High Energy Physics (Phenomenology)
Suppressing Extra-Dimensional Axion Isocurvature Dynamically
Gongjun Choi and Tony Gherghetta
Extra-dimensional QCD
axion is well motivated by string compactifications and enjoys enhanced protection against quality-violating effects. If present during inflation, however, its
quantum fluctuations generate isocurvature perturbations that strongly constrain the inflationary scale. We propose a dynamical suppression mechanism in warped five-dimensional models, where a radion-inflaton coupling sets the radion minimum at small inter-brane separation during inflation, temporarily enhancing the effective four-dimensional
axion decay constant. After inflation, the radion minimum shifts to larger separation, restoring the standard QCD
axion window. In a warped orbifold GUT with Goldberger-Wise stabilization, this mechanism can satisfy CMB isocurvature bounds while allowing substantially higher inflationary scales than in conventional pre-inflationary
axion cosmology.
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Solar and Stellar Astrophysics
Intrinsic iron abundance spreads in globular clusters
J. Schiappacasse-Ulloa, S. Lucatello, L. Magrini et al. (+2 more)
Globular Clusters (GCs) host multiple
stellar populations, likely composed of a subset of FG
stars that enriched the intracluster medium and gave rise to SG
stars, each characterised by distinctive chemical patterns. These patterns typically include enhancements in elements such as N, Na, and Al, coupled with depletions in C, O, and Mg in SG
stars. Traditionally, heavier elements such as those in the Fe-peak were considered unaffected in most GCs. However, recent studies have reported significant internal spreads in these elements, suggesting a more complex picture of chemical enrichment within GCs. This study seeks to derive precise and homogeneous differential iron abundances in a large sample of GCs. By doing so, our aim is to investigate the presence of intrinsic iron spreads within them and to assess the existence of differences in Fe between their
stellar populations. We used the Python-based tool Q2 to determine both differential
stellar parameters and iron abundances for 92 sibling
stars, defined by the similarities in their
stellar parameters, across 13
Galactic GCs. This differential approach reduces the influence of non-LTE effects, and minimises observational errors, and systematic biases linked to
stellar parameters. We performed Monte Carlo simulations to evaluate the statistical significance of the measured spreads. Most of the GCs in our sample do not show evidence of statistically significant Fe spreads. Only a few exceptions emerge, namely NGC1851, NGC3201, and NGC5634, which display a highly significant iron spread. In particular, NGC3201 shows a particularly pronounced spread in its FG population, reflecting a potential inhomogeneous iron abundance in its pristine material. Finally, through statistical tests, we conclude that our data do not support the presence of a widespread iron variation in GCs.
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All authors J. Schiappacasse-Ulloa, S. Lucatello, L. Magrini, A. Bragaglia, E. Carretta
Astrophysics of Galaxies
Faraday depth similarities across scales with LoTSS & DRAGONS
Anna Ordog, Rebecca A. Booth, Ana Erceg et al. (+5 more)
Faraday rotation of diffuse
Galactic synchrotron emission is a powerful tracer of the complex, magnetised interstellar medium (ISM), whose structures span a wide range of spatial scales, requiring both interferometric and single-
antenna broadband
radio polarisation observations for full characterisation. We compare Faraday rotation in the interferometric LOw-Frequency ARray Two-Metre Sky Survey (LoTSS; 120-168 MHz) and the single-
antenna Dominion
Radio Astrophysical Observatory Global Magneto-Ionic Medium Survey of the Northern Sky (DRAGONS; 350-1030 MHz), which are complementary in their sensitivity to spatial and Faraday-depth scales. We calculate first moments (M1) of polarised intensity versus Faraday depth, producing polarised-intensity-weighted mean Faraday depth maps of the regions common to both surveys. These maps show remarkable agreement between the surveys despite the lack of overlap in frequency or spatial-scale coverage. In the northern
Galactic region, the M1 maps are morphologically similar with only small spatial shifts in the boundaries between positive and negative M1, and strong pixel-by-pixel correlation. In the southern
Galactic region, both surveys trace the Faraday-depth gradient with
Galactic longitude previously identified in LoTSS. Faraday depth spectra show consistent numbers and locations of peaks for more than half of the pixels. The strong structural similarity between the surveys, demonstrated by computing structure functions, suggests coupling across spatial scales in the magnetised ISM, enabling both interferometric and single-
antenna observations to trace the same features. Instances of differences point to ISM configurations where observational effects such as depolarisation dominate or where this coupling breaks down due to local physical conditions.
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All authors Anna Ordog, Rebecca A. Booth, Ana Erceg, Vibor Jelić, Jo-Anne C. Brown, Marijke Haverkorn, Alex S. Hill, T.L. Landecker
Astrophysics of Galaxies
Predicting ionised gas emission in 3D with SKIRT. I. Framework and validation
Anand Utsav Kapoor, Maarten Baes, Aaron Smith et al. (+7 more)
Emission lines from ionised gas are key diagnostics of
star formation,
metallicity, and ionisation conditions in
galaxies. Interpreting spatially resolved observations from integral-field surveys (e.g. MaNGA, MUSE, JWST/NIRSpec) and comparing them with hydrodynamical simulations requires 3D photoionisation models that handle realistic geometries,
dust attenuation, and synthetic instrument output. We present a new photoionisation module for the Monte Carlo radiative transfer code SKIRT that predicts emission-line luminosities of ionised gas in 3D, combining pre-computed Cloudy tables for gas temperature and opacity with a direct calculation of ion fractions and line emissivities. The local ionising radiation field (1-6 Ryd) is characterised by log U and four spectral-shape ratios; Cloudy tables map these to temperature and opacity, converging through SKIRT's existing iteration cycle. An inline solver then determines ion fractions from the converged field and temperature and evaluates line emissivities. We validate against Cloudy on 60 spherical shell models and against COLT on a Milky Way-analogue
galaxy. On the 1D grid, hydrogen recombination lines agree with Cloudy to within a few per cent (Halpha median ratio 0.97) and the forbidden lines to within ~5%, except [S II] 6717 (1.23), whose offset traces a temperature overestimate near the ionisation front. In 3D, integrated luminosities agree with COLT to within 18% for the hydrogen lines and 2% for [N II], while [O III] and [S II] are elevated by ~70 and ~80%. Pixel-by-pixel correlation coefficients reach r >= 0.92, with luminosity-weighted scatter of 0.14-0.31 dex and broadly consistent BPT ratios. The module enables self-consistent synthetic observations in which ionised-gas emission lines,
dust attenuation, and
dust re-emission are computed in a single MCRT run, applicable to any hydrodynamical simulation.
