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Physics

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Saturday 19 September

Strongly Correlated Electrons

Correlation-assisted spin-selective metallicity in strained and bilayer altermagnets

Marnin J. Di Nunzio, Frank Lechermann and Ilya M. Eremin

Altermagnets combine vanishing net magnetization with a momentum-dependent spin-split electronic structure, providing a route to spin-polarized carriers without ferromagnetism. Here, we investigate how electronic correlations, doping, uniaxial strain, and interlayer coupling control altermagnetism within a minimal Hubbard-type model for mono- and bilayer systems. Comparing Hartree–Fock theory with the rotationally invariant slave-boson (RISB) approach, we demonstrate the robustness of altermagnetic order against quasiparticle renormalization and reveal a separation between the onset of magnetic order and the loss of quasiparticle coherence at stronger coupling. In the monolayer, doping produces a pronounced particle–hole asymmetry, while its combination with uniaxial strain generates a fully spin-polarized Fermi surface close to half-filling. In the bilayer, stacking that favors ferroic alignment of the layer altermagnetic order parameters allows their momentum-dependent spin splittings to combine constructively. Weak asymmetric doping additionally induces intra-unit-cell charge order, resulting in fully spin-polarized low-energy carriers. At a bilayer filling of five electrons in four orbitals, we find a continuous paramagnet-to-altermagnet transition followed, at stronger coupling, by an evolution toward a Mott-like regime with strongly suppressed quasiparticle weight. Our results establish correlations, strain, doping, and stacking as complementary means of controlling altermagnetic metals and generating fully spin-polarized Fermi surfaces.
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Atmospheric and Oceanic Physics

ClimTip-GML: A global bias-corrected and downscaled dataset for assessing impacts of climate tipping events

Philipp Hess, Sebastian Bathiany, Lucas Ferreira Correa et al. (+3 more)

Assessing the impacts of future climate scenarios including tipping events of major Earth system components such as the Amazon rainforest (ARF) or the Atlantic meridional overturning circulation (AMOC), requires accurate and high-resolution simulations. Here, we present ClimTip-GML, the first globally bias-corrected and downscaled climate dataset for impact assessment of large-scale tipping scenarios, comprising eight key variables at 0.25{\deg} spatial resolution from three general circulation models (GCMs): CESM1-CAM5, HadGEM3-GC31-MM, and MPI-ESM1-2-HR. The dataset includes 100-year-long climate simulations with preindustrial and historical conditions, as well as scenarios at a +2{\deg}C warming level with and without tipping transitions of the AMOC or ARF. We apply generative machine learning (GML) techniques trained on reanalysis data to bias-correct and downscale the GCMs in a manner that is physically consistent across space, time, and all eight variables. Comprehensive validation shows substantially reduced biases, improved small-scale spatial variability, multivariate correlations, and consistent long-term climate responses to the external forcing and tipping events. The results hence permit substantially improved impact assessments of tipping transitions of the ARF and AMOC, directly informing mitigation and adaptation policies.
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All authors Philipp Hess, Sebastian Bathiany, Lucas Ferreira Correa, Laura C. Jackson, Casey R. Patrizio, Niklas Boers

Astrophysics of Galaxies

Surveying the Universe in 4D: Beating Cosmic Variance with Wide-Field Slitless Spectroscopy from HST, JWST, Euclid, Roman, and Beyond

Andreea Petric, Gaël Noirot, Stacey Alberts et al. (+71 more)

We summarize strategies, lessons learned, and future directions from the Space Telescope Science Institute workshop Surveying the Universe in 4D: Beating Cosmic Variance with Wide-Field Slitless Spectroscopy from HST, JWST, Euclid, Roman, and Beyond, held August 24–28, 2026. The workshop examined scientific results, observational and data analysis challenges, extraction tools, and future opportunities. Discussions highlighted (1) the transformative potential of WFSS for the study of transient phenomena, galaxy evolution –both spatially-resolved and within the broader context of the cosmic web–, and rare populations and (2) the synergies among Euclid and Roman surveys, Rubin-LSST monitoring, JWST WFSS, and high-resolution integral-field observations. Participants identified advances in forward modeling and physics-informed machine learning as essential for addressing spectral overlap, crowded fields, and upcoming, very large data volumes. Realizing WFSS's full potential will require community-wide infrastructure, science-ready data products, accessible cloud-based analysis tools, and robust benchmarking of reduction pipelines. Crucially, participants called for systemic changes to properly recognize early-career researchers who invest significant efforts in pipeline, code, and calibration developments that enable WFSS science, and stressed that progress requires collaborative, multidisciplinary practices that optimize the participation and benefits of the next generation.
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All authors Andreea Petric, Gaël Noirot, Stacey Alberts, Russell Ryan, Louis-Gregory Strolger, Vicente Estrada-Carpenter, Mainak Singha, Adrian E. Bayer, Olivier Gilbert, Farhanul Hasan, Mason Huberty, Bingcheng Jin, Xiangyu Jin, Anika Kumar, Kasra Mokhtarpour, Preethi Nair, Eleni Tsiakaliari, Vivian U, Brittany N. Vanderhoof, Arshia Akhtarkavan, Natalia Alvarez-Ibanez, Roman Fernandez Aranda, Tri L. Astraatmadja, Clive Binu, Claire Bolda, Westley Brown, Guillermo Romero Cruz, Mohamed H. Abdullah, Jeremy Favaro, Mason Footh, Helen Fraser, Yuming Fu, Annie Giman, Nicolas Gomez, Massimo Griggio, Peter Gwartney, Aryana Haghjoo, Fabian Hervas-Peters, Jiamu Huang, Sandra Jaison, Jeyhan S. Kartaltepe, Sarah Kendrew, Ivan Kramarenko, Sahana Kumar, Zhaoran Liu, Arianna S. Long, Sangeeta Malhotra, Faezeh Manesh, Jasleen Matharu, Vihang Mehta, Edward M. Molter, Ivelina Momcheva, Zhiwei Pan, Yuxuan Pang, Pallavi Patil, Rachel Plesha, Marc Rafelski, Mitchell Revalski, Jyotika Roychowdhury, Gregory Rudnick, Swetha Sankar, Maya Seagraves, Lu Shen, Sabnam Shrestha, Manuchehr Taghizadeh-Popp, Jo Taylor, Wei Leong Tee, Scott Tompkins, Feige Wang, Xin Wang, Isak Wold, Jerry J.-Y. Zhang, Qianqiao Zhou, Zihao Zuo

