Peer Revenue Now accepting positions

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Watch Physics

Monday 5 October

Optics

Compact Circuit Models for Nanoantenna-Based Lightwave Electronics

Adina Bechhofer, Felix Ritzkowsky, Karl K. Berggren et al. (+1 more)

As the field of nanoscale lightwave electronics matures from centering around fundamental science to focusing on device engineering, there is a growing need for compact models that can provide rapid and scalable quantitative analysis of the performance of petahertz-frequency optical-field-driven electronics. In this work, we developed a circuit model framework for describing nano-scale lightwave electronics. Our framework captures the physics governing nanoscale optical devices, such as electrically-connected nanoantennas, using compact circuit models that predict their electromagnetic response, their electron emission, and their charge transfer dynamics. This approach allows scalable simulation of large integrated systems containing networks of nanoscale lightwave electronic components, which is not possible using full-wave electromagnetic and particle-in-cell simulation methods. We implemented the compact model in an free commercial circuit solver (LTspice) and validated its electromagnetic response against a full-wave electromagnetic solver (MEEP). We propose an experiment to fully benchmark the model's ability to capture non-linear charge-transfer-based coupling between devices. The circuit model implementation speeds up the electromagnetic analysis from hours to seconds and accounts for charge-driven coupling, enabling rapid quantitative studies of device operation which provide new insights into how femtosecond signals propagate through nanoscale lightwave electronic structures. We anticipate that the methods we introduce here will become essential to the development and performance analysis of nanoscale lightwave electronics for communication, computation, and signal processing at optical frequencies.
Read the full abstract

All authors Adina Bechhofer, Felix Ritzkowsky, Karl K. Berggren, Phillip D. Keathley

High Energy Physics (Phenomenology)

Born-Oppenheimer Effective Field Theory as a unified framework for all the XYZ exotics

Tommaso Scirpa

We discuss some recent applications of the Born-Oppenheimer effective field theory (BOEFT) formalism, directly derived from QCD and grounded in scale separation and symmetries, to hadronic systems containing two heavy quarks. This formalism provides a unified description of both ordinary and exotic quarkonium states (i.e., hybrids, tetraquarks, pentaquarks, ...) dynamics via coupled Schrödinger equations, whose potentials are computable on the lattice. The aim is to unveil the elusive pattern of the XYZ exotic hadrons. Here, we apply the BOEFT formalism to the $\chi_{c1}(3872)$, $T_{cc}(3875)^+$, and their bottom counterparts. Moreover, we assess the threshold effects on the quarkonium spectrum and discuss the inclusive production cross section for $\chi_{c1}(3872)$.
Read the full abstract

Earth and Planetary Astrophysics

Tracing the main belt origins of S-complex near-Earth objects: From space mission targets to meteorite sources

P. N. Simon, P. Vernazza, M. Marsset et al. (+5 more)

Context. Space missions to near-Earth objects (NEOs) provide unique opportunities to study and characterise their physical and compositional properties. Interpreting these results requires knowledge of their provenance, i.e. their source family in the main asteroid belt. Aims. We aim to identify the family sources of six S-complex NEOs visited or soon to be visited by space missions, and to investigate the size-dependent orbital behaviour of the broader S-complex NEO population using the MITHNEOS dataset. Methods. We combine near-infrared spectral fitting with ordinary chondrite (OC) analogues reddened by a space-weathering model, using reduced $\chi^2$ minimisation, and cross-validation with probabilistic dynamical maps of the main NEO source families. Results. We identify LL6-7 chondrites and the Flora family for Eros, Itokawa, Apophis, and Torifune; LL3 chondrites and the Nysa family for Toutatis; L chondrites and the Massalia family for Didymos-Dimorphos. Where in situ observations exist (Itokawa and Eros), the classifications are consistent. Applied to the broader S-complex NEO population, the spectral classification and orbital properties distributions are broadly consistent with dynamical models. Accounting for observational biases, we find that at small diameters ($\leq$100 m), the fractions of H- and L-type objects increase at the expense of LL6-7 types, with low-inclination orbits consistent with origins in the Massalia (L) and Koronis (H) families. Conclusions. Combining spectral fitting with OC analogues and dynamical probability maps robustly identifies the source families of individual NEOs. Below $D\sim$100 m, the compositional distribution of S-complex NEOs approaches that of meteorite falls, providing direct observational evidence, based on spectroscopic measurements of S-complex NEOs, of the emergence of the source regions of OC meteorites.
Read the full abstract

All authors P. N. Simon, P. Vernazza, M. Marsset, M. Brož, R. P. Binzel, F. DeMeo, C. A. Thomas, L. Jorda

Quantum Physics

Benchmarking exchange-only control of a 48-spin singlet manifold

HRL Quantum Team & Microsoft Collaborators: Stephen Carr, Matt Abbitt, Michael Abraham et al. (+122 more)

Exchange-only quantum computing benefits from high fidelity and straightforward control afforded by the exchange interaction. However, independently controllable qubits must be encoded into subsystems of at least three electron spins, restricting computation to only a fraction of the available spin Hilbert space. The remaining states are treated as leakage and used only transiently in gate sequences. By contrast, a quantitative, system-wide measure of exchange-only performance can exploit the full available Hilbert space, including states conventionally treated as leakage. Here, we apply this approach to arrays of up to 48 electron spins, accessing a total-spin-zero Hilbert space with dimension exceeding $2^{40}$. Measurements of out-of-time-order correlators (OTOCs) reveal rich scrambling dynamics and demonstrate access to regimes relevant to quantum computational advantage. Using generalized forms of cross-entropy and mirror randomized benchmarking, we also assess the aggregate performance of the full exchange-only system per fundamental two-body interaction: the two-spin exchange. We obtain an effective system-level error of $3 \times 10^{-4}$ per exchange, incorporating the complete experimental control sequence and all associated noise sources. This value is up to an order of magnitude lower than those reported from comparable benchmarks on other platforms at the time of writing.
Read the full abstract

