General Physics
New Tsallis holographic dark energy with the Granda-Oliveros cutoff in a non-flat universe: curvature tracking and DESI DR2 constraints
Umesh Kumar Sharma, Pankaj, Bramha Dutta Pandey et al. (+1 more)
Holographic dark energy ties the dark-energy density to an infrared length. We study new Tsallis
holographic dark energy (NTHDE), built on the exponential Tsallis
entropy, with the local Granda-Oliveros (GO) cutoff $L^{-2}=\alpha H^2+\gamma\dot H$ in a spatially curved universe. Writing the background as an autonomous system for $(\Omega_d,u,\Omega_k)$, we obtain four exact results. (i) In the closed-form solution without the Tsallis deformation, the dark energy splits into a matter-like and a
curvature-like part. (ii) Because the GO cutoff lacks the term $k/a^2$ of the
Ricci scalar, the coefficient of $(1+z)^2$ in $H^2/H_0^2$ is $R_k\Omega_{k0}$ with $R_k=(1-\alpha+\gamma)^{-1}>1$, while distances and the Clarkson-Bassett-Lu test return $\Omega_{k0}$; the
Ricci completion restores $R_k=1$. (iii) Big-bang nucleosynthesis locks the matter-era dark-energy fraction to $1/(1+3|w_{\rm GO}|)$, where $w_{\rm GO}$ is the equation of state of the GO mode. (iv) The finite-time fold singularity of the flat model survives
curvature. Against Pantheon+SH0ES
supernovae, 32
cosmic chronometers and DESI DR2 BAO, curved GO-NTHDE gives $\Omega_{k0}=-0.001^{+0.041}_{-0.043}$, consistent with flatness, and $\Delta\chi^2=-2.82$ relative to flat $\Lambda$CDM, but the
Bayesian evidence prefers flat $\Lambda$CDM ($\ln B=-2.66\pm0.24$), and allowing
curvature costs $\ln B=-1.39\pm0.25$. The data cannot yet measure $R_k$: the GO and
Ricci cutoffs fit equally well ($\ln B=+0.28\pm0.26$). With Union3
supernovae the model is on a par with $\Lambda$CDM ($\ln B=+0.53$). A fraction 0.91 of the posterior reaches the finite-time fold.
Read the full abstract ▾
All authors Umesh Kumar Sharma, Pankaj, Bramha Dutta Pandey, P. Suresh Kumar
Statistical Mechanics
Migration Flows: Population Scaling and Heavy Tails
Cook Hyun Kim, Sangjoon Park, Seoyoung Jin et al. (+1 more)
We show how migration between counties in different cities can explain both the population scaling of mean intercity flows and heavy-tailed intercity net-flow distributions. Density-dependent departure and arrival activities determine how mean flows scale with the populations of the origin and destination cities. We assume Gaussian county-pair net flows with standard deviations proportional to their mean directional flows. At a fixed correlation between county-pair net flows, their sum is Gaussian. Averaging this conditional Gaussian density over the correlation distribution can produce an intermediate power law with a Gaussian cutoff. We also present a
stochastic model that generates the variance distribution used in this mixture.
Read the full abstract ▾
All authors Cook Hyun Kim, Sangjoon Park, Seoyoung Jin, Jaiyong Lee
Fluid Dynamics · Cross-listed from cs.LG
A Data-Free Physics-Informed Neural Operator for Level-Set Interface Advection
Muhammad Akbar Khan
Operators for interfacial problems are trained on reference solutions produced by the solver they are intended to replace. This work develops a data-free physics-informed neural operator for level-set interface advection, in which the interface is the equation's unknown and the operator maps an initial interface to the full spatiotemporal trajectory under a prescribed flow. Training uses only the transport residual and a
geometric constraint; no reference solution enters the objective at any point. A spacetime
Fourier backbone emits the entire trajectory in one pass, and the initial condition is imposed by construction rather than by penalty, which removes the competition between the anchoring term and the residual that otherwise arises when no solution data are available. Supervised and hybrid operators are trained under an identical architecture, family, budget and test set, and are reported throughout as baselines that quantify what refusing labels costs. On a reversed single
vortex the data-free operator reaches 1.614 +/- 0.067% relative L2 error on 100 held-out initial interfaces against 0.369 +/- 0.035% for the supervised baseline, a factor of 4.4; on solid-body rotation the corresponding figures are 3.804 +/- 1.075% and 2.576 +/- 0.159%, a factor of 1.5. The two
benchmarks rank the arms differently, and the difference is attributable to the eikonal constraint: the exact solution violates |grad phi| = 1 over 0.3% of the domain under rotation and 86.9% under the
vortex. Where the constraint is valid the physics-trained operator conserves enclosed area 2.7 times better than the supervised baseline despite a larger field error, and a hybrid arm using eight reference solutions outperforms a supervised arm using sixteen.
Read the full abstract ▾
Mathematical Physics
Quasi-exponentials and semi-classical limits for the chordal BPZ system
Mo Chen and Hao Wu
We study the nonlinear Hamilton–Jacobi system arising as the formal semi-classical limit of the chordal Belavin–Polyakov–Zamolodchikov equations with a common
eigenvalue parameter $\lambda$. We determine the number of global real-valued solutions modulo additive constants. When $\lambda=0$, the number of solutions can be derived using the connection between the solutions and rational functions, due to Eremenko. We focus on the case when $\lambda\neq 0$ in this article. For $\lambda>0$, a Schwarzian correspondence relates the algebraic equations for the gradients to quasi-exponentials with prescribed critical points. Enumeration and transversality results of Mukhin, Tarasov, and Varchenko yield smooth real branches, and a Poisson bracket identity establishes their exactness. An energy bound rules out global real-valued solutions for $\lambda<0$.
