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Friday 18 September

History and Philosophy of Physics · Cross-listed from math.HO

Descartes' Circle Theorem, Princess Elizabeth, and Spinors

Daniel Parrochia

In this article, on Descartes' famous "circle theorem," we first attempt to explain how the philosopher could have arrived at the equation that he presents without demonstration in a letter to Princess Palatine Elizabeth of Bohemia in November 1643 (a previously unpublished proof, to our knowledge). Then we report some stages of the subsequent generalization of this theorem, whose Cliffordian flavor, via the equivalence of a quadratic form and the square of a linear form, still mobilizes mathematicians today. This statement, which, over time, has undergone different extensions, Euclidean and non-Euclidean, has found, in fine, a spinor formalization. We see there the proof of what we may call, in a Bachelardian style, an "inductive value" of the truth, which extends by successive generalizations. We conclude, more briefly, with the contacts between Elizabeth and Descartes, and the perhaps symbolic meaning of these considerations on "kissing circles," as they are called in Anglo-Saxon countries, in the context of their correspondence on the soul and the body, and the question of passions.
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Nuclear Theory

A novel method to determine the 4th moment of the 208Pb charge density from low-momentum-transfer electron scattering

Rika Danjo, Toshimi Suda and Toshio Suzuki

We propose a new method to determine the 4th moment of the nuclear charge-density distribution of 208Pb, with high precision from low-momentum-transfer elastic electron scattering.

Soft Condensed Matter

On the ratio between longitudinal and transverse Ioffe-Regel frequencies in glasses

Licun Fu, Mingyu Zhu, Xinyu Chang et al. (+1 more)

The temperature dependence of thermal conductivity in glasses differs characteristically from that in crystals, and is largely controlled by how sound waves are damped. The Ioffe-Regel (IR) frequency sets the high-frequency limit of well-defined sound waves. Although the transverse IR frequency has been established to coincide with the boson peak frequency and reported to be far below the longitudinal IR frequency, the quantitative relation between longitudinal and transverse IR frequencies has remained unknown. Here we examine this relation in two- (2D) and three-dimensional (3D) model glasses with vastly different stability. We observe that, in 3D glasses, the longitudinal-to-transverse IR frequency ratio is approximately equal to the ratio of the low-frequency transverse to longitudinal sound attenuation coefficient, whereas this correspondence is not observed in 2D glasses. Moreover, we find that the glass stability strongly controls the longitudinal-to-transverse IR frequency ratio in both 2D and 3D glasses: the ratio decreases significantly with increasing glass stability and approaches unity for the most stable glasses under study. Accordingly, in sufficiently stable glasses, the longitudinal sound attenuation should be comparable to the transverse attenuation, and therefore cannot be treated as negligible, challenging common assumptions adopted especially in theoretical studies. Our work is another demonstration of the glass stability as a key parameter for investigating glass properties, and cautions against simply extrapolating observations from poorly annealed glasses to stable glasses.
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All authors Licun Fu, Mingyu Zhu, Xinyu Chang, Lijin Wang

Fluid Dynamics

Stabilization of Yih's Viscosity Jump Interface in a Channel

Miroslav Krstic

Two immiscible viscous fluids in pressure-driven channel flow can be unstable through their interface when their viscosities differ, at arbitrarily small Reynolds number — the instability Yih found in 1967. The unstable state is the interface itself: a curve inside the domain, separating the two fluids, whose displacement is governed by a partial differential equation of its own and which moves the fluid domain with it. Actuation is at one wall only, so the state to be controlled is reached across a fluid. We stabilize this interface at any rate below the limit set by the streamwise mean flow, by static feedback of the two velocity components of that wall, through a Fredholm backstepping transformation acting jointly on the two layers. The target is the two-fluid Stokes problem, shifted, with the transmission of stress between the fluids kept and the coupling of the interface into them removed. Two findings about the two-fluid spectrum carry the design: joined at the interface, the eigenvalue sequences of the two layers, which collide for a dense set of layer ratios when the layers are uncoupled, avoid each other uniformly, so no degeneracy has to be assigned; and the slowest mode left to viscosity is not a bulk mode but the capillary relaxation of the interface, whose rate is linear rather than quadratic in the wavenumber, which sets the band of actuated wavenumbers. The controller is tested on the nonlinear two-fluid channel, switched on against a saturated interfacial wave.
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Popular Physics

Mass in the Light of Special Relativity

Francisco Caruso and Vitor Oguri

The text analyzes the concept of mass within Special Relativity, initially deconstructing the interpretation of Einstein's equation ($\varepsilon_\circ = m c^2$) as a principle of equivalence. Based on the adoption of the conservation laws of momentum and energy, the non-additivity of mass in composite systems is established. While in atomic and nuclear systems the total mass is less than the sum of its constituents, in the subnuclear domain the opposite occurs: the positive potential energy of confinement of quarks causes the mass of a hadron to be greater than the sum of the masses of its quarks; in the case of nucleons, it is much greater. It is concluded, then, that the mass of baryonic matter in the observable Universe comes, for the most part, from the energy associated with strong interactions.
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High Energy Physics (Theory)

Multi-Boundary Spinning $AdS_5$ Black Holes, Strongly Coupled Plasma Balls and a dual locally de Sitter spacetime

Andrés Anabalón, Guillermo Buckle, Annelies Fullgraff et al. (+1 more)

We construct a new family of exact spinning black hole solutions in five-dimensional General Relativity with a negative cosmological constant, which are dual to strongly coupled spinning plasma balls on four-dimensional Minkowski spacetime. In analogy with the recent discovery of such black solutions in four bulk dimensions, the boundary Lorentz factor acts as a new coordinate in the bulk, giving rise to a new UV region that, in our case, is locally a three-dimensional de Sitter spacetime times the real line. The dual energy-momentum tensor in this region describes a conformal anisotropic fluid that satisfies the weak and strong energy conditions.
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All authors Andrés Anabalón, Guillermo Buckle, Annelies Fullgraff, Marcelo Oyarzo