All authors HRL Quantum Team & Microsoft Collaborators: Stephen Carr, Matt Abbitt, Michael Abraham, Edwin Acuna, I. Alverado, Carter Andrews, Hussein Anton, Katherine M. Beech, Aaron J. Bluestone, Jacob Z. Blumoff, Matthew G. Borselli, Brydon Boyd, Jacob T. Boyer, Peter Brewer, Steven L. Brown, Joseph D. Broz, Tyler A. Cain, John B. Carpenter, Faustin W. Carter, Brittany Carter, Matthew D. Chambers, James M. Chappell, Kevin C. Chen, Edward H. Chen, Maxwell D. Choi, Matthew N. H. Chow, Justin E. Christensen, Aaron M. Chronister, Andrew M. Clapper, Michael D. Cornelius, Gregory M. Crosswhite, Stanislav Culaclii, Erik S. Daniel, Dominic Daprano, John K. David, Charles R. Elliott, Kevin Eng, Colin P. Feeney, David J. Fialkow, Dylan H. Finestone, Bryan H. Fong, Richie Fu, Zachary A. Geiger, Bradley W. Greene, Rafael Guerra-Fuentes, Hrayr K. Gurgenian, Alex Hamill, Brooke M. Hardesty, Jim W. Harrington, Alex Hirman, Donald A. Hitko, Silas Hoffman, Dominic Holloman, Daniel R. Hulbert, Jake Hundley, Clayton A. C. Jackson, Paul C. Jerger, B. Johnson, Aaron M. Jones, Michael P. Jura, Adour V. Kabakian, Tyler Keating, Joseph Kerckhoff, Andrey A. Kiselev, Patrick W. Krantz, Thaddeus D. Ladd, Sanaaya Lakdawala, Elias Lawson-Fox, Alwina R. Liu, Dwight Luhman, Manny Macias, Theodore K. Macioce, Ryan M. Martin, Daniel S. Matic, Gavin C. Mazur, Ryan McGeehan, Olivia Means, Austin Meyer, Samuel Mumford, Tina Niknejad, Riley P. O'Neil, Andrew Pan, Winston Pouse, Eric M. Prophet, Matthew D. Reed, Marcus Rentie, Alec Roberson, Zechariah Rogers, Golam Sabbir, Spencer Sager, Christopher D. Sanborn, Jonathan Sanchez, Rachel H. Sarmiento, Christian J. Schnaible, Cole Scott, Aaron Smith, Daniel E. Smith, James Soash, Kevin C. Staley, Andrea Su, Bo Sun, Christopher M. Swank, Noah Swimmer, Charles Tahan, Bryan J. Thomas, Yessica Torres, Alan Tran, Ivan Tran, James R. van Meter, Franklin Vartanian, John Samuel Venker, Daniel Volya, Annette L. Wagner, Daniel R. Ward, Aaron J. Weinstein, Abigail L. Wessels, Thomas V. Westrick, Evan T. White, Randall M. White, Parker Williams, Catrina E. Wilson, Courtney P. Wilt, Matthew Wingert, Clifford S. YoungSciortino, Andrew Ziegler

Soft Condensed Matter

Mechanics of a Model Frictional Knitted Fabric

Laura Michel, Antoine Faulconnier, Audrey Steinberger et al. (+2 more)

We present a study of the shapes and mechanical properties of a knitted loop made of elastic and frictional yarns. First, for non-frictional yarns, we investigate how the elastic energy of a loop varies with its shape. This allows us to quantify the energetic contributions of stretching and bending, and to identify energetically favorable loop configurations. We then consider the case of thin frictional yarns. In this case, the stability of a loop can be reduced, even in the presence of friction, to a simple planar elastica problem. Friction gives rise to a multiplicity of stable loop shapes in a knitted fabric at rest, i.e., in the absence of externally applied forces. We show that, in the limit of thin yarns, a 2D elastica model can predict these rest shapes. Furthermore, the force-deformation curves under uniaxial stretching can be obtained straightforwardly within this framework. Measurements of loop dimensions and forces during uniaxial stretching of nylon knitted fabrics allow us to assess the qualitative and quantitative validity of the planar elastica model. Finally, we examine the limitations of this model for dense knitted fabrics.
Read the full abstract

All authors Laura Michel, Antoine Faulconnier, Audrey Steinberger, Samuel Poincloux, Jérôme Crassous

Astrophysics of Galaxies

Occam's Razor and a Three-Family Ultralight Fermionic Dark Matter Model

Fabian Hernandez-Gutierrez and Juan Barranco

Inspired by the three generations in the Standard Model, we propose that dark matter particles are simply three non-interacting ultralight fermions. This model is tested at galactic scales with the SPARC catalog of rotational velocity curves. This is done by modeling the dark matter halo as the self-gravitating configuration of three gravitationally coupled fermion species. This configuration is capable of forming more complex rotational curves which gives it flexibility to describe more complex and diverse morphologies of galaxy rotation curves. The core of the halos will be described by degenerate fermions and the transitions from a degenerate core to a non-degenerate halo will be described by either a perfect-fluid-like halo or a NFW density profile. In order to construct the priors of the three-fermion model, first we performed a single-fermion analysis and obtained three characteristic mass regions around 20, 40, and 65-70 eV, for both halo types. It is found that the three-component fermion model improves the goodness of fit for 94.9% of the galaxies considered. To estimate if the additional parameters are favored despite the added complexity by the corresponding improvement in the fit, the information criteria of AICc and BIC were computed and we found that more than $50\%$ of the galaxies analyzed prefer the three-component fermion model over a single fermion model. The three-fermion model is particularly favored for galaxies with larger radial extent and more complex rotation curves. The multicomponent fermionic dark sector is able to describe a large diversity of rotation curves while maintaining characteristic fermion mass scales across the galaxy sample.
Read the full abstract