Read the full abstract ▾
Data Analysis and Statistics
Constrained surrogates for arbitrary families of continuous probability distributions
Jack Murdoch Moore and Eduardo G Altmann
Empirical regularities described by parametrized families of probability distributions can shape how complex systems are interpreted and explained. A recurring problem is to determine the extent to which these descriptions are supported by observations, and how they can be used to characterize the underlying system. Here, we introduce a general framework for constructing constrained surrogates capable of representing arbitrary families of continuous distributions. We demonstrate its utility by providing explicit
algorithms for several canonical distributions in statistical physics, including continuous powerlaw, lognormal, exponential, and truncated Gaussian distributions. These constrained surrogates enable unbiased estimation and accurate tests of model validity based on arbitrary (physically meaningful) sample statistics, without requiring specification or estimation of model parameters. We show how these theoretical advantages translate into more informative and nuanced conclusions in applications ranging from bushfire magnitudes and word usage in texts to
brain connectomes and city populations.
Read the full abstract ▾
Materials Science
Thermally Robust and Strongly Pressure-Responsive NIR Luminescent Manometer Based on Cr3+-Ni2+ Emission
Weijia Xie, Maja Szymczak, Tongxi Luo et al. (+3 more)
The increasing demand for highly sensitive luminescent manometers capable of precise pressure determination, particularly those operating in the near-infrared (NIR) spectral range, motivates the continuous search for new pressure-responsive luminescent materials. In this work, we introduce NaLu2Ga3Ge2O12:Cr3+, Ni2+ as a highly sensitive NIR luminescent manometer in which pressure not only induces pronounced spectral shifts of the Cr3+ and Ni2+ emission bands but also strongly modulates their relative luminescence intensities. Remarkably, the 3T2(3F)->3A2(3F) emission band of Ni2+ exhibits a record-high absolute pressure sensitivity of SA = 34 nm GPa-1. Furthermore, by appropriately selecting narrow spectral ranges within the pressure-responsive emission bands, a ratiometric NIR luminescent manometer was developed, providing a maximum relative pressure sensitivity of SR = 158% GPa-1. Most importantly, the proposed ratiometric readout exhibits a thermal-invariance manometric factor (TIMF) of 19,900 K GPa-1, which, to the best of our knowledge, is the highest value reported to date for a luminescent manometer. The combination of exceptionally high-pressure sensitivity, NIR operation, and remarkable resistance to thermal interference establishes NaLu2Ga3Ge2O12:Cr3+, Ni2+ as a highly promising luminescent pressure sensor for reliable pressure determination under conditions involving simultaneous temperature variations.
Read the full abstract ▾
All authors Weijia Xie, Maja Szymczak, Tongxi Luo, Chan Wang, Lukasz Marciniak, Xinguo Zhang
Cellular Automata and Lattice Gases
Diagonal Bases and Diagonal Periods of Elementary Cellular Automata
Tigran Nersissian
Which cellular-automaton diagonal families form bases in every finite window? For canonical
polynomial lifts of elementary rules, two truth-table bits determine triangularity, and units on the
matrix diagonal determine invertibility. Exactly 24 rules give universal binary bases; all remain universal over every modulus. Among triangular binary coordinate maps, the Pascal transform is uniquely characterized by converting OR convolution into pointwise multiplication, while increment becomes strict prefix summation. Explicit inverses and coordinate comparisons distinguish sparsity from evaluation cost. A Rule 30
polynomial construction gives Fibonacci bounds on interpolation order and
prime-modulus periods. Exact additive periods anchor a finite census modulo two and three. These results separate all-window basis classification from optimization of a representation and from period patterns observed in finite windows.
Read the full abstract ▾
Cellular Automata and Lattice Gases
Diagonal Periods and Newton Supports of Rules 30, 86 and 135
Tigran Nersissian
The single-seed Rule 30 cone has unbounded least diagonal periods in both directions. On the finite-support side, first contact fixes the least Newton index and an integer
polynomial lift gives a Fibonacci ceiling. For reflected Rule 86, a backward map on periodic tail profiles retains the zero boundary and bounds periods independently of transients. At depth $m$, the Rule 30 period is at least $\lfloor m/2\rfloor+1$; for natural Rule 86 cuts through depth $m$, the largest period is at least $\tfrac12\log_2(m+2)$. This proves infinitely many reset/integration period doublings. The physical Rule 135 orbit is a translated complement of Rule 30 after its first step, yielding finite or cofinite supports. A separately initialized auxiliary recurrence has exact index-by-index stabilization. Residue tables and block formulas describe the remaining structure and permit evaluation from supplied representations. Construction and minimization remain separate costs.
Read the full abstract ▾
Chemical Physics · Cross-listed from q-bio.QM
Reactive molecular dynamics simulations of atenolol first steps degradation by 9CL6 ammonia monooxygenase
Pascal Brault, Matthieu Wolf, Yana Gouzi et al. (+2 more)
The persistence of beta-blockers like atenolol in aquatic environments necessitates efficient remediation strategies, such as enzymatic biodegradation. This study employs reactive molecular dynamics (rMD) simulations to investigate the initial degradation steps of atenolol by the oxidoreductase 9CL6 ammonia monooxygenase. Using the ReaxFF reactive forcefield within a simulated aqueous environment, the degradation processes were modeled at 300 K and 350 K over 6.5 nanoseconds. Results indicate initial degradation rates of 24% at 300 K and 18% at 350 K, with each enzyme molecule degrading approximately 20 atenolol molecules before reaching a saturation point. Mass spectrum analysis reveals the primary formation of C8 and C6 fragments at both temperatures. However, at 300 K, additional intermediate fragments (C1, C3, C11, C13) are observed, which are completely bypassed at the higher temperature of 350 K. Furthermore, increasing the temperature to 350 K accelerates the initial degradation phase from 2 ns to 0.5 ns, despite yielding a slightly lower overall degradation rate. Ultimately, these atomistic insights provide a foundational computational methodology for predicting biodegradation rates and pathways of pharmaceutical contaminants at the molecular scale.
