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Physics

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Thursday 20 August

High Energy Physics (Phenomenology)

A Hydrogen-Like Model for Pion and Kaon Masses Based on Dirac Quark-Hamiltonians and Numerical Methods

Zhenhua Ning, A. S. Davuluru, H. Raposo et al. (+1 more)

We consider a relativistic hydrogen-like model for meson mass spectra. The model is based on a Lagrangian with a new general Yang-Mills symmetry. The strong interactions involve a fourth-order field equation that generates a linear confining potential. Notably, this model for meson masses requires quarks to carry only a single `confining charge' $f_c$ rather than three color charges. We classify meson mass spectra into sub-spectra defined by isospin, G-parity, total angular momentum and parity. By applying a numerical solver to the Dirac Hamiltonians–incorporating two short-range confining potentials, we obtain energy eigenvalues in natural units. The model has three coupling constants and one parameter. It provides a robust fit of 31 pions and kaons masses (from $\approx 140 MeV$ to $\approx 2,300 MeV$) to within $\approx 18\%$ of relative percentage error. The model suggests that the confining charge $f_c$=0.045/MeV = 8.87 fm plays the role of the basic length in the quark interactions.
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All authors Zhenhua Ning, A. S. Davuluru, H. Raposo, Jong-Ping Hsu

General Physics

Coherent Oscillations of Protons in Hydrogen-loaded Metals

G. Modanese

We review recent calculations and numerical simulations showing the formation of coherent states of protons in hydrogen-loaded metals with a cubic crystal lattice. In these states protons oscillate coherently at frequencies of the order of $10^{13}\,\mathrm{Hz}$ and in a fixed phase relation with a strong high-frequency electric field which is trapped in the material, especially if the material is made of micro-powders. The energy gap of the coherent ground state is estimated to be well above thermal energies, of the order of a fraction of an eV per particle, and therefore large enough to make the state robust against thermal fluctuations. The analytical calculations address the realistic case of a large number of protons, in the rotating-wave approximation. The numerical calculations are presently limited to a small number of protons but go beyond the rotating-wave approximation and allow one to take into account a dissipation term associated with the strong oscillating electric field. The next task of this theoretical model is to compute the excited states of the coherent system. There are strong indications that in those states protons can be excited by an external pump to energies much larger than those achievable by single incoherent protons in condensed matter. Such energies are large enough to make possible some electron-capture processes, with generation of slow neutrons. This dynamical mechanism offers an alternative to the Widom–Larsen hypothesis of “heavy electrons”, and is closer to current models in mainstream physics. The consequences, in terms of nuclear transmutations, of neutron generation via electron capture would be similar to those predicted by Widom and Larsen, plus several other processes like those recently re-examined by Metzler et al.
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Statistical Mechanics

Power Series for the Quantum Statistical Mechanics Probability with Results for the Second Virial Coefficient of Helium

Phil Attard

A power series for the Wigner-Kirkwood pair commutation function for quantum statistical mechanics in classical phase space is given with terms automatically generated by recursion. The calculated second virial coefficient agrees with the measured values of helium for temperatures greater than 65 K. Prospects for a general quantum Monte Carlo algorithm are discussed.
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Disordered Systems and Neural Networks

Aging Phase Diagram and Exact Asymptotic Energies of Mixed Spherical Spin Glasses

Johannes Lang, Vincenzo Citro, Luca Leuzzi et al. (+1 more)

We determine the aging phase diagram of mixed spherical $(p+s)$-spin glasses quenched from random configurations to zero temperature. Solving the asymptotic dynamical equations of Cugliandolo and Kurchan, we find transitions between aging states with one, two, and continuously many effective temperatures, including phases in which discrete and continuous hierarchies coexist. We obtain analytic expressions for the energies reached asymptotically by the dynamics. In models combining pairwise and higher-order interactions, and sufficiently separated interaction orders ($s>3$), a fully continuous phase exists, where the gradient descent relaxation converges to the algorithmic energy lower bound. Instead, in mixed models with only high-order interactions ($p\ge3$) the energy relaxation remains strictly above it. Numerical integration of the dynamical equations is consistent with the predicted two-step and mixed discrete–continuous aging states.
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All authors Johannes Lang, Vincenzo Citro, Luca Leuzzi, Federico Ricci-Tersenghi

Optics

Sidewall-Poled Nanophotonic Lithium Niobate with Bidirectional Characterization

Aditya Tripathi, Michael S. Bullock, Parash Thapalia et al. (+10 more)