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All authors Anand Utsav Kapoor, Maarten Baes, Aaron Smith, Arno Lauwers, Andrea Gebek, Peter Camps, Sven De Rijcke, Arjen van der Wel, Kosei Matsumoto, William McClymont
Soft Condensed Matter
Nonreciprocal multi-body interactions activate liquid state of acoustically levitated particle ensembles
Nina M. Brown and Heinrich M. Jaeger
Nonreciprocal forces are often a consequence of asymmetry in the properties of the interacting objects. However. even if all objects are identical and isotropic, and the pairwise interactions between two objects are completely reciprocal, nonreciprocal forces can still appear when an arrangement of many objects breaks configurational
symmetry in the presence of non-pairwise, multi-body interactions. Here we demonstrate that such emergent nonreciprocity can activate a particle ensemble to behave like a
liquid, albeit with unique traits. In our experiments, passive microspheres are acoustically levitated in air, where they form a freely floating monolayer containing up to a couple hundred particles and collectively behave like a two-dimensional
liquid droplet. The particles interact via nonreciprocal multi-body forces that arise from the combination of acoustic scattering and sound-induced viscous microstreaming. We find that these forces drive superdiffusive particle motion with non-Gaussian tails in the particles' speed distribution. Using probes that reach laterally into the levitation plane, we perform
liquid pendant drop and pinch-off experiments. Compared to ordinary
liquids, the droplets are found to have a kinematic viscosity similar to that of water, but in combination with an extremely low interfacial tension. The pinching-off is driven by nonreciprocity-induced active fluctuations and exhibits the self-similar double-cone neck profile seen also in
liquid nanojets close to rupture, however here characterized by power law behavior with a scaling exponent that is anomalously small.
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High Energy Astrophysical Phenomena
A new likely pulsar binary in 47~Tucanae from continuum searches
Thomas J. Maccarone, Alessandro Paduano, Arash Bahramian et al. (+6 more)
We present evidence that the X-ray source 47~Tuc~W41, long considered to be an X-ray source powered by coronal activity, is actually a redback
pulsar binary. The source continually shows $L_X = 3 \times 10^{31}$ erg s$^{-1}$ (0.5–10 keV), which is well in excess of the coronal saturation limit for active binaries in quiescence, but is consistent with the intrabinary shock observed in redback
pulsars, as is its
photon index of $\Gamma = 1.4\pm0.1$. In addition, using deep data from the Australia
Telescope Compact Array, we show that W41 is a faint ($9.8\pm1.4 \mu$Jy at 5.5 GHz) steep spectrum ($\alpha = -1.8\pm0.4$)
radio continuum source, as expected for a
pulsar. Light curve modelling of Hubble Space
Telescope photometry shows evidence for ellipsoidal modulation with mild irradiation of a $\sim 0.5$–$0.55 M_{\odot}$ secondary around an invisible companion, also consistent with the redback interpretation. The precise position of W41, along with its well-measured 10.4-hr orbital period, should enable it to be matched to a newly-discovered
radio pulsar in future data. Our result shows that close
pulsar binaries are still hiding, misclassified among active binaries, even in well-studied clusters like 47 Tuc.
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All authors Thomas J. Maccarone, Alessandro Paduano, Arash Bahramian, Liliana Rivera Sandoval, Jay Strader, James C.A. Miller-Jones, Angiraben D. Mahida, Craig O. Heinke, Laura Chomiuk
Medical Physics
Artificial Intelligence Across the Cardiac Amyloidosis Diagnostic and Management Pathway: From Single-Modality Detection to Multimodal Clinical Integration
Diana Shadibaeva, Rochak Dhakal, Kui Zhang et al. (+4 more)
Cardiac amyloidosis (CA) is increasingly recognized but remains substantially underdiagnosed because its clinical and imaging phenotype overlaps with more common cardiomyopathies. Definitive subtype assignment and management further require integration of
multimodal evidence to distinguish transthyretin from light-chain disease. Machine learning and deep learning have been applied across the diagnostic and management pathway. These applications span electrocardiography (ECG), echocardiography, and health record-based case finding, as well as cardiac
magnetic resonance (CMR) and
nuclear interpretation, including single-
photon emission computed
tomography/computed
tomography (SPECT/CT) biomarker quantification, prognostic modeling, and treatment response assessment. This narrative review synthesizes these studies by clinical tasks, namely screening, detection, quantification, prognosis, and longitudinal assessment after treatment initiation, rather than by input modality. This task-based organization clarifies why apparently similar AI models require different cohorts, reference standards, evaluation metrics, and implementation thresholds. The evidence reveals a maturity gradient. Binary detection and AI-assisted interpretation of cardiac scintigraphy with bone-avid tracers and SPECT/CT currently represent one of the more mature AI applications in cardiac amyloidosis, supporting standardized image interpretation and quantitative biomarker extraction. However, patient-level diagnosis still requires integration with monoclonal
protein testing, SPECT/CT localization, clinical context, and biopsy or tissue typing when indicated.