Read the full abstract ▾
All authors Pascal Brault, Matthieu Wolf, Yana Gouzi, Claire Albasi, Jeanne Trognon
Materials Science
Multimodal Visual Sensing of Temperature and Pressure: From Spectroscopic Readout to Multiple Linear Regression-Enhanced RGB Analysis
Maja Szymczak, Yufan Meng, Guanjun Xiao et al. (+4 more)
Transforming a single luminescent host into distinct temperature- and pressure-sensing systems through composition control provides a powerful route toward multifunctional optical sensors. Here, we introduce a concentration-tunable KGaGeO4:Bi3+,Eu3+ platform whose sensing function can be selectively directed toward thermometry or manometry by adjusting the dopant balance. Spectroscopically distinct Bi3+ centers and Eu3+ emission exhibit differentiated responses to temperature and pressure, enabling
multimodal readout through ratiometric luminescence, chromaticity coordinates, spectral shifts, and visible color changes. Importantly, these color changes were translated into quantitative temperature and pressure maps using RGB imaging combined with multiple linear regression (MLR). By simultaneously exploiting multiple color channels, MLR increased the maximum relative thermal sensitivity from approximately 1% K-1 for conventional RGB ratios to 8.8% K-1 and the pressure sensitivity from 169% GPa-1 to nearly 721% GPa-1. This work presents the first application of MLR-assisted RGB analysis for quantitative luminescence pressure sensing. The proposed strategy integrates composition-controlled functionality,
multimodal spectroscopic sensing, direct visual readout, and data-assisted imaging, demonstrating the synergy between material engineering and multivariate analysis for highly sensitive multifunctional optical sensing.
Read the full abstract ▾
All authors Maja Szymczak, Yufan Meng, Guanjun Xiao, Miguel A. Hernández-Rodríguez, Iga Sawaryn, Bo Zou, Lukasz Marciniak
Chemical Physics
Mass-Scaling of Quantum Tunnelling in Hydrogen Bonds: Analytical Model and Comparison with Multidimensional Potentials
Krishna Kingkar Pathak
Quantum tunnelling plays a central role in the structure and spectroscopy of hydrogen-bonded systems, and its sensitivity to isotopic substitution provides a stringent probe of the underlying potential-energy landscape. Despite extensive numerical studies, many high-level approaches tend to obscure the simple physical relationships linking effective mass, barrier geometry, and tunnelling amplitudes. Here, we develop a Cornell-type analytical–numerical framework to describe
proton and deuteron tunnelling, combining a semi-analytical localized wavefunction ansatz with numerical solutions of the one-dimensional Schrödinger equation. The resulting tunnelling splittings exhibit an exponential dependence on the square root of the effective isotope mass,$\ln(\Delta E)\propto -\sqrt{\mu_{\mathrm{eff}}}$, in agreement with semiclassical Wentzel–Kramers–Brillouin (WKB) theory. Comparison with multidimensional reaction-space calculations for the formic acid dimer shows that this scaling persists in fully coupled 3D and 5D
quantum models, yielding an empirical relation $\ln(\Delta E)= -1.75\sqrt{\mu_{\mathrm{eff}}}+2.60$. The present framework provides a transparent and computationally efficient approach for quantifying mass-scaling and tunnelling dynamics in hydrogen-bonded and other double-well systems.
Read the full abstract ▾
Plasma Physics
Reactive Trace Species Modeling with the Simulation Tool PICLas
Simone Lauterbach, Kim-Sophie Ellenberger, Stefanos Fasoulas et al. (+1 more)
A species-specific weighting scheme for the Natural-Sample-Size collision model within the Direct Simulation Monte Carlo method is developed and implemented in the open-source gas and
plasma solver PICLas. The implemented weighting scheme places particular emphasis on chemical reactions and ionization processes of trace species in order to guarantee physically accurate and low-noise simulations of atmospheric entry processes. The successful implementation and the conservation of momentum and energy during relaxation processes and chemical reactions are verified through a reservoir simulation of a reacting air mixture. As a more sophisticated validation case, atmospheric entry simulations of a cylinder at an altitude of 108 km are investigated. In a final step, the developed weighting scheme is employed to investigate ionization processes in the shock layer surrounding the RAM-C II reentry probe during atmospheric entry. The simulations showed very good agreement with experimental flight data and reduced noise in the rarefied regions for the charged species.
Read the full abstract ▾
All authors Simone Lauterbach, Kim-Sophie Ellenberger, Stefanos Fasoulas, Marcel Pfeiffer
Medical Physics · Cross-listed from math.OC
Parallel Optimization: Theory, Algorithms, and Applications,
Yair Censor and Stavros A. Zenios
This 30 years old book is posted for free download by the generosity of Oxford University Press that granted permission to allow access to future generations of young scientists. A printed copy can be purchased from the publisher. The authors received for this book "The 1999 INFORMS Computing Society Prize for Research Excellence in the Interface Between Operations Research and Computer Science" from the Institute for Operations Research and the Management Sciences (INFORMS). For a book review by Janos D. Pinter go to: Journal of Global Optimization, 16: 107-108, 2000.
