effectiveness of the proposed method and validate it through comparisons with the
Fourier transform based formulation of Ohira . The proposed framework may provide a promising foundation for solving non linear delay differential equations involving transcendental terms, as both the OLCT and the resulting Volterra integral equation possess the essential properties required to handle non linearities and transcendental terms.
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Materials Science
Evidence for Distributed Fault Energetics and Their Impact on Deformation in a Chemically Complex Alloy
Kaijun Yin, Jun-Ping Du, Peijun Yu et al. (+7 more)
Chemically complex
alloys feature intrinsically heterogeneous local chemical environments and, consequently, fluctuations in local fault energetics. However, experimentally quantifying their relationship remains challenging, leaving the role of this distributed energy landscape in deformation mechanisms incompletely resolved. Here, we develop a distribution based framework linking experimentally measured stacking fault widths to deformation relevant apparent fault energy, revealing a distributed local fault-energy landscape in CrCoNi. The framework reveals the stabilizing role of energy fluctuations and captures an upward shift in the apparent fault energetics, from negative values toward zero following heat treatment, which atomistic simulations associate with the emergence of L12 type chemical short-range order. Using one-dimensional kinetic Monte Carlo simulations, supported by electron microscopy observations, we further show that history-dependent changes in the local fault-energy landscape bias the competition among stacking faulting, nano-twinning and HCP transformation in CrCoNi. Our results provide an experimentally anchored, distribution-based framework for understanding deformation in chemically complex
alloys as it evolves within a distributed fault-energy landscape shaped by local chemical order.
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All authors Kaijun Yin, Jun-Ping Du, Peijun Yu, Rui Feng, Hanyu Hou, Haw-Wen Hsiao, Ke An, Peter K. Liaw, Shigenobu Ogata, Jian-Min Zuo
Instrumentation and Detectors
Development and Performance Study of a Capillary Liquid Scintillator Neutron Detector
Guang Luo, Jian Yu, Dikai Li et al. (+9 more)
Capillary
liquid scintillator detectors are promising for high-resolution
neutron imaging, yet experimental data on their light spread mechanism and spatial performance remain limited. Here, we report a
neutron detector based on a hexagonal capillary array filled with EJ-309
liquid scintillator, with an inner diameter of about 50 um and a camera readout of 9 um pixels.
Laser experiments show that the FWHM of the full light spot decreases from 260 um to 90 um with a metal light absorber, confirming effective suppression of lateral light spread. Using an AmBe
neutron source, an effective field of view with a 5-sigma threshold was established from background frames. For single-capillary events, the pulse height spectrum follows a Landau distribution with a most probable value of 0.133 +/- 0.001 (stat.), and the intrinsic detection efficiency is 10.07% +/- 1.26% (stat.) +/- 1.43% (syst.), corresponding to about 13.55% when normalized to the active
liquid scintillator area. The point spread function core yields a radial FWHM of 12.8 um and a centroid positioning precision of approximately 5.5 um (1 sigma), while the intrinsic position resolution is limited by the capillary pitch to 54 um. Linearity is good for 1 to 2 capillaries, with deviation appearing for 2 to 3 capillaries due to additional capture of spread light. These results provide experimental basis and physical understanding for imaging applications of capillary
liquid scintillator
neutron detectors.