Instrumentation and Methods for Astrophysics

SPECULATE: A synthetic spectral library, emulator and fitting package for accretion disc winds – Infrastructure and application to CVs

Austen G. W. Wallis, Christian Knigge, James H. Matthews et al. (+6 more)

Disc winds are critical components of accreting astrophysical systems and their observations can yield a wide variety of spectral line profiles. Yet, inferring disc wind parameters remains challenging: the underlying parameter spaces are high-dimensional and degenerate, while the radiative-transfer simulations are imperfect and computationally expensive. This paper tackles bridging this gap. Here, we present 'Speculate', an open-source framework for rapidly emulating and fitting observations with synthetic accretion disc wind spectra, generated from the Monte Carlo radiative-transfer code Sirocco. Speculate includes the release of our cataclysmic variable (CV) training data, a library of 88,680 sparsely gridded Sirocco spectra spanning the ultraviolet and optical wave bands, a suite of pre-trained emulators, and its interactive Marimo user interface. Speculate compresses spectral grids using principal component analysis and then provides three approaches to interpolate the resulting latent representation: with a regular-grid interpolation, a neural network, or a Gaussian process. All three architectures enable Speculate to generate a Sirocco spectrum between $1-40\,\mathrm{ms}$, thereby enabling efficient inference. The first two support rapid $\chi^2$ optimisation. The Gaussian process utilises a Bayesian inference engine coupled with a covariance-aware, flexible likelihood function, adapted and accelerated from the Starfish framework. This function helps absorb correlated discrepancies between simulations and data. Tests show all architectures reproduce unseen Sirocco spectra with broadly comparable accuracy and can recover their physical parameters. Subsequently, we apply Speculate to 5 representative nova-like CV spectra, reproducing several observed line features while also exposing mismatches where the current model grid omits relevant physics.
Read the full abstract

All authors Austen G. W. Wallis, Christian Knigge, James H. Matthews, Knox S. Long, Madeleine-Mai Ward, Stuart A. Sim, Adam B. Hill, Amin Mosallanezhad, Nicolas Scepi

Astrophysics of Galaxies

The universal thickness of mid-infrared bubbles

Michael M. Schulreich and A. Beate C. Patzer

Several hundred ring-like structures seen at $8\mu$m in the Spitzer GLIMPSE surveys share a uniform morphology: the shell thickness $\Delta R$ is a nearly constant fraction of the outer radius $R$, $\Delta R/R\sim0.3$, across a factor of 40 in size and all exciting spectral types. This invariance is unexplained. We ask what sets this thickness and whether its near-constancy is physical or a measurement artifact. We derive analytic constraints on the location, temperature, and heating of the emitting grains, and confront the predicted scaling with radius against the GLIMPSE I and II catalogs (591 objects, 91 with kinematic distances). Grains in radiative equilibrium at the observed radii reach only 20-35 K and fall short of the required $8\mu$m emissivity by more than 20 orders of magnitude; the emission must come from stochastically heated PAHs and very small grains, and therefore from the photon-dominated region, where the ring width is the far-ultraviolet penetration depth. This gives $\Delta R/R=A_V^{\rm PDR}/A_V^{\rm cloud}$, independent of radius; a swept-up shell instead predicts $\Delta R/R\propto(R/R_S)^{3/2}$, with $R_S$ the initial Strömgren radius. We find a pronounced angular-resolution systematic that inflates the ratio for the smallest bubbles; once this is accounted for, $\Delta R/R=0.217$, with a residual dependence on physical radius of $0.03\pm0.05$, consistent with zero. A fixed ambient density is excluded at $20\sigma$, the swept-up shell at 9-28$\sigma$. The implied columns are $N_{\rm cloud}\approx8.7\times10^{21}$ cm$^{-2}$ with only 0.112 dex of scatter. The near-universal appearance of mid-infrared bubbles follows from the ratio of two nearly invariant column densities – the dust-opacity-fixed far-ultraviolet shielding column and the Larson-like column of the parent molecular cloud – and requires no reference to stellar winds.
Read the full abstract

Instrumentation and Methods for Astrophysics

A Classifier Framework for ALMA Bandpass Calibration Anomalies

Ci Xue, Brian S. Mason, Gazi A. Rakib et al. (+8 more)

Bandpass calibration corrects instrumental responses across observing frequencies in interferometric radio observations, so the measured calibration solutions inherently contain spectral variation that varies with instrumental configurations and noise conditions. However, some signals contain anomalies, which if not caught can lead to poorly constructed science products. Observatory pipelines often use scalar metrics with individual, linear decision boundaries. Constructing a simple parametric model can be effective for observations with a relatively limited parameter space, but it becomes progressively less accurate as the parameter space expands. To address this challenge, we design a machine learning framework that treats anomaly identification as a supervised classification task and learns complex, non-linear decision boundaries across multiple features optimized for predictive performance. In particular, we use an XGBoost model that sits on top of several features and specialized scan statistic models to classify anomalies in amplitude solutions from ALMA bandpass calibrations. Trained on an extensive, quality-controlled ALMA dataset, this classifier framework leverages features derived from kernel-based scan statistics to characterize deviating spectral intervals, while remaining extensible to additional feature sets. This method substantially reduces misclassifications in bandpass anomaly detection compared to the current pipeline heuristics. By improving flagging decisions and calibration quality, this classifier framework provides a scalable supplement for observatory operations and is generalizable to next-generation radio facilities.
Read the full abstract