Plasma Physics

Real-Time Plasma State Prediction via FPGA-Accelerated Quantized Recurrent Probabilistic Neural Networks

Daniel Gaytan-Villarreal, Aiken Xie, Tu Pham et al. (+5 more)

Real time plasma state estimation for control of Tokamak devices are challenging due to the stringent latency requirements of the plasma control system (PCS). We present an end-to-end workflow for deploying a recurrent probabilistic neural network (RPNN) on FPGA hardware. We combine architecture size reduction with quantization-aware training via QKeras. The model is then synthesized using hls4ml, targeting a Xilinx Alveo U50 device. We report a design that fits comfortably within all four resource budgets (DSP, LUT, FF, BRAM) at deterministic sub-10~$\mu$s single-timestep latency, meeting the requirements for real-time inference inside a model-predictive-control-style plasma control loop.
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All authors Daniel Gaytan-Villarreal, Aiken Xie, Tu Pham, Rohit Sonker, Chiara Amendola, Matteo Cremonesi, Cong Hao, Jeff Schneider

Astrophysics of Galaxies

Star formation and morphological trends in the Antlia cluster: Probing environmental influence out to 5R200

Ciria Lima-Dias, Antonela Monachesi, Gissel P. Montaguth et al. (+48 more)

Galaxy evolution in dense environments such as clusters is strongly affected by environmental processes that can alter both morphology and star formation activity. We investigate these effects in the Antlia cluster out to 5R200 using Southern Photometric Local Universe Survey (S-PLUS) data. We derive H-alpha-based star formation rates from the J0660 band and Sersic indices with GALFITM. Our analysis focuses on 154 spectroscopically confirmed galaxies brighter than mr = 16. We classify galaxies as early- or late-type systems using colour and Sersic index, and as quenched or star-forming using specific star formation rate. We examine their dependence on clustercentric distance, projected phase-space, substructure, and local density. We find that star-forming galaxies dominate from 1 to 5R200, while quenched galaxies are more common within 1R200. Early- and late-type galaxies show similar radial trends, with comparable fractions within 1R200 and a higher late-type fraction at larger radii. Quenched galaxies dominate at log(Sigma10 [Mpc^-2]) >= 1.5, whereas late-type galaxies dominate at log(Sigma10 [Mpc^-2]) <= 1.0. We identify substructures extending from the cluster centre to the outskirts. Substructures outside the central region are dominated by star-forming and late-type galaxies, with fractions similar to those of galaxies not associated with detected substructures. However, when the massive central structure is included, the fraction of star-forming galaxies in substructures decreases, indicating a more environmentally processed population in the central region. Altogether, the presence of a massive central substructure together with additional substructures detected out to 5R200 indicates that Antlia is still undergoing mass assembly through group accretion, consistent with a dynamically active and young cluster that is still assembling its galaxy population.
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All authors Ciria Lima-Dias, Antonela Monachesi, Gissel P. Montaguth, Rodrigo F. Haack, Daniela E. Olave-Rojas, Hugo Méndez-Hernández, Sergio Torres-Flores, Luis Otárola, Juan Pablo Calderón, Analía V. Smith Castelli, Yara L. Jaffé, Christopher P. Haines, Diego Pallero, Vitor M. Sampaio, Cristóbal Sifón, Alvaro Alvarez-Candal, María Argudo-Fernández, Simón Véliz Astudillo, Maiara S. Carvalho, Letizia P. Cassarà, Cheng Cheng, Arianna Cortesi, Ricardo Demarco, Alexis Finoguenov, Marcos Fonseca-Faria, Thiago S. Gonçalves, Eduardo Ibar, Iván Lacerna, Elismar Lösch, Angela C. Krabbe, Ulrike Kuchner, Erik V. R. Lima, Amanda R. Lopes, Vitor H. Lopes-Silva, Amrutha B. Manjunatha, Natanael M. Cardoso, Sebastián Ortiz-Gómez, Gustavo B. Oliveira Schwarz, Umberto Rescigno, Boudewijn F. Roukema, Nicolás Tejos, Eduardo Telles, Benedetta Vulcani, Stephane V. Werner, Laerte Sodré Jr, Fábio R. Herpich, Felipe Almeida-Fernandes, Antonio Kanaan, Tiago Ribeiro, William Schoenell, Claudia Mendes de Oliveira

Chemical Physics

ECENet: An Edge Cluster Expansion Line-Graph Neural Network

R. Allen LaCour and Teresa Head-Gordon

Machine-learned interatomic potentials (MLIPs) have emerged as a promising alternative to classical force fields and first-principles theory for predicting the properties of chemical and material systems. Many MLIPs are graph neural networks with O(3)-equivariant features, whose accuracy comes at substantial computational cost. Here we introduce the edge cluster expansion (ECE), an analogue of the atomic cluster expansion in which the environment is expanded around edges between atom pairs rather than single atoms, and build upon it to develop the line-graph neural network ECENet. ECENet uses O(2)-equivariant features that persist on the edges between atoms, giving it natural access to O(2) operations that are cheaper and less restrictive than their O(3) counterparts. ECENet performs at the state of the art on the MD22 benchmark and lies on the accuracy-cost Pareto frontier when trained on the SPICE-MACE-OFF dataset. Furthermore, with long-range electrostatics implemented via latent Ewald summation, ECENet accurately predicts molecular dipole moments and the infrared spectrum of liquid water. The frontier ECENet architecture establishes equivariant edge-centered representations as an efficient and physically expressive foundation for equivariant MLIPs.
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Mesoscale and Nanoscale Physics