Read the full abstract ▾
Earth and Planetary Astrophysics
The Science Potential of Characterizing Gas Giant Exoplanets with HWO
Beck Dacus, Jean-Baptiste Ruffio, Quinn Konopacky et al. (+19 more)
With the ability to directly image Earth-like
exoplanets and search their atmospheres for biosignatures, the upcoming Habitable Worlds Observatory (HWO) will also collect high signal-to-noise ratio (S/N) reflected-light photometry and spectra of nearby gas
giant exoplanets. Such high-quality data would allow novel investigations into gas
giant atmospheric composition, formation, and kinematic properties, and could enable the detection of exomoons around these
planets. We use the EXOSIMS direct imaging mission simulator to model HWO observations of Jupiter-radius gas
giants at Earth-like and Jupiter-like instellations around the 164
stars in the ExEP target list. We find that HWO should be able to achieve S/N $\geq$ 5 broadband visible-light detections of gas
giants in this instellation range within 5 minutes of integration. 10 hours of R=1000 near-IR spectroscopy with HWO should reveal water, methane, and ammonia absorption features in the atmospheres of Jupiter-like gas
giants. HWO time-series photometry should exceed 1% flux precision in one hour for any Earth-instellation gas
giants around ExEP
stars, and for Jupiter-like gas
giants at $d\leq$ 7 parsecs. Time-series light curves at this cadence and precision could, over tens of hours, reveal rotation-induced variability comparable to Jupiter's. Eclipses of Mars-sized exomoons may be detectable in high-cadence light curves of Jupiter sized
planets in the habitable zones of ExEP
stars at $d\leq$ 10 parsecs. For any hypothetical Earth-like exomoons with oxygen-rich atmospheres at $d\leq$ 7 parsecs from the
Solar System, HWO might be able to detect the spectral signature of molecular oxygen amid the parent
planet's
photon noise in deep ($\sim$400 hour integration) spectroscopic HWO observations at R=1000. Such moons, if they exist, represent additional habitable worlds that HWO could investigate for biosignatures.
Read the full abstract ▾
All authors Beck Dacus, Jean-Baptiste Ruffio, Quinn Konopacky, Renyu Hu, Tyler D. Robinson, Mary Anne Limbach, Kielan Hoch, Katelyn Horstman, Bruce Macintosh, Dimitri Mawet, Michael W. McElwain, Bertrand Mennesson, Charley Noecker, Marshall D. Perrin, Laurent Pueyo, Dmitry Savransky, Corey Spohn, Sarah Steiger, Connor Vancil, Ji Wang, Nicole Wolff, Shelley Wright
Materials Science
Highly Lattice-Mismatched Selective Area Epitaxy and Coalescence of PbSe Nanostructures on GaAs
Ashlee M. García, Hosni A. Kaissi, Jarod E. Meyer et al. (+9 more)
Selective area growth of PbSe has the potential to realize deterministic placement of high-density, defect-tolerant nanostructure networks toward a scalable
quantum platform. PbSe is a narrow bandgap
semiconductor with advantageous (opto)electronic properties that has been shown to have a desirable defect-tolerance, enabling bright emission even when grown on highly-dissimilar platforms, and could be leveraged in combination with selective growth for site-selective
quantum emitters and low-disorder hybrid nanowire networks. In this work, we achieve site-selective growth of well-faceted and ordered PbSe nanostructures, despite a large 8%
lattice mismatch. Structural and morphological characterization reveal that $>$99% of selectively grown islands within 100 nm opening are single-orientation and cube-on-cube oriented with sub-nm root-mean-square surface roughness. Defect analysis showed that 74% of the islands and 86% of the coalesced regions between different mask openings were free of threading dislocations. These PbSe islands achieved equivalent emission in the mid-infrared despite having a higher surface-to-volume ratio than the planar control. Further, we present a gate-tunable two-terminal Josephson junction fabricated from the PbSe nanowires grown with conditions identified in this study. The combination of the accessible selective growth regime, morphological control of island growth and demonstrations of optical and electrical transport properties indicates promise for PbSe SAG as a defect-tolerant scalable
quantum platform.
Read the full abstract ▾
All authors Ashlee M. García, Hosni A. Kaissi, Jarod E. Meyer, Kira J. Martin, Maksim Gomanko, Laura A. Stern, Pooja D. Reddy, SeongJin Park, Wilson J. Yánez-Parreño, Sergey M. Frolov, Vlad S. Pribiag, Kunal Mukherjee
Applied Physics
Dose-Insensitive Defect Engineering, Carrier Kinetics, and Reproducible Chromaticity Tuning in Ion-Implanted InGaN/GaN Quantum Wells
Quan-Shan Liu, Mason Adshead, Sadia Sheraz et al. (+3 more)
Post-growth defect engineering via ion implantation provides a powerful pathway for spatial optical profiling and colour patterning in III-V alloying photonic integration. However, the comprehensive recombination kinetics governing deep-level defect saturation and excitonic recovery under high-temperature annealing remain insufficiently understood. Here, we present a systematic study on the optical dynamics, rate-equation kinetics, and chromaticity
evolution of indium-implanted InGaN/GaN multiple
quantum wells (MQWs) across implantation doses (5E14 to 5E16 ions cm^-2) and subsequent thermal annealing stages (500 to 1100 deg C). Photoluminescence (PL) spectrum analysis reveals that a dose of <= 5E14 ions cm^-2 induces a modification of the optical response that does not further change upon high-dose implantation. A two-channel coupled rate-equation model is fitted to the data, optimised via differential
evolution, allowing the extraction of transition rate constants. This demonstrates that thermal processing at 1000 deg C suppresses the carrier capture rate into deep-level states and also reduces its radiative recombination rate. This kinetic bottleneck drives an order-of-magnitude extension in the channel-specific radiative lifetime. Leveraging the excitation power density dependence of the differential recombination kinetics, where deep defects saturate whilst MQW emission scales near-linearly, we achieve a universal and power density-tunable chromaticity trajectory from warm yellow to cool white-blue emission. These insights enable microscopic defect physics to be linked to the macro-scale colour tailoring observed.