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All authors Guang Luo, Jian Yu, Dikai Li, Yanmeng Dai, Meiling Chen, Jiaqiang Zou, Ke Yan, Shaoxuan Cui, Ge Jin, Zhao Xu, Chunhui Zhang, Leifeng Cao
Astrophysics of Galaxies
Testing KMTNet–PRIME Optical–Near-Infrared Source-Color Constraints in KMT-2024-BLG-0211 and KMT-2024-BLG-1522
Kansuke Nunota, Jennifer C. Yee, Takahiro Sumi et al. (+37 more)
We present analyses of two 2024 microlensing events, KMT-2024-BLG-0211 and KMT-2024-BLG-1522, jointly observed by KMTNet in the optical and
PRIME in the near-infrared. For KMT-2024-BLG-0211, the KMTNet–
PRIME $I-H$ color provides a useful constraint on the angular source radius for a short-timescale finite-source event with a
giant source. The event is consistent with a low-mass
stellar lens, although the weak parallax constraint leaves the lens mass and distance uncertain. For KMT-2024-BLG-1522, we compare the results obtained from $V-I$, $I-H$, $V-H$, and $J-H$ color constraints. The microlensing parameters are nearly identical among the four analyses, yielding a robust binary-lens solution with nearly equal masses. However, the inferred source properties and lens physical parameters depend on the adopted source color because the different color estimates imply different angular source radii. Comparing the $(V-I)_{\rm KMT}$ versus $(I-H)_{\rm KMT,PRIME}$ plane shows that the inferred source colors lie off empirical color–color relations but within the scatter of observed
stars. The prevalence of such deviations should be tested with a larger sample of KMTNet–
PRIME events and this specific case can be further tested with future adaptive-optics follow-up, which can directly measure the lens–source relative proper motion and lens flux.
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All authors Kansuke Nunota, Jennifer C. Yee, Takahiro Sumi, Ryusei Hamada, Ian A. Bond, Andrew Gould, Weicheng Zang, David P. Bennett, Aparna Bhattacharya, Kotaro Daimon, Yuki Hirao, Stela Ishitani Silva, Shuma Makida, Shota Miyazaki, Tutumi Nagai, Seiya Nakayama, Ryo Ogawa, Ryunosuke Oishi, Hideaki Ose, Nicholas J. Rattenbury, Yuki K. Satoh, Daisuke Suzuki, Takuto Tamaoki, Motohide Tamura, Sean K. Terry, Chihiro Ueda, Aikaterini Vandorou, Hibiki Yama, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Hongjing Yang, Dong-Jin Kim, Chung-Uk Lee, Byeong-Gon Park
General Relativity and Quantum Cosmology
Correspondence between multileaf topology of closed geodesics and spatiotemporal autocorrelations of hotspot images in Schwarzschild spacetime
Fengting Xie, Qing-Hua Zhu and Xin Li
The classification of relativistic closed orbits by their multileaf structures provides a framework for studying strong-field dynamics. Identifying these structures in astronomical images remains challenging. Using ray tracing, we construct the spatiotemporal autocorrelations of the primary image of a pointlike hotspot moving along bound closed geodesics around a Schwarzschild black hole. These orbits are classified by three integers $(z,w,v)$, where $z$ counts the leaves, $w$ counts the additional whirls during each radial period, and $v$ specifies the order in which the orbital leaves are traced. For the orbit families examined, our numerical results establish a correspondence between the topological integers $(z,w,v)$ and the numbers of correlation bands $N_{\rm band}$ and recurrence points $N_{\rm rec}$. The integers are recovered as $z=N_{\rm rec}-1$, $w=\left\lfloor (N_{\rm band}+1)/(N_{\rm rec}-1)\right\rfloor-1$, and $v=(N_{\rm band}+1)\bmod(N_{\rm rec}-1)$. Here, $\lfloor x\rfloor$ denotes the greatest integer not exceeding $x$, and $\bmod$ denotes the remainder operation. These relations provide a quantitative method for recovering closed-orbit
topology from hotspot image autocorrelations.
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High Energy Physics (Theory)
Dirichlet gravitons in AdS$_4$ and $\mathcal{L}_{\Lambda}w_{1+\infty}$ wedge algebra
Hare Krishna
We derive the AdS deformation of the flat-space soft-graviton
algebra with Dirichlet boundary conditions. Starting from the AdS$_4$ spinor-helicity representation, we Mellin-transform linearized graviton solutions and construct the AdS wedge, including its Laurent completion. The Dirichlet boundary condition pairs opposite helicities, while AdS covariance fixes their relative normalization. Assuming linear closure and normalizing the global modes to reproduce the
geometric AdS isometries, covariance and the Jacobi identities uniquely determine the soft-mode bracket. The result is the wedge of $\mathcal L_\Lambda w_{1+\infty}$, where $\Lambda=-\ell^{-2}$. This provides a bulk derivation of the cosmological-constant deformation that incorporates the AdS boundary condition, without relying on collinear splitting functions or a self-dual truncation.