General Relativity and Quantum Cosmology

Rotating Neutron Star Migrations as a Standardized Test for 3+1 Numerical Relativity

Óscar H. Petit, José A. Font and Nikolaos Stergioulas

When simulating dynamically unstable neutron stars, truncation errors can introduce perturbations that drive the stellar configuration either toward gravitational collapse into a black hole or toward migration to a dynamically stable, lower-density configuration. This mechanism has become a standard benchmark for validating general-relativistic hydrodynamics codes in the case of spherically symmetric neutron-star models. In this work, we extend the analysis to the more general case of uniformly rotating neutron stars evolved in three spatial dimensions. We investigate these transitions using two equations of state: a cold polytrope and a hybrid prescription, which allow us to distinguish the barotropic response from the effects of shock-generated thermal pressure. We find that the migrated remnant remains close to uniform rotation after the transition, and we trace its quasi-radial pulsations through complementary diagnostics involving the central density, the rotation profile, and the axisymmetric gravitational-wave channel. We investigate the properties of these transitions and propose a standardized test for validating numerical-relativity codes by requiring the migration behavior to be consistent with the dynamics reported here.
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Statistical Mechanics

Universal Eigenvector Statistics of Non-Hermitian Random Matrices

Ze Chen, Zhenyu Xiao and Shinsei Ryu

Eigenvector overlaps quantify nonorthogonality and govern the response and dynamics of non-Hermitian systems. We extend the universality of non-Hermitian random matrices to the statistics of these overlaps. We obtain analytical expressions for eigenvector overlaps in the spectral bulk and near the origin, covering ten symmetry classes in the limit of large matrix size. Using fermionic replica nonlinear $\sigma$ models, we relate these overlaps to Hermitian level statistics, symmetry class by symmetry class and topological sector by topological sector. Numerical calculations in various physical models support the universality of the normalized overlaps in the regimes studied. Our work establishes a duality between Hermitian level statistics and non-Hermitian eigenvector overlaps.
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Astrophysics of Galaxies

The AGN Channel in 3D: Scattering Belts and the Importance of Eccentricity in the Black Hole Population

Connar Rowan and Martin E. Pessah

Active galactic nuclei (AGN) are a promising origin for observed gravitational wave mergers. Current population synthesis models are limited to 1D N-body or Monte Carlo methods which rely on statistical approaches to resolving dynamical scatterings. We present three-dimensional hybrid $N$-body simulations of a population of black holes (BHs) surrounding an AGN using a new code in development, AGNBI, where close interactions are directly simulated for both single and binary objects. Our results show binary formations occur throughout the AGN disk, particularly where the migration time is long. While BHs efficiently migrate and pair up in migration traps, they are frequently disrupted by ionisation or exchanges from binary-single and binary-binary interactions. We report a broadened radial distribution of formations and mergers about the trap radius when accounting for binary-single and binary-binary interactions, which we describe as a "scattering belt”. We assess the influence of the pre-existing BH population. When we model a non-zero eccentricity distribution in the BH population, the binary formations and mergers are suppressed by an order of magnitude compared to a non-eccentric population as fewer BHs embed in the AGN disk. We report an approximate merger rate of $\mathcal{R}_\mathrm{GW}\approx2\text{--}12\,\mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$ with maximum BH masses of $10^2\text{--}10^3\,M_\odot$ through hierarchical mergers, where lower initial velocity dispersions produce larger BHs. The mass and mass ratio distributions are comparatively flat, suggesting AGN may be more relevant for high-mass or unequal-mass gravitational wave sources.
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Solar and Stellar Astrophysics

Multi-Epoch Stability in the Rotational Modulation of the Planetary-Mass Companion Ross 458C

Elena Manjavacas, Jared Bull, Paulo Miles-Paez et al. (+7 more)

Spectroscopic variability is detected in brown dwarfs across all spectral types, suggesting atmospheric patchiness in brown dwarf atmospheres. We present JWST/NIRSpec time series observations of the T8.0 planetary-mass companion Ross 458C. We compared our derived spectral variability and light curve to those obtained using HST/WFC3 observations more than 7.5 yr before and published by Manjavacas et al. (2019). We found that the light curve of Ross 458C is remarkably similar in the two epochs in terms of shape and variability amplitude potentially created by stable weather patterns. We measured a rotational period of 11.57+\-0.09 hr, demonstrating that the previously reported HST/WFC3 period of 6.75+\-1.58 hr is most likely a second-order harmonic produced by an unresolved double-peaked rotational modulation, likely due to the higher uncertainties of the HST/WFC3 light curve and the short time baseline of those observations. We measured the variability amplitude in the white light curve created using only the wavelength range covered by HST/WFC3 (1.10-1.63 micron), obtaining a value of 1.47+\-0.18%, which is consistent with that measured in the HST/WFC3 light curve.
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All authors Elena Manjavacas, Jared Bull, Paulo Miles-Paez, Natalia Oliveros-Gomez, Theodora Karalidi, Ben W. P. Lew, Zhoujian Zhang, Yifan Zhou, Daniel Apai, Xianyu Tan

Astrophysics of Galaxies

Discovery, Characterization, and Potential Origins of a Stream in the Stellar Halo of Nearby LMC-Mass Galaxy NGC 55

Benjamin N. Velguth, Burçin Mutlu-Pakdil, Erik Tollerud et al. (+32 more)