Read the full abstract ▾
All authors Quan-Shan Liu, Mason Adshead, Sadia Sheraz, Maddison Coke, Nicholas Lockyer, Richard J. Curry
Disordered Systems and Neural Networks
Extreme-Scale Ising Machines with Cluster Mean-Field Theory
Xiuqi Zhang, Shuvro Chowdhury, Shaila Niazi et al. (+3 more)
Scaling analog and digital Ising machines to larger problems requires overcoming finite device capacity and the cost of communication between devices. We present cluster mean-field theory (CMFT), a framework that partitions a large interaction graph into clusters sized to fit available hardware. Each cluster performs local updates independently, while interactions across cluster boundaries enter through periodically updated effective biases computed from boundary-
spin averages. To reduce the error introduced by fixed cluster boundaries, we introduce dynamic partitioning, which cycles through multiple partitions so that interactions approximated by mean fields at one stage can act through instantaneous
spins at another. On three-dimensional
spin glasses and planted Pegasus instances, dynamic CMFT exhibits power-law decay of residual energy over sweep budgets. This shows that solution quality continues to improve with computational effort despite the mean-field approximation. An automated graph partitioner combined with a weighted recovery ratio provides a practical heuristic for selecting partition combinations on graphs without natural cut directions. We demonstrate CMFT on four GPUs with approximately four million p-bits, reaching comparable energy densities up to 15 times faster than a single-GPU implementation of the full graph. By coupling locally evolving clusters through programmable effective biases, CMFT provides a route to extreme-scale Ising machines on both analog and digital hardware.
Read the full abstract ▾
All authors Xiuqi Zhang, Shuvro Chowdhury, Shaila Niazi, Christian Z. Pratt, Navid Anjum Aadit, Kerem Y. Camsari
General Relativity and Quantum Cosmology
Black Holes as Frequency-Dependent Filters of Stochastic Gravitational Waves
Sefi Katznelson, Aidan Minger and Stefano Profumo
Black holes ring when perturbed, whereas their response to a stationary gravitational-wave background is a real-frequency scattering problem, not a source of additional quasi-normal-mode lines. We make this standard distinction quantitative by treating a black hole as a frequency-, angle-, and polarization-dependent filter. For an isotropic stationary background around Schwarzschild holes, elastic scattering produces no net monopole signal, so horizon absorption is the only population-level spectral distortion. We calculate this transfer function for Schwarzschild holes in detail, identify its absorptive and phase-delay signatures, and connect the stationary response to the causal ringdown excited by a finite wave packet. We then promote the single-hole result to an angular and polarization transport kernel for a cosmological population. The resulting optical depth is negligible for realistic black-hole populations, including asteroid-mass
primordial black holes comprising all dark matter. We then extend the analysis to Kerr holes, for which superradiance allows genuine amplification in selected co-rotating modes, but isotropic incidence and random
spin orientations strongly dilute the diffuse signal. Observable effects are therefore more likely in rare, nearby, aligned, rapidly spinning, or transiently illuminated systems than through cumulative cosmological propagation.
Read the full abstract ▾
High Energy Physics (Phenomenology)
New bounds on light scalars from the tip of the red giant branch
Natnael Debru, Audrey Fung, Saniya Heeba et al. (+3 more)
Light, weakly coupled particles can be copiously produced in the hot and dense interior of
stars, and the resulting energy loss can leave observable imprints on entire
stellar populations. For instance, additional energy loss from red
giant cores delays helium ignition and brightens the tip of the red
giant branch (TRGB). We revisit the TRGB bounds on light scalars coupled to electrons, of which the
Higgs portal is the prototypical example. In the degenerate cores of red
giants, scalar emission is dominated by resonant conversion of longitudinal plasmons, which we compute using finite-temperature field theory. Rather than rescaling
neutrino emission rates at fixed
benchmark core conditions, we implement this emissivity in the MESA
stellar evolution code and self-consistently simulate the
evolution of red
giants, including the backreaction of the scalar energy loss on the
stellar structure. Comparing our predictions with the observed bolometric TRGB magnitudes of 27 Milky Way globular clusters, we exclude scalar-electron couplings $\alpha_{\phi ee} = g_e^2/4\pi > 1.6 \times 10^{-34}$ at 95% confidence for sub-keV masses, improving on previous bounds by nearly two orders of magnitude. In the context of the
Higgs portal, this corresponds to an exclusion on values of the mixing angle $\sin\theta > 2.2\times 10^{-11}$, providing the tightest bound for scalar masses in the $\sim 1\,\mathrm{eV} - 10\,\mathrm{keV}$ range.