Accurate characterization of integrated nonlinear photonic devices is often limited by unknown facet-coupling losses and fabrication-induced non-uniformities, leading to systematic over- or underestimation of the intrinsic on-chip performance. Here, we present and demonstrate a unified bidirectional characterization framework that exploits nonlinear interactions under forward and backward propagation to independently extract facet-specific coupling efficiencies, intrinsic nonlinear conversion efficiency, and the longitudinal quasi-phase-matching profile using only classical power measurements. We experimentally validate the method using sidewall-poled thin-film lithium niobate waveguides, obtaining a normalized second-harmonic generation efficiency of $(1850 \pm 20)~\%\mathrm{W}^{-1}$ while simultaneously demonstrating broadband non-degenerate optical parametric amplification and parametric generation spanning more than $10~\mathrm{THz}$. Our framework is non-destructive, relies solely on classical power measurements, requires neither time-intensive microscopy nor calibrated internal references, and is compatible with wafer-scale testing, providing a general route to rigorous benchmarking and high-throughput characterization of photonic devices across material platforms.
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All authors Aditya Tripathi, Michael S. Bullock, Parash Thapalia, Pooja Kulkarni, Jaber Balalhabashi, Robert Kwolek, Shiva Behzadfar, Kazuki Hirota, Shion Eto, Rintaro Tsuchida, Liam Beaudoin, Sasan Fathpour, Rajveer Nehra

Solar and Stellar Astrophysics

Statistical Analysis of Minifilament Eruptions Using Full-disk H$\alpha$ Blue-wing Observations at Big Bear Solar Observatory

Artin Khaleghi, Qin Li, Nengyi Huang et al. (+2 more)

This paper presents a comprehensive statistical analysis of minifilament eruptions (MFEs) using high-cadence full-disk H$\alpha$ blue-wing observations from Big Bear Solar Observatory. Despite the recognized importance of MFEs for coronal dynamics and solar wind structuring, previous efforts were often limited by small sample sizes or restricted fields of view, leaving open questions about their global occurrence and characteristic properties. We developed an algorithm incorporating intensity thresholding and temporal tracking to detect sudden enhancements in H$\alpha$ blue-wing images. A total of 1986 such events were identified during a 4 hr period on 2020 June 9. These detections were cross-validated using H$\alpha$ line-center observations to confirm the presence of associated filament structures. The analysis yields an occurrence rate of $\sim$6.6$\times 10^4$ per day, an average length of $\sim$17 Mm, and a typical lifetime of $\sim$21 minutes. A power-law distribution in eruption lengths (with slope $\sim$-4.8) and a sublinear scaling between duration and length suggest that larger eruptions tend to last longer. The length distribution of MFEs was further analyzed relative to active region proximity, revealing that eruptions occurring nearby a sunspot region were, on average, larger than the global mean eruption length. Additionally, an eruption density map was used to analyze the spatial distribution of MFEs relative to coronal hole boundaries. The results indicate a mild suppression of activity inside coronal holes and intermediate eruption frequency in the boundary regions. We briefly discuss their potential role in structuring the small-scale solar wind features such as magnetic switchbacks and small-scale magnetic flux ropes.
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All authors Artin Khaleghi, Qin Li, Nengyi Huang, Jeongwoo Lee, Haimin Wang

Astrophysics of Galaxies

Mapping the z>=5 SiIV Column Density Distribution onto the Galaxy Stellar Mass Function Using the Cumulative Absorption Cross Section

Kristian Finlator, Sam Patterson, Nora Nava et al. (+4 more)

Efforts to constrain directly the activity in low-mass galaxies confront sensitivity limits even in the JWST era. Metal absorbers offer a complementary probe and are easier to detect, but leveraging them requires a known relationship between absorber strength and host mass. To this end, many studies assume a simple monotonic relationship between absorber strength and host mass. This ansatz ignores evidence that galaxies at fixed luminosity host absorbers spanning a variety of strengths. We address this issue by deriving a six-parameter model for the cumulative absorption cross section from cosmological simulations that combines with the galaxy stellar mass function to predict the absorber column density distribution (CDD). A maximum-likelihood analysis confirms that this approach reconciles the observed galaxy stellar mass function with the observed SiIV CDD at z=5-6. The extrapolated CDD grows uncertain outside the observed range and the resulting constraints contain degeneracies, highlighting the need for improved measurements. Galaxies of all masses host absorbers of all strengths, but a weak empirical association between massive galaxies and strong absorbers is indicated. Faint galaxies (M* < 10^8 Msun) host the majority of weak SiIV absorbers (log N < 13), emphasizing emission/absorber complementarity. The assumption of a power-law relationship between absorbers' geometric cross sections and host galaxy masses is empirically disfavored. The model may be applied to any combination of ion and redshift if the galaxy stellar mass function is well-constrained. Future observational tests incorporating improved host statistics will extend the model's range.
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All authors Kristian Finlator, Sam Patterson, Nora Nava, Ayanah Cason, Samir Kušmić, Ezra Huscher, Farhanul Hasan

Strongly Correlated Electrons

Note on proliferation transitions of non-Abelian anyons

Meng Cheng

We study phase transitions out of a (2+1)d topological phase driven by the proliferation of anyons in a braided fusion subcategory. We describe a general theoretical framework for such transitions, in which the topological quantum field theory (TQFT) is coupled to dynamical matter associated with anyons in the subcategory. We interpret this construction using symmetry topological field theory (SymTFT), where the dynamics is localized on the symmetry boundary of the (3+1)d slab. We analyze several examples, and present explicit Chern-Simons-Higgs (CSH) field theories realizing the proliferation transitions. We also examine proliferation transitions that implement gauging of non-invertible one-form symmetry in the parent TQFT. This includes a general construction for ${\rm Rep}(G)$ one-form symmetry for a finite group $G$, and a CSH realization of the non-invertible one-form gauging ${\rm SU}(2)_{10}\rightarrow {\rm Spin}(5)_1$. We discuss which anyons proliferate at these transitions.
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Quantum Physics