All authors Ci Xue, Brian S. Mason, Gazi A. Rakib, Tristan Ashton, Jeff M. Phillips, Ignacio Toledo, Ryan A. Loomis, Ilsang Yoon, John E. Hibbard, Omkar Bait, Eric J. Murphy

High Energy Physics (Theory)

The QCD phase diagram and critical end point at finite magnetic field from holography with neural networks

Shaojie Liu, Yehong Zhang, Hui Liu et al. (+1 more)

We study the magnetic-field-driven critical end point (CEP) of the QCD thermal transition at zero baryon chemical potential using a five-dimensional Einstein–Maxwell–dilaton (EMD) model. We calibrate the model to lattice entropy at zero and finite magnetic fields using a neural-network formulation of holographic radial evolution. As the magnetic field increases, the thermal transition changes from a crossover to a first-order transition. The merger of temperature turning points, a divergent specific heat, and a vanishing squared sound speed identify $(eB_c,T_c)\simeq(7.22\,\mathrm{GeV}^{2},95.9\,\mathrm{MeV})$. The transition-region inflection of $s/T^3$ defines the crossover temperature, while an equal-pressure Maxwell construction determines the first-order coexistence line. The two lines meet at the CEP. The change of transition order agrees qualitatively with lattice results. The phase boundary is a prediction of the calibrated model.
Read the full abstract

All authors Shaojie Liu, Yehong Zhang, Hui Liu, Xuanmin Cao

Quantum Physics

Classical chaotic signatures in Krylov space

Gastón F. Scialchi, Augusto J. Roncaglia and Diego A. Wisniacki

In recent years, Krylov space approaches have emerged as a useful framework for characterizing dynamical chaos in a wide variety of physical systems. However, the connection between Krylov dynamics and the established structures of classical chaos remains largely unexplored. Classical chaos is characterized by exponential stretching and mixing. For quantum maps with a classical limit, we show that these two signatures are encoded in different structures within Krylov space: stretching is encoded in the geometry of the Krylov operators as determined by the Lyapunov exponent, while mixing manifests itself as an exponential decay of the Arnoldi sequences in agreement with the Ruelle-Pollicott resonances.
Read the full abstract

High Energy Physics (Phenomenology)

Spectator Dark Matter and the Higgs Portal

Stephen E. Henrich, Yann Mambrini and Keith A. Olive

Light scalar spectators generically acquire large stochastic fluctuations during inflation, which can lead to a catastrophic overproduction of dark matter if the resulting primordial condensate survives until late times. We show that this inflationary memory can be sufficiently suppressed by an extremely feeble Higgs portal interaction with sub-freeze-in couplings ($10^{-28} \lesssim \lambda_{HS} \lesssim 10^{-9}$). The Higgs portal induces both a radiative self-interaction for the spectator as well as a thermal mass, both of which can lead to early onset of oscillations and efficient redshifting of the condensate's energy density without thermalizing the spectator or destroying the condensate. The Higgs portal also alters the stochastic equilibrium distribution of the spectator fluctuations, leading to a suppression of the field variance relative to an isolated spectator. We include a detailed treatment of the possibility that inflation may not have lasted sufficiently long for the spectator to reach its equilibrium distribution of fluctuations, finding the major constraint on such a scenario to come from isocurvature, which requires $N \gtrsim10^{10}$ e-folds. We also consider the addition of a non-minimal gravitational coupling, which extends the parameter space significantly. This model generally favors sub-GeV light dark matter ($0.1 \text{ eV} \lesssim m_S \lesssim 10 \text{ GeV}$) and in the absence of non-minimal gravity it also favors low reheating temperatures. While this mechanism can supply the entire relic abundance with sub-freeze-in portal couplings, it also naturally provides a suppressed initial condition for standard Higgs portal freeze-in.
Read the full abstract

Physics and Society · Cross-listed from cs.DL

Large scientific teams are more, not less, disruptive

Junming Huang and Yu Xie

Modern science has moved decisively toward larger and more collaborative research teams. Yet an influential 2019 study reported that small teams are more disruptive than large teams, a conclusion difficult to reconcile with both the well-known trend toward increasing collaboration and the disproportionately large teams behind widely recognized disruptive research, such as work that has been awarded Nobel Prizes. Here we show that the reported disruptive advantage of small teams is largely an artifact of measurement rather than a fact about teams. Analyzing about 60 million scientific publications, we find that larger teams cite more references and that the standard disruption index declines mechanically as reference lists lengthen. Equalizing reference-count distributions across team sizes reverses the negative gradient within the index's own framework. Evaluating each paper against one reference at a time yields a reference-robust measure that distinguishes recognized breakthroughs from ordinary papers more sharply and more consistently than the standard disruption index across six independently curated benchmarks, including the Nobel Prize. Under this validated measurement, scientific disruption increases with team size across four scientific domains and in every decade from the 1970s to the 2010s. For scientific publications, we conclude that larger teams are more, not less, disruptive.
Read the full abstract