We present a previously undetected stellar stream in the halo of the LMC-mass dwarf galaxy NGC 55 (2 Mpc), as part of an ongoing effort to characterize the stellar halos of LMC/SMC-mass dwarfs in the DEEP component of the DECam Local Volume Exploration (DELVE) survey. This structure is aligned with an outflow traced by H$\alpha$ emission, a spur and cloud of neutral hydrogen, and the ultra-diffuse and possibly disrupting satellite galaxy NGC 55-dw1. We investigate possible ex-situ progenitor scenarios for this stream through the local luminosity-metallicity relation and a set of toy dynamical models that include gaseous, stellar, and dark matter components. If the stream is a product of a previous merger, the progenitor galaxy had an absolute magnitude $M_V \leq -7.2$ and a stellar mass $M_* \geq 10^5 M_{\odot}$ based on extrapolations of the detected stellar populations. If it is disrupted material from the ultra-diffuse satellite, their shared progenitor had an absolute magnitude $M_V \leq -8.3$ and a stellar mass $M_* \geq 10^{5.2} M_{\odot}$. We compare our stream and progenitor scenarios to those for NGC 300, a galaxy with a stellar mass similar to that of NGC~55 and known to host multiple structures in its halo. Our results demonstrate that even relatively isolated LMC-mass galaxies can have complex accretion histories, providing new tests of hierarchical galaxy formation at low masses.
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All authors Benjamin N. Velguth, Burçin Mutlu-Pakdil, Erik Tollerud, Sarah Pearson, Kristine Spekkens, Amandine Doliva-Dolinsky, Michael G. Jones, Denija Crnojević, Jeffrey L. Carlin, David J. Sand, Paul Bennet, Guy Stringfellow, William Cerny, Alex Drlica-Wagner, Joanna D. Sakowska, Jaclyn Jensen, Laura C. Hunter, Eric F. Bell, David Martínez-Delgado, Anirudh Chiti, Adam Smercina, Nitya Kallivayalil, Deepthi S. Prabhu, Alexander H. Riley, Yumi Choi, Noelia E. D. Noël, Sasha N. Campana, Guinevere Herron, Alistair R. Walker, Andrew B. Pace, Clara E. Martínez-Vázquez, Clecio R. Bom, Julio A. Carballo-Bello, Pol Massana, Gustavo E. Medina

Mathematical Physics

Generalized Hamiltonian formalism for spatially nonlocal nonlinear differential equations

Ali Pazarci, Nadir Ghazanfari and Ilmar Gahramanov

In this work, we develop a generalized Hamiltonian formalism for spatially nonlocal field theories whose Lagrangian densities depend explicitly on both the local field and its spatially reflected counterpart. Starting from a generalized variational principle, we derive generalized Euler-Lagrange equations and introduce a generalized functional derivative that consistently accounts for reflected-field contributions. The proposed formalism is applied to three spatially nonlocal nonlinear Schrödinger equations. For the Ablowitz-Musslimani equation, we construct, to the best of our knowledge, the first standard Lagrangian density formulated directly in terms of the complex fields and derive its complete Hamiltonian formulation. The same framework is subsequently applied to the two Lagrangian nonlocal nonlinear Schrödinger equations introduced by Velasco-Juan and Fujioka, yielding consistent Hamiltonian formulations that reproduce the corresponding generalized Euler-Lagrange equations. These results establish a unified Hamiltonian framework for a broad class of spatially nonlocal nonlinear field theories.
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High Energy Physics (Phenomenology)

Resurrecting Electroweak Dark Matter via Type-II Seesaw in light of recent LZ Event

Partha Kumar Paul, Sujit Kumar Sahoo, Narendra Sahu et al. (+1 more)

The recent observation of the high-energy nuclear recoil event LZ230616 with a recoil energy around 248 keV provides an interesting possibility to probe inelastic doublet dark matter (iDM). However, the electroweak doublet DM scenarios face strong constraints from solar DM capture for DM masses around the TeV scale which give rise to correct thermal relic density. In this work, we revive the inelastic doublet DM (iDM) scenario via type-II seesaw. In particular, we consider an inert lepton doublet (ILD) DM. While the minimal ILD scenario gives the correct relic abundance around the TeV scale, it is strongly constrained by direct detection and solar DM capture. In the type-II seesaw, the presence of the scalar triplet generates the required mass splitting and provides additional annihilation channels, allowing the correct relic abundance for much larger DM masses. The larger DM mass also helps evade the solar capture and indirect detection constraints. Additionally, the scalar triplet gives sub-eV neutrino masses required by the oscillation data.
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All authors Partha Kumar Paul, Sujit Kumar Sahoo, Narendra Sahu, Shashwat Sharma

Cosmology and Nongalactic Astrophysics

Non-linear halo bias for accurate modelling of cosmic infrared background anisotropies

Baptiste Jego, Matthieu Béthermin, Katarina Kraljic et al. (+3 more)

Halo models provide the standard framework for interpreting cosmic infrared background (CIB) anisotropies and inferring the connection between dusty star-forming galaxies and their host dark matter halos. Recent studies have shown that inaccuracies in the modelling of halo clustering may bias the inferred parameters governing star formation in dark matter halos. In this work, we investigate whether a more detailed description of halo clustering can alleviate these shortcomings. We incorporate a scale-dependent, non-linear correction to the halo bias within a halo-model framework based on a simple SFR-halo mass parametrisation. We consider both a full mass-dependent implementation and a computationally efficient approximation. We also investigate the impact of updated (sub)halo mass functions. We validate the revised framework using mock observations derived from a dedicated simplified version of the SIDES-Uchuu simulation, combining the SIDES empirical galaxy model with the Uchuu N-body simulation, specifically designed to match the SFR prescriptions adopted in our halo-model. The corrections modify the predicted CIB clustering by up to 30% on intermediate scales, while the effective implementation reproduces the full treatment at the sub-percent level. The updated model removes the scale-dependent discrepancies previously identified and accurately reproduces the measured power spectra over the full multipole range. In MCMC analyses, the input SFR parameters are recovered with substantially reduced biases, with all input parameters recovered within their $1\sigma$ confidence intervals. Our results demonstrate that accurately modelling non-linear halo clustering is essential not only to reproduce CIB anisotropies, but also to reliably recover the underlying galaxy-halo connection. The framework presented here provides a validated foundation for future analyses of observational data.
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All authors Baptiste Jego, Matthieu Béthermin, Katarina Kraljic, Athanasia Gkogkou, Guilaine Lagache, Abhishek S. Maniyar

