Atmospheric and Oceanic Physics
Statistical Downscaling of Daily Precipitation from ERA5 Atmospheric Fields to IMERG over West Africa
David Sagna, Redouane Lguensat and Samo Diatta
Global reanalyses are too coarse to resolve the convective systems that produce most West African monsoon rainfall. In this work, we use U-Net based architectures to downscale daily ERA5 fields (0.25{\deg}) to IMERG V07 satellite precipitation (0.1{\deg}) over West Africa for the June to October seasons of 2000 to 2024, using geopotential, temperature, humidity and wind at three pressure levels together with elevation and land fraction. Adding ERA5 precipitation as input slightly improves performance for this particular challenging region. We find that all the deterministic networks investigated for this work are too dry and lose almost all observed variance below a few hundred kilometers, which motivated our use of a GAN-based alternative. We also investigated permutation importance for the U-Net that ranks 500 hPa specific humidity first, consistent with the sensitivity of deep convection to mid-tropospheric moisture.
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Atomic Physics
Cavity-modified static polarizabilities of atoms and small molecules within QED full configuration interaction
T. Zalialiutdinov and D. Solovyev
Static dipole polarizabilities of H$_2$, LiH, and helium confined in a single-mode optical cavity are computed using
quantum-electrodynamical full configuration interaction (QED-FCI). Response properties are obtained as finite-field derivatives of the coupled electron-
photon energy. The cavity-induced modification is found to arise from the competition of two contributions of opposite sign, the dipole self-energy and
photon exchange, whose relative strength depends on both the cavity frequency and the number of
photons involved in the exchange. The residual change suppresses the response of the molecular ground electronic states. For the metastable states of helium atom this balance changes qualitatively, and the differential response of the $2\,^3S_1 \to 2\,^1S_0$ clock transition, which governs its sensitivity to static electric fields and to thermal radiation, is strongly enhanced instead. Cavity confinement can therefore either reduce or increase the dc Stark and blackbody-radiation shifts of a frequency standard, depending on the electronic structure of the states involved. The reported data serve as a reference for cavity-modified response and underscore the need for an exact treatment of light-matter correlation in cavity-QED predictions.
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Astrophysics of Galaxies
Evidence for Hierarchical Turbulent Scaling in Nearby Star-Forming Galaxies
Luna Maria Scipio, Fernando A. N. Santos and Jay Armas
We find recurring signatures of intermittency in molecular-gas velocities from cloud to galactic scales. In 31 selected
galaxies from PHANGS-ALMA, velocity-centroid exponents through sixth order show nonlinear order dependence and nearly linear relations between consecutive exponents across
galaxies. Positive estimated offsets from single-exponent scaling occur in all 52
galaxies with a valid power law fit and 99 of 100 clouds. A generalized She-Leveque hierarchy accommodates these signatures, supporting a hierarchical description of turbulent scaling in molecular gas across these environments.
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General Relativity and Quantum Cosmology
Hamiltonian surface charges in General Parallel Relativity
Tomi Koivisto
General Parallel Relativity is a dynamically equivalent formulation of Einstein
gravity in which the parallel frame supplies explicit boundary reference data. In this formulation, finite-region energy-momentum and horizon
entropy arise as distinct
Hamiltonian surface charges. Diffeomorphisms along canonical frame directions define a quasi-local energy-momentum including a matter surface term, while normal-plane boosts at a smooth horizon give
entropy. These covariant formulas are applied to the Reissner-Nordström black hole and to a dilatonic charged black hole. In both examples, the matter contribution and its Legendre transform complete the Misner-Sharp mass into the
Hamiltonian energy appropriate to the chosen electromagnetic boundary datum. The resulting horizon charges satisfy the thermodynamic relation obtained independently from the Euclidean boundary action.
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Disordered Systems and Neural Networks · Cross-listed from cs.IT
Information-Theoretic Limits for Rectangular Spiked Matrix Models with Rotationally Invariant Noise
Qun Chen, Rudy Skerk, Jean Barbier et al. (+3 more)
We study the information-theoretic limits of inference in rectangular rank-one spiked
matrix models with additive rotationally invariant noise, thereby going beyond the standard assumption of independent noise entries. Using the replica method from statistical physics, we derive a variational formula for the mutual information between the signal and the data, together with a system of saddle point equations predicting the minimum mean squared error in estimating the rank-one spike. We further show that, in the Bayes-optimal setting, these saddle point equations coincide with the fixed point equations of the state
evolution of a recently proposed orthogonal approximate message passing
algorithm with Bayes-optimal denoisers. This equivalence provides an algorithmic interpretation of the replica prediction and supports the Bayes-optimality of orthogonal approximate message passing whenever the relevant fixed point is unique. Numerical evaluations of the saddle point equations for several rotationally invariant noise ensembles and signal priors, together with finite-size simulations of the
algorithm, confirm the asymptotic predictions. They illustrate both regimes with a unique informative fixed point, where orthogonal approximate message passing is predicted to attain the minimum mean squared error, and regimes with multiple fixed points, where a statistical-to-computational gap exists.