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All authors Diana Shadibaeva, Rochak Dhakal, Kui Zhang, Diana Paez, Xiaofeng Yang, Saurabh Malhotra, Weihua Zhou
Mathematical Physics · Cross-listed from math.PR
Statistics on Yau's conjecture: Variance asymptotics
Michele Stecconi and Anna Paola Todino
We investigate the probabilistic counterpart of Yau's
conjecture on the nodal volume of Laplace eigenfunctions on compact
manifolds, by studying the high-frequency variance asymptotics of Riemannian random waves.
Theorem A gives quantitative bounds on the fluctuations of their nodal volume for all regimes of spectral windows, including the monochromatic one, of spectral size 1. For every non-monochromatic window the variance has the exact order $1/N$, where $N$ is the dimension of the underlying space of eigenfunctions, on any compact
manifold. In the monochromatic regime, on
manifolds without conjugate points and in particular on negatively curved ones, we prove that the variance is $o(1/N)$: this improves the previous best bound, cf. Canzani and Hanin 2020, to its square divided by a logarithmic factor, and exhibits a form of Berry's cancellation, relative to the natural scale $1/N$, for monochromatic random waves on such chaotic
manifolds. Our proofs rely on a local and global analysis combining the Kac-Rice formula, the Wiener–Itô chaos decomposition recently obtained by the authors Stecconi and Todino 2025, and a sharp analysis of the error in the pointwise Weyl law associated to an arbitrary spectral window (
Theorem B). We also introduce a general machinery (
Theorem C) that yields variance decay for the nodal volume of an arbitrary Gaussian field under broad
geometric conditions, subject to correlation decay assumptions.
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Medical Physics
APHABAMAS: An analytical phantom-based scheme for assessing the accuracy of high-resolution 3D MRI motion-artifact simulations
Tianqi Wu and Hui Zhang
Purpose: Motion compromises the utility of high-resolution 3D MRI, an established tool in quantitative neuroimaging research. Deep learning-based methods have shown promise for mitigating motion-induced artifacts, but their development typically requires simulated motion-corrupted data. Several open-source tools exist for this task, each implementing different
algorithms. However, no scheme currently exists for evaluating the accuracy of these simulations, making it difficult for users to choose the most suitable tool. This study aims to develop such a scheme. Methods: The essential ingredient of the desired scheme is a ground-truth reference that does not suffer from sampling-induced error. To meet this requirement, the proposed scheme, APHABAMAS, leverages a digital phantom whose image- and
Fourier-domain representations can be expressed analytically under arbitrary rigid-body transformations. APHABAMAS is used to quantify sampling-induced errors of three existing
algorithms under synthetic and tracking-data-derived motion trajectories at different motion severity levels. Results: All three
algorithms produce distinct but visually plausible artifacts, demonstrating the need for a ground-truth reference. APHABAMAS shows that the
algorithm utilizing the uniform-to-non-uniform (Type-2) NUFFT provides the most consistent agreement with the ground-truth reference across motion types and severity levels. The non-uniform-to-uniform (Type-1) NUFFT-based
algorithm, which does not mimic the MR acquisition process, deteriorates substantially with increasing motion severity. Conclusions: APHABAMAS provides a rigorous tool for assessing the accuracy of high-resolution 3D MRI motion-artifact simulations. It enables accuracy-based assessment of three existing
algorithms, thereby facilitating informed selection of the most suitable one for synthesizing motion-corrupted data.
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Cosmology and Nongalactic Astrophysics
Assessing the large-scale angular clustering of UNIONS Lyman Break Galaxies via cross-correlations
Constantin Payerne, Christophe Yèche, William d'Assignies Doumerg et al. (+8 more)
Lyman-break
galaxies (LBGs), selected via the strong spectral break blueward of the Lyman limit, are powerful tracers of large-scale structure at
redshifts $z>2$. In this work, we assess the feasibility of using LBGs selected from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) multi-band photometric catalog as cosmological probes of the high-
redshift Universe using two-point statistics. We demonstrate that spatially varying imaging systematics, driven by variations in PSF depth, seeing across the UNIONS footprint, limit robust measurements of the LBG auto-angular power spectrum on large scales, even after correcting the LBG field with linear or non-linear mitigation techniques. This study shows that clustering analyses of faint
galaxy samples close to survey depth are challenging. We therefore turn to cross-correlation measurements with external tracers, in particular the Planck CMB
lensing convergence and
quasars from DESI DR1 and Quaia, which are less sensitive to the angular imaging systematics. Using both data and mock catalogues, we demonstrate that the LBG–CMB
lensing cross-power spectrum can be measured more robustly than the auto-spectrum, with an amplitude consistent with theoretical predictions. Residual systematics primarily manifest as excess variance at large angular scales, without introducing a significant bias in the recovered signal. Taken together, these results establish UNIONS-selected LBGs as reliable tracers for cross-correlation cosmology at $z\sim 2.5$, and highlight cross-correlation techniques as a powerful and robust avenue for extracting cosmological information from photometric high-
redshift galaxy samples in the presence of complex imaging systematics.