Scaling Behavior of Parameterized Quantum Circuits from a Lie-Algebraic Perspective

Hiroshi Ohno

Understanding how the performance of parameterized quantum circuits scales with available resources is important for characterizing their trainability and effective model capacity. In this study, we numerically investigate data scaling, model scaling, and compute scaling in parameterized quantum circuits and examine Lie-algebraic quantities as alternative measures of model size. In addition to the number of circuit parameters, we consider the dimension of the dynamical Lie algebra, the observable-orbit dimension, and a Jacobian effective dimension defined as the rank of the Jacobian of the parameterized observable orbit. Using a regression task with randomly generated Pauli-string generators, we observe decreasing loss with increasing training dataset size, parameter size, and number of optimization iterations over the ranges investigated. For model scaling, the dynamical Lie algebra and observable orbit dimensions rapidly saturate as the parameter size increases, whereas the Jacobian effective dimension remains strongly correlated with the parameter size and exhibits comparable scaling behavior. These results suggest that the Jacobian effective dimension provides a geometry-aware measure of the locally accessible observable degrees of freedom of finite-depth parameterized quantum circuits and may serve as a useful scaling parameter beyond the nominal parameter size.
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High Energy Physics (Theory)

From Gross-Manes to Alday-Maldacena

Leonardo Pipolo de Gioia, Sabrina Pasterski and Pedro Vieira

Minimal surfaces govern the classical limit of several important observables in string theory. Two basic examples are the Gross–Manes saddle for high-energy string scattering in flat space and the Alday–Maldacena surface for gluon scattering at strong coupling in ${\cal N}=4$ SYM. In this paper we study a family of null polygonal minimal surfaces in AdS interpolating between these two regimes by moving the cusps from a small region deep in the bulk to the AdS boundary. We do this both numerically and – in interesting simplifying limits – analytically. In particular, we derive the leading AdS-radius correction around flat space and show that the resulting classical amplitude agrees with the recent prediction of Alday, Armanini, Häring, and Zhiboedov, supporting an underlying worldsheet description of their bootstrap construction.
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Materials Science

Machine Learning Guided Discovery of Corundum High Entropy Oxides

Abraham A. Mancilla, Oliver A. Dicks, Solveig S. Aamlid et al. (+5 more)

Early thinking in the field of high entropy oxides (HEOs) emphasized their likely abundance, with combinatorial arguments hinting at a myriad of new materials. The experimental reality has proven more challenging: the stability of HEOs cannot be straightforwardly predicted based on ionic radii, lattice geometry, and charge-balancing considerations alone. In this work, we employ machine learning interatomic potentials (MLIPs) to predict the synthesizability of HEOs of the form $A_2$O$_3$ derived from a selection of trivalent cations. From nearly 500 possible compositions, we identify 16 promising candidates for experimental validation with solid-state and combustion synthesis. We discover three new HEOs in the corundum structure, including (Al,Cr,Fe,Rh,Sc)$_2$O$_3$, and one novel cation-ordered phase, (Al,Fe,Ga,Sc)$_2$O$_3$. By far the most common synthesis outcome was a mixture of competing phases, sometimes involving redox reactions. Our results also reveal profound synthesis method dependence for the final product, where qualitatively equivalent outcomes between the two synthesis methods were only observed for 3 of the 16 tested compositions. We conclude that the occurrence rate of HEOs is far rarer than initially believed and that machine learning approaches can effectively guide us to the "needle in the haystack".
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All authors Abraham A. Mancilla, Oliver A. Dicks, Solveig S. Aamlid, Mario Ulises González-Rivas, Karl Tsang, Dongjoon Song, Jörg Rottler, Alannah M. Hallas

General Relativity and Quantum Cosmology

Causal Gravitational-Wave Production Does Not Generate Infrared Adiabatic Curvature

Ruth Durrer and Alessandro Melchiorri

Short tensor modes can generate a white noise contribution to the local scalar $K=8\pi G\rho/3-\theta^2/9$, but this does not induce an infrared-enhanced adiabatic curvature spectrum. For a conserved causal source, analyticity of the longitudinal velocity correlator requires $P_V=\mathcal O(k^2)$, hence $P_{\mathcal R}=\mathcal O(k^0)$ and $\Delta_{\mathcal R}^2=\mathcal O(k^3)$, excluding the $\Delta_{\mathcal R}^2\propto k^{-1}$ relic. We also construct a conserved conversion of radiation into gravitational waves: the white field resides in a compensated entropy mode, and the fluid response cancels the slowly decaying $a^{-2}$ relic. Adiabatic bounds on such sources are therefore source- and matching-dependent.
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Quantum Physics