Quantum Physics

Advantage of Entangled Learning Rules in Quantum Measurement Class Learning

Arka Prabha Das and Abram Magner

Learning with data in the form of quantum states is of current interest and has led to a variety of problems that boil down to interaction with the available data via quantum measurement and classical post-processing of observed classical outcomes. In quantum measurement PAC learning, one is given a sequence of unknown, prepared quantum states and classical labels, along with a hypothesis class of candidate measurements. The task is to select a measurement from the hypothesis class that minimizes a fixed notion of error in prediction of the classical labels via measurement of a new state by the selected hypothesis. In this work, we consider the advantage of interacting with the given data in the measurement learning framework using learning rules given by measurements that cannot be implemented using local operations and classical communication (LOCC), as opposed to single-copy learning rules. We provide a construction showing that there exist learning scenarios wherein single-copy learning rules are asymptotically suboptimal compared to optimal ones. We then show that learning rules based on entangled measurements enjoy at most a polynomial sample complexity advantage over single-copy learning rules in the PAC learning setting (under a natural joint measurability covering assumption).
Read the full abstract

High Energy Astrophysical Phenomena

A spatially resolved view of Fast Radio Burst host metallicities with Integral-field Spectroscopy

Sunil Simha, Hsiao-Wen Chen, Wen-fai Fong et al. (+15 more)

Magnetar sources are the leading theory for Fast Radio Burst (FRB) progenitors. If magnetars are indeed the dominant sources, we may thus expect any metallicity preference for magnetar formation to be reflected in the FRB site in host galaxies. Here, we leverage Integral Field Unit (IFU) spectroscopy to spatially resolve gas-phase metallicity distribution in five FRB host galaxies: FRB 20240210A, FRB 20240312D, FRB 20250227A, FRB 20211127I, and FRB 20250316A, at $z < 0.05$, including the FRB site, with the O3N2 index. We observed the first four sources with the newly commissioned Large Lenslet Array Magellan Spectrograph (LLAMAS) IFU on the Magellan Telescopes and used archival Keck/KCWI data for FRB 20250316A. We find ISM metallicity variations of at least 0.3 dex within individual hosts for the majority of the sample, with median values spanning $12 + log(O/H) \approx$ 8.5–8.7. At the burst sites, four have metallicities of $12 + \log(O/H) \approx 8.5$–8.9, while the fifth has a metallicity below 8.5. These findings reveal substantial metallicity variations both among FRB host galaxies and within the local environments of the bursts. Consequently, our study shows that longslit-based global estimates of host galaxy metallicity do not always represent the true burst-site distributions. We therefore advocate for IFU follow-up of larger host samples to ultimately provide FRB-site-relevant observational constraints on metallicity preferences for FRB occurrence.
Read the full abstract

All authors Sunil Simha, Hsiao-Wen Chen, Wen-fai Fong, Sarah Hughes, Yuxin Dong, J. Xavier Prochaska, Nicolas Tejos, Tarraneh Eftekhari, Alexa C. Gordon, Stuart D. Ryder, Mawson W. Sammons, Alice P. Curtin, Victoria M. Kaspi, Adam E. Lanman, Calvin Leung, Kiyoshi W. Masui, Aaron B. Pearlman, Ryan M. Shannon

Accelerator Physics

Limits on energy recovery for positron acceleration in a warm plasma column

Max Varverakis, Spencer Gessner, Severin Diederichs et al. (+1 more)

Beam-driven plasma wakefield acceleration (PWFA) is a promising candidate for realizing a future linear collider, owing to the extremely high field gradients that are produced in plasmas. Despite recent success in high-gradient and high-efficiency electron PWFA, efficient positron PWFA remains a challenge. The warm plasma column regime offers stable, high-quality acceleration of positron beams in a plasma electron filament, albeit at low energy-transfer efficiencies. We explore the possibility of employing an electron energy recovery beam to extract residual energy from the plasma wakefield and increase the efficiency of this scheme. Our particle-in-cell simulations reveal that certain mechanisms, including higher-order ionization and ion motion, limit our ability to further extract energy from the plasma wakefield.
Read the full abstract

All authors Max Varverakis, Spencer Gessner, Severin Diederichs, Carl A. Lindstrøm

Mesoscale and Nanoscale Physics

Theory of resonance Raman profiles in transition metal dichalcogenide monolayers: Interference effects due to inter-valley phonon scattering

Daniel Groll, Daniel Wigger and Tilmann Kuhn

The optical properties of monolayer transition metal dichalcogenides (TMDCs) are strongly impacted by exciton-phonon coupling, especially inter-valley scattering in the case of tungsten-based materials. Together with strain-tunability of the energetic K-Q valley separation this material class therefore provides a platform for semiconductor optomechanics. Here we investigate the influence of inter-valley scattering and strain on resonance Raman scattering in monolayer TMDCs using a microscopic model based on an effective deformation potential coupling for the exciton-phonon interaction. Considering exemplarily the resonance Raman profile of the A$_1$-mode in hBN-encapsulated monolayer WSe$_2$, we find that inter-valley scattering between the electronic K- and Q-valley leads to destructive interference between a first order and a third order Raman process. As a result we obtain a suppression of the incoming resonance in WSe$_2$, consistent with recently published experimental data.
Read the full abstract

Fluid Dynamics

Equations of motion for dust particles in dust-collecting devices (Translated article from USSR Journal Otoplenie i Ventilyatsiya, No. 4 (1934): 27-29)

L. S. Klyachko

Preface for the English Translation: While checking out early USSR journal articles for our literature search, we recently had tremendous difficulty acquiring this 1934 Klyachko original publication through our library systems. After obtaining and reading a scanned copy of it supplied by the Russian library in Moscow, we realized that relatively scarce citations of this work in the Western literature are often accompanied by inaccurate descriptions and comments, indicating that most Western authors might have gotten only second-hand knowledge about it and never seemed to have read the original article. Compared with various correlation formulas in the modern literature, the Klyachko 1934 formula for sphere drag in fluid flow appears to be the most elegant and cleanest one thus far. Therefore, we decided to make an effort to translate this historical work and publish it in the open literature to facilitate its accessibility to English readers worldwide.
Read the full abstract