Magnetic Quadrupole Lens and Current-Induced Quadrupolar Dynamics of Antiskyrmion

Linfeng Du, Yang Liu, Peng Yan et al. (+1 more)

We demonstrate that antiskyrmions can serve as magnetic quadrupole lenses that focus or defocus electric currents traversing them. We showcase the antiskyrmion core as a focal point where electron beams converge for specific injection directions, leading to anisotropic and nonuniform current distributions. Thus the current-induced antiskyrmion dynamics is profoundly modified by the magnetic quadrupole lensing via the spin-transfer torque. By incorporating quantum transport and micromagnetic simulations iteratively, we self-consistently capture the coupled dynamics of conduction electrons and antiskyrmions. Our results unveil a quadrupolar antiskyrmion Hall effect that is highly anisotropic with respect to the current direction and can be effectively tuned by the spin-orbit coupling. In particular, the current focusing (defocusing) dramatically enhances (suppresses) the antiskyrmion speed while simultaneously reducing its Hall angle, thereby overcoming a key challenge for antiskyrmion racetrack memories. Our work establishes the intrinsic current lensing as a powerful mechanism for manipulating topological magnetic textures and opens new avenues for antiskyrmion-based spintronic devices.
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All authors Linfeng Du, Yang Liu, Peng Yan, Ying Su

Quantum Physics

Performance optimization of cascaded traveling wave Josephson parametric amplifiers

Ilari Lilja, Ekaterina Mukhanova, Stanislav Khaldeev et al. (+3 more)

Traveling-wave parametric amplifiers (TWPAs) based on Josephson metamaterials provide broadband gain with near-quantum-limited added noise. Whereas long nonlinear metamaterial devices can deliver high gain, short arrays suffer less from dissipation, pump depletion, and internal standing waves which can degrade noise performance. Here, we demonstrate a cascaded TWPA architecture that combines the advantages of both approaches by employing a short (736-element), low-dissipation Superconducting Nonlinear Asymmetric Inductive eLement (SNAIL)-based TWPA as the first amplification stage, followed by a conventional long (1632-element) TWPA that provides additional gain. The resulting amplifier cascade achieves nearly 30 dB of total gain over a tunable bandwidth of approximately 1 GHz while maintaining added noise close to the quantum limit. Our results establish a cascade of TWPAs as a practical approach for high-gain, broadband, quantum amplification with applications in quantum information processing, multi-mode entanglement, and quantum sensing applications at microwave frequencies.
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All authors Ilari Lilja, Ekaterina Mukhanova, Stanislav Khaldeev, Ilya Golokolenov, Visa Vesterinen, Pertti Hakonen

Earth and Planetary Astrophysics

Searching for Embedded Protoplanets with the Keck/NIRC2 Vortex Coronagraph: Confirmation of a Core-accretion Planet in the Narrow Gap of the Elias 2-24 Disk

Andrea Bernardi, Alice Zurlo, Lucas A. Cieza et al. (+8 more)

We present high-contrast imaging observations of seven stars obtained with the Keck/NIRC2 vortex coronagraph between 2018 May and June in the $L'$ and $M_s$ bands. All targets host protoplanetary disks with substructures such as gaps and cavities, potentially tracing ongoing planet formation. Our aim is to assess whether these embedded planets can be directly detected. We reduced the observations with a custom pipeline based on the VIP Python package. Postprocessed images were obtained using angular differential imaging and reference differential imaging combined with principal component analysis. Finally, 5$\sigma$ contrast curves and detection limits were derived for all targets. We confirm the planetary candidate around Elias 2-24, previously proposed in the literature, at a separation of 394$\pm$31 mas (54.9$\pm4$.3 au) and a position angle of 298.8$\pm$3.2$^\circ$, within the narrow gap of the protoplanetary disk. Comparing the derived photometry with 1 Myr isochrones, we infer a mass between 1.9 and 4.0 Jupiter masses for Elias 2-24 b, without considering accretion effects, in agreement with estimates considering the properties of the gap and planet-disk interactions. For all the systems in the survey, the 5$\sigma$ detection limits reach sensitivities down to 1-11 Jupiter masses at separations $\gtrsim$0.25". Since Elias 2-24 b (age $\lesssim$1 Myr) is the youngest exoplanet discovered to date, its confirmation has important implications for planet formation timescales and the origin of the gaps observed in very young disks.
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All authors Andrea Bernardi, Alice Zurlo, Lucas A. Cieza, Garreth Ruane, Valentin Christiaens, Anuroop Dasgupta, Greta Guidi, Dimitri Mawet, Dino Mesa, Sebastián Pérez, Jonathan P. Williams

Mathematical Physics

Long time stability of low–frequency packets of modes at finite total energy

Dario Bambusi and Antonio Ponno

We consider the FPUT $\alpha$-model with $N$ particles and initial data with small total energy $E$, independent of $N$. In particular, we prove that if the energy is initially given to Fourier modes of wave number $\pi k/N\leq \theta_*$, then it does not flow to modes of wave number larger than $\theta_*$ up to long times of order $E^{-(1-\epsilon/2)}$, $\theta_*$ and $\epsilon$ being small numbers. The proof relies on the closeness of the Toda lattice to the FPUT system. Unlike previous approaches, we do not make use of the action-angle variables of the Toda system, but we exploit the Flaschka integrals of the latter. Actually, we find a suitable recombination of the Flaschka integrals whose quadratic part is used to control the packet, the higher order part fulfilling very good estimates.
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Instrumentation and Detectors