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All authors Constantin Payerne, Christophe Yèche, William d'Assignies Doumerg, Hendrik Hildebrandt, Martin Kilbinger, Calum Murray, Thomas de Boer, Kenneth C. Chambers, Scott Chapman, Michael J. Hudson, Alan W. McConnachie
General Relativity and Quantum Cosmology
Entropy and Non-Collapse in Lorentzian Geometry
Rohit Dhormare
In this paper, we establish a
geometric correspondence between the Lorentzian Raychaudhuri equation and Perelman's non-collapsing
theorem for the
Ricci flow. By interpreting the Raychaudhuri equation as a Lorentzian analogue of
Ricci flow, we connect geodesic focusing in general relativity to the monotonicity and
entropy functionals of
geometric analysis. Using this correspondence, we derive a Lorentzian non-collapsing
theorem and introduce a covariant
entropy functional governing causal volume
evolution. Finally, we propose the concept of geodesic
entropy capacity, a
curvature-bounded limit on the information that can be stored in spacetime regions, providing a unified
geometric framework linking gravitation, thermodynamics, and information.
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High Energy Physics (Theory)
Bosonization versus the Nielsen-Ninomiya theorem
Saif Ullah Baig, Shi Chen, Aleksey Cherman et al. (+1 more)
Thanks to bosonization, bosonic
lattice models can offer a
lattice regularization of
chiral fermions. We construct
chiral lattice fermion operators in the 2D modified Villain scalar model and evaluate their correlation functions. This microscopic bosonic model has an ultra-local action and an ultra-local
symmetry that realizes the fermionic
chiral symmetry under bosonization. The reconstructed
lattice Dirac operator has no doublers, but is consistent with the Nielsen-Ninomiya
theorem because it turns out to be non-local. The non-locality of this derived quantity at finite
lattice spacing does not pose any obstructions to gauging the non-anomalous
symmetries of the model, which is itself ultra-local.
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All authors Saif Ullah Baig, Shi Chen, Aleksey Cherman, Maria Neuzil
Fluid Dynamics
A Multispecies ESBGK Model for Gas Mixtures with Variable Hard Sphere Transport: Theory and Verification
Marcel Pfeiffer, Franziska Tuttas, Julien Mathiaud et al. (+1 more)
A multi-species Bhatnagar-Gross-Krook (BGK) model for gas mixtures is presented that achieves the correct species-wise relaxation of velocities, temperatures, and pressure tensors according to the Boltzmann collision integral, as well as the correct mixture Prandtl number, while retaining a single relaxation term per species. The model extends the ellipsoidal statistical BGK (ESBGK) model by introducing relative relaxation targets for each species, derived from the Variable Hard Sphere (VHS) production rates of the Grad 13 approximation. Three approaches for the species relaxation frequency are proposed and analyzed: a Grad 13-based per-species frequency, a mixture-averaged frequency, and an empirical harmonic mean of the two. The model is implemented in the particle-based code PICLas and verified against Direct Simulation Monte Carlo (DSMC) results for a range of test cases, including 0D reservoir relaxation, mass
diffusion, supersonic Couette flow, and hypersonic flow around a 70{\deg} blunted cone for binary and ternary gas mixtures. Across all test cases, the proposed model reproduces the correct Prandtl number, species temperature, velocity relaxation rates and pressure tensor relaxation, with the empirical relaxation frequency consistently yielding the best agreement with DSMC.
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All authors Marcel Pfeiffer, Franziska Tuttas, Julien Mathiaud, Luc Mieussens
Quantum Physics
Device-independent certification of tripartite quantum networks with bilocal Bell inequalities
Patryk Michalski, Arturo Konderak and Remigiusz Augusiak
While
quantum networks have been extensively studied as a natural extension of the standard Bell scenario with a richer correlation structure, general constructions of nonlinear Bell inequalities with self-testing properties are still largely lacking. In this work, we present a general method for constructing such inequalities in the simplest network scenario, in which two independent sources distribute bipartite
quantum states to three spatially separated observers. These inequalities allow for arbitrary numbers of binary measurements and are maximally violated by maximally entangled states of the corresponding local dimensions together with sets of pairwise anticommuting Clifford observables. Importantly, their maximal
quantum values can be determined analytically, which makes them particularly promising for device-independent applications. In particular, we prove that these Bell inequalities can be used to device-independently certify the underlying
quantum network, including both the
quantum states produced by the sources and the observables measured by all parties. To the best of our knowledge, this is the first self-testing result for
quantum networks that relies solely on the maximal violation of a nonlocality witness.
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Soft Condensed Matter
Odd Polycatenanes Tank-Tread in Strong Shear Flow
Ali Seyedi, Charles W. Manke and Alex Albaugh
Polycatenanes are mechanically interlocked
polymers composed of ring molecules linked through mechanical bonds. Here, we investigate the single-molecule dynamics of linear polycatenanes under strong steady shear flow using coarse-grained Brownian dynamics simulations with hydrodynamic interactions. We identify a stable tank-treading state in which individual rings rotate continuously while the overall
polymer remains highly extended and aligned with the flow direction, adopting conformations typically associated with extensional flow. Remarkably, tank-treading is observed almost exclusively in odd polycatenanes, polycatenanes with an odd number of rings. We attribute this odd-even effect to the orientation of the terminal rings within the flow-gradient plane, where they act as anchors that stabilize
polymer extension, a configuration accessible only to odd polycatenanes. Furthermore, our simulations and a Markov state model demonstrate that this dynamic behavior remains stable over long timescales. Finally, we show that tank treading polycatenanes can be used to fully extend other molecules in strong shear flow, hinting at applications of this behavior to manipulate molecules in rotational flows.