Strongly Correlated Electrons

Correlation enhanced magnetism at a superconducting cuprate/manganite interface

Vitor A. M. Lima, Marcello Civelli and Walber Hugo de Brito

Motivated by experimental studies on cuprate-manganite heterostructures, we study a correlated bilayer Hubbard model subject to a local interfacial exchange field using cluster dynamical mean-field theory in the underdoped cuprate regime. We find that superconductivity coexists with a manganite-induced Cu spin polarization. Remarkably, throughout this coexistence regime, the superconducting solution carries a larger magnetic moment than the corresponding constrained normal state. Analysis of the magnetic response shows that this reversal is driven by correlations, which enhance magnetism already in the normal state and even more strongly in the superconducting solution. At stronger exchange fields, superconductivity collapses abruptly, displaying hysteresis consistent with a first-order transition, and a strongly spin-polarized pseudogap emerges. These results show that, under strong electronic correlations, superconductivity can enhance rather than suppress interfacial magnetism.
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Quantum Physics

Asymmetric quantum cloning on orthogonal orbits and four-mode fermionic states

Piotr Ćwikliński and Michał Studziński

In this work, we study asymmetric $(1\to2)$ quantum cloning for pure states belonging to orbits generated by the orthogonal group. For every dimension $(d\geq3)$, we determine the full region of achievable pairs of average single-copy fidelities. Using orthogonal covariance and the Brauer algebra, we reduce the optimization over all CPTP maps to a finite-dimensional spectral problem and construct explicit optimal cloning channels. We then apply the general results to four-mode fermionic states in the even-parity sector. Using triality, we identify the fixed-concurrence fermionic families with the orthogonal orbits considered in the first part of the paper. In particular, for pure Gaussian states we show that the symmetric locally optimal cloner is unique. We also compare local and global cloning and find that the channel optimal for the joint two-copy fidelity is different from the one optimal for the single-copy fidelities. Finally, we show that the locally optimal cloner cannot be implemented using only operations which preserve fermionic Gaussian states.
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Quantum Physics

Persistent Quantum-Enhanced Frequency Sensing with T^{-3/2} Scaling

Clayton Z.C. Ho, Hao Wu, Grant D. Mitts et al. (+2 more)

Quantum sensing uses nonclassical states to improve measurement sensitivity, but the same states that provide metrological gain also decohere more rapidly. This limits the usable interrogation time and, in practice, often precludes improvement in ultimate sensitivity - realized useful quantum advantage has consequently remained rare. Here, we restore persistent quantum advantage by embedding Fock-state enhancement within a quantum heterodyne (Qdyne) protocol, decoupling sensitivity from the decoherence-limited interrogation time {\tau}. Measurements are acquired at short {\tau} where the quantum-enhanced gain is optimal, while precision accumulates with the total measurement time. Demonstrated on the motional mode of a trapped 40Ca+ ion, we observe quantum-enhanced precision that persists to measurement times seven orders of magnitude beyond the dephasing limit, scaling as T^{-3/2} with no indication of saturation. Using the n=3 Fock state, we reach a frequency precision of 0.5uHz relative to an 86MHz carrier, achieving a fractional precision ~6x10^{-15}. This represents a quantum-enhanced gain of 7.1(10) dB over the n=0 state, in agreement with Fisher information predictions. This is the first demonstration of Qdyne beyond solid-state spin-defects. Further, by using the quantum harmonic oscillator to perform frequency mixing, we extend operation beyond 1GHz, two orders of magnitude above the ceiling of pulsed dynamical-decoupling implementations. These results recover quantum advantage at the long timescales required to improve ultimate sensitivity, with direct implications for nanoscale NMR and quantum logic spectroscopy.
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All authors Clayton Z.C. Ho, Hao Wu, Grant D. Mitts, Joshua A. Rabinowitz, Eric R. Hudson

Earth and Planetary Astrophysics

Asteroids Impacting the Solar System Planets and the Moon. III. Real Impacts from Known Objects and LSST Discovery Predictions

Qifeng Cheng and Daniel Scolnic

Impact rates predicted using pre-impact source-population models and those inferred from observations disagree by a factor of a few to $\sim200$ across the Solar System planets and the Moon. An exciting opportunity for an additional observational constraint is the discovery of asteroids before impact and their tracking until impact. We evaluate this prospect based on both known objects and forecasts of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). First, we identify impacts from known objects, confirming multiple past cases and predicting two coming impacts: 2015 FK488, a $\sim1.8$ km Centaur whose nominal orbit predicts an impact with Jupiter in $\sim200$ yr, and 2022 KG1, a $<10$ m NEO recently removed from the impact-risk lists but whose nominal trajectory leads to an Earth impact in $\sim260$ yr. Both orbits are poorly constrained. Second, assuming the model-based impact rate, we predict that LSST will discover 7 of the 59 synthetic impactors quantified in our previous analysis. All of the discovered impactors will impact Jupiter, and they have a size range of $\sim200-2000$ m and expected discovery-to-collision lead times of $1.94-257.4$ yr. Two of them are discovered inside Jupiter's Hill sphere, offering rare opportunities to observe the transition from a temporary bound orbit to impact before it happens. If instead we assume the observation-inferred impact rates, LSST will at most discover $\sim20$ future Earth impactors ($>10$ m) and $\sim300$ future Jupiter impactors ($>10$ m), with a wider range on both ends for discovery-to-collision lead times. These results demonstrate that LSST can identify a subset of planetary impactors years to centuries before collision, providing a new observational pathway for testing source-population models and the impact-rate mismatch.
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Earth and Planetary Astrophysics