Single-electron detection in a high-purity Ge device

Antoine Armatol, Corinne Augier, Laurent Bergé et al. (+69 more)

High-purity germanium (HPGe) detectors are among the most powerful instruments for gamma ray spectroscopy, combining exceptional energy resolution with large active volumes. Although they operate close to the fundamental resolution limit at high energies, their performance at very low energies has long been limited by electronic noise, restricting detection thresholds to above approximately 30 electron-hole pairs ($\sim$100 eV). Here we introduce a cryogenic HPGe detector architecture that achieves single electron-hole pair sensitivity by calorimetrically measuring ionization at temperatures near 20 mK. The device integrates a NbSi transition-edge sensor into a point-contact-inspired geometry, concentrating athermal phonon energy generated during charge drift and enabling eV-scale sensitivity ultimately set by the semiconductor band gap. Beyond single-charge detection, the device rejects the low-energy excess background that limits existing cryogenic low-threshold technologies, establishing a pathway towards discrimination between electron- and nuclear-recoil events below 100 eV. These advances open a route towards next-generation detectors for direct dark matter searches, coherent elastic neutrino-nucleus scattering, and nuclear reactor monitoring for non-proliferation applications.
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All authors Antoine Armatol, Corinne Augier, Laurent Bergé, Julien Billard, Harvey Birch, Juliette Blé, Clarence Chang, Yen-Yung Chang, Luke Chaplinsky, Gordon Cline, Alec Cochard, Ion Cojocari, Jules Colas, Simon Connolly, Maryvonne De Jesus, Pierre de Marcillac, Kamil Dwinger, Romain Faure, Simon Fiorucci, Maurice Garcia-Sciveres, Jules Gascon, Ryan Gibbons, Gil Gilchriese, Cloé Girard-Carillo, Wei Guo, Leila Haegel, Scott Haselschwardt, Scott Hertel, Tyler Horoho, Keith Hunter, Leslie Juigne, Alexandre Juillard, Alex Kavner, Jacob Lamblin, Tatiana Le-Bellec, Junsong Lin, Rupak Mahapatra, Stefanos Marnieros, Claire Marrache-Kikuchi, Nicolas Martini, Will Matava, Daniel McKinsey, Connor McLaughlin, Johann Menu, Knut Moraa, Valentina Novati, Emiliano Olivieri, Björn Penning, Mark Platt, Denys Poda, Matt Pyle, Yinghe Qi, Rafsan Rabbi, Ivar Rydstrom, Bernard Sadoulet, Silvia Scorza, Bruno Serfass, Peter Sorensen, Gabrielle Soum-Sidikov, Samara Steinfeld, Henry Su, Toki Suzuki, Ronald Vaughn II, Charlie Veihmeyer, Paul Vittaz, Gensheng Wang, Yue Wang, Michael R. Williams, Joanna Wuko, Volodymyr Yefremenko, Alexandre Broniatowski, Louis Dumoulin

Fluid Dynamics

Channel confinement mollifies roll wave instabilities

Jake Langham, Cyril Gadal, Jamie P. Webb et al. (+2 more)

Under certain conditions, gravity currents spontaneously develop large-amplitude streamwise undulations on their free surfaces ('roll waves'). The effect of channel geometry on this instability is investigated herein. Via a section-averaged stability analysis conducted independently of the rheology of the flowing material, convex open channels are found to be stabilising, relative to unconfined flows. This is shown to agree with experimental observations of laterally shallow currents of water and dry granular material in trapezoidal channels. For such flows, the influence of the geometry can be characterised by a single dimensionless parameter, which predicts stabilisation as the channel width narrows. Including the cross-stream velocity profile in the analysis further stabilises predictions and can render steady flows in triangular channels unconditionally stable - a finding borne out by our experiments. Consequently, laterally tilting a trapezoidal channel can also stabilise flows by adjusting the wetted region towards a triangular one. Implications for observations in natural channels are considered by adapting an existing model of roll waves in the Illgraben, Switzerland, to incorporate channel geometry. The resulting simulations produce suitable waves for a realistic cross-section, but are stabilised by a modest narrowing of the channel. Complementary nonlinear wave solutions are then constructed and used to show that channel confinement also diminishes amplitudes of observed waves. Finally, exceptions to the analysis are discussed, including the possibility for static material to shield waves from the effects of geometry. We demonstrate this using observations of undamped granular avalanches travelling through an arrested deposit in a triangular chute.
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All authors Jake Langham, Cyril Gadal, Jamie P. Webb, Chris G. Johnson, J. M. N. T. Gray

Fluid Dynamics

Equivariant Neural Prediction of the Stokes Resistance Tensors for Arbitrary Microparticle Shapes

Sanjay Pradeep, David Dandy, Candace S.J. Tsai et al. (+1 more)