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Quantum Physics
A {\lambda}-Resonance Theorem for Constrained QAOA: Spectral Structure and Recurrence Bounds
Krit Grover
Training the variational angles of the
Quantum Approximate Optimization
Algorithm once on a small instance and reusing them on larger ones, known as parameter transfer, is the standard route past the exact-simulation wall. Existing explanations of parameter transfer focus primarily on structural similarity, but constrained encodings introduce a second quantity that must also be tracked: the penalty scale. We characterize the dependence on the deployment penalty scale when the
circuit angles are held fixed. We show that for a scalarized cost C{\lambda} = C + {\lambda}v with integer-valued violation count v, the feasible probability F({\lambda}) at arbitrary fixed depth p is a finite real trigonometric
polynomial whose frequencies are integer linear combinations of the fixed {\gamma} angles. We call this dependence {\lambda}-resonance. It recasts penalty mismatch as a phase-interference problem and yields an explicit spectral-support formula, a Bernstein lower bound on the detuning required to change F by a specified amount, and exact recurrences when the layer phases share a common period. These statements hold for arbitrary fixed angles, including untrained angles; they establish spectral support and recurrence conditions without asserting that the training penalty is a preferred operating point. Exact-statevector experiments on a 20-
qubit resource-allocation QUBO exhibit sharp and blunt response profiles and empirical recurrences consistent with the predicted spectral support. Independent penalty-phase sampling recovers the full
Fourier coefficients and allows coefficient-based recurrence bounds to be evaluated. Together, the theory and experiments motivate a conditional transfer protocol: treat (e̱ta}, {\gamma}, {\lambda}0) as a single calibrated parameter set, verify target validity, and bracket the matched penalty with a small fixed-angle sweep when feasible.
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Strongly Correlated Electrons
A d-Electron Heavy-Fermion-Like Superconductor with Frustration-Induced Flat Bands
Chaoguo Wang, Hyeonhu Bae, Jiaqi Tian et al. (+11 more)
Heavy-
fermion superconductors are mostly associated with f-electron materials with Kondo
lattices, while known d-electron heavy-
fermion-like systems are often linked to orbital-selective local moments, Hund-metal physics, or a charge-density-wave mechanism. Here we report Mo4PtGa17, a noncentrosymmetric itinerant d-electron
superconductor with a geometrically frustrated breathing-pyrochlore Mo
lattice. Thermodynamic, transport and NMR measurements reveal heavy-
fermion-like behavior superconductivity and dominant
ferromagnetic spin fluctuations near a
ferromagnetic instability. Theoretical calculations identify nearly flat bands, van Hove singularities and Kramers nodal lines near the
Fermi energy, derived intrinsically from Mo-4d states and are robust against on-site electronic correlations. These results suggest that the geometrically frustrated
lattice in Mo4PtGa17 generates an intriguing electronic structure that enhances the density of states,
spin susceptibility and quasiparticle mass. Mo4PtGa17 therefore identifies a unique route to heavy-
fermion-like superconductivity in d-electron materials through geometrical frustration, different from the previously reported systems.
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All authors Chaoguo Wang, Hyeonhu Bae, Jiaqi Tian, Qing-Ping Ding, Yongbin Lee, Yuji Furukawa, Shannon Gould, Brianna R. Billingsley, Si Athena Chen, Matthias Frontzek, Tai Kong, Binghai Yan, Sheng Ran, Xin Gui
Fluid Dynamics
Flow and Heat Transfer Characteristics of Forced Convection Past an Isoflux Circular Cylinder in Galinstan for Reynolds Numbers up to 600
Dipjyoti Nath
A numerical investigation of steady forced convection heat transfer from an isoflux circular cylinder immersed in the
liquid metal Galinstan is presented. The governing streamfunction, vorticity, and energy equations are solved using a fourth-order compact finite difference scheme in cylindrical coordinates (FOCS–CC) coupled with a stable pseudo-time iteration (PTI) technique. The influence of the Reynolds number ($1 \leq Re \leq 600$) on the flow and heat transfer characteristics is systematically investigated for Galinstan with a Prandtl number of $Pr=0.025$. The performance and accuracy of the proposed scheme are first established through grid independence studies and validation against previously published numerical results for the average Nusselt number and total drag coefficient over a range of Reynolds numbers. Excellent agreement with the available literature confirms the reliability and robustness of the present formulation. The effects of Reynolds number ($1\leq Re\leq600$) on the flow and thermal fields are examined through streamline patterns, isotherm distributions, and local Nusselt number variations. The results reveal that increasing the Reynolds number promotes flow separation, enlarges the wake region, intensifies downstream thermal transport, and significantly enhances convective heat transfer from the cylinder surface. Furthermore, a new empirical correlation for the average Nusselt number is proposed for Galinstan fluid over the Reynolds number range $1\leq Re\leq600$, exhibiting excellent agreement with the numerical data with a coefficient of determination of $R^2=0.99939$.
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Astrophysics of Galaxies
SuperMIGHTEE : Spectral Ages of Remnant Radio Galaxy Candidates in the XMM-LSS Field
Sushant Dutta, Veeresh Singh, C.H. Ishwara Chandra et al. (+8 more)
Remnant
radio galaxies, whose lobes are no longer replenished by jets from the active
galactic nucleus (AGN), offer key constraints on AGN duty cycles and the timescales of
radio jets. We present a spectral-ageing study of 14 candidate remnant
radio galaxies in the XMM-LSS field, combining new broad-band data from the MeerKAT MIGHTEE (L-band) and uGMRT superMIGHTEE (band-3 and band-4) surveys with complementary observations from LOFAR, GMRT, and JVLA, covering 144 MHz-1.5 GHz. Spectral modeling confirms 12 sources as genuine remnants, while two are reclassified as active, emphasising the importance of sensitive, multi-frequency coverage for robust remnant identification. Pixel-based spectral age maps yield results (~3-43 Myr) broadly consistent with integrated estimates, revealing relatively short spectral ages (~8-42 Myr). These ages likely reflect enhanced inverse-Compton losses at higher
redshifts (0.35 < z < 2.85; median z = 1.25) and possible rapid lobe expansion in low-density environments. The ratios of remnant to total source ages (t_OFF}/t_s) span 0.04-0.83, indicating that the sample traces a broad range of evolutionary stages. Our findings reveal a previously underrepresented population of faint, rapidly fading remnants, suggesting that the remnant phase may be shorter and more dynamic than previously thought. This study highlights the crucial role of MIGHTEE and superMIGHTEE surveys in reliably classifying genuine remnants and provides a framework for constraining AGN life cycles in preparation for forthcoming SKA surveys.