Asteroids Impacting the Solar System Planets and the Moon. II: Comparison with Observational Impact Records

Qifeng Cheng and Daniel Scolnic

Planetary impact rates are difficult to infer from observations alone because impacts are rare, observational records are target-dependent, and converting observed flashes, bolides, and craters to an intrinsic impact rate depends on uncertain selection effects and conversion parameters. Building on the simulations in Paper I, we examine whether observational systematics can explain the order-of-magnitude mismatch between observed and modeled impact rates on Earth, and whether comparable discrepancies extend to other Solar System bodies. We convert 12 observed impact records for Earth, the Moon, Mars, and Jupiter to a common pre-atmospheric impact rate for $D>10$ m, propagate uncertainties through the conversion chain, and compare the resulting rates with the intrinsic rates derived in Paper I. We find discrepancies for Earth (observation-to-model median ratio $2.2-21.0$), the Moon ($3.4-132.1$), Mars ($14.2-118.6$), and Jupiter ($2.6-47.7$), with the dominant source of the discrepancy differing by body. The simulated Jupiter-family comet (JFC) contribution substantially reduces the Earth discrepancy, suggesting that an additional dynamical source may help explain the gap. The lunar records disagree with each other by two orders of magnitude, with the discrepancy dominated by size-extrapolation uncertainties. The Mars mismatch is dominated by crater-to-impactor conversion. The Jupiter comparison depends mainly on uncertainties in the inferred number of bound impactors and in the observational completeness thresholds. Further investigation of this mismatch requires incorporating cometary modeling and tighter constraints on size-extrapolation scaling and improved observational completeness.
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Earth and Planetary Astrophysics

Asteroids Impacting the Solar System Planets and the Moon. I. Collision Rates from N-body Simulations

Qifeng Cheng and Daniel Scolnic

Previous studies have shown a mismatch between the simulated rate of asteroids impacting the Earth and the observed rate, posing an important problem for planetary defense. Extending this analysis to other planets offers a new opportunity to examine minor body populations and impactor models. We present a unified simulation framework that estimates intrinsic $D\gtrsim10$~m impactor rates on the eight planets and the Moon. We construct size-calibrated source populations of Near Earth Objects (NEOs), Main Belt Asteroids (MBAs), Jupiter-family comets (JFCs), Centaurs, and scattering trans-Neptunian objects (TNOs), and propagate them with a 300-year $N$-body simulation. To avoid relying on black-box-like collision flags, we identify close encounters and estimate impact rates in two complementary ways: a direct count of realized impactors from object-level minimum-distance calculation and a collision expectation based on population-level impact parameter statistics. We predict over 300 years there will be $6.0^{+3.8}_{-2.7}$ impactors on Venus (all NEOs), $10.0^{+11.3}_{-4.9}$ on Earth (NEOs and JFCs), $\sim$$2981^{+481}_{-469}$ on Jupiter (mainly MBAs and JFCs), $1228^{+2759}_{-1017}$ on Saturn (mainly Centaurs), and none on the remaining planets with the $1\sigma$ upper limits spanning $<1.8$ (inner planets) to $<1\times10^{8}$ (outer planets; weak constraint). Jupiter uniquely receives both fast unbound impactors ($>50\, \mathrm{km\,s^{-1}}$) and slower bound ones reaching down to $\sim$$20\,\mathrm{km\,s^{-1}}$. In a companion paper, we compare our predictions with observations and test whether the gap extends across the Solar System and whether current telescopes can observe these collisions.
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Accelerator Physics

Moderator Modeling for High Intensity Slow Positron Sources

Sophie Crisp, Ryland Goldman and Spencer Gessner

Slow positron beams enable diverse applications, from surface-sensitive materials studies to positronium physics, but progress is limited by source intensity and brightness. In linac-based sources, mono-energetic, slow positrons are produced by moderating the broad, divergent distribution of fast positrons produced by high-energy electrons incident on a high-Z target. This process is intrinsically inefficient. Conventional linac-based designs place the moderator close to the target. Tungsten moderators become less efficient when heated by high-power, fast positrons, leading to defect-related losses. Cryogenic moderators, like solid neon, melt when exposed to high-power, fast positrons. Following the method of O'Rourke et al., we use Monte Carlo simulations combined with a diffusion model to investigate how moderator geometry, material, and incident fast positron energy affect slow positron production. We compare single tungsten foil and multi-foil configurations with solid neon moderators in reflection and transmission geometries. We find that for fast positron energies below 300 keV, solid neon offers order-of-magnitude higher efficiency than tungsten due to its larger diffusion length, whereas at MeV-scale energies multi-foil tungsten has higher efficiency due to the maximization of scattering. We also find that including a target proxy in simulation increases low-energy efficiency up to fourfold by allowing a fraction of initially reflected positrons to return to the moderator. We conclude that substantial gains in start-to-end efficiency at linac sources will likely require combining a decelerating cavity with a decoupled cryogenic moderator.
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High Energy Physics (Phenomenology)