The Stokes-flow hydrodynamics of an irregular microparticle is encoded by its grand resistance matrix, a 6x6 tensor whose translational and rotational blocks (A and C) govern settling, diffusion, and orientational transport. Empirical drag correlations compress these tensors to a single scalar, discarding drag's orientation dependence and the rotational response. We present an SO(3)-equivariant neural network that predicts the full symmetric positive-definite A and C blocks from a particle's spherical-harmonic surface representation, equivariant by construction to floating-point precision. Trained on 1.1x10^5 random shapes from near-spherical to very rough, with a sealed test set of 18,000, it achieves 1.4% and 2.7% mean relative error on the two blocks while evaluating each shape 4-5 orders of magnitude faster than the regularised-Stokeslet solver that generated its labels. A spectral-convergence study confirms the representation is faithful: truncating a shape at spherical-harmonic degree 15 changes its resistance by a median of 0.14% (translation) and 0.38% (rotation), while the training shapes, generated band-limited at degree 15, carry no truncation error. Across 1.16x10^6 orientation-sampled settling, rotation and diffusion events, the surrogate reveals lateral drift up to 11 deg, rotational misalignment up to 46 deg, and shape-induced diffusion spreads of 30% (translational) and 2.4x (rotational), all identically zero under any scalar or spheroid reduction. Even the orientation-averaged scalar friction the correlations target, accurate to 1.7-2.8% (median; 2.2-3.2% mean), carries no tensor orientation, whereas the surrogate reproduces that scalar to ~1% while supplying the full anisotropic tensors. A fast, equivariant tensor surrogate can replace both solver and scalar approximation in atmospheric dust transport, microplastic fate and colloidal Brownian dynamics.
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All authors Sanjay Pradeep, David Dandy, Candace S.J. Tsai, Jeff D. Eldredge

Mesoscale and Nanoscale Physics

Non-Hermitian Topology from Edge Transport in Hermitian Quantum Anomalous Hall Systems

Humian Zhou, Ming Lu, Chui-Zhen Chen et al. (+1 more)

Non-Hermitian physics, known for exotic phenomena like exceptional points and the skin effect, has been most prominently realized in engineered systems relying on controlled gain and loss. Here we show that it can also arise naturally as an intrinsic transport response of a globally Hermitian quantum anomalous Hall system, without the need for external non-Hermitian engineering. We show that the interplay between unidirectional chiral edge modes and diffusive normal edge modes induces intrinsic non-reciprocal transport described by a continuum Hatano-Nelson model. Consequently, the non-Hermitian skin effect is encoded directly in experimentally accessible Hall-bar observables: the electrochemical potential and local heat dissipation acquire chirality-dependent exponential spatial profiles, while the longitudinal conductance decays exponentially with system size and the Hall conductance remains quantized. Using Landauer–B{"u}ttiker simulations, we confirm these transport signatures and identify magnetic topological insulators as a realistic platform for an intrinsic non-Hermitian transport response. Our results bridge non-Hermitian topology with mesoscopic transport, opening a pathway toward non-Hermitian topological devices in solid-state systems.
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All authors Humian Zhou, Ming Lu, Chui-Zhen Chen, X. C. Xie

High Energy Physics (Phenomenology)

The 248 keV LZ Recoil: A Possible Hint of Non-SM-Like Quark Yukawa Couplings with a Scalar-Portal Dark Matter

Bibhabasu De

The recent observation of an isolated nuclear recoil event at an energy of $248\pm 23 (stat)\pm 23 (sys)$ keV, as reported by the LUX-ZEPLIN (LZ) collaboration, can be an intriguing signature for Beyond the Standard Model (BSM) possibilities, particularly for dark matter (DM). This paper explores a scenario in which the observed recoil could simultaneously signal inelastic DM and a flavor-specific New Physics (NP) interaction in the quark sector. Considering a minimal extension of the Standard Model (SM) with two closely degenerate $Z_2$-odd vector-like fermions (VLFs), interacting with the SM via a scalar portal, the analysis shows that a perfect agreement with the observed 248 keV nuclear recoil can be achieved if the quark Yukawa couplings are allowed to deviate from their SM values. The underlying quarkophilic NP can originate from a dimension-6 effective operator at a NP scale $\Lambda\leq \mathcal{O}(10)$ TeV. Future collider searches can be crucial to test/falsify the proposal.
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Earth and Planetary Astrophysics

Super-Earth Interiors Shrink by About 10% as They Crystallise

Tim Lichtenberg, Mara Attia, Harrison Nicholls et al. (+26 more)

Super-Earth exoplanets are among the most abundant planets known, yet their bulk densities leave the interior state degenerate. The static structure models used to interpret them, and the interior retrievals built on them, typically describe the cold, solidified end state of an evolution that begins hot and molten. During this magma ocean stage the interior, the outgassed atmosphere, and the surface co-evolve and set the long-term climate and geophysics of super-Earths. We develop and validate a fully coupled model for the structural and thermal evolution of super-Earth exoplanets within the PROTEUS framework, including new and upgraded models of the interior structure, mantle energetics, and volatile outgassing. In volatile-poor super-Earths of 1 to 10 Earth masses, the silicate interior contracts by about 10 % of its molten radius through cooling and crystallisation, nearly independent of planet mass and driven by the thinning silicate shell alone. The solidified radius is set by planetary mass and core fraction, insensitive to the host star, irradiation, and initial thermal state. In contrast, volatile-rich super-Earths at and above about 5 Earth masses may not solidify: their thick outgassed atmospheres throttle the surface heat loss until the interior settles into a deep magma ocean, keeping the planet inflated and limiting the contraction to about half its volatile-poor value. Mantle contraction alone thus shapes the low-mass exoplanet transit population, motivating joint interpretation of atmospheric and geophysical signatures in upcoming exoplanet surveys.
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All authors Tim Lichtenberg, Mara Attia, Harrison Nicholls, Mariana Sastre, Dan J. Bower, Karen Stuitje, Flavia C. Pascal, Laurent Soucasse, Daniel Apai, Patrick Bos, Robb Calder, Lorenzo Cesario, Lisa Dang, Emeline Decocq, Marijn van Dijk, Mohammad Farhat, Kaustubh Hakim, Tadahiro Kimura, Imre Kisvárdai, Sebastiaan Krijt, Yamila Miguel, Ioannis Panagiotou, Emma Postolec, Martin Schlecker, Sara Seager, Anat Shahar, Oliver Shorttle, Paolo A. Sossi, Wim van Westrenen

Soft Condensed Matter

Apparent Breakdown of the Stress-Optic Rule in Rigid-Rod Suspensions: A Stress-Partitioning Interpretation