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All authors Qun Chen, Rudy Skerk, Jean Barbier, Francesco Camilli, Junjie Ma, Haochuan Zhang
Soft Condensed Matter
Self-phoresis on a one-dimensional periodic domain
Leah Anderson and David S. Dean
We study the spontaneous motion and collective dynamics of self-phoretic particles on a one-dimensional periodic domain. The particles act as localized chemical sources (of a particle-dependent strength) of a field and the particles themselves respond to the gradients of the field they generate (with a particle-dependent phoretic mobility). The chemical field itself diffuses and evaporates. For a single particle, we derive the exact threshold for spontaneous propulsion and establish the emergence of stable constant-velocity states near onset through a supercritical pitchfork bifurcation. We then consider an active source coupled to a non-emitting tracer and determine the conditions for slipping and stable phase-locked motion. For two mutually coupled sources, the stationary antipodal configuration can lose stability through either a pitchfork or a Hopf bifurcation, depending on the relative source strengths and phoretic mobilities. We determine the competing instability thresholds and compare them with direct numerical simulations of the coupled particle-field equations. Beyond onset, the resulting translating and oscillatory states provide qualitative counterparts to modes of motion observed experimentally for camphor disks in annular water channels. These results connect the onset of individual propulsion, tracer entrainment, and collective motion within a common analytically tractable framework.
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Quantum Gases
Information Entropy as a Sensitive Diagnostic of Relaxation Dynamics in a Quasiperiodic Mott Insulator
N. D. Chavda, Antônio M. S. Macêdo, Robin P Sagar et al. (+1 more)
We study the nonequilibrium dynamics of a bosonic Mott
insulator following a sudden quench from a periodic to a quasiperiodic
lattice. Using ab initio multiconfigurational (MCTDHB) continuum many-body dynamics, we characterize the
evolution through momentum distributions, fragmenta- tion, correlation functions, and information
entropy. We find that melting of Mott correlations does not necessarily imply relaxation of the many-body state. In the weakly interacting regime, the initial Mott-like correlation undergo recurrent melting and partial recovery, while the information
entropy displays large, intermittent fluctuations within the simulated time window. In contrast, a strongly interacting and fully fragmented Mott
insulator retains its characteristic Mott correla- tions, up to partial distortions, while the many-body information
entropy approaches a well-defined stationary regime plateau with comparatively small fluctuations. These results indicate that Mott- correlation dynamics and many-body relaxation can be dissociated in this finite system and support the use of information
entropy, evaluated in the multiconfigurational representation, as a sensitive complementary diagnostic of nonequilibrium relaxation.
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All authors N. D. Chavda, Antônio M. S. Macêdo, Robin P Sagar, Barnali Chakrabarti
High Energy Physics (Phenomenology)
Two-pion source analysis in small to large systems at SPS energies
Barnabás Pórfy and Zsombor Marcell Rácz
Over the past decade, femtoscopic measurements using Lévy-stable source functions have been carried out in collision systems ranging from small to large at SPS, RHIC, and LHC energies. In recent years, these have been accompanied by a number of phenomenological studies of the same systems and energies. We contribute to this line of work by investigating the shape of two-pion pair-source distributions in central $^7$Be+$^9$Be and $^{129}$Xe+$^{139}$La collisions simulated with the UrQMD model in cascade mode. To make the comparison with measurements meaningful, kinematic selections similar to the experimental ones are applied to the simulated events and particles. One-dimensional Lévy fits are performed, and the resulting source parameters are studied as functions of pair transverse mass, collision energy, and system size. We find that the simulated sources are well described by Lévy distributions in all systems considered, which offers a common phenomenological picture of the space-time structure of pion emission. Finally, we compare our findings with results from an intermediate system, Ar+Sc. The results serve as a purely hadronic reference for past and upcoming femtoscopic measurements of the NA61/SHINE experiment.
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Strongly Correlated Electrons
Quantum Ising transition on the Cayley tree: boundary criticality, universality, and an effective Bethe line
Pietro Richelli and Natalia Chepiga
We investigate
quantum criticality in the transverse-field Ising model on finite Cayley trees and demonstrate that their extensive boundary fundamentally changes the nature of the
quantum phase transition compared with the infinite, boundary-free Bethe
lattice. Using tree tensor-network simulations for systems with up to $N=12286$ sites, we identify a boundary-driven continuous transition at $h_x^c\approx1.76$, distinct from the mean-field Bethe-
lattice transition at $h_x^c\approx2.23$. We characterize this transition through finite-size scaling of the magnetization and
magnetic susceptibility and extract a consistent set of critical exponents. By introducing next-nearest-neighbor interactions, we demonstrate the robustness of the extracted critical exponents, providing numerical argument for the Ising boundary universality class on the Cayley tree. Furthermore, we show that the physics of the boundary-free Bethe
lattice can be efficiently recovered on a finite Cayley tree by fine-tuning a local boundary field. The resulting effective Bethe line, whose existence is tied to the mean-field nature of the bulk transition, effectively screens the extensive boundary and restores both the critical point and the mean-field critical scaling of the infinite Bethe
lattice.