Clifford-efficient sparse state preparation for molecular wavefunctions

Yingrong Chen, Nathan A. Baker, Rushi Gong et al. (+7 more)

Sparse quantum state preparation concerns an $n$-qubit target state that is a superposition of only $d \ll 2^n$ computational basis states. Existing approaches exploit this sparsity by compressing these $d$ basis states and their amplitudes onto a smaller set of qubits, called the dense register, before expanding the prepared state to the full register. Rather than relying on the permutation-based compression used in prior work, we exploit affine relationships among the binary configurations over the finite field $\operatorname{GF}(2)$ to reduce both the non-Clifford gate count and the ancillary qubit count. Invertible affine transformations over $\operatorname{GF}(2)$, comprising Gaussian elimination and all-ones-row removal, first reduce the dense register from $n$ to the rank $r$ using only Clifford gates and no ancillary qubits. An optional binary encoding stage then trades additional Toffoli gates and ancillary qubits for further compression to the minimum $\lceil\log_2 d\rceil$ dense qubits needed to represent $d$ distinct configurations. For chemically relevant wavefunctions, such as those obtained from selected configuration interaction calculations, shared electronic excitation patterns produce many of these affine relationships, enabling substantial Clifford-only compression before binary encoding. Across the molecular benchmarks, our method requires the fewest ancillary qubits among the evaluated sparse state preparation methods while maintaining comparable non-Clifford gate counts when using binary encoding.
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All authors Yingrong Chen, Nathan A. Baker, Rushi Gong, Conrad S.N. Johnston, Brad Lackey, Hongbin Liu, Sasha Schmidt, Yuan Su, David B. Williams-Young, Yinuo Yang

Computational Physics · Cross-listed from q-fin.CP

Calibrating Inelastic Markets to Options: The Lean Marketron and the Generalized Langevin Equation

Andrey Itkin

The Marketron model of \cite{HalperinItkin2025Mark} and its option pricing extension in \cite{HalperinItkinMarketron2} suffer from structural non-identifiability: an eighteen-parameter space traps solvers in suboptimal local minima and renders economic quantities unmeasurable. By removing exact scaling gauges and sign symmetries, freezing non-financial parameters by explicit criteria, and adiabatically eliminating the fast hidden signal, we derive a robust nine-parameter reduced model. A Gauss-Newton Hessian with empty null space and a manifold-boundary analysis confirm that the reduced core carries no exact symmetry and admits no further reduction. A diffusive correlation between flow and return innovations captures the short-maturity skew. A staged calibration from the physical measure to the risk-neutral measure, illustrated on SPX options, fits the whole surface with a single parameter set. The same reduction turns the wedge between the physical and pricing values of the flow block into a well-defined market price of flow risk rather than a ridge artifact, identifiable here for the first time, though a single surface constrains its level only weakly. Finally, our analysis reveals that in the Marketron model the log-price obeys a generalized Langevin equation with a closed-form, state-modulated memory kernel, and that the memory variable itself is the exact Markovian lift of this kernel. This mapping also yields a testable condition, the equality of the signal and memory relaxation rates, which on the SPX surface come out well separated, though both weakly identified, placing the fitted market tentatively in the driven, non-equilibrium regime and turning the active-matter reading from an analogy into a falsifiable constraint.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.PL

Portability of Fortran's 'do concurrent' on GPUs II

Ronald M. Caplan, Miko M. Stulajter, Jon A. Linker et al. (+6 more)

There continues to be growing interest in using standard language constructs for parallel and accelerated HPC computing, avoiding the need for (sometimes vendor-specific) external APIs. For Fortran applications, language features such as 'do concurrent' loops open the door for compilers to implement multi-threaded, GPU-accelerated, and even distributed multi-node code with only the standard language. Here, we explore the current status of using 'do concurrent' for GPU-accelerated Fortran applications across three major GPU vendors (NVIDIA, AMD, and Intel). Using a production application, we test their current capabilities, showing where the standard language alone can be used, and where augmenting the code with a directive-based API (e.g., OpenMP) is still desirable or required. Multi-GPU tests are performed with GPU-aware MPI libraries. We find that the three GPU vendors can now GPU-accelerate pure Fortran (zero directives), but that manual data movement directives can help with performance and compatibility. The results show that there is rapid advancement towards making GPU-accelerated scientific HPC code performance portable using the Fortran standard language.
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All authors Ronald M. Caplan, Miko M. Stulajter, Jon A. Linker, Jeff Larkin, Nikolaos Tselepidis, Harald Servat, Shiquan Su, Giacomo Capodaglio, Johanna Potyka

Nuclear Experiment

Multi-Differential DVCS Cross Section Measurement on the Proton in the Valence Region with CLAS12