William Kai Alexander Worby, Yuto Yokoyama, Misa Kawaguchi et al. (+1 more)

A fundamental problem in the field of anisotropic macromolecular materials concerns how the flow-induced orientational order connects microscopic structure to macroscopic rheological stress and optical anisotropy. This study considered cellulose nanocrystal suspensions as rigid-rod model systems for the purpose of isolating orientational effects from chain stretching. Simultaneous rheo-optical measurements of birefringence, orientation angle, and shear stress were combined with a Fokker-Planck orientation model and stress decomposition. Our results show that, at low values of the Peclet number, birefringence and total stress exhibit proportionality similar to the stress-optic rule. However, the concentration dependence indicates that this proportionality reflects stress partitioning rather than a unique material coefficient. With increasing flow strength, orientational saturation is accompanied by a reduced relative Brownian stress contribution and a corresponding change in the total stress-based relation. Referencing the optical response to an estimated Brownian stress contribution yields a substantially more unified response across concentrations and flow conditions, supporting a stress-partitioning interpretation of apparent stress-optic rule breakdown.
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All authors William Kai Alexander Worby, Yuto Yokoyama, Misa Kawaguchi, Yoshiyuki Tagawa

High Energy Physics (Theory)

Toroidal Charged AdS Branes and Deformed Toda Equations

Sangheon Yun

We show that the equations of motion for magnetically charged $p$-branes in $(n+p+2)$-dimensional AdS reduce to coupled one-dimensional Toda-type equations, and use this structure to construct static toroidal black branes with $T^n$ symmetry and $p$ translation-invariant directions. In the pure-Maxwell case we obtain an exact $\sinh$ solution–a $(p+2)$-dimensional black brane times an $n$-torus, asymptotically $\mathrm{AdS}_{p+2}\times T^n$–whose dilatonic analogue, with a scalar coupled through $e^{a\phi}$, has a running torus modulus and a non-trivial dilaton. A perturbative expansion reduces the linearized system to a pair of Pöschl-Teller equations, one elementary and one solved by associated Legendre functions of non-integer degree, so that the general solution is non-elementary; at weak coupling $\epsilon=a^2$ we construct the $O(a^2)$ backreaction explicitly. From the surface gravity, horizon area, and holographic renormalization we obtain the Hawking temperature, entropy density, and mass density, verifying the first law $d\mathcal{M}=T_H\,ds$ and the traceless conformal stress tensor of the dual $(p+1)$-dimensional theory. At $O(a^2)$ the first law persists, but the dilaton source shifts the Stefan-Boltzmann exponent to $p_{\rm eff}=p+a^2/2$, breaking the clean power law $s\propto T_H^p$ while the normalizable dilaton hair decouples from the entropy.
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Fluid Dynamics

Exact explicit wave-angle solutions for equilibrium oblique detonations

Jing Li and Changtong Luo

The equilibrium oblique-detonation polar is a fundamental gasdynamic relation. This relation links the deflection angle, the wave angle, the flow state and the heat release. However, the wave angle is usually determined by numerical iteration. There is no explicit formula to determine the wave angle from a prescribed deflection angle, referred to as the inverse problem, even for the classical oblique-detonation model: a calorically perfect gas with a constant specific-heat ratio and a fixed heat release. This is inconvenient in practical applications. In this work, we solve this inverse problem for the classical model and derive explicit formulae for the wave angle. Inspired by the derivation of the oblique-shock inverse relation, the oblique-detonation inverse relation also reduces to a cubic equation. Heat release only changes the cubic coefficients, so the equation can still be solved explicitly. We also derive the complete analytical branch structure. We further find that the detachment point and the downstream total-sonic point can be determined explicitly by solving a cubic and a quadratic equation, respectively. We extend the explicit formulae to the two-$\gamma$ model and apply them to oblique-detonation calculations with equilibrium chemistry. These explicit formulae for the wave angle and critical points promote the theoretical understanding of oblique detonations and support their practical calculation.
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Physics and Society

What a collective can hold in common: a gauge framework for private representations

Mohammad Salahshour

Many models of collective behavior write headings, beliefs, and meanings in one experimenter-defined frame. Organisms do not live there: each represents the world in a private space, and comparison requires translation. Consensus becomes an existence problem before it becomes a dynamical one. Reciprocal pairwise translations need not compose consistently around a loop. This return transformation (the holonomy) can expose a mismatch no isolated reciprocal pair can carry. We develop a gauge-covariant theory in which physical predictions are invariant under private relabeling. For reciprocal unitary translations, the kernel of the connection Laplacian is isomorphic to the joint fixed space of loop holonomies: a collective can hold in common exactly what all its loops leave unchanged. A blind-subgroup criterion identifies invisible defects. Common-frame comparison, such as in traditional models of collective behaviour, occupies the flat sector. For independent uniform translations from a finite group $G$, a connected graph with $E$ relations among $N$ individuals is flat with probability $|G|^{-(E-N+1)}$. Exact cycle spectra determine persistence under linear relaxation. The consequence is operational as well as structural. For unrecorded routes under a specified model with isotropic Gaussian source and readout noise, we derive the smallest mean-squared error achievable by any decoder. At fixed signal-to-noise ratio, the jointly preserved feature fraction fixes its long-route limit. Networks with identical loop angles can differ in recoverable content when their preserved axes differ. The relational geometry of a collective sets both the states it can share and the content it can recover.
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Quantum Physics