Read the full abstract ▾
All authors Natnael Debru, Audrey Fung, Saniya Heeba, Hugo Schérer, Katelin Schutz, Aaron C. Vincent
Earth and Planetary Astrophysics
Exoplanet Atmosphere Spectral Sensitivity Analysis with PICASO: Jacobians, Linear-Gaussian Approximations, and Information Content
Natasha E. Batalha and Nicholas F. Wogan
Designing observatory and instrument architectures for complex missions like the Habitable Worlds Observatory (HWO) requires a rapid and rigorous mathematical framework to evaluate trade-offs across bandpass, spectral resolution, and signal-to-noise regimes. While full
Bayesian atmospheric
retrievals are the gold standard for atmospheric inference, they are too computationally expensive to explore this full parameter space. Here, we present a sensitivity analysis and
retrieval diagnostic toolkit within the open-source code PICASO. The core addition to the code base is a flexible solution for computing finite-difference Jacobian
matrices, which provides a local linearization of the forward model. These Jacobian
matrices characterize the sensitivity of the spectrum (either reflected, thermal, or transmission) to perturbations in any atmospheric state parameter, such as molecular abundances. Given the Jacobian for a certain reference atmosphere, our toolkit provides a suite of analytic diagnostic quantities under Gaussian assumptions for the prior, likelihood, and posterior. These include Fisher-
matrix-based estimates of 1$\sigma$ constraint intervals of atmospheric parameters, averaging kernels, singular-value-decomposition diagnostics for parameter degeneracies, and an information-content metric. We validate the results of our toolkit by comparing them to that of a full
Bayesian retrieval of an Earth-like
planet with an HWO-like facility. We show that our metrics can provide rapid understanding of model parameter sensitivity and that local linear-Gaussian approximations can diagnose dominant degeneracies seen in
retrievals as well as provide first order estimates of posterior probability distributions. Ultimately, this provides the community with a complementary toolkit for optimizing instrument design and conducting spectral sensitivity diagnostics.
Read the full abstract ▾
Optics
Cascaded Brillouin-Kerr microcombs in surface nanoscale axial photonic resonators
Emily Eadie, Juan Diego Mazo-Vásquez, Sophia Padvaiskas et al. (+3 more)
Surface nanoscale axial photonic resonators (SNAPRs) provide an axially structured whispering-gallery-mode platform in which nanoscale effective-radius variations produce spatially localized optical resonances. Here, we demonstrate cascaded Brillouin-Kerr microcomb generation in a SNAPR fabricated from 660 micrometer diameter silica fiber. Under continuous-wave pumping, cascaded stimulated Brillouin scattering generates first- and second-order Stokes fields that seed Kerr four-wave mixing within the cavity. The resulting nonlinear spectrum contains two comb families with a common azimuthal spacing of 100.2 GHz and a relative offset of 9.6 GHz, consistent with the Brillouin shift in silica. A low-power transmission spectrogram provides a spatially resolved modal analysis of the resonator, revealing localized resonances with loaded quality factors on the order of ten million, and optical resonance pairs compatible with the measured Brillouin spacing. These results establish SNAPRs as a platform for studying cascaded stimulated Brillouin scattering, Kerr four-wave mixing, and comb formation in axially structured whispering gallery resonators.
Read the full abstract ▾
All authors Emily Eadie, Juan Diego Mazo-Vásquez, Sophia Padvaiskas, Flore K. Kunst, Lewis Hill, Pablo Bianucci
Plasma Physics
Interactions Between Two Magnetized Plasma Pressure Filaments: Drift-Alfvén Modes and Transport
Thomas Simala-Grant, Scott Karbashewski, Richard Sydora et al. (+1 more)
A set of experiments on merging dynamics of localized magnetized
plasma pressure filaments in close proximity has been carried out in a large linear magnetized
plasma device. A two filament configuration is used to determine the separation scale of cross-field interaction. Fluctuation analysis of the ion saturation current confirms the presence of unstable drift-Alfvén modes on each filament which are predominantly driven by the steep electron temperature gradient. When the filaments are separated a distance of approximately five times the size of a single filament or greater, no interaction is observed and the drift-Alfvén modes remain uncoupled. When brought closer together, significantly stronger interaction occurs with transfer of charge and energy, leading to the generation of inter-filament electric fields. This has the effect of rotating the filaments and influencing the merging dynamics. When the filaments are asymmetrically heated, the cooler filament becomes wrapped around the other, and the drift-Alfvén modes become fully coupled in a global mode structure. Transport between the filaments is explained in terms of E x B drift and the local potential wells of the filaments, and drift-Alfvén mode coupling occurs when the filaments are brought within the distance of a collisionless skin depth.
Read the full abstract ▾
All authors Thomas Simala-Grant, Scott Karbashewski, Richard Sydora, Bart Van Compernolle
Astrophysics of Galaxies
Balmer Absorption Series and Broad Metal Lines in Two Luminous Little Red Dots
Bingjie Wang, Jenny E. Greene, Hanpu Liu et al. (+21 more)
Balmer absorption is common among little red dots (LRDs), but absorbers at or redward of systemic are rare, occurring in only $\sim10-15$% of H$\alpha$ absorbers. In this paper, we study two such exceptional cases with deep JWST/NIRSpec spectroscopy: 15 hr of high-resolution (G395H) observations of RUBIES-EGS-49140 (z=6.68), resolving the absorption in all four transitions from H$\alpha$ through H$\delta$, and medium-resolution spectroscopy (10 hr of G235M, 2 hr of G395M) of UNCOVER-A2744-45924 (z=4.46; 1.7x magnification). Both sources are among the optically reddest and most luminous LRDs known, and both show deep, near-systemic Balmer absorption troughs. We find two systematic trends along the Balmer series: the absorption centroids become more redshifted toward higher-order transitions, while the absorbed equivalent widths decline only weakly with increasing order, far less than expected from the atomic optical-depth ratios for a single attenuating screen. Ca\,{\sc{ii}}\,K is detected in absorption in both sources, whose offset follows the H$\alpha$ trough rather than the more redshifted higher-order Balmer lines. We further report the detection of a broad base in [Ne\,{\sc{iii}}]\,$\lambda$3870, along with broad [O\,{\sc{iii}}]\,$\lambda$4364, [O\,{\sc{iii}}]\,$\lambda5008$, and He\,{\sc{i}}\,$\lambda5877,\lambda7067$, while He\,{\sc{ii}}\,$\lambda$4687 remains undetected or weak. Standard AGN photoionization models cannot reproduce the observed line ratios, whereas AGNs with high gas densities provide a consistent explanation, as also indicated by the anomalously high He\,{\sc{i}}\,$\lambda7067/\lambda5877$ ratio. A possible explanation for the relative strengths of the Balmer absorption lines could be a dense, optically thick medium whose re-emission modifies their apparent absorption strengths, while the velocity progression may arise from stratification in the absorbing gas.