Quantum Physics

Analytic construction of dimension-dependent steering witnesses from generalized equiangular measurements

Adam Rutkowski and Katarzyna Siudzińska

We construct a dimension-dependent family of generalized equiangular measurements that gives explicit steering witnesses in every prime dimension $d\geq5$. The construction consists of $d-1$ mutually unbiased measurements and an additional normalized family of $2d-1$ Hermitian operators depending on a parameter $\tau$. Positivity of the latter family is the main technical problem. We show that the noncentral operators reduce to three-dimensional invariant blocks, while the remaining central operator is exactly solvable in a two-dimensional subspace. Two unitarily equivalent $3\times3$ matrix representations describe the same active spectrum, but yield different Gershgorin enclosures because Gershgorin bounds are basis dependent. Combining the stronger endpoint from each representation gives a fully analytic asymmetric interval for $\tau$ that guarantees a valid POVM. Combining this POVM with the $d-1$ MUMs yields an explicit GEAM. Finally, using a maximally entangled realization and the local-hidden-state bound previously derived for generalized equiangular measurements, we obtain an explicit steering inequality and a sufficient criterion guaranteeing quantum violation in every prime dimension $d\geq5$.
Read the full abstract

High Energy Physics (Phenomenology)

Probing axion-like particles through associated gauge-boson recoil and polarization at the LHC

Amandip De, Monoranjan Guchait and Arnab Roy

Axion-like particles (ALPs) appear in many well-motivated extensions of the Standard Model (SM) and can exhibit characteristic interactions with electroweak gauge bosons ($V = W^\pm/ Z$) through higher-dimensional operators. We explore the production of ALPs ($a$) in association with $V$ at the HL-LHC, with $\sqrt{s}=14~{\rm TeV}$ and an integrated luminosity of $\mathcal{L}=3~{\rm ab}^{-1}$. We study the process $pp\to Va$, with $a\to\gamma\gamma$, for ALP masses in the range $20~{\rm GeV}\leq m_a\leq 200~{\rm GeV}$. This analysis extends existing associated-production searches by exploiting characteristic recoil and polarization features induced by the momentum-dependent $\rm {V-V-a}$ interaction. Using both cut-based selections and an XGBoost multivariate analysis, we demonstrate that these observables provide robust discrimination against SM backgrounds beyond the diphoton mass peak, improving the sensitivity to electroweak ALP couplings to $C_{WW} \gtrsim 5.6 \times 10^{-3}~\mathrm{TeV}^{-1}$ and $C_{BB} \gtrsim 2.8\times 10^{-2}~\mathrm{TeV}^{-1}$. We further show that, if a resonance peak is observed in data, the same observables can help distinguish an ALP-like signal from a Higgs-like spin–0 state of the same mass.
Read the full abstract

Quantum Physics

Quantum dynamics of spin systems using quantum-like resources

Debadrita Saha, Ethan Dickey, William Horvat et al. (+2 more)

Recent publications have introduced the concept of quantum-like (QL) bits, along with their associated QL-states and QL-gate operations, emerging from the dynamics of complex synchronized networks. The present work builds on this framework to present a simulation of quantum dynamics in spin systems. We focus on the transverse field Ising model, a widely studied Hamiltonian for interacting spin systems. We show how circuits, built using the QL analog of quantum gates, can be used to prepare an arbitrary initial wavepacket and simulate the time evolution of the resulting state for extracting physical observables such as magnetization. Beyond the statevector dynamics, we introduce a set of metrics that characterize how QL-circuit operations transform the underlying graph connections. These metrics quantify the microscopic coupling, phase coherence, and effective inter-block coupling generated by the circuit. These graph-level quantities provide constraints and design targets for potential physical implementations, indicating where interconnection resources, phase control, and effective coupling strength must be engineered in a hardware realization. Overall, this study demonstrates how classical resources can be harnessed to simulate quantum systems and we discuss the advantages and limitations.
Read the full abstract

All authors Debadrita Saha, Ethan Dickey, William Horvat, Sabre Kais, Gregory D. Scholes

Fluid Dynamics

Small density differences, large Richardson numbers: buoyancy decides where gypsum deposits in a centifluidic confluence cell

Isaac Appelquist Løge, Candela Almazán Pérez and Maike W. Baltussen

The mixing of two aqueous streams in small channels is usually modeled with constant density when the difference in density between the streams is only a few percent or less. In this paper, we investigate whether this holds in a confluence cell where calcium chloride and sodium sulfate meet and form gypsum. A constant density simulation of the reacting flow results in deposition on the floor along the channel centreline. However, in the experiment, gypsum instead forms bands on both side walls, and the deposition bands start further upstream as the flow rate decreases. Dye experiments with density differences between the streams of 0.14 to 2.1\,%, three channel heights, and 32 flow rates show that the distance at which the dyed stream reaches the opposite side wall is governed by the bulk Richardson number, $Ri=g'H/U^2$, and follows $L/H = 3.31\,Ri^{-0.66}$ over four decades of $Ri$ ($R^2=0.89$). When the two streams' densities match, the dyed stream no longer reaches the opposite wall under most conditions, and in a density-matched reacting experiment, gypsum deposits on the floor, as the constant-density simulation predicts. A small relative density difference is thus not a sufficient condition for neglecting buoyancy: the Richardson number must also be small. For the flow rates typical of centifluidic devices, it often is not.
Read the full abstract

Plasma Physics

Analytic non-axisymmetric 3D MHD equilibria without stellarator symmetry

Opal Issan, Jonathan Citrin, Matt Landreman et al. (+1 more)