clifford_qc: A Python Toolkit for Quantum Simulation

Ginanjar Utama and Hermawan Kresno Dipojono

clifford_qc is a Python research toolkit for constructing quantum models, comparing variational and subspace eigensolvers, and estimating measurement resources. A common sparse Pauli algebra connects Hamiltonians, density operators, gates, and candidate-selection observables; dedicated interfaces handle circuits, execution, and statistical estimates. A worked gradient example illustrates shared measurements, and a molecular workflow separates reusable preparation, solving, and reference validation. Matrix-element banks support virtual subspaces, exact Ritz residuals, and folded-spectrum roots. Process-isolated benchmarks show that packed coefficients and streaming reduce observed peak memory on the larger tested inputs at increased runtime. Measurement studies separate setting counts, shot requirements, and device cost: fully commuting readout certifies a fixed first-order Ritz functional with fewer shots, while anticommuting cliques help some fixed reference energies and not others. Entangling-gate time and connectivity can offset shot savings or make a protocol inadmissible under illustrative device models. Further studies expose subspace bias, indeterminate encoding comparisons, failed approximate-restriction screens, and high residual-measurement costs under the tested uniform allocations. Generated tables, provenance records, a versioned evidence contract, and manuscript checks connect claims to their inputs. These small-system results support reproducible method development and establish neither hardware performance nor a general simulation speedup.
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Quantum Physics

A Quantum-Inspired Two-Dimensional Lattice Polarized Radiative Transfer Simulator

Shan Zeng, Bing Lin and Ali Omar

A quantum inspired framework was developed for polarized radiative transfer in the atmosphere to jointly model multiple scattering, absorption, and emission processes. The radiative field is represented by the Stokes vector and discretized using an n-directional two-dimensional spatial lattice on 3-dimensional uniformly distributed zenith and azimuth angular vectors. The formulation of this quantum computation system is based on the Lattice Boltzmann Method, which incorporates a physics-based polarized phase matrix. A classical lattice solver employing identical spatial and angular discretization and physical modeling as in quantum algorithm is implemented. The corresponding quantum algorithm is evaluated using the IBM Qiskit quantum simulator, enabling direct comparison of numerical accuracy to a classical simulation reference. The results demonstrate that fully physics-based polarized radiative transfer can be embedded within a quantum lattice framework, which provides an initial benchmark toward scalable quantum atmospheric radiative transfer and future quantum climate modeling
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Quantum Physics

A Coherent Memory Register for Sequential Quantum Generative Modeling, with Application to Calorimeter Showers

Jamal Slim. Saverio Monaco, Ran Xue, Dirk Kruecker et al. (+1 more)

Simulating the showers that particles deposit in a calorimeter, the detector that records their energy across many cells, is one of the largest computing costs in high-energy physics, and fast generative surrogates are needed. Quantum circuits have been proposed as such surrogates, but demonstrations on calorimeter data have either required a register that grows with the image, roughly one qubit per cell, or have passed the information between parts of the image through a classical channel. We remove both constraints for this problem, using a construction drawn from the sequential-generation and hidden-quantum-Markov-model literature. A shower image is generated block by block on a fixed register of six qubits. Three of them, the memory, are never measured. They hold what the circuit knows about the blocks already generated as a quantum state, so the correlations between distant parts of the image cross each block boundary as unmeasured amplitudes. The other three are measured and reset once per block, and each outcome selects the energy pattern of one block. The register size is set by the block, so adding cells to the image adds steps to the sequence, not qubits. We call the model a coherent-memory Born machine (CoMB), a Born machine being a circuit whose measurement statistics are the generated distribution. Its training loss grows only linearly with the number of blocks and never requires enumerating the image distribution, and a depth-two instance runs on an IBM superconducting processor. On a twelve-cell benchmark the model reproduces the energy distribution of every cell, the correlation matrix between cells, and the total-energy spectrum. Removing the three memory qubits, with everything else unchanged, produces independent blocks. Every correlation between blocks is carried by the unmeasured qubits and by nothing else.
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All authors Jamal Slim. Saverio Monaco, Ran Xue, Dirk Kruecker, Kerstin Borras

Quantum Physics

Where to Decide: Control-Plane Geometry in Coherence-Limited Quantum Networks

I. Dey and N. Marchetti

Quantum networks are usually framed by two hardware limits: how fast entanglement can be heralded, and how long a memory can hold it. We establish a third, geometric limit: entanglement decoheres while control information travels, so the distance to whoever allocates resources enters the fidelity budget directly. We develop a functional-graph abstraction weighting each link by its predicted multiplicative contribution to end-to-end fidelity, separating global but delayed state from local and immediate state, and compare centralized against local allocation in a replicated discrete-event model. Centralized delivery latency grows with network diameter while local latency is nearly scale invariant, differing up to twenty-fold for short-range traffic; the coherence threshold at which a global view outweighs a fresh one does not shift across the tested sizes; and as heralding accelerates, the dominant cost moves into the control plane. Slot synchronization instead obeys the product of slot rate and one-way link delay, so it is bounded by repeater spacing rather than diameter. Controller placement, decision locality, repeater spacing and slot rate are physical design parameters, not implementation details.
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Quantum Physics

Universality in Terms of The BECs Bloch-Sphere Manipulations

Genji Fujii

Quantum computing promises to outperform classical computing for certain computational tasks. One of the key concepts underlying this potential is universality. Universality has been extensively studied not only for qubits but also for higher-dimensional quantum systems, such as qutrits and qudits, which span Hilbert spaces of dimension greater than two. However, the concept of universality in Bose-Einstein condensates (BECs) qubit systems, which have been proposed relatively recently, remains insufficiently understood. In this work, we analyzed universality in BECs qubit systems. Our results clarify the theoretical aspects of universality in quantum computation within the class of ((N+1))-dimensional representations of SU(2), taking into account two distinct representations of the quantum states.
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General Relativity and Quantum Cosmology