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General Relativity and Quantum Cosmology
Analytic Brill wave initial data with trapped surfaces
Piotr Koc
Since Brill's work of 1959, the conformal factor of finite-amplitude Brill waves, the axisymmetric and time-symmetric
vacuum initial data on $\mathbb{R}^3$ that describe pure gravitational radiation, has been obtained only numerically, up to the most recent studies. Here an explicit one-parameter family of such data is constructed: the first explicit real-analytic, non-trivial, asymptotically flat
vacuum initial data with trivial
topology and a single end. The free metric function is a closed-form combination of elementary functions and a dilogarithm. The data have the toroidal conformal
symmetry of Beig and Husa, and a change of variable of Natanzon type reduces every mode equation to the Gauss hypergeometric equation, so that the conformal factor is a series with explicit Gamma-function coefficients. The quantities that have so far required numerical work are thereby obtained exactly. A ground-state identity gives a sharp existence criterion: complete, asymptotically flat data exist precisely for $k<k_c=0.8048016772\ldots$, and the explicit series is identified with the unique variational solution. The ADM mass is an absolutely convergent digamma series, with $m/a=\pi k^2/10+O(k^3)$ for small amplitudes and an explicit residue at its critical divergence. Sufficiently strong waves contain trapped surfaces: it is proved that for $k$ close to $k_c$ the rescaled conformal factor converges to an explicit function and explicit
tori and spheres become outer trapped, so that the data contain an apparent horizon. A numerical search, restricted to equatorially symmetric
star-shaped surfaces, finds marginally trapped (minimal) spheres, which appear in a fold near $k=0.7670$. No thin-
torus or weak-field approximation is used.
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Solar and Stellar Astrophysics
TESS flares and chromospheric variability in the Pleiades, the Hyades, and Praesepe
A. Görgei, K. Vida, B. Seli et al. (+5 more)
Magnetic activity is a result of the interaction between rotation and dynamo processes in cool
stars with outer convection zones. Since open cluster members share a common age, distance, and chemical composition, they provide an opportunity to study the
magnetic activity of cool
stars in a controlled astrophysical context. We used 120s cadence observations from the Transiting
Exoplanet Survey Satellite (TESS) to study the
flare activity of
stars in three open clusters with different ages: the Pleiades (100 Myr), the Hyades (700 Myr) and Praesepe (700 Myr). We used the Ohio State Multi-Object Spectrograph (OSMOS) at MDM Observatory with the goal of identifying coronal mass ejections (CMEs) in the Pleiades and Praesepe. We investigated the flaring characteristics of the cluster members using the TESS light curves: we identified the
flares, then divided the
dataset into different categories based on the effective temperature and light curve amplitude. We calculated the
flare energies and investigated the
flare frequency distributions. We studied the dynamic spectra of the H$\alpha$ line and its environment to search for indication of CMEs. The power-law indices of the
flare frequency distributions obtained in our analysis span the 1.8-2.8 range. We found the highest
flare rates in the Pleiades for all investigated spectral types. Our results show that the
flare rate of M dwarfs is similar in the Pleiades and the Hyades while for K-type
stars the
flare rate in the Pleiades is an order of magnitude higher. Our analysis reveals that the
flare rate in M
stars changes with their effective temperature: the rate is highest for T$_{eff}$ $\sim$3200-3300 K -coinciding with the transition between partially and fully convective
stars - with smooth decrease in
flare rate towards cooler and hotter M dwarfs. We used the MDM/OSMOS spectra to place an upper limit on the CME rate.
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All authors A. Görgei, K. Vida, B. Seli, K. Oláh, P. Sági, B. Schmercz, R. M. Roettenbacher, Zs. Kővári
Materials Science
Engineering Ferroelectric Phases in BaTiO$_3$ Films via Buffer-Layer Induced Misfit Strain Reversal
A.S. Mikheykin, N.V. Lyanguzov, A.S. Konstantinov et al. (+4 more)
Controlling ferroelectric phase
symmetry through strain engineering is crucial for tailoring polarization
topology and functional properties in oxide-based devices. Here, we show that a thin conductive buffer layer can override substrate-induced strain in BaTiO$_3$ (BTO) films on MgO. Although the
lattice parameter of MgO(001) would be expected to induce tensile misfit strain, in 500~nm BaTiO$_3$ films the thermal-expansion mismatch dominates, resulting in effective compressive stress upon cooling. Inserting a 50-nm La$_{0.67}$Sr$_{0.33}$MnO$_3$ (LSMO) buffer layer reverses the effective strain state from compressive to tensile. Using temperature-dependent polarized Raman spectroscopy, X-ray diffraction, and piezoresponse force microscopy, we reveal an unconventional phase sequence upon cooling: paraelectric $\rightarrow$ orthorhombic ($\textit{aa}$-phase, $\sim$407 K) $\rightarrow$ monoclinic ($\textit{r}$-phase, $\sim$300-345 K), characterized in-plane and tilted polarization components. The LSMO layer not only serves as a bottom electrode but also modifies the strain state, while interfacial charge redistribution induces a built-in electric field, evidenced by self-polarization and asymmetric PFM hysteresis. These findings highlight the critical role of conductive buffer layers in controlling ferroelectric
symmetry and enabling oxide
heterostructures with tailored polarization textures for low-power spintronics, tunable microwave devices, and neuromorphic computing.