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All authors Sushant Dutta, Veeresh Singh, C.H. Ishwara Chandra, Yogesh Wadadekar, Russ Taylor, Mattia Vaccari, Lucia Marchetti, Matt Jarvis, Catherine Hale, Solohery Randriamampandry, Zara Randriamanakoto
Cosmology and Nongalactic Astrophysics
Do Primordial Black Hole Clusters Survive the Galaxy? Collisional Disruption and Microlensing Implications
M.V. Tkachev and S.V. Pilipenko
We study the collisional disruption of
primordial black hole (PBH) clusters in the Milky Way
halo. Encounters between clusters strip PBHs into a diffuse component, and the fraction of PBH mass in this smooth component along a sightline determines how microlensing constraints divide between isolated compact objects and extended cluster lenses. We combine an analytic NFW-based collision-rate model, $72$ direct N-body binary collision simulations that calibrate the escaped-mass fraction as a universal function $\tilde f(\tilde v,\tilde b)$ of the relative velocity and impact parameter in units of the cluster velocity scale and half-mass radius, and cosmological N-body simulations of a Milky Way-like
halo ($M_{200}\simeq 8\times10^{11}\,M_\odot$, $c_{200}\simeq 11$) that record the encounter history of every cluster from $z=9$ to $z=0$. For $10^6$ and $10^7\,M_\odot$ clusters – bracketing the maximum mass in the Carr et al.\ formation scenario – the local encounter rate at the
Solar circle is $2.9\times10^{-3}$ and $1.2\times10^{-2}\,\rm Myr^{-1}$, consistent with the simulations to within ${\sim}40\%$. Because the peak-disruption velocity of Carr-radius clusters ($12$–$20\,\rm km\,s^{-1}$) lies far below typical
halo encounter velocities, disruption accumulates through many weak encounters, most effectively during the early, cold phases of
halo assembly: half of the total mass loss is inflicted before $z\approx2$, a channel that $z=0$ analytic estimates miss entirely. The surviving mass fraction at the
Solar circle is $S\simeq0.50$ ($10^6\,M_\odot$) and $0.04$ ($10^7\,M_\odot$), and the DM-mass-weighted smooth fraction toward the LMC and SMC is $0.49$ and $0.92$, respectively. Cluster-cluster disruption is thus substantial over the
Galaxy's lifetime, and reanalyses of microlensing surveys must account for the radially varying smooth fraction $f_{\rm sm}(r)$ derived here.
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Optics
Photonic Theta Cavity: Engineering Bound States in the Continuum in Topological Resonators Beyond the Limitations of Near Field Coupling
Eric Seabron, Robert E. Coleman, Chuanyu Lian et al. (+3 more)
The Theta Cavity is a unique topological resonator architecture which utilizes interferometric coupling to overcome fundamental design limitations associated with near-field evanescent coupling which currently dominates the design space for integrated photonics. The defining device physics is established by the mirror symmetric cross junctions which preserves efficient power transfer between a waveguide and ring resonator creating a strongly correlated phase relationship between the multiple paths. The unique mode selection physics allows for interference driven suppression of radiative pathways enabling strong cavity confinement and the emergence of Bound States in the Continuum (BICs). Analytical models reveal non-Hermitian optical band structure displaying non-trivial topological transitions between BIC and quasi-BIC modes that are robust to attenuation, temperature variations, and typical fabrication non-idealities, which is critical for overcoming intrinsic limitations associated with silicon based integrated photonics. The Theta Cavity architecture also circumvents limitations that arise from proximity requirements of the physical gap used in near-field coupled waveguides which enables a flexible design space for new devices. In this study, we demonstrate phase mediated long-range strong coupling of multiple ring resonators in the Nested Theta Cavity architecture showcasing band structure hybridization resulting in the formation of anti-crossing bandgaps, Dirac crossings, and Fano resonances. The photonic Theta Cavity architecture provides a scalable, topologically robust platform for engineering modes across a multidimensional parameter space with high resilience to perturbation and attenuation, enabling a new approach for the designing of integrated cavity devices.
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All authors Eric Seabron, Robert E. Coleman, Chuanyu Lian, Malcolm Bogroff, Carlos Rios, Antonio Levy
Materials Science
Improved Heat Dissipation in CsPbBr${_3}$-hBN Heterostructures
Liudmila Starodubtceva, Ahmed Kadid, Naho Kurahashi et al. (+8 more)
Metal halide perovskite
semiconductors are promising materials for optoelectronic and photonic devices, including
solar cells and next-generation coherent light sources. However, their low thermal conductivity limits the practical operation of devices under high excitation levels. Integrating thermally conductive, large band-gap two-dimensional (2D) materials into perovskite devices could suppress heat accumulation, while preserving their optical properties. Here, we show that planar hot-pressed (PHP) cesium lead bromide (CsPbBr${_3}$) thin films capped with few-layer 2D hexagonal boron nitride (hBN) are less affected by
laser-induced heating under high-power continuous-wave excitation than uncapped perovskite samples. A large-scale semidry transfer method was developed to integrate 2D hBN onto PHP CsPbBr${_3}$ thin films. The process is chemically and thermally compatible with perovskites. Microscopic and spectroscopic analyses show that the hBN capping layer does not alter the morphology and optical properties of the perovskite thin film. The PHP CsPbBr${_3}$-hBN
heterostructure exhibits a thermal conductivity of 3 W/(m * K), approximately seven times higher than that of the bare perovskite films of 0.45 W/(m * K). Heat
diffusion simulations confirm enhanced heat dissipation in the
heterostructure relative to bare perovskite films. Our experiments demonstrate an effective approach to enhancing heat dissipation in perovskite devices using transparent, thermally conductive 2D materials.