Analytical solutions to the three-dimensional ideal magnetohydrodynamic equilibrium equations $(\nabla \times \vec{B}) \times \vec{B} = \nabla p$ and $\nabla \cdot \vec{B} = 0$ provide benchmarks for stellarator equilibrium codes. Two families of non-axisymmetric solutions were recently discovered by Landreman [arXiv:2609.26742] as counterexamples to Grad's conjecture, but both satisfy stellarator symmetry. Here, we generalize both families by introducing a symmetry-breaking parameter into each of the solutions, resulting in new non-axisymmetric solutions that break stellarator symmetry and reduce to the stellarator symmetric solutions when the newly introduced parameter is set to zero.
Read the full abstract

All authors Opal Issan, Jonathan Citrin, Matt Landreman, Brendan Tracey

Biological Physics

Threat Evasion and Information Propagation in Cognitive Flocks

Priyanka Iyer, Cecilia Soroco and Gerhard Gompper

Information sharing, threat perception, and collective evasion highlight the advantages of swarm intelligence. Here, we study the behavior of flocks of cognitive agents, based on numerical simulations of the augmented inertial spin model, with an explicit predator. Each agent on the predator-facing side of the flock perceives the threat, triggering collective turns through local interactions. We show that the augmented inertial spin model sustains nearly linear information propagation in the under-damped regime, even with realistic flocking interactions such as local collision avoidance and swarm cohesion in addition to alignment. The turning distance of the flock to a stationary predator scales with the ratio $\Delta_p/(v_0\sqrt{\eta})$, identifying an optimal balance between response strength $\Delta_p$, flock speed $v_0$, and damping $\eta$ of information propagation. Fragmentation arises when different parts of the flock turn in different directions, however, fast information propagation can synchronize these responses and maintain flock cohesion while under pursuit. For two predators, a combination of stability analysis and simulations reveals a stark contrast between flock and single-particle reactions, with scattering angle shaped by flock geometry, predator position, and the heterogeneous responses of the detecting front. Together, these results show how information propagation, flock geometry, and dynamics together shapes collective escape, providing general principles relevant to both biological flocks and robotic swarms.
Read the full abstract

Strongly Correlated Electrons

Odd-parity magnon spin polarization from chiral four-spin exchange in a honeycomb antiferromagnet

Bektur Murzaliev and Mikhail Titov

Chiral four-spin exchange generates a momentum-dependent magnon spin in a compensated honeycomb antiferromagnet at zero magnetic field. For a Néel vector tilted by an angle $\theta_0$ from the layer normal, the interaction contributes to intersublattice magnon pairing already at harmonic order, with an amplitude proportional to $\cos\theta_0\sin^2\theta_0$. Biaxial anisotropy mixes the two longitudinal-spin sectors, producing nonquantized mode spins that are odd in momentum, while a sublattice-exchange relation keeps the magnon energies reciprocal. A temperature gradient then induces a spin density along the Néel axis through a redistribution of magnon occupations. Reversing the four-spin coupling reverses this spin density and the mode spins without changing the magnon energies. MnPS$_3$ motivates the magnetic geometry; realizing the interaction requires a structural modification compatible with the symmetry assumptions of the model.
Read the full abstract

High Energy Astrophysical Phenomena

Investigating X-ray Emission from Radio-detected Broad- and Narrow-line Seyfert 1 Galaxies

Minhua Zhou, Minfeng Gu, Lei Xu et al. (+2 more)

Context: This paper presents a study of the X-ray emission for a sample of radio-detected (RD-) broad- and narrow-line Seyfert 1 galaxies (NLS1s and BLS1s). Aims: To investigate the X-ray emission properties of early-stage accretion activity or early jets in NLS1s. Methods: By fitting XMM-Newton X-ray spectra and combining with multi-band data from SDSS and FIRST, we conducted a statistical comparative study on the X-ray emission and multi-band correlations of NLS1s and BLS1s. Results: NLS1s and BLS1s show no significant difference in their soft X-ray blackbody temperatures, but NLS1s exhibit steeper hard X-ray photon indices and optical-to-X-ray slopes ($\alpha_{\rm ox}$). Moreover, correlation analyses of various parameters reveal intrinsic differences in the X-ray emission between the two samples. For instance, at comparable optical luminosities, NLS1s exhibit a higher $ \alpha_{\rm ox} $ (i.e., weaker X-ray emission), marginally distinct dependencies between radio luminosity and black hole mass in the fundamental plane, and different correlations between $\alpha_{\rm ox} $ and radio loudness. Based on the relationship between UV luminosity and $\alpha_{\rm ox} $ in RQ-AGN, the estimated X-ray excess ($\Delta \alpha_{\rm ox} $) in both samples is positively correlated with radio loudness. RQ-BLS1s generally display the X-ray excess, whereas RQ-NLS1s tend to show an X-ray deficiency. The Eddington ratio of RQ-NLS1s derived from X-ray luminosity is lower than that inferred from optical luminosity, further supporting their intrinsically weaker X-ray emission. Conclusions: These differences in X-ray emission between NLS1s and BLS1s may ultimately stem from the earlier evolutionary stage of NLS1s. Multivariate linear fits among radio luminosity, X-ray luminosity, and radio loudness for NLS1s and BLS1s support a multi-wavelength radiative connection associated with jets.
Read the full abstract

All authors Minhua Zhou, Minfeng Gu, Lei Xu, Mai Liao, ZhengXue Chang

Chaotic Dynamics

Adiabatic confinement and escape in an open billiard

Matheus Rolim Sales, Leonardo Costa de Souza, Ricardo Luiz Viana et al. (+2 more)