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All authors A.S. Mikheykin, N.V. Lyanguzov, A.S. Konstantinov, V.B. Shirokov, E.D. Linnik, T. Bondar, A.G. Razumnaya
Mesoscale and Nanoscale Physics
Transport Determines Spectral Distance in Mesoscopic Thermodynamics
Giorgio Sonnino
We derive a distance between thermodynamic states from a positive Hermitian transport tensor within a mesoscopic canonical model. An exact first-order factorization of the
evolution generator gives a commutator norm and the metric $G=2g^{-1}$, where $g$ denotes the symmetric transport tensor. Gradients of the antisymmetric tensor can change the
evolution, but they leave this distance unchanged. The construction allows coordinate-dependent coefficients. For constant Onsager coefficients, a Clifford representation gives the same metric. In a two-channel thermoelectric system, the ratio of normalized principal distances is $\sqrt{1+ZT}+\sqrt{ZT}$. Transport coupling thus fixes the anisotropy of this metric. The construction requires neither an independent metric nor a physical
spin variable.
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Cosmology and Nongalactic Astrophysics
A census of Dark Energy Survey Year 3 redMaPPer galaxy clusters in a high exposure eROSITA All Sky Survey region
P. A. Giles, A. K. Romer, J. Pilling et al. (+64 more)
We present the cross-match of
galaxy clusters detected by redMaPPer using the first three years of Dark Energy Survey (DESY3RM) operations, and the first release of the eROSITA-All Sky Survey (eRASS1) taken by eROSITA on board the Spectrum Roentgen Gamma
telescope. We define a sky region ($60^{\circ}<{\rm R.A.}<90^{\circ}$ and $-58^{\circ}<{\rm Dec}<-48^{\circ}$) whereby the mean eRASS1 exposure time of clusters falling within this footprint is $\sim$2.5 times longer than the mean exposure time of the full eRASS1–DESY3RM overlap. Limiting to a
redshift range $0.2 < z < 0.65$ and redMaPPer estimated richnesses to $>$50, we obtain a sample of 57 clusters. We match these clusters to the cluster catalogue constructed for the eRASS1, finding 45 clusters with a match and 12 with no match in the catalogue. X-ray properties of the 12 unmatched clusters are estimated via a forced photometry analysis. We investigate the form of the luminosity-richness relation, finding the relation using the full 57 cluster sample is statistically consistent with using only the 45 matched clusters, and will require the deeper data of future eRASS releases (or dedicated X-ray follow-up) to explore further potential differences. Using external data from XMM, ACT and SPT, we find detections of 5 of the 12 unmatched clusters, indicating the presence of virialised gas. Finally, we found the 12 unmatched clusters occupy a higher
redshift range and lower richness range (compared to the matched clusters), and find no evidence for an underlying physical reason for the lack of X-ray emission.
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All authors P. A. Giles, A. K. Romer, J. Pilling, R. Wilkinson, D. J. Turner, T. Jeltema, A. Farahi, M. E. Ramos-Ceja, F. Balzer, M. Kluge, S. Grandis, E. Bulbul, M. Hilton, S. Bhargava, E. Aljamal, A. E. Evrard, E. W. Upsdell, P. T. P. Viana, A. Abdulghafour, M. Aguena, S. S. Allam, O. Alves, F. Andrade-Oliveira, D. Bacon, D. Brooks, R. Camilleri, A. Carnero Rosell, J. Carretero, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, P. Doel, C. Doux, B. Flaugher, J. Frieman, J. Garc, M. Gatti, D. Gruen, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, K. Kuehn, O. Lahav, S. Lee, J. L. Marshall, J. Mena-Fernández, F. Menanteau, R. Miquel, R. C. Nichol, R. L. C. Ogando, A. A. Plazas Malagón, S. Samuroff, E. Sanchez, D. Sanchez Cid, M. Smith, M. E. da Silva Pereira, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, C. To, D. L. Tucker, V. Vikram, A. R. Walker, N. Weaverdyck, J. Weller
Cosmology and Nongalactic Astrophysics
The XMM Cluster Survey: Cross-Calibration of eROSITA and XMM using Dark Energy Survey Y3 Galaxy Clusters
J. E. Pilling, D. J. Turner, P. A. Giles et al. (+9 more)
We present the cross-calibration of the eROSITA and XMM
telescopes, using
galaxy clusters detected by redMaPPer from the first three years of Dark Energy Survey observations (DESY3RM). We use the X-ray: Generate and Analyse (XGA) Python module to measure eROSITA properties, and validate our methodology using a deep pointed eROSITA CAL-PV observation of A3158, and a sample of 119 clusters from the expanded HIgh FLux
Galaxy Cluster Sample (eeHiFLUGCS). Next, we construct a sample of DESY3RM clusters matched to XMM observations analysed by the XMM Cluster Survey (XCS), and to clusters in the first release of the eROSITA All-Sky Survey (eRASS1). This produced a sample of 114 DESY3RM clusters with both XMM and eROSITA detections. Our resulting X-ray temperatures determined from eROSITA were compared to eRASS1 catalogue values, showing consistency between the two analyses. Comparisons between XMM and eROSITA temperatures reveal a systematic offset, with XMM temperatures 28$\pm$7% higher on average. Finally, we fit $L_{\rm X,soft}$-$\lambda_{\rm RM}$ and $T_{\rm X}$-$\lambda_{\rm RM}$ scaling relations for both eROSITA and XMM using the same cluster sample, finding minimal differences in the $L_{\rm X,soft}$-$\lambda_{\rm RM}$ relation but a clear normalisation offset in the $T_{\rm X}$-$\lambda_{\rm RM}$ relation, particularly for the highest richness systems. This study will enable future work combining eROSITA and XMM observatories for DESY3RM clusters.