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All authors Liudmila Starodubtceva, Ahmed Kadid, Naho Kurahashi, Cedric Kreusel, Jasper Ruhkop, Sebastian Lukas, Ulrich Plachetka, Ralf Heiderhoff, Thomas Riedl, Maryam Mohammadi, Max C. Lemme
Quantum Physics
Absolute displacement calibration of a levitated nanoparticle with real-time heterodyne demodulation
Daniel Tandeitnik, Gabriel Dias and Thiago Guerreiro
We report a heterodyne scheme for the position readout of an optomechanical system, in particular an optically levitated nanoparticle, based on digital in-phase and quadrature demodulation on a field-programmable gate array. Compared to the standard homodyne approach, it offers three key advantages: it requires no phase lock, it produces a signal linearly proportional to the particle displacement, and its calibration is immune to drifts in the optical power of the local oscillator and of the scattered field. Combined with a vectorial model of the focal field, it measures the displacement in length units without free parameters. Through simultaneous homodyne and heterodyne measurements on the same trapped particle we demonstrate these advantages: the heterodyne follows a driven particle linearly up to amplitudes at which the homodyne response folds back, and calibrates the homodyne, whose standard thermometric calibration we find biased by 33 %. Inverting equipartition, the calibrated readout measures the mass of the particle with an uncertainty below 1 %, after removing a bias of up to 20 % caused by absorption heating at 1550 nm. The method can be used in any optomechanical system based on phase readout.
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Materials Science
Auditing Machine-Learning Models and Their Training Data with Explainability and First-Principles Verification: Application to Spin Hall Conductivity
Mohammed Mahshook and Rudra Banerjee
Machine-learning models for materials properties rest on two assumptions that standard validation never tests: that a model's features reflect the physics of the property rather than accidents of the training distribution, and that the training labels are themselves correct. We introduce a model-agnostic audit protocol for both, combining SHAP attribution, counterfactual partial dependence analysis, and Rashomon-style cross-model verification, with every finding adjudicated by targeted density functional theory (DFT). Demonstrated on intrinsic
spin Hall conductivity using a composition-only Random Forest, the model needs no relaxed
crystal structure, reaching accuracy competitive with structure-aware graph networks while remaining applicable to the far larger space of compositions for which no structure has been computed. The model audit reveals that the average p-valence descriptor becomes statistically entangled with Pt content - a property of the learned representation rather than the physics; DFT confirms the consequence, a Pt-free compound (HgOsPb$_2$) whose true SHC is nearly four times the prediction. The data audit exposes a thirtyfold error in the HfC training label, inherited undetectably by every black-box model trained on the same data. The protocol audits a model and its training data for the cost of a few DFT calculations, wherever one element dominates the high-property regime.
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Quantum Physics
Depth-Efficient Quantum Topological Data Analysis for Regime-Specific Detection of Financial Stress
Arul Rhik Mazumder and Shreyan Ronit Mazumder
We present, to our knowledge, the first adaptation of Pauli Correlation Encoding (PCE) to
quantum topological data analysis, reformulating Betti number estimation as a depth-efficient variational optimization over a compressed
qubit register. From a Takens
embedding and Vietoris-Rips filtration of S&P 500 returns, we extract combinatorial
Laplacians and recast null-space counting as a continuous-PCE Rayleigh-quotient minimization with variational deflation, encoding $n_k$ simplex indices into $O(n_k^{1/\kappa})$
qubits with shallow, ancilla-free
circuits. Because the resulting loss is rational rather than bilinear in the correlators, the barren-plateau bound of Sciorilli et al. does not transfer; empirically the gradient variance decays only polynomially, with no exponential barren plateau, over $n=4$-$12$
qubits. The classical stage matches ripser on all 190 sliding windows (2003-2010). On the real
market Laplacians ($\beta_1=1$-$22$), PCE-VQE recovers no null vector from a random start, but warm-starting from a classical null-space surrogate recovers $\beta_1$ exactly on all seven windows tested ($n_k \le 259$), placing the obstacle in the optimization landscape rather than the encoding. Chronologically split classification gives in-regime ROC AUC 0.818, but out-of-distribution evaluation on the 2020 COVID shock and 2022 rate cycle (AUC 0.009, 0.515) shows the calibration does not generalize across crisis regimes.
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Quantum Physics
When Classical Baselines Are Tuned as Carefully as the Quantum Model, Does Quantum Reservoir Computing Still Win?
Tushar Pandey
Can a small
quantum computer forecast a changing signal better than an ordinary classical method? Many studies say yes, but the classical methods they compare against are often left in a basic, untuned state while the
quantum model is carefully optimised. We ask what happens when the classical competitor is given exactly the same care: the same size and the same amount of tuning effort. We study two popular reasons a
quantum reservoir is thought to help, using exact simulations of small
quantum systems (up to eleven
qubits) on prediction tasks. In both cases the
quantum advantage disappears once the comparison is fair. In the first, extra
quantum measurements add nothing that a simple classical formula of the same size does not already provide. In the second, a feedback loop genuinely helps the
quantum model, turning a useless setup into a working predictor, yet a well-tuned classical network still predicts slightly more accurately, and the gap is statistically reliable. Our point is not that
quantum reservoirs can never win, but that two of their commonly cited advantages do not hold up against fair classical competitors at this scale. We provide these matched comparisons as a simple, reusable checklist for honest benchmarking. All results are fully reproducible from fixed random seeds.