We introduce a stationary, field-free billiard that reproduces the adiabatic confinement mechanism of a magnetic mirror through boundary geometry alone. Rapid transverse reflections generate an approximately conserved action that plays the role of the magnetic moment, producing an effective longitudinal barrier and a nominal loss cone for escape. For the half-width profile considered here, confinement is controlled by a competition between mirror strength and adiabaticity: shortening the profile increases the mirror ratio but also reduces the accuracy of the adiabatic approximation. As a result, the escaping fraction is nonmonotonic and confinement is strongest at an intermediate profile length. We characterize the associated phase-space structure, escape-time statistics, and escape basins, revealing long-lived transient motion and a strong sensitivity of the final escape direction to the initial condition that persists as the uncertainty in the initial condition is reduced.
Read the full abstract

All authors Matheus Rolim Sales, Leonardo Costa de Souza, Ricardo Luiz Viana, Edson Denis Leonel, Iberê Luiz Caldas

Astrophysics of Galaxies

Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VII. First interstellar detection of fully deuterated methanol

A. Belloche, S. Spezzano, A. Coutens et al. (+12 more)

There have been no robust identifications of fully deuterated methanol, CD3OD, in the interstellar medium (ISM) to date. Our goal is continue the search for CD3OD in star-forming regions to determine the deuteration pattern of methanol and set constraints on the deuteration process. We used a sensitive imaging spectral survey of the protostellar system IRAS4A in the NGC1333 molecular cloud performed as part of the large program carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) called Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS). The column densities of methanol and several of its less abundant isotopologs, including deuterated ones, were derived under the assumption of local thermodynamic equilibrium (LTE). Along with the detection of several methanol isotopologs toward the binary component IRAS4A2, we report the first interstellar detection of CD3OD. The deuteration pattern of methanol in IRAS4A2 is similar to the pattern measured in other low-mass protostars, with an increase in the apparent D/H ratio from the singly to multiply deuterated isotopologs. Chemical models of prestellar and protostellar cores focused on deuteration do not reproduce this pattern quantitatively. This discrepancy is even more exacerbated by the detection of CD3OD. Our LTE modeling of the spectra yields low column density ratios of methanol to its 13C and 18O isotopologs while the 13C to 18O and 18O to 17O ratios are consistent with the isotopic ratios expected in the local ISM. We suspect that the column density of methanol is underestimated. One possible explanation is that the emission is clumpy rather than monolithic. The first detection of a fully deuterated COM highlights the power of deuterium fractionation as a diagnostic tool for investigating the formation and inheritance of organic molecules during the process of star formation.
Read the full abstract

All authors A. Belloche, S. Spezzano, A. Coutens, M. N. Drozdovskaya, J. K. Jørgensen, J.-E. Lee, A. L. Plunkett, D. Harsono, S. Maret, F. Cruz-Sáenz de Miera, J.-H. Jeong, P. Nazari, Y.-L. Yang, H.-S. Yun, S. Zeng

Astrophysics of Galaxies

Multiple H I 21-cm absorbers towards blazar PKS 1158+007

Abhisek Mohapatra, R. Srianand and R. Dutta

We report an interesting line of sight towards the blazar PKS 1158+007 (J1201+0028) ($z_{\rm em}$ = 1.369), revealing the rare detection of two intervening HI 21-cm absorption systems within a narrow redshift interval ($\Delta z \sim 0.04$) using the MeerKAT radio telescope. The stronger absorber at $z_{\rm abs}$ $=0.5653$ ($\int\tau dv = 1.31\pm0.04$ \kms) is associated with a strong MgII $\lambda2796$ system seen in the Sloan Digital Sky Survey (SDSS) and Dark Energy Spectroscopic Instrument (DESI) spectra, with rest-frame equivalent widths of $W_{2796} = 1.40\pm0.07$~Å\ and $1.21\pm0.11$~Å, respectively. In stark contrast, the second detection at $z_{\rm abs}$ $= 0.5305$ reveals a distinct HI 21-cm absorption feature ($\int\tau dv = 0.31 \pm 0.04$ \kms) with no associated metal absorption detectable in the optical spectra. This system represents a prime example of a "metal-poor” HI 21-cm absorber. Using photometric redshifts from Hyper Suprime-Cam (HSC) PDR3 and DESI Legacy Surveys DR10, we identify a broad galaxy overdensity (at $z \sim0.53\pm0.06$) coincident with these absorbers, suggesting the sightline pierces a complex large-scale structure or filament, which would be interesting to confirm with follow-up observations. These results underscore the power of blind HI 21-cm surveys to uncover the "invisible” cold gas phase of the Universe that optical/UV metal-line selection may systematically miss.
Read the full abstract

Mathematical Physics · Cross-listed from math.PR

Gaussian free field with logarithmic singularities and reduced Green's energy

Mingchang Liu, Titus Lupu and Hao Wu

We analyze the level lines of the Gaussian Free Field with logarithmic singularities in polygonal domains. We focus on the (none-zero) singular case and compare it to the singular-free setting. The law of the level lines for the field in singular case is absolutely continuous with respect to the law for the singular-free case, with a Radon-Nikodym derivative related to the reduced Green's energy which is introduced by F. Viklund and D. W. Nyström~[VN24]. These level lines admit a Brownian motion representation. In the singular-free case, such representation involves Poisson point processes of Brownian loops and excursions; while for the singular case, it additionally includes Poisson point processes of Brownian bubbles and bridges. The special cases of one or two singularities yield moment-generating functions of the conformal radius, which can be interpreted as one-point and two-point correlation functions of vertex operators in conformal field theory at the free-boson point. While the Radon-Nikodym derivative is bounded away from the singularities, the behavior of the level lines near the singularities is markedly different from the singular-free case, with different asymptotic probabilities for all level lines to remain close to the singularity.
Read the full abstract