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All authors J. E. Pilling, D. J. Turner, P. A. Giles, A. K. Romer, R. Wilkinson, P. J. Rooney, M. Hilton, S. Bhargava, J. Hall, R. Wang, A. Abdulghafour, B. J. Maughan
Soft Condensed Matter
Impact of shear and dilational membrane viscosities on capsule shape and dynamics under shear flow: a theoretical study
Paul Regazzi and Marc Leonetti
In artificial (micro)capsules or
cells such as red blood
cells for example, the two-dimensional (2D) rheology of the membrane (or the shell) is viscoelastic and not only elastic. The deformation and inclination of such a capsule are theoretically studied under shear and extensional flows. The membrane mechanics is described by the Kelvin-Voigt model: the 2D dissipation with the Boussinesq-Scriven law associated to specific dilational and shear Boussinesq numbers $Bq_d$ and $Bq_d$ respectively while the elastic constitutive law is either Hookean, strain-softening (neoHookean) or strain-hardening (Skalak). The dynamics depends on the elastic capillary number $Ca$, the Poisson ratio (or $C$ in Skalak law), the viscosity ratio $\lambda$, the nonlinearities included in the constitutive law and both boussinesq numbers. Three dynamics are identified in the limit of weak deformations: a tank-treading motion in the limit of small elastic capillary number with a characteristic time depending on $\lambda$, $Bq_s$ and $Bq_d$, an oscillation without any elasticity and a damped oscillation leading to a tank-treading motion in the limit of large Boussinesq numbers. In all cases, both shear and dilational 2D dissipations contribute differently leading to non-trivial results. In the case of a Skalak law with $C=1$, $Bq=Bq_s=Bq_d$ and $Bq>>\lambda$, the deformations in the limits $Ca<<1$, $Bq=O(1)$ and $Ca=O(1)$, $Bq>>1$ determined in the seminal work of \cite{barthes1985role} are recovered.
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Mesoscale and Nanoscale Physics
Emergent Spinorial Structure in Mesoscopic Irreversible Thermodynamics
Giorgio Sonnino
We reconstruct a geometry of thermodynamic coordinates from transport coefficients within a mesoscopic canonical model. Self-adjoint flux observables determine a compatible
evolution generator containing symmetric and antisymmetric transport coefficients. When the Hermitian transport tensor is positive, an exact graded first-order factorization reproduces this generator on its scalar sector. Its commutators define a spectral distance whose metric depends only on the symmetric tensor. Gradients of the antisymmetric tensor can change the
evolution while leaving the metric unchanged. The construction allows coordinate-dependent coefficients. In the constant Onsager regime, a Clifford representation gives the same distance and an
algebra fixed by the transport
matrix. Published transport data for a $\mathrm{Bi_2Te_3}$ film give a principal-distance ratio of approximately $2.12$ in normalized coordinates at $ZT\simeq0.68$. We also examine a separate quadratic
entropy-production observable and distinguish its discrete spectrum from the spectrum of the
evolution generator. The spinorial representation adds no physical
spin degrees of freedom.
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Optics
Finite-event modulation transfer through forward-scattering media
Chong Wang, Liangfeng Hu, Yuchen He et al. (+5 more)
How spatial structure is transferred through a forward-scattering medium depends jointly on pattern scale and propagation distance. Starting from
photon exit displacements, we derive modulation transfer while retaining the number, depths, and projected angles of individual deflections, with event occurrences described by a homogeneous Poisson process along the propagation path. The second angular moment yields a leading low-frequency loss proportional to $k^2z^3$, where $k$ is angular spatial frequency and $z$ is thickness. At finite frequency, the model predicts two coupled departures: loss bends below its low-frequency quadratic extrapolation at fixed thickness, and transfer curves separate by thickness at fixed $k^2z^3$. The leading corrections to both effects arise from the same fourth angular moment. For symmetric, nondegenerate projected-angle distributions, the full response further establishes increasing loss with thickness in the same medium at fixed joint variable. Binary-pattern measurements through TiO$_2$ suspensions span five nominal loadings, seven thicknesses, and 20 spatial frequencies, supporting the approximate low-frequency scaling and showing both departures. A Gaussian effective-angle response calibrated only on lower-frequency data predicts the held-out higher-frequency band without refitting, with a logarithmic root-mean-square error of 0.0181 compared with 0.1021 for quadratic extrapolation. The results show that finite-event statistics provide a common physical origin for spectral bending and thickness-dependent departure from low-frequency scaling, linking coarse-pattern transport to finer spatial structure.