Analytic results on the massive three-loop form factors: gluonic contributions

J. Blümlein, A. De Freitas, P. Marquard et al. (+2 more)

We compute the gluonic contributions to the three-loop heavy-quark form factors for the vector, axial-vector, scalar, and pseudoscalar currents. In the low-energy limit, $q^2/m^2 \rightarrow 0$, we used guessing algorithms to derive closed-form difference and differential equations from the rational sequences associated with the multiple zeta values and other constants appearing in the expansion coefficients, which required up to 26000 coefficients in the most demanding cases. Part of the results are obtained analytically in terms of harmonic polylogarithms and square-root valued iterated integrals by solving the obtained differential equations. For the remaining contributions, arbitrarily deep series expansions around the singularities of the form factors can be obtained by matching local expansions at intermediate points and by exploiting the differential equations obeyed by the functions associated with each transcendental constant in the expansions around $s = q^2/m^2 = 0$. For all these calculations advanced computer algebra methods have been employed. By using analytic continuation methods for differential equations matching the expansions at different values of $s$ and using PSLQ, we derive analytic results in the high-energy limit, $q^2/m^2 \rightarrow \infty$. The expansion coefficients are expressed in terms of multiple zeta values up to weight $w = 6$ together with three additional constants, two related to sixth-root-of-unity letters and one associated with quadratic-form implied iterated integrals. We also derive deep expansions about the threshold and pseudo-threshold. Numerical results are presented in the whole kinematic range and compared to results in the literature.
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All authors J. Blümlein, A. De Freitas, P. Marquard, J. Obrovsky, C. Schneider

Solar and Stellar Astrophysics

Searching for Massive Remnant Planetary System Hosts with White Dwarf Gaia XP Spectra

Lou Baya Ould Rouis, J.J. Hermes, Pierre Bergeron et al. (+5 more)

Remnant planetary systems around massive white dwarfs ($M_{\rm WD} > 0.8\,{\rm M}_\odot$) are intrinsically rare and remain poorly characterized. As the evolutionary endpoints of intermediate-mass B- and A-type stars, these white dwarfs provide valuable constraints on the formation and survival of planetary systems around higher-mass progenitors. In the absence of large, dedicated spectroscopic surveys, extremely-low-resolution Gaia XP spectra provide a powerful means of identifying candidate metal-polluted white dwarfs. We obtained follow-up observations with low-resolution optical spectroscopy (R=500-4000) to search primarily for Ca II H & K absorption in massive, metal-polluted white dwarf candidates selected from Gaia XP spectra to increase the sample of massive remnant planetary system hosts among objects with effective temperatures below $\sim15{,}000$ K. We find that Gaia XP spectra recover metal-polluted white dwarfs efficiently, confirming 82$\pm$5% recovery of photospheric metals (59 of 72 targets) in high-confidence candidates of our sample (with classifier probability $P_{\rm DZ} > 0.65$). However, Gaia photometric masses derived from $G$, $G_{BP}$, and $G_{RP}$ broad-band photometry are not sufficient to identify the most massive systems, as reliable mass determinations require detailed metal-enriched atmospheric fits. We present a selection of cool white dwarfs confirmed to be both massive and metal polluted, demonstrating that Gaia XP spectra can substantially expand the sample of white dwarf exoplanet hosts. Our search led to the discovery of a new transiting debris system, SDSS J1624+5404, the 21st published system to date and eighth to show periodic transits.
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All authors Lou Baya Ould Rouis, J.J. Hermes, Pierre Bergeron, Simon Blouin, Stefan Arseneau, Tim Cunningham, Joseph A. Guidry, Ciarra Coston

Materials Science

Symmetry Classification of Multipolar Orders in Crystals: Theory, Property Tensors and Automated Analysis with MagSymMultipoles

Maxime Braun and Quintin N. Meier

Many structural and magnetic phases and properties of crystalline materials can be related to the ordering of electric and magnetic multipoles. Examples include ferroelectricity, linear magnetoelectricity, and altermagnetism. Determining the symmetry-allowed multipoles in a crystal is therefore useful for characterizing its ordered phases and physical properties. Here, we present a unified Cartesian framework for decomposing moment tensors of arbitrary rank into ordinary, toroidal, and poloidal multipoles, and for determining, from crystallographic and magnetic symmetry, their ferroic, antiferroic, and noncollinear arrangements within the crystal. We further establish the direct symmetry relationship between multipolar order and the allowed components of associated physical-property tensors in both relativistic and non-relativistic settings. We implement this methodology in MagSymMultipoles (https://mag-sym-multipoles.com), an interactive web application for calculating and visualizing symmetry-adapted electric and magnetic multipoles. The application uses magnetic symmetries both with and without spin-orbit coupling to derive the allowed multipoles as well as the underlying Cartesian moment tensors, making it easy to explore the connection between a given multipolar order and the corresponding physical response tensors. We demonstrate the approach for ferroelectric BaTiO3, antiferroelectric PbZrO3, magnetoelectric Cr2O3, and the altermagnets MnF2, MnTe, and Mn3IrSi. These examples demonstrate how our method allows us to obtain an intuitive picture linking the multipolar order of a material directly to its physical properties, thereby facilitating the interpretation of theoretical and experimental results.
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Instrumentation and Methods for Astrophysics

The optical high-resolution spectral archive of the HERMES spectrograph mounted on the 1.2m Mercator telescope

Hans Van Winckel, Saskia Prins, Gert Raskin et al. (+13 more)