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Materials Science
The Precursor Genome: A Pairwise Reaction Dataset for Solid-State Synthesis
Lauren N. Walters, Matthew J. McDermott, Bernardus Rendy et al. (+3 more)
Solid-state reactions remain the dominant route to inorganic materials, yet no large, machine-readable
dataset reports their experimental protocols and outcomes with consistent provenance; this gap obstructs first-principles, data-driven, and machine-learning approaches to synthesis science. Here, we present the Precursor Genome, a
dataset of 1,035 pairwise solid-state reactions generated autonomously by the A-Lab self-driving laboratory, spanning 46 precursors and 39 elements. Every reaction is reported together with its full experimental metadata, including measured thermal profiles, precursor and recovered masses, and instrument configuration. Every product mixture is identified from raw X-ray diffraction (1,351 scans) through automated Rietveld refinement with the Dara framework, yielding 1,950 refinement cases that are independently validated by human experts on a three-tier quality scale. Raw pattern files, serialized refinement objects, and reviewer annotations are distributed through a Pydantic-validated JSON ledger, preserving full traceability from each precursor pair to its final phase assignment. The Precursor Genome establishes a FAIR, reusable
benchmark for training and evaluating predictive models of solid-state reactivity.
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All authors Lauren N. Walters, Matthew J. McDermott, Bernardus Rendy, Yuxing Fei, Kristin A. Persson, Gerbrand Ceder
Materials Science
Bragg Interferometry of Moiré Superlattices: From Geometric Phase Principles to Atomic Reconstruction
Isaac M. Craig and D. Kwabena Bediako
The emergence of moiré superlattices formed by twisting and stacking two-dimensional materials has created a need for characterization techniques capable of mapping sub-angstrom atomic reconstruction across micron-scale fields of view. This review surveys a suite of methodologies developed to extract
geometric phases in electron microscopy and X-ray spectroscopy, with a primary focus on the interference of overlapping Bragg reflections in the dark field. We provide a comparative analysis of some established techniques, including
geometric phase analysis, converged beam electron diffraction holography, and various ptychographic paradigms, culminating in a discussion of Bragg interferometry for measuring interlayer displacement fields and strain in moiré materials. We demonstrate the utility of Bragg interferometry through case studies of twisted
bilayer and trilayer
graphene as well as transition metal dichalcogenide moiré systems. Special
attention is given to the unique advantages of this dark-field interferometric method for probing buried interfaces and encapsulated
heterostructures, as well as the inherent challenges of interpreting incomplete phase information in the presence of dynamical scattering. By examining the physical principles underlying these approaches, this review highlights the conceptual similarities and practical trade-offs involved in high-resolution structural mapping of materials in which the interplay between structural relaxation and electronic behavior defines a scientific frontier at the nexus of modern condensed matter physics, nanomaterials engineering, and interfacial chemistry.
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Nuclear Theory
Absence of a shell closure in $^{140}$Sn
Francesca Bonaiti, Bingcheng He, Gaute Hagen et al. (+1 more)
There are conflicting theoretical results about the presence of a shell closure in the
neutron-rich
nucleus $^{140}$Sn. We address this controversy by performing ab initio computations, using a
nuclear interaction from
chiral effective field theory that accurately reproduced and predicted low-lying states in doubly magic
nuclei. We verify that this interaction accurately reproduces low-lying states in $^{133}$Sn. We assume that $^{140}$Sn exhibits a closed $7/2^-$
neutron subshell beyond $^{132}$Sn and compute its first excited $2^+$ state. The resulting energy is small and this contradicts the assumption.
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All authors Francesca Bonaiti, Bingcheng He, Gaute Hagen, Thomas Papenbrock
Optics
Dark Optical Trapping of Resonant Transition-Metal Dichalcogenide Particles
Patrick Illetschek, Gleb Fedorovich, Albert Seredin et al. (+6 more)
Mitigating
recoil events and minimizing optically induced heating are central challenges in the precise control and cooling of macroscopic particles. To overcome this, we propose trapping resonant dielectric particles for applications in ultra-high
vacuum (UHV) levitodynamics. Contrary to other approaches, where suppressing the parasitic resonant scattering was achieved in a standing wave geometry, here we propose a single beam geometry in a dark trap regime. As a promising material platform, we focus on a class of transition-metal dichalcogenide (TMD) particles with high polarizability, characterized by refractive indices in the range $3.7$-$4.8$ and densities up to $9.3~\mathrm{g\,cm^{-3}}$. Using full Mie theory, we identify a range of TMD particle radii that support stable axial and radial
magnetic quadrupole trapping in a bottle-beam configuration. We predict that for WS$_2$ particles with a mass of $0.5 \times 10^{12}\,\mathrm{amu}$, one can expect suppression of the scattering rate relative to the mechanical frequency down to $\Gamma/\Omega \simeq 0.02$. This corresponds to a coherence time extended by approximately three orders of magnitude compared with silica particles of the same mass trapped in conventional bright optical traps at UHV. Combined with significantly reduced internal heating, remaining well below the melting point of the material, dark trapping of resonant TMD macroscopic particles emerges as a promising platform for exploring
quantum physics with large masses.
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All authors Patrick Illetschek, Gleb Fedorovich, Albert Seredin, Gleb Tselikov, Valentin S. Volkov, Nikolai Kiesel, Markus Aspelmeyer, Mihail Petrov, Anton V. Zasedatelev