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Materials Science
Synthesis and modification of thin NaSICON solid electrolytes using ion beams
Giovanni Ceccio, Jiri Vacik, Ivan Mastronardo et al. (+3 more)
Solid electrolytes (SEs) for sodium-based superionic conductors (NaSICON) were first introduced in 1976 and quickly recognized for their excellent ionic conductivity. While considerable effort has been made to develop thin electrolytes for all-solid-state batteries (ASSBs), only a few sodium-based SEs have been successfully fabricated as thin films. These thin films are particularly desirable for their reduced electrical resistance, which typically increases with the thickness of the SE. By reducing the thickness of the SEs to the nanometer scale, their ionic conductivity can be significantly enhanced. In this study, the NASICON composite was initially prepared in the form of pellets using the mixed
oxide technique with a planetary ball mill and synthesized by the solid-state method at 1300 {\deg}C. The resulting pellets were used as sputtering targets in a low-energy ion facility to prepare continuous NASICON nanofilms. To explore the effect of ion implantation on the electrical properties of NASICON, the prepared films were bombarded with Ni ions at 1.1 MeV and varying fluences, using the Tandetron accelerator at the CANAM infrastructure (NPI Řež). The electrical properties of both the synthesized and implanted films were analyzed through electrochemical impedance spectroscopy (EIS). The results, describing the impact of irradiation on NASICON's properties, are presented here.
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All authors Giovanni Ceccio, Jiri Vacik, Ivan Mastronardo, Clausia D Urso, Eva Stepanovska, Romana Miksova
Applied Physics
Study of LAGP coating on polyethylene separator for polysulfide suppression in thin Li-S batteries
Giovanni Ceccio and Jiri Vacik
The use of a thin solid electrolyte layer on polyethylene (PE) separators has been explored as a potential strategy to mitigate the polysulfide shuttle effect in lithium-sulfur (Li-S) batteries, a phenomenon responsible for significantly reducing their lifespan. While some solid electrolytes, such as LAGP , have demonstrated the ability to effectively suppress the shuttle effect, their brittle ceramic nature limits their application, particularly in flexible electronics. Coating PE separators with LAGP nanofilms offers a promising solution by combining the mechanical flexibility and thinness of
polymer separators with the electrochemical advantages of LAGP, due to its NASICON-like structure and high ionic conductivity. In this study, PE separators were coated with LAGP nanofilms using the ion sputtering technique and further modified with ferroic elements such as Ni and Co. The surface morphology of the coated separators was analyzed using scanning electron microscopy (SEM), and staircase voltammetry was employed to evaluate the electrochemical performance and modifications induced by the coatings. The results demonstrate that the use of PE separators with a thin LAGP layer significantly influences polysulfide
diffusion and suppresses the shuttle effect, thereby reducing unwanted processes in Li-S batteries.