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All authors Chong Wang, Liangfeng Hu, Yuchen He, Huaibin Zheng, Hui Chen, Jianbin Liu, Yu Zhou, Zhuo Xu
General Relativity and Quantum Cosmology
Optical Signatures of a Black Hole in Effective Quantum Gravity
Jonibek Khasanov, Xuwei Zhang, Mirzabek Alloqulov et al. (+3 more)
In this article, we present an investigation of observational signatures of a black hole (BH) in effective
quantum gravity (EQG), particularly gravitational weak
lensing and shadow analyses with the assumption that the BH is surrounded by uniform and non-uniform
plasma. First, we review the spacetime by comparing it with well-known BH spacetimes such as Schwarzschild and Reissner–Nordström BHs. Subsequently, we explore the effect of the uniform and non-uniform
plasma on the BH shadow. The results indicate that shadow radii decrease under the influence of the BH charge and both uniform and non-uniform
plasma parameters. In addition, we obtain theoretical constraints on the spacetime parameters using observational data from the Event Horizon
Telescope (EHT) collaboration. Finally, we study gravitational weak
lensing around the BH in EQG surrounded by uniform and non-uniform
plasma. It was found that increasing the uniform
plasma frequency leads to a rise in the deflection angle and vice versa for the non-uniform
plasma.
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All authors Jonibek Khasanov, Xuwei Zhang, Mirzabek Alloqulov, Sanjar Shaymatov, Chen Zhou, Chengxun Yuan
Quantum Physics
Realistic simulation of universal multiport interferometers with losses within a Gaussian formalism
Sebastiano Corli, Dario Chemoli, Samuele Altilia et al. (+4 more)
Photonic technologies are among the leading platform contenders for demonstrating
quantum advantage. Nevertheless,
photon losses represent the major hurdle for the realization of a fault-tolerant optical
quantum computer, and the need for an accurate characterization of this phenomenon is crucial for classical simulations of
quantum algorithms on noisy backends. The noisy regime would require the simulation of the
algorithm on a Fock backend or rather assuming the a priori hypothesis on the uniformity of the optical losses, which may lead to wrong predictions about the outcome from the
algorithm on a cerain hardware. We propose a Gaussian model that can reproduce a lossy dynamics through the experimental characterization of imperfect interferometers, yielding the corresponding mean vector and the covariance
matrix. Such model can be adapted to any continuous-variable architecture (spatial or time-bin encoded) and for both the Gaussian
boson sampling or general-dyne based
algorithms. Eventually, we quantify the drift of optical losses from being uniform throughout the multiport interferometer by a numerical simulation. This work proposes a blueprint for future characterizations, tailor-suited for specific devices and architectures, as well as for potential error correction and mitigation techniques, and it paves the way for realistic simulations of
quantum algorithms on NISQ optical platforms.
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All authors Sebastiano Corli, Dario Chemoli, Samuele Altilia, Edoardo Suerra, Dario Tamascelli, Simone Cialdi, Enrico Prati
Fluid Dynamics
Versatile two-layer model for thermohydraulic prediction of microchannel heat sinks
Chih-Hsiang Chen and Kentaro Yaji
Three-dimensional conjugate heat-transfer simulations provide detailed predictions for microchannel heat sinks but can be computationally demanding when many geometries and operating conditions are evaluated. This study develops a versatile two-layer model (VTLM) that reduces the three-dimensional problem to two coupled two-dimensional fields while retaining the in-plane geometry of the flow passages and fins. Effects associated with the unresolved channel-height direction are incorporated through hydraulic and thermal closures that account for wall friction and the fluid- and fin-side contributions to interlayer heat transfer. The closures are evaluated from the representative channel geometry, flow-development condition, and fin configuration. The VTLM was assessed against three-dimensional reference models across broad ranges of channel aspect ratios and operating conditions, including uniform and nonuniform fin arrangements. Compared with the existing two-layer models, the VTLM showed improved overall agreement with the three-dimensional reference results. The results showed that prediction accuracy was governed mainly by the flow-development condition and channel aspect ratio, from which a conservative screening guideline was proposed for the examined straight-channel configurations. The assessment of finned expansion–contraction channels further supported the applicability of the VTLM to the investigated passages with abrupt width changes. Overall, the VTLM provides a reduced-dimensional framework for thermohydraulic analysis across the range of microchannel heat-sink configurations examined in this study without explicitly resolving the channel-height direction.
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Atmospheric and Oceanic Physics
Forecasting carbon-risk hotspots ahead of the extreme 2026 El Niño
Xiaomeng Du, Runda Jiang, Philippe Ciais et al. (+13 more)
A potentially super El Niño is forecasted in 2026, raising the need to anticipate land carbon-cycle risks before its impacts unfold. We develop a prospective early-warning framework that uses dynamic global vegetation models driven by an ensemble of ECMWF seasonal
climate forecasts and machine-learning burned area predictions. Forecasts indicate a $0.23 \pm 0.21$ PgC reduction in global net biome productivity in the second half of 2026, with hotspots of sink weakening in eastern South America and elevated fire risk in Southeast Asia.