Context. The HERMES spectrograph is a high-resolution, fibre-fed optical spectrograph of the 1.2m Mercator telescope operated from the Roque de los Muchachos observatory in Spain. HERMES started its scientific operations in June 2009 and has been the workhorse instrument since then. Regular instrument updates have been crucial. They have helped to ensure the continued provision of high-quality spectra. This will continue both now and in the future. Aims. With this contribution we review over 16 years of HERMES operations and we launch and introduce the archive to the interna- tional community at large. We describe the overall performances of the HERMES spectrograph and list the most important instrument upgrades since the start of the operations. We release about 150 000 high-resolution spectra to the community and describe global properties of the datarelease. We use a standard propriety period of 1 year with some exceptions. Methods. We used the German Astrophysical Virtual Observatory (GAVO) DaCHS platform to present the archive in a Virtual Ob- servatory (VO) compatible form with both an access via a dedicated webinterface, and via VO-compliant tools like PyVO, TOPCAT, Aladin etc. We illustrate the use in several worked-out examples to search and download the fully wavelength-calibrated, cosmic- cleaned and barycentric corrected 1D spectra. Results. With this contribution we provide the needed information of the data product and offer a reference paper for the users of the HERMES archive.
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All authors Hans Van Winckel, Saskia Prins, Gert Raskin, Jesus Perez Padilla, Wim Pessemier, Wim De Meester, Maarten Dirickx, Yves Frémat, Alain Jorissen, Holger Lehmann, Kwinten Missiaen, Maddalena Reggiani, Hugues Sana, Andrew Tkachenko, Bart Vandenbussche, Christoffel Waelkens

Earth and Planetary Astrophysics

Rotational Mapping and Regional Atmospheric Retrievals of Variable Brown Dwarfs: Application to Luhman 16B and SIMP 0136

Ruizhe Wang, Heather A. Knuton, Julie Inglis et al. (+1 more)

We present a Bayesian framework for converting time-resolved spectroscopy into rotation-inferred regional spectra and atmospheric constraints for variable brown dwarfs. We derive an analytic mapping framework with evidence-optimized regularization and uncertainty propagation by marginalizing over physical parameters and model complexities. We provide methods for selecting characteristic spectral end-members from the inferred surface maps, and highlight the advantage of analyzing these rotation-inferred regional spectra over the disk-integrated time-resolved observations, while explicitly accounting for the geometric degeneracies inherent to rotational mapping. We apply this framework to published JWST/NIRSpec rotational monitoring of Luhman 16B and SIMP 0136. For both objects, we identify dominant spectral regions and retrieve regional variations in cloud structure, thermal gradients, and chemistry that are consistent with cloud radiative feedback. In addition, we demonstrate the importance of limb darkening in deriving surface maps. These results establish a statistically controlled method for linking rotational spectral variability to atmospheric heterogeneity and enable future rotational mapping and regional atmospheric studies of giant planet atmospheres.
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All authors Ruizhe Wang, Heather A. Knuton, Julie Inglis, Xianyu Tan

Quantum Physics

Cavity-QED analysis of InAs quantum-dot single photon production

W. W. Chow, S. Peana, D. I. Herman et al. (+6 more)

Cavity quantum electrodynamics is used to study the extent cavity enhancement affects single photon performance of an InAs quantum dot, in terms of emission rate, purity and indistinguishability at different temperatures. Parametric studies show a tradeoff between single photon production rate and purity, as well as between indistinguishability and purity. The results indicate the importance of quantum carrier-photon correlations that yield substantial corrections to mean-field treatments, especially at high light-matter coupling strength, where cavity enhancement is most effective.
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All authors W. W. Chow, S. Peana, D. I. Herman, K. Y. Lee, A. Cejan, C. Shang, G. Moody, J. E. Bowers, F. Jahnke

Mesoscale and Nanoscale Physics

Non-Hermitian impurity scattering in graphene: Boltzmann transport and thermoelectric response

Juan A. Cañas, Daniel A. Bonilla and A. Martín-Ruiz

We investigate charge and thermoelectric transport in monolayer graphene containing a dilute distribution of finite-range non-Hermitian scattering centers. The impurities are modeled as circular complex potentials, whose imaginary component describes local carrier loss or gain. By solving the Dirac scattering problem exactly within a partial-wave approach, we obtain the nonunitary scattering matrix and derive the transport and absorption cross sections, which separately characterize momentum relaxation and net carrier exchange with the environment. To connect the microscopic scattering problem with stationary transport, we formulate a semiclassical Boltzmann description in which an external reservoir compensates the equilibrium particle loss or gain. This leads to an effective relaxation time governed by both elastic momentum scattering and non-Hermitian flux exchange. Using the full energy-dependent relaxation time, we evaluate the Onsager coefficients and the resulting electrical conductivity, electronic thermal conductivity, Seebeck coefficient, Lorenz ratio, and electronic thermoelectric figure of merit. We find that weak gain increases the effective carrier lifetime and enhances both charge and heat conductivities, while absorption produces the opposite behavior. More importantly, gain enhances the magnitude of the thermopower and the electronic figure of merit, whereas loss suppresses them. The Lorenz ratio remains close to the Sommerfeld value, with non-Hermiticity mainly modifying its finite-temperature corrections. Our results show that non-Hermitian scattering provides an additional mechanism for controlling the energy dependence of carrier relaxation and, consequently, the thermoelectric response of graphene.
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Chemical Physics

cboamd: A Machine Learning Molecular Dynamics Framework for Vibrational Strong Coupling

Yifan Li, Roberto Car and Johannes Flick

Under vibrational strong coupling (VSC), molecular vibrations hybridize with an optical cavity mode to form polaritons, offering a route to modify chemical and material properties without external driving. In this work, we develop a machine-learning interatomic potential (MLIP) based framework to study VSC inside optical cavities. By using the cavity Born-Oppenheimer approximation and treating the photonic degrees of freedom as an effective electric field, we provide a framework that can describe VSC solely based on the electronic ground-state potential energy surfaces (PES), electronic dipole moment, and polarizability, all quantities obtained outside the cavity. We train PES, polarization, and polarizability models to drive the molecular dynamics (MD) simulations of systems under VSC. We demonstrate the approach for both a single CO$_2$ molecule and liquid CO$_2$, showing that the polarizability renormalizes the effective cavity resonance: at fixed cavity frequency this renormalization renders the Rabi splitting strongly asymmetric, while with renormalized cavity frequency the symmetric splitting is capped by polarizability screening. The collective Rabi splitting of the liquid is connected quantitatively to the single-molecule splitting involving the $\sqrt{N/3}$ orientational enhancement and the local-field enhanced effective charges of the coupled vibration, while the equilibrium pair structure of the CO$_2$ liquid remains unchanged. These simulations are the first MLIP-driven simulations of collective VSC in the condensed phase and open further pathways to the exploration of chemical effects under VSC.
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Earth and Planetary Astrophysics