Read the full abstract ▾
All authors Bingjie Wang, Jenny E. Greene, Hanpu Liu, Nicholas Kaaz, Gabriel B. Brammer, Raphael E. Hviding, Ivo Labbé, Joel Leja, Jorryt Matthee, Rohan P. Naidu, Alberto Torralba, Josephine F.W. Baggen, Nikko J. Cleri, Seiji Fujimoto, Lukas J. Furtak, Anna de Graaff, Michaela Hirschmann, Vasily Kokorev, Erini Lambrides, Ian McConachie, Erica J. Nelson, Adèle Plat, Weichen Wang, Adi Zitrin
Fluid Dynamics
Modelling friction and heat transfer in turbulent forced convection over porous lattices
Aneek Chakraborty, Stefan Hickel and Davide Modesti
We perform direct numerical simulations (DNS) to investigate how cubic-
lattice porous substrates influence momentum and heat transfer in turbulent channel flows. The simulations span friction Reynolds numbers from 260 to 1500, Prandtl numbers of 0.5, 1, and 2, and substrate porosities of 50%, 71%, and 87%. We show that theories developed for rough- wall
turbulence can be extended to porous surfaces by replacing the roughness height with the inverse of the streamwise Forchheimer coefficient. The shifts in the mean velocity and temperature profiles follow existing fully rough momentum and thermal theories, enabling their prediction with rough-wall models. Combining these models with synthetic temperature and velocity profiles, we derive analytical formulas for the friction coefficient and Stanton number that agree with our DNS data to within 5%. The performance enhancement factor, which measures heat-transfer augmentation relative to the pressure-drop penalty at constant pumping power, is comparable to that obtained for rough surfaces. This suggests that porous substrates provide an alternative method for enhancing heat transfer in turbulent flows.
Read the full abstract ▾
Strongly Correlated Electrons
Probing $d$-wave pairing in the $t$-$t'$-$U$ Hubbard model with tensor-backflow wave functions
Xiao Liang
Building on the recently developed tensor-backflow method, which accurately describes energies and stripe states in the
Fermi-Hubbard model, we investigate $d$-wave pairing in the two-dimensional $t$-$t'$-$U$ Hubbard model. For the $8\times8$
lattice, we improve the wave function using
symmetry projections followed by one Lanczos step, whereas for the $12\times 12$ and $16\times 16$
lattices, we apply one Lanczos step without
symmetry projection. We focus primarily on the parameter regime with filling $n=0.875$, on-site repulsion $U=8$ and next-nearest-neighbor hopping $t'=-0.2t$, a regime in which enhanced $d$-wave pairing has been reported. The resulting energies are competitive with those obtained using state-of-the-art neural
quantum states. For example, on a $16\times 16$
lattice with periodic boundary conditions, the tensor-backflow wave function after one Lanczos step without explicit
symmetry enforcement achieves a relative energy difference of $4.4\times 10^{-3}$ from the
symmetry-preserving neural
quantum state result. From the real space pair correlations, for $t'=-0.2t$, we observe stronger $d$-wave pair correlations together with the characteristic relative sign between horizontal and vertical bond-pair components. Compared with $t'=0$, finite negative $t'$ increases the spectral weight of the corresponding pair-density
matrix, which indicates the enhanced overall $d$-wave pair fluctuations. The leading
eigenvalue is enhanced on the $8\times8$
lattice for both with and without
symmetry projections. For larger
lattices such as $12\times 12$ and $16\times 16$, the leading pair-density
matrix spectral weight is distributed among several nearly degenerate eigenmodes rather than being concentrated in a single dominant mode. This indicates enhanced and more broadly distributed $d$-wave pair fluctuations, but no single
eigenvalue exhibits the extensive scaling required for ODLRO.
Read the full abstract ▾
High Energy Physics (Theory)
Phase Transitions at More Unusual Values of Theta
Dhruv Aldas, Hitoshi Murayama, Bea Noether et al. (+1 more)
We calculate the $\theta$ dependence of the
vacuum energy in an infinite family of cousins of QCD, where the
vacuum structure can be analyzed exactly. These theories are $\mathcal{N}=1$ EFTs that descend from $\mathcal{N}=2$ $SU(N_c)$ gauge theory with $N_f$
flavors of fundamental hypermultiplets, that are then deformed by anomaly mediated supersymmetry breaking (AMSB). We reproduce results found in previous work that used the full $\mathcal{N}=2$ machinery but via a much simpler $\mathcal{N}=1$ method. Our method easily extends to infinitely many more theories for which the full $\mathcal{N}=2$ approach becomes intractable. We identify values of $\theta$ for which the theory undergoes a phase transition, and find that they can occur at both fractional and irrational values of $\theta/\pi$.