LQG-inspired black hole solutions in (2+1)-dimensions

Zijian Shi and Xiangdong Zhang

It is well known that in (2+1)-dimensional general relativity, black hole solutions exist only in the anti-de Sitter case–the so-called Banados-Teitelboim-Zanelli (BTZ) black hole. In this letter, we construct, for the first time, three independent LQG-inspired frameworks for (2+1)-dimensional black holes: the $\bar{\mu}$-scheme holonomy corrections, the quantum Oppenheimer-Snyder collapse, and a covariant effective model. Remarkably, all three approaches yield the same qualitative picture: when LQG-inspired corrections are included, we find three distinct types of solutions corresponding to asymptotically flat, anti-de Sitter, and de Sitter geometries. Our results demonstrate that the asymmetry between classical (2+1)-dimensional and (3+1)-dimensional solutions is eliminated upon incorporating effective quantum gravity effects.
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Quantum Physics

The Requirement of (at least) Complex Structure for Quantum Mechanics

M.P. Vaughan

It is argued that many real-valued constructions of quantum mechanics are only nominally real in that the operators and states are restricted to impose a complex structure on the Hilbert space. That is, complex algebra between pairs of elements representing complex numbers is preserved in these formulations. It is therefore mistaken to think of these constructions as being `real' as they are actually a representation of complex linear algebra. It is then shown that under the assumptions of state normalisation and strict energy conservation, this complex structure (at the very least) is required to allow for time evolution in quantum mechanics. This is only a minimum requirement, as our arguments do not preclude the formulation of quantum mechanics in terms of hyper-complex entities, such as quaternions.
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Medical Physics · Cross-listed from eess.IV

Signal recovery in the polychromatic computed tomography model: Injectivity and complexity

Xuanzhou Chen and Ashwin Pananjady

We consider a nonlinear model motivated by polychromatic computed tomography (CT). Here, $W$ distinct $d$-dimensional signals $x^*_1, \ldots, x^*_W \in \mathbb{R}^d$ must be recovered from $n$ measurements $(a_i, y_i)_{i = 1}^n$ that obey the nonlinear model $\mathbb{E}[y_i|a_i] = h(\langle a_i, x^*_1 \rangle, \ldots, \langle a_i, x^*_W \rangle)$, where $h: \mathbb{R}^W \to \mathbb{R}$ is a known nonlinearity that models a certain type of exponential attenuation law. Even when there is no noise in the measurements, the sample size $n$ (for any measurement ensemble $\{a_i\}_{i = 1}^n$) must exceed the number of unknowns $Wd$ to guarantee that the underlying signals are identifiable. We construct a measurement ensemble that ensures perfect signal recovery almost surely provided $n \geq Wd + W - 1$, thereby isolating the injectivity threshold up to an additive factor $W - 1$. We also study computational complexity of signal recovery in this model with a general measurement ensemble $\{a_i\}$. We show that if $W \geq 2$, then there is a measurement ensemble for which deciding whether there exist signals consistent with the measurements is NP-hard. In particular, this implies that polychromatic, multimaterial CT reconstruction is NP-hard in general. This finding stands in sharp contrast to the single-material setting, for which a polynomial-time algorithm can provably perform signal recovery for any measurement ensemble.
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Mathematical Physics

Higher-order and non-geometric symmetries and Noether's theorem in k-cosymplectic Hamiltonian field theory

Manuel de León and Xuefeng Zhao

In this paper, we investigate higher-order symmetries and non-geometric symmetries within the framework of $k$-cosymplectic Hamiltonian field theory. We introduce the concept of generalized infinitesimal symmetry, which relaxes the standard symmetry condition, and then define two new classes of symmetries: higher-order general infinitesimal Cartan symmetries and good non-geometric symmetries. For each of these symmetry classes, we establish a Noether-type theorem that provides explicit conserved quantities for exact $k$-cosymplectic Hamiltonian systems. These results extend and generalize previous work on standard Cartan symmetries in the $k$-cosymplectic setting. Furthermore, we extend all of these results in a parallel fashion to Hamiltonian systems on $k$-symplectic manifolds, demonstrating the unifying nature of our approach. Concrete examples are provided to illustrate the existence and applicability of the proposed symmetries. Our framework offers a systematic geometric treatment of generalized symmetries and their associated conservation laws in classical field theories.
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Astrophysics of Galaxies

Sulfur-bearing molecules in a sample of active star-forming cores

R. D. Taboada, N. C. Martinez, S. Paron et al. (+3 more)

Astrochemical processes involving sulfur are not yet well understood because cosmic sulfur reservoirs and the production pathways of sulfur-bearing species remain elusive. Addressing this, requires high-resolution interferometric observations capable of probing individual molecular cores. Following our previous study focused on early molecular cores, we are motivated to expand this investigation toward a sample of evolved cores to understand their chemical transition. We analyzed data from ALMA toward 16 molecular cores in massive star-forming regions associated with methanol masers, targeting the same six sulfur-bearing species studied in a previous work toward early molecular cores: SO, SO2, H2CS, SO+, NS, and 34SO. Column densities and abundances were derived assuming LTE, and temperatures were estimated from methanol transitions. Comparisons were made between the results obtained for the evolved cores and those previously obtained for the early ones. We find that the abundances of the sulfur-bearing molecules are higher in the evolved cores than in the early ones, confirming a general time-dependent enrichment of sulfur in the gas phase. While abundances increase within the 100-220 K range, their correlation with temperature weakens, suggesting that gas kinematics become increasingly more important in the sulfur chemistry. This evolutionary transition involves a chemical reorganization where SO2 becomes dominant. We confirm the validity of SO2/SO as a chemical clock, though chemical modeling reveals a discrepancy in sources with more pronounced kinematic processes, namely a steeper increase in the SO2/SO ratio. The line-width analysis of the molecular species indicates that core evolution and kinematics lead to a well-mixed gas, erasing the spatial stratification where different species trace distinct layers in the cores at earlier stages.
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All authors R. D. Taboada, N. C. Martinez, S. Paron, A. Petriella, M. E. Ortega, L. Supán