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Materials Science
Fabrication framework for three-dimensional colloidal particles with decoupled geometry and material composition
Hamed Almohammadi, Gurminder K. Paink, Vasumathi Venkat et al. (+6 more)
Shape-programmable particles offer significant opportunities for microrobotic systems at the individual level and for hierarchical materials with emergent functionalities arising from collective particle behavior. However, fabricating shape-changing stimuli-responsive particles with complex three-dimensional geometries at colloidal length scales remains a major challenge. Here, we introduce a general fabrication framework that decouples particle geometry from material composition to produce free-standing three-dimensional colloidal particles with complex architectures. Our approach combines soft lithography, swelling-assisted extraction, and sacrificial adhesive transfer to fabricate particles with high
geometric fidelity. We establish a predictive framework that defines the accessible design space for increasingly complex particle geometries. We further extend our framework to fabricate high-aspect-ratio pillar arrays with intricate three-dimensional architectures at colloidal length scales. To demonstrate material versatility, we fabricate particles from both
liquid crystal elastomers and hydrogels. We show reversible shape-changing behavior of
liquid crystal elastomer particles with cylindrical and
chiral shapes under thermal and optical stimuli. In suspension, these particles display collective optical dynamic behavior arising from coupling between changes in the programmed
liquid crystal organization within the particles and stimulus-induced
geometric reconfiguration of the particles. Collectively, this work establishes a versatile platform for geometry-programmable colloidal particles with emergent collective functionalities, providing a route toward materials and fluids with dynamically programmable properties.
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All authors Hamed Almohammadi, Gurminder K. Paink, Vasumathi Venkat, Jacopo Movilli, Atalaya Milan Wilborn, Haritosh Patel, Haichao Wu, David Weitz, Joanna Aizenberg
Astrophysics of Galaxies
Broadband reverberation mapping of quasars at cosmic noon
Juan V. Hernández Santisteban
Broadband reverberation mapping provides a powerful tool to investigate the structure of the
accretion flow around supermassive black holes. The ultraviolet region of the
quasar spectrum is of particular interest, as it enables the disentanglement of the relative contributions from the
accretion disc and the broad-line region to the observed variability of
quasars in the local Universe. Observations of
quasars at
cosmic noon ($z\sim 1-2$) offer the opportunity to probe the UV emission across a diverse population, spanning a broad range of black hole masses and luminosities. Here we re-analysed the 36 multi-year
quasar lightcurves from the Dark Energy Survey (DES) between $z\sim0.7-2$ to retrieve interband delays and analyse their spectral energy distribution. Using PyROA, we were able to fit all multiple years of observations and the four optical bands simultaneously, significantly improving the lag detection as this method is able to interpolate over the seasonal gaps. We find robust detections of interband delays in 31/36
quasars, suggesting high-Eddington ratios for a large fraction of objects. Their spectral energy distribution is consistent with a geometrically thin disk $f_\nu\propto\lambda^{-1/3}$, with an ensemble slope of $-0.28\pm0.02$. The full sample of
quasars do not show excess around the Balmer jump region, suggesting the impact of the broad-line region to the reverberation signals in high-Eddington sources could be small as documented in some AGN in the local Universe. The prospect of LSST to observe thousands of
quasars in this
redshift range should motivate the detailed study of the UV-rest frame of high-Eddington
quasars to account for the BLR contribution and properly infer disc sizes.
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Nuclear Theory
Short-range correlated pairs from nucleon density profiles as a new probe of the nuclear equation of state
L. Ponnath, N. Barnea, I. Korover et al. (+6 more)
We investigate to what extent the observed
nuclear systematics of Short-Range Correlations (SRCs) can be described by the geometry of the underlying
proton and
neutron density distributions. Building on previous connections between
nuclear SRC contacts and one-body densities, we formulate an explicit density-overlap representation in which
proton–
proton,
proton–
neutron, and
neutron–
neutron SRC source terms are constructed from the full spatial density profiles obtained with Energy Density Functionals (EDFs). The framework contains two global parameters describing the overall SRC pair formation strength and the relative contribution of the
spin-singlet channel, while the
nucleus-dependent
evolution is generated by the density-overlap integrals. The framework simultaneously reproduces several independent experimental SRC observables, including
proton–
proton to
proton–
neutron pair ratios, relative SRC pair abundances, and
proton and
neutron high-momentum double ratios. A comparison between relativistic and Skyrme-type EDF families demonstrates the sensitivity of these observables to the underlying density geometry and allows the effect of the complete density profiles to be distinguished from simple radius-based geometrical estimates. Applied to
neutron-rich oxygen isotopes, the framework predicts a pronounced
evolution of the
neutron–
neutron pair abundance. Comparison with an independent calculation based on occupied harmonic-oscillator wave functions and an explicit finite-distance criterion supports the predicted isotopic
evolution in
neutron-rich oxygen isotopes. This agreement identifies the
proton–
proton to
neutron–
neutron SRC pair ratio as a promising experimental probe of
neutron-skin thicknesses in
neutron-rich
nuclei and, through their connection to the
symmetry energy, of the
nuclear equation of state.