S. Lee, T.B. Hayward, L. Elouadrhiri et al. (+138 more)

We report the measurement of the four-fold differential cross section of deeply virtual Compton scattering (DVCS) on the proton using a longitudinally polarized 10.6 GeV CEBAF electron beam incident on a liquid-hydrogen target with the CLAS12 detector. The analysis provides 1312 data points, expanding the measured phase space in the valence quark region, 0.06 < $x_B$ < 0.58, 1.00 < $Q^2$ < 5.76 GeV$^2$, and 0.11 < $|t|$ < 1.00 GeV$^2$. DVCS cross section measurements directly constrain the real part of the DVCS amplitude through its interference with the Bethe-Heitler process, making them essential inputs to global extractions of the Compton Form Factors (CFFs), particularly the dominant CFF $H$. These data improve sensitivity to these observables and can contribute to future determinations of the proton's internal mechanical structure.
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All authors S. Lee, T.B. Hayward, L. Elouadrhiri, R.G. Milner, P. Achenbach, J. S. Alvarado, M.J. Amaryan, W.R. Armstrong, H. Avakian, N.A. Baltzell, M. Bashkanov, M. Battaglieri, F. Benmokhtar, A. Bianconi, A.S. Biselli, M. Bondi, S. Boiarinov, F. Bossù, K.-Th. Brinkmann, W.J. Briscoe, N. L. Bucuru Rodriguez, S. Bueltmann, V.D. Burkert, T. Cao, D.S. Carman, A. Celentano, P. Chatagnon, V. Chesnokov, H. Chinchay, G. Ciullo, E.W. Cline, P.L. Cole, M. Contalbrigo, A. D'Angelo, N. Dashyan, R. De Vita, S. Diehl, C. Dilks, C. Djalali, R. Dupre, H. Egiyan, M. Ehrhart, A. El Alaoui, L. El Fassi, C. Fanelli, M. Farooq, S. Fegan, I. P. Fernando, E. Ferrand, A. Filippi, C. Fogler, S. Frantzen, K. Gates, D.I. Glazier, R.W. Gothe, Y. Gotra, B. Gualtieri, K. Hafidi, H. Hakobyan, D. Heddle, M. Hoballah, D. Holmberg, M. Holtrop, Y. Ilieva, D.G. Ireland, E.L. Isupov, H.S. Jo, S. Joosten, M. Kerr, A. Kim, V. Klimenko, I. Korover, A. Kripko, V. Kubarovsky, S.E. Kuhn, C. Lama, L. Lanza, P. Lenisa, X. Li, D. Martiryan, V. Mascagna, B. McKinnon, A. Mehta, Z.E. Meziani, R. Milton, M. Mirazita, V. Mokeev, E. F. Molina Cardenas, P. Moran, S. Muduganti, C. Munoz Camacho, P. Nadel-Turonski, T. Nagorna, K. Neupane, G. Niculescu, M. Osipenko, P. Pandey, M. Paolone, L.L. Pappalardo, R. Paremuzyan, E. Pasyuk, C. Paudel, S.J. Paul, W. Phelps, N. Pilleux, L. Polizzi, J. Poudel, Y. Prok, A. Radic, K. Ramage, M. Ripani, M. Ronayette, P. Rossi, A.A. Rusova, S. Schadmand, A. Schmidt, Y.G. Sharabian, E.V. Shirokov, S. Shrestha, E. Sidoretti, B. Singh, N. Sparveris, S. Stepanyan, I.I. Strakovsky, S. Strauch, J.A. Tan, M. Tenorio, F. Touchte Codjo, R. Tyson, M. Ungaro, D.W. Upton, S. Vallarino, C. Velasquez, L. Venturelli, H. Voskanyan, Y. Wang, U. Weerasinghe, X. Wei, N. Wuerfel, Z. Xu, M. Zurek

Fluid Dynamics

Wind farms as sensor arrays of turbulent boundary layer spatio-temporal flow structure

Manuel Ayala, Dennice Gayme and Charles Meneveau

Temporal fluctuations of wind farm-generated power arise from the interaction between atmospheric turbulence, turbine properties, and wind-farm layout. However, accurately characterizing these fluctuations remains an open challenge. We here present and extend an analytical framework to predict the temporal spectrum of wind farm power-fluctuations, and compare its predictions with detailed large-eddy-simulations (LES) of a wind farm operating within a conventionally neutral boundary layer. The modeling framework assembles several established concepts from turbulent boundary layer physics: a spatio-temporal turbulence spectral model accounting for mean advection and assuming random sweeping by large eddies, a top-down wind farm model of a fully developed wind turbine array boundary layer flow providing the required mean-flow and turbulence scales, and a spatial sampling kernel representing turbine positions and finite rotor size. The latter is extended to three dimensions to represent filtering of spatial fluctuations of turbulence along the vertical direction. Using only atmospheric, turbine, and layout parameters, the model predictions are evaluated against an extensive LES database of a large wind farm on flat terrain. The model accurately predicts the aggregate power frequency spectrum, including peaks associated with advection between turbine rows, the decay of inertial-range turbulence fluctuations due to rotor averaging, and spectra of aggregate power signals from various arrangements of groups of turbines within the array (e.g. staggered or random subsets). The ability to predict wind power fluctuation spectra from fundamental fluid dynamics and existing boundary layer turbulence models could help improve wind farm grid integration.
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General Relativity and Quantum Cosmology

Perturbative vacuum constraints in higher-curvature gravity: Schwarzschild deformations and strong-field observables

Gustavo Melgarejo, Daniel Molano and Jonathan Ramírez

Higher-curvature terms modify the action but do not necessarily generate new vacuum geometries on the branch perturbatively connected to GR. We develop a first-order framework for static, spherical vacuum black holes in 4D metric theories with $\mathcal L_{\mathrm{grav}}=R/2+\lambda\Psi(R,X,Y)$, $X=R_{\mu\nu}R^{\mu\nu}$, and $Y=R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma}$. On the coupling-analytic branch, purely Ricci-based terms $\Psi(R,X)$, analytic in curvature with $\Psi(0,0)=0$, do not deform a Ricci-flat background under adopted regularity and boundary assumptions. Riemann-dependent terms can, since Kretschmann scalar is nonzero. In areal-radius gauge, we derive model-independent first-order expressions for the horizon shift, ISCO, epicyclic frequencies, periapsis advance, photon sphere, critical shadow impact parameter, Wald entropy, and Hawking temperature. For $\Psi_\eta=\ell_\lambda^{-2+4\eta}\mathcal G^\eta$, treating noninteger powers as phenomenological parametrizations of nonlinear curvature, we obtain a closed first-order Schwarzschild-connected solution. Perturbations decay for $\eta>1/2$, while fixed-ADM interpretation requires $\eta>2/3$; at $\eta=2/3$, sourced $1/r$ term mixes with asymptotic mass mode. For positive effective coupling, the horizon, ISCO, photon sphere, and critical shadow impact parameter increase for $2/3<\eta<1$ and decrease for $\eta>1$. On the fixed-ADM branch, mass, Wald entropy, and Hawking temperature satisfy $dM=T_H,dS_{\rm W}$ to first order at fixed couplings. At $\eta=1$, the linear 4D Gauss–Bonnet term leaves local geometry and geodesic observables unchanged but adds a constant topological entropy shift. Finally, an Event Horizon Telescope-inspired shadow-size criterion gives a conservative first-order sensitivity estimate for the effective dimensionless coupling, a geometric consistency test rather than a complete observational constraint.
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Quantum Physics

Nonlinear Diamagnetic Interactions in Ultrastrongly Coupled 2D Electrons

Dasom Kim, Kiran M. Kulkarni, Vaibhav Sharma et al. (+15 more)

The quantum Hopfield model is widely used to describe ultrastrong light–matter coupling between cavity photons and collective bosonic excitations in solids, where the diamagnetic interaction is conventionally assumed to be a constant. We experimentally demonstrate that the diamagnetic response of Landau polaritons is reduced under strong terahertz field excitation. We show that this behavior originates from field-driven redistribution of electrons into the nonparabolic regime of the conduction band of GaAs, which reduces the plasma frequency and consequently the diamagnetic interaction strength. A microscopic hot-electron model reproduces the observed nonlinear response. Motivated by this microscopic picture, we propose a nonlinear extension of the Hopfield model with a Kerr-like interaction. Our results establish a route toward nonlinear cavity quantum electrodynamics and driven ultrastrong light–matter coupling beyond the conventional linear Hopfield description, which is capable of creating uniquely quantum optical effects such as squeezed light generation.
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All authors Dasom Kim, Kiran M. Kulkarni, Vaibhav Sharma, Dukhyung Lee, Geon Lee, Sunghwan Kim, Jonas Grumm, Shuang Liang, Hongjing Xu, Fuyang Tay, Andrey Baydin, Motoaki Bamba, Andreas Knorr, Christopher J. Stanton, Michael J. Manfra, Minah Seo, Stephen Hughes, Junichiro Kono

Optics

Impact of Plasmonic Modes and Thermophysical Properties on the Double-Pulse Structuring of Highly-Ordered LIPSS for Biosensing Applications

G.D. Tsibidis, F. Fraggelakis, P. Lingos et al. (+5 more)

The fabrication of highly ordered laser-induced periodic surface structures (LIPSS) on thin metallic films is dictated, predomaninatly, by a synergy of periodic electromagnetic energy deposition and complex fluid dynamics. In this work, we present a combined experimental and theoretical study on the formation of ultra-regular LIPSS on 32-nm-thick Au films using a double-pulse femtosecond laser scheme. We demonstrate that for thin films, the excitation of coupled Surface Plasmon Polaritons (SPPs) at both interfaces dictates the initial energy distribution. On the othe hand, the final morphology is greatly influenced by hydrodynamical processes. Interestingly, due to the low electron-phonon coupling of Au and the high thermal confinement of the thin film, single-pulse irradiation leads to uncontrolled hydrodynamic instabilities a non uniform topographies. Thus, we demonstrate that a double-pulse approach with an optimized interpulse delay ({\Delta}{\tau}=1.2 ns) effectively controls the melt duration and viscosity, suppressing complex fluid motion and promoting the growth of highly ordered arrays. These structures support narrow surface lattice resonances (SLRs) suitable for high-sensitivity plasmonic biosensing.
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All authors G.D. Tsibidis, F. Fraggelakis, P. Lingos, E. Cusworth, V.G. Kravets, A.N. Grigorenko, A.V. Kabashin, E. Stratakis

Materials Science

AutoMOOSE: Use Case and Logical Views of Agentic Phase-Field Simulation Software

Sukriti Manna, Henry Chan and Subramanian Sankaranarayanan

AutoMOOSE is an agentic software framework that converts a natural-language request into an executed, screened, and interpreted MOOSE phase-field simulation. Here, we deploy AutoMOOSE as a agentic software, complementing our prior work which focused on development of the agentic tool. We describe our software framework and architecture through Use Case and logical views of the 1+5 architectural-views model, covering its user roles, component structure, six-agent pipeline, physics plugin layer, Model Context Protocol interface, and screening/falsification/recovery loop. Our architecture separates physical falsification from automatic repair, so corrected simulations remain inspectable and must be re-admitted before acceptance. We focus on software design, extensibility, interoperability, and reuse of the AutoMoose framework for broad utilization in multiphysics materials design problems.
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Fluid Dynamics

Actuator Disk Models reproduce Actuator Line Model power and thrust fluctuation statistics in wind farm simulations

Manuel Ayala, Dennice Gayme and Charles Meneveau

Actuator-disk models (ADM) are widely used in wind-farm simulations, but their accuracy in reproducing power and thrust temporal fluctuation statistics has not yet been compared to the more accurate and detailed predictions of actuator-line models (ALM). This work provides a detailed comparison of such model predictions under three distinct atmospheric conditions. Data is obtained from a database (JHTDB-Wind) containing actuator-line turbine-response and time-resolved flow field data from a large-eddy simulation of a small windfarm operating over a full diurnal cycle. Power and thrust time series corresponding to ADM are constructed from disk-averaged velocity signals and compared with the corresponding more detailed actuator-line signals over three temporal windows within the diurnal cycle. The analysis compares time series, power spectral densities, and both the fluctuation and increment probability density distributions. The results show that the ADM time-series capture the dominant temporal, spectral, and statistical features of the ALM values at resolved and disk-averaged flow-field time scales, i.e. slower than the rotor frequency. Effects of temporal filtering that are often applied to ADM inputs are examined. Overall, the results provide strong support for the use of ADM for predicting power and thrust fluctuation statistics in wind-farm simulations.
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Optics

Beat-spectrum design for 100-km-range optical correlation-domain reflectometry with localized 15-cm resolution

Takaki Kiyozumi, Yuta Higa, Soshi Yoshida et al. (+4 more)

Conventional optical correlation-domain reflectometry (OCDR) based on sinusoidal frequency modulation exhibits a coupling between measurement range and spatial resolution because both are governed by the modulation frequency. Here, we formulate OCDR for arbitrary periodic frequency modulation and relate the modulation waveform to the resulting beat spectrum. By expressing the instantaneous optical frequency as a Fourier series, the beat spectrum is written as successive convolutions of the spectral contributions from the harmonic components. This formulation relates the harmonic composition of the modulation waveform to the spatial response. Periodic pseudo-random modulation (PPRM) was used to test this relation experimentally. We first measured the full-length reflectivity distribution along an approximately 100-km fiber using sinusoidal modulation and then performed PPRM-based random access interrogation near the fiber end. In the local measurement, two closely spaced reflection points were resolved with a correlation-peak width of approximately 15 cm. These results show that beat-spectrum design can reduce the range-resolution coupling of conventional sinusoidal-modulation OCDR and combine long-range surveying with localized high-resolution interrogation.
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All authors Takaki Kiyozumi, Yuta Higa, Soshi Yoshida, Keisuke Motoda, Sze Yun Set, Shinji Yamashita, Yosuke Mizuno

Medical Physics · Cross-listed from eess.IV

Consistency Models for Fast MRI Reconstruction Using Regularization by Denoising

Merve Gülle, Junno Yun, Yaşar Utku Alçalar et al. (+1 more)

Diffusion models (DMs) have emerged as powerful generative priors for MRI reconstruction with promising results. Yet DM-based methods require extensive iterative refinement, limiting their practical deployment. Consistency models (CMs) provide a compelling alternative, aiming to map out the diffusion trajectory in a single pass, enabling faster generation. In this work, we propose CM-RED, a novel MRI reconstruction method that integrates a pretrained CM into the regularization by denoising (RED) scheme. Our method builds on accelerated proximal gradient RED (RED-APG), and further incorporates controlled noise injection during the update steps to enhance generative diversity and accelerate convergence. Extensive experiments on the fastMRI knee and brain datasets demonstrate that CM-RED achieves high-quality reconstructions across multiple anatomies, contrast weights, acceleration factors, and undersampling patterns, using only 4 network function evaluations (NFEs). The proposed method consistently outperforms existing DM- and CM-based approaches in both quantitative metrics and visual fidelity, and exhibits strong robustness to hyperparameter variations, highlighting CM-RED as an efficient and effective generative framework for accelerated MRI reconstruction. The source code and pretrained models are publicly available at https://github.com/MerveGulle/CM-RED.
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All authors Merve Gülle, Junno Yun, Yaşar Utku Alçalar, Mehmet Akçakaya

Mesoscale and Nanoscale Physics

Interband plasmons due to Mexican hat dispersion in two-dimensional materials with inverted bands

Vladimir A. Sablikov

Two-dimensional topological materials with Mexican-hat dispersion exhibit numerous nontrivial features, such as double-valued isoenergetic contours in k-space, strong mixing of electron and hole states, a van Hove singularity in the density of states, and specific quantum geometric properties. We find that, due to these features, Mexican-hat dispersion significantly strengthens interband plasmons, reduces their damping, and gives rise to an additional branch of the plasmon spectrum when electron-hole symmetry is broken. The plasmon spectra are limited to a finite range of the wave vector, the boundaries of which depend on the strength of the electron-electron interaction. We also reveal a relationship between the features of the plasmon spectrum and singularities of the joint density of states with a finite plasmon wave vector q, as well as features of the interband quantum metric, which also depend on q.
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Physics and Society

Exact Scaling Theory of Social Tipping Phenomena in Finite Populations

Bianca Y. S. Ishikawa and José F. Fontanari

Granovetter's threshold model provides a classical framework for social mobilization, where collective action spreads through cascades as individuals join once movement size reaches their personal threshold. Here, we characterize social tipping points-the minimum seed required for global mobilization-using the initial fraction of instigators, $\rho_0$, as a control parameter. For a finite population of size $N$ with Beta-distributed thresholds $(\alpha, \beta)$, we present an exact analytical study of the cascade dynamics. By evaluating the asymptotic active fraction $\rho_\infty$, we map the thermodynamic phase diagram separating partial cascades ($\rho_0 \le \rho_\infty < 1$) from complete mobilization ($\rho_\infty = 1$), revealing continuous and discontinuous transition lines that meet seamlessly at a critical endpoint. For interior-peaked distributions ($\alpha > 1, \beta > 1$), the regimes are separated by a hybrid phase transition combining a first-order discontinuity with second-order bottleneck singularities. Combining exact finite-$N$ combinatorial formulations with large-deviation theory, we establish how finite-size fluctuations smooth these singularities. For power-law thresholds ($\alpha > 1, \beta = 1$), the critical scaling window shrinks as $N^{-1/3}$, while the expected inactive fraction vanishes as $N^{-1/3}$ at criticality. For interior-peaked distributions ($\beta > 1$), the order parameter is bimodally distributed: realizations either achieve full mobilization or stall near a bottleneck $\rho^*$. Excluding fully mobilized trajectories, $\rho^* - \langle \rho_\infty \rangle$ vanishes as $N^{-1/4}$ and the scaling window compresses to $N^{-1/2}$. Together, these results establish an exact finite-size scaling theory for threshold-driven tipping phenomena.
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Mathematical Physics · Cross-listed from math.PR

One-point fluctuations for exponential last passage percolation under upper-tail conditioning

Jinho Baik and Tejaswi Tripathi

We study exponential directed last passage percolation conditioned on the last passage time to a specified macroscopic point being atypically large. We determine the one-point fluctuations throughout two of the three spatial regions arising under this conditioning, as well as on the boundaries between these regions, extending the work of Baik-Cordaro-Tripathi. Depending on the location of the observation point, the limiting fluctuations are governed by the GUE Tracy-Widom distribution, a Gaussian distribution, or the one-spike BBP distribution on the boundaries between these regions. Through the correspondence with tandem queues, our results also describe how an atypically late departure at one customer-station pair affects departure epochs elsewhere in the network.
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Soft Condensed Matter

A molecular perspective on the yield and flow of polymer glasses: The role of enhanced segmental dynamics during active deformation

M.D. Ediger and Kelly Hebert

The mechanical properties of polymer glasses are often critical in determining the best material for a particular application. Extremely stiff materials (high modulus) may be important for some applications while avoiding catastrophic failure due to fracture (high toughness) may be more important for others. The mechanical properties of a polymer glass will depend upon both molecular structure and many experimental variables, including temperature and the mode of deformation (tension, compression, or shear). In this chapter we discuss the mechanical response of polymer glasses from a molecular perspective. In particular, we consider how deformation changes the rate at which polymer segments rearrange and how this in turn influences the mechanical response of the material. It will be shown that this focus on the changes in dynamics provides an understanding of many important features of polymer glass deformation. Of course, it is also true that the structure of a polymer glass must be altered by nonlinear deformation. Although not a major focus, we will make some comments about these structural changes at the end of this chapter.
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Earth and Planetary Astrophysics

JWST Spatial-Spectral Mapping of Green Comet C/2022 E3 (ZTF)

Stefanie N. Milam, Nathan X. Roth, Geronimo L. Villanueva et al. (+9 more)

We report a survey of molecular emission from cometary volatiles using the James Webb Space Telescope (JWST) toward Oort cloud comet