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All authors Xiaomeng Du, Runda Jiang, Philippe Ciais, Pierre Friedlingstein, Stephen Sitch, Mike O'Sullivan, Jefferson Goncalves de Souza, Tim Stripp, Piyu Ke, Yi Xi, Minxuan Sun, Xiaoran Wu, Mengjie Han, Shanshan Song, Qiang Zhang, Wei Li
Mesoscale and Nanoscale Physics
1/f frequency-noise reduction in nanomechanical resonators by dissipation dilution
Kostas Kanellopulos and Silvan Schmid
The frequency noise of a resonant nanomechanical sensor is well understood down to its thermomechanical limit, but the longest useful averaging time is set by a flicker, or $1/f$, frequency-noise floor whose origin has remained unknown. We show that this floor is the thermal noise of the tension. By the fluctuation-dissipation
theorem, the tension of a resonator with fixed ends fluctuates by an amount set by the loss angle of its material; for structural damping, these fluctuations produce $1/f$ frequency noise with a flicker coefficient $h_{-1}=E k_{\mathrm{B}} T/(2\pi V\sigma_0^2 Q_{\mathrm{el}})$, with $Q_{\mathrm{el}}$ the intrinsic loss under elongation, that contains no free parameter and is diluted by the tensile stress $\sigma_0$ in the same way as damping is in dissipation dilution. Silicon nitride strings and membranes from 30 to 340~nm thickness follow the predicted volume scaling, the predicted $\sigma_0^{-2}$ dilution across resonators and within stress-engineered strings, and the predicted thickness dependence, which places noise-active two-level systems in the volume and at the surfaces of the resonators, all at the absolute level set by the independently measured intrinsic loss. The same relation accounts for published data between 78 and 296~K; below 78~K, the loss measured at the resonance no longer represents the loss probed by the noise, marking the limit of the structural-damping assumption. Dissipation dilution therefore lowers the $1/f$ floor, and the longest useful integration time of a resonant sensor is set by its prestress, volume, temperature, and intrinsic loss angle.
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Astrophysics of Galaxies
Environmental Dependence of Satellite Planarity and Orbital-Pole Coherence around Milky Way Analogues in a Hydrodynamical Cosmological Simulation
Peng Wang, Yu Luo, Jiang Chang et al. (+2 more)
We examine whether the unusual spatial flattening and orbital-plane coherence of the Milky Way's classical satellites are connected to the
Galaxy's location in the
cosmic web. We compare the 11 classical satellites with the 11 most massive satellites of 11,922 Milky Way-mass hosts in the TNG300-1 hydrodynamical simulation. We measure flattening with both the simple inertia tensor (SIT), which retains radial information, and the reduced inertia tensor (RIT), which isolates angular anisotropy. Orbital-plane coherence is characterized by the minimum opening angle containing the axes of the eight most coplanar satellite orbits. For the Milky Way, we find $(c/a,b/a)=(0.183,0.558)$ for SIT and $(0.364,0.736)$ for RIT, together with an eight-orbit opening angle of $21.9^\circ$. The corresponding fractions of simulated systems at least as extreme are $4.94\%$, $12.28\%$, and $5.04\%$, respectively. We describe the environment using the velocity-shear tensor smoothed on $2\,h^{-1}\mathrm{Mpc}$ and compare the full sample with Local Group-like pairs, systems whose shear
eigenvalues match those reconstructed for the Local Group, and hosts in
knots, filaments, sheets, and voids. Among the well-sampled environmental subsets, the shape and opening-angle distributions differ only weakly. Although the
cosmic web imprints preferred orientations on host
spins and satellite orbital-plane axes, the Milky Way combines orientations that are uncommon in the simulation. We conclude that the present-day
cosmic-web environment alone does not substantially increase the occurrence of Milky Way-like satellite configurations. This result does not rule out an origin in anisotropic
accretion, since neither the present-day web class nor its shear
eigenvalues fully encodes the assembly history of an individual satellite system.
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All authors Peng Wang, Yu Luo, Jiang Chang, Xi Kang, Shi Shao
High Energy Physics (Theory)
About P-adic Numbers and Professor Igor Volovich on the Occasion of his 80th Anniversary
Paul H Frampton
We recall a 1987 paper written by Volovich and our subsequent work with Okada which established the Feyman rules for the p-adic string and the related non-local field theory which found diverse physical applications. We add some
memories of visits to Moscow during 1989-91.