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All authors L. Ponnath, N. Barnea, I. Korover, S. Paschalis, M. Petri, E. Piasetzky, X. Roca-Maza, S. Typel, I. Wischnevsky Shlush
Astrophysics of Galaxies
Population search for dark matter spikes in megamaser rotation curves
Gonzalo Herrera
A black hole growing adiabatically inside a dark matter
halo is expected to develop a dense spike, with a power-law slope between 1.5 and 2.5, depending on
redshift and baryonic activity. Direct dynamical tests of this prediction are almost non-existent. Here we show that water megamaser disks offer one; their masers orbit within a parsec of the black hole and are mapped individually with very long baseline interferometry, so the enclosed mass at each radius can be read off the rotation curve. We develop a search method and apply it to eleven megamaser disks with public kinematics. Compared with a black hole alone, a spike is preferred in NGC 1194 and NGC 4258 and moderately improves the fit in several others. Allowing the disks to warp removes this preference in all but NGC 4258 and NGC 6264. No combination of disks, warped or not, allows a spike heavier than about ten per cent of the black hole mass, a sensitivity validated with mock injection tests. Mapping the warps with maser accelerations and detecting fainter inner masers, where a spike and a tilt differ most, can break the remaining degeneracy. Megamaser disks open a window onto dark matter around supermassive black holes, and, importantly, one that enables population statistics.
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Optics
Multiplexed chiral and helical acoustic anomaly bulk states in an inverse-designed metamaterial
Xueyun Wen, Zhihao Lan, Zhongming Gu et al. (+2 more)
Valley and pseudospin are fundamental degrees of freedom (DOFs) in topological acoustics. However, they have so far been realized mostly in separate systems. Here, we achieve the multiplexing of valley and pseudospin DOFs in one acoustic system. An acoustic metamaterial simultaneously hosting single and double Dirac cones is inversely designed by the developed
topology optimization method. Thereafter, under a hard-boundary condition, valley-locked
chiral states and pseudospin-locked helical states emerge within two separate frequency windows and can be selected by tuning the operating frequency. Furthermore, their applications for multifrequency acoustic energy enhancement are experimentally demonstrated. Our work provides a strategy to modulate acoustic waves carrying distinct topological DOFs within a single integrated platform, facilitating the development of multiplexed acoustic devices with robustness.
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All authors Xueyun Wen, Zhihao Lan, Zhongming Gu, Yafeng Chen, Jie Zhu
Computational Physics
Label-Permutation Symmetry and Stability in Oscillator Potts Machines
E.M. Hasantha Ekanayake and Nikhil Shukla
Oscillator Potts machines (OPMs) provide a physics-inspired, energy-minimization framework for solving combinatorial optimization problems described by the $q$-state Potts
Hamiltonian. Although OPMs may be viewed as multistate extensions of oscillator Ising machines (OIMs), here, we show that they exhibit dynamical properties absent in the binary case. Specifically, we derive a configuration-dependent local-stability condition for a recently proposed multiharmonic OPM formulation and show that configurations with the same Potts energy need not be dynamically equivalent. In particular, for $q\geq4$, permutations of the Potts labels can alter the Jacobian spectrum and, consequently, the regularization strength required to locally stabilize a given Potts configuration. Thus, different phase encodings of the same Potts solution can exhibit different local stability properties despite having identical Potts energies.
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