Read the full abstract ▾
All authors Dhruv Aldas, Hitoshi Murayama, Bea Noether, Digvijay Roy Varier
Physics and Society
Asymptotic Invariance of Kelly Allocation Under Power-Law Asset Dynamics: Evidence from Bitcoin
Ivan J. Vera-Marun
We examine log-optimal portfolio allocation when the long-run price of an asset follows a power-law trajectory, $P(t)=At^\alpha$, and its instantaneous return variance decays as $\sigma^2(t)=\sigma_0^2 t^{-2\gamma}$. Under a zero risk-free-rate
benchmark, the continuous-time Kelly fraction scales as $K^\ast(t)=(\alpha/\sigma_0^2)t^{2\gamma-1}$. Exact temporal invariance therefore occurs when $\gamma=1/2$, whereas deviations from this value produce systematic age dependence in the allocation. We propose a scaling hypothesis connecting growth in network participation, effective
market liquidity, and declining
volatility. Under a specified set of scaling assumptions, this model predicts the
benchmark exponent $\gamma=1/2$. Using historical daily Bitcoin prices, we estimate the power-law price exponent and examine the sensitivity of the
volatility exponent to the length of the rolling window. For windows of four to nine years, the estimated
volatility exponents have an arithmetic mean of 0.53 and a cross-window standard deviation of approximately 0.03. Because these estimates are obtained from overlapping observations and the same underlying price history, this spread is interpreted as a measure of model sensitivity rather than a formal confidence interval. Finally, we show that a time-dependent multiplicative contribution to return variance generally breaks exact Kelly invariance. We illustrate this result using a scenario in which Bitcoin transaction-fee variability affects the effective variance process. The results identify the conditions under which log-optimal allocation can remain stable under non-stationary power-law asset dynamics and clarify the assumptions required when applying this result to Bitcoin.
Read the full abstract ▾
Materials Science
LiNiO2/NiO Phase Prediction Using Artificial Neural Networks
Jonas Scheunert, Shamail Ahmed, Thomas Demuth et al. (+2 more)
In the realm of material analysis, identifying different material phases is of key importance. Artificial intelligence in the form of neural networks provides a very fast and, once trained, computationally inexpensive method for analysing large amounts of image data, like the sets of diffraction patterns generated during four-dimensional scanning transmission electron microscopy (4DSTEM)
dataset acquisition. In this work, we train multiple network architectures on images of this type to distinguish between the phases of LiNiO2 and NiO, an important and challenging distinction in the lithium-ion battery community, since the formation of NiO limits battery capacity. We test both classical convolutional neural networks (CNNs) and different forms of
vision transformers (ViTs). Our networks are trained on synthetic images and tested on experimentally recorded diffraction patterns. Additionally, we also investigate the decision-making of our networks using the GradCAM method. We test our networks on both synthetic as well as experimental diffraction patterns. Our networks exhibit very robust results, especially when dealing with highly varying data, an area where traditional template-matching methods typically struggle.
Read the full abstract ▾
All authors Jonas Scheunert, Shamail Ahmed, Thomas Demuth, Andreas Beyer, Kerstin Volz
Mathematical Physics
Cohomology of $\mathfrak{psl}(n|n)$ in trivial and in adjoint representations
Thiago Oliveira Ferreira
We compute the
cohomology of the projective special linear Lie superalgebra $\mathfrak{psl}(n|n)$ over a field of characteristic zero in trivial and in adjoint coefficients in full detail through its associated Hochschild–Serre spectral sequences. Applications in physics exist for its real form, the projective special
unitary Lie superalgebra $\mathfrak{psu}(n|n)$ — in particular, $\mathfrak{psu}(2,2|4)$ for AdS/CFT. We also find the
cohomology of $\mathfrak{sl}(m|n)$ in trivial coefficients along the way and we point out a discrepancy with a previous statement in the literature. We present the explicit
cohomology groups of low degree for $n\leqslant4$.
Read the full abstract ▾
Adaptation and Self-Organizing Systems
Deviations from global coupling in adaptive oscillator networks: a mean-field theory for the variance of coupling weights
Richard Gast, Shotaro Takasu, Juergen Kurths et al. (+1 more)
A wide range of physical and biological systems are adaptive networks, in which the dynamics of the nodes and of the edges connecting them co-evolve. Mean-field reductions of such systems typically track only the average coupling strength, and therefore cannot determine when the coupling stays effectively homogeneous and when structured connectivity emerges. Here, we present a second-order moment closure that allows us to derive mean-field equations for the coupling-weight variance in networks of heterogeneous phase oscillators with adaptive coupling, starting from uniform coupling weights. In agreement with network simulations, we find a nonlinear, non-monotonic dependence of the relative weight variance on the oscillator heterogeneity that is mediated by the phase coherence. Moreover, we find that deviations from global coupling strongly depend on an interaction between the oscillator heterogeneity and the adaptation rule. Whereas symmetric adaptation causes a strongly coupled core of coherent oscillators to emerge and creates a bistable regime that is absent without adaptation, antisymmetric adaptation leads to antisymmetric coupling within the same core, thereby destabilizing it. Our equations therefore delineate the regimes in which adaptive networks behave like globally coupled systems from those in which more complex coupling patterns form.
Read the full abstract ▾
All authors Richard Gast, Shotaro Takasu, Juergen Kurths, Ann Kennedy