Quantum Physics
Fisher-Information Certification from Bell Statistics: CHSH Bounds, Information Loss, and Finite-Data Guarantees
Juan Sumaya-Martínez, Omar Olmos-López and Jorge Mulia Rodríguez
Bell-test data are typically used to certify nonlocal correlations, while
quantum metrology is concerned with the sensitivity of measurement statistics to unknown parameters. Here we connect these tasks at the level of experimentally accessible Bell statistics. Using standard moment-based Fisher-information inequalities, we derive lower bounds on the classical Fisher information directly from Bell scores and their parameter dependence, without requiring full state
tomography. For CHSH measurements we establish a hierarchy between the information contained in the full outcome record, the set of individual correlators, and the compressed Bell parameter, thereby quantifying the metrological cost of data compression. In polarization-phase sensing, this hierarchy reveals a Bell-metrology tradeoff: the point of maximal CHSH violation need not maximize, and can even suppress, the Fisher information carried by the Bell score itself. We further derive finite-sample lower-confidence bounds from coincidence counts and analyze the effects of biased marginals, accidental coincidences, visibility loss, and multipair emission. The framework provides a practical route for extracting metrological guarantees from Bell-type experiments using only standard correlation measurements.
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Soft Condensed Matter
Colloid-Colloid Interactions Impact Network Morphology of Confined Colloidal Drying Patterns
Andreas Andersen Hennig, Natalia Kizilova, Ilaria Beechey-Newman et al. (+1 more)
Colloidal suspensions that are confined between two closely spaced plates and left to evaporate slowly form maze-like labyrinth patterns in the final stage of evaporation. The fingers in these patterns form bifurcations and occasionally loops, which we may quantify with a skeletonization method. We compare drying patterns formed with two different salt concentrations in the droplet which changes the screening length and therefore the effective colloid interactions. We find that the junctions generally follow Murray's law for optimal transport networks, and that the typical bifurcation angles peak around 53. Screened droplets additionally show more loopy networks, and is characterized by bands of transversal fingers before merging into a central non-fingering colloidal aggregate. Our observations suggest that colloid-colloid interactions can strongly influence the large-scale
topology of the pattern while leaving the local geometry of the individual fingers unchanged.
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All authors Andreas Andersen Hennig, Natalia Kizilova, Ilaria Beechey-Newman, Erika Eiser
High Energy Physics (Theory)
A No-Go Theorem for Nonspherical Bounces with a Single Negative Mode
Guangshang Chen, Jianpeng Dai and Yang Xiao
False
vacuum decay is conventionally described by a spherically symmetric bounce with a single negative fluctuation mode. This raises a fundamental question: can the single negative mode requirement itself enforce spherical
symmetry, independently of action minimization? For a single real scalar field with a smooth potential in flat spacetime, we rigorously prove that every localized nonspherical saddle with zero initial velocity has at least three negative modes. Additional reflection
symmetries further tighten these bounds, as illustrated in a sextic scalar model. Our findings exclude nonspherical bounce candidates with a single negative mode, providing a complementary spectral foundation for the spherical bounce description of false
vacuum decay.
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Strongly Correlated Electrons
Destructive Interference of a Charge Density Wave in the Skyrmion Magnet GdRu2Si2
G. D. A. Wood, D. A. Mayoh, F. Orlandi et al. (+10 more)
In skyrmion magnets, charge density waves induce higher-order exchange interactions that can select multi-Q ground states. Using resonant X-ray scattering and
neutron diffraction, we measure temperature-dependent
spin-charge coupling in GdRu2Si2. A minimal Landau model with one critical exponent and two ordering temperatures reproduces all six observed order parameters.
Spin-density wave components of the multi-Q ground state drive charge ordering, but the onset of a
magnetic helix suppresses it via destructive interference.
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All authors G. D. A. Wood, D. A. Mayoh, F. Orlandi, A. Bombardi, D. D. Khalyavin, P. Manuel, S. H. Moody, P. D. Hatton, R. D. Johnson, T. W. Chamberlain, O. A. Petrenko, M. R. Lees, G. Balakrishnan
Materials Science
Domain-wall-to-domain interconversion in a polar conducting oxide
Martin F. Sarott, Majid Ahmadi, Johanna van Gent González et al. (+13 more)
Domain walls in ferroic
crystals are topological defects with a
symmetry distinct from the domain interior, allowing them to display functionalities that are otherwise forbidden in the host material. Despite their unique properties, domain walls are strictly confined to two-dimensional interfaces, which hinders unveiling their true nature and limits their applicability. Here, we demonstrate reversible dimensionality control by expanding nanoscale domain walls into three-dimensional functional regions in polar epitaxial tungsten trioxide ($\text{WO}_3$). This domain-wall-to-domain interconversion is enabled by the conducting, non-polar domain walls adopting the parent-phase structure. An alternating electric field applied through a scanning probe tip induces localized heating, which expands this domain-wall phase into the adjacent polar domains. This approach enables reversible spatial control to switch between mutually exclusive properties of domains (polarity) and domain walls (conductivity), offering a new paradigm for reconfigurable oxide electronics.
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All authors Martin F. Sarott, Majid Ahmadi, Johanna van Gent González, Ewout van der Veer, Mads C. Weber, Jacopo Pinna, Daniel A. Chaney, Arijit Sinha, Hamideh Hassani, Horatio R. J. Cox, Thomas Perrault, Amir Sabet Ghorabaei, Maria A. Loi, Philippe Ghosez, Bart J. Kooi, Beatriz Noheda