Multiband Color Monitoring of 3I/ATLAS through Ground-Based Relay Observations

Ariel Graykowski, Bryce Bolin, Laura-May Abron et al. (+140 more)

We present multiband, long-baseline photometric observations of interstellar comet 3I throughout its 2025–2026 apparition using coordinated ground-based global relay observations. Our dataset combines measurements from professional observatories and citizen-operated Unistellar eVscopes distributed worldwide, providing dense temporal coverage from 2025 July 2 through 2026 April 1 and spanning the comet's pre- and post-perihelion trajectory. Broadband photometry was obtained in bandpasses equivalent to the Johnson–Cousins $B$ (436 nm), $V$ (545 nm), and $R$ (641 nm) filters and the Sloan $g$ (477 nm), $r$ (623 nm), and $i$ (763 nm) filters. The photometry was measured using projected aperture radii of approximately 10{,}000~km to provide a consistent probe of the inner coma across the heterogeneous dataset. We measure representative mean colors of $B-V=0.86\pm0.06$, $V-R=0.50\pm0.03$, $B-R=1.36\pm0.08$, and $g-r=0.58\pm0.08$, demonstrating a persistently red optical coma. Constant-color models provide an adequate description of the data, with little evidence for long-term color evolution with time or heliocentric distance despite substantial changes in the coma's brightness, gas production, and volatile composition. This suggests that the ensemble-averaged optical scattering properties of the coma remained relatively stable over the period sampled by our observations, even as other properties of the coma evolved. These observations provide the first densely sampled, apparition-long characterization of the broadband optical colors of an interstellar comet and establish a benchmark for comparison with future interstellar objects.
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All authors Ariel Graykowski, Bryce Bolin, Laura-May Abron, Franck Marchis, Martin Mašek, Filipp D. Romanov, Ahmed M. Abdelaziz, Dimitrios Athanasopoulos, Matthew Belyakov, Luca Buzzi, Michael W. Coughlin, Ergün Ege, Nicolas Erasmus, Thomas M. Esposito, Christoffer Fremling, Josep M. L. Garcia, Marek Husárik, Oleksandra Ivanova, Tarek M. Kamel, Sergey Karpov, Myung-Jin Kim, Tomasz Kwiatkowski, H.-J. Lee, Sofiia Mykhailova, Alessandro Nastasi, Dagmara Oszkiewicz, John W. Pickering, Alexey Sergeyev, Roman Telesnikov, Josep M. Trigo-Rodríguez, Al Alicea, Jin Beniyama, Otabek A. Burkhonov, Kamoliddin E. Ergashev, Y.H.M. Hendy, Jeong-Han Kim, Cheng-Han Hsieh, M. Emir Kenger, Thomas Lehmann, Igor Luk'yanyk, Ali Takey, Dušan Tomko, Murat Tekkesinoglu, Shane Winter, Joel Alonzo, Michael Beddo, Axel Bienefeld, Mario Billiani, John K. Bradley, Olivier Clerget, Sabine Cremer, Nicolas Delaunoy, José Donas, John Dunn, Jiří Dvořáček, Michael Edwards, Taj Entabi, Raffaele Esposito, Karen Fischer, Robert Foster, Edward Friday, Keiichi Fukui, Francois Gagnon, Matthieu Garisson, George Ghreichi, Patrice Girard, Tateki Goto, Michael Grant, Chris Greenfield, Bruno Guillet, Josef Hanus, John Harrison, David Havell, Kevin Heider, Kirt Hufstedler, Kachi Iwai, Maxime Johnson, Christian Joisten, Scott Kardel, Suzanne Kavic, Vamshi Kesireddy, Rachel Knight, David Koster, Jericho Kuehl, Ryuichi Kukita, Jan Kunc, Petri Kuossari, Alain Lambert, Scott Lancelle, Jean-Marie Laugier, Stephen Lawrence, Pedro Lemos, Jeffrey Linn, Joseph Llanes, Steeve Loisel, Gaël Lombart, Margaret A. Loose, Yohann Lorand, Chris Mahar, Scott Manley, Vincent Marcouiller, Sevastos Mastrogiorgis, Nicola Meneghelli, Mike Mitchell, Iaroslav Mokroguz, Jacques Molne, Fabrice Mortecrette, Ioannis Mytakos, Anouchka Nardi, Wataru Ono, James Owen, Larry Parchman, Bruce Parker, Michael Primm, Darren Rivett, Facundo Robles, Van Ruckman, Matthew Ryno, Nikolaj Schraufl, Jean-Pierre Schulz, Christoph Seidler, Lauren A. Sgro, Masao Shimizu, Francois Simard, Georges Simard, Bran Solo, Grant Sorenson, Marcelo Souza, David Swalander, Akimitsu Takahashi, Lydia Tamez, Petri Tikkanen, Bryan Tobias, Ian Transom, William Turnipseed, Charles Urban, Claudio Vantaggiato, Aad Verveen, Andrew Wendelborn, Stefan Will, Mark Wilson, Neil Yoblonsky, Wai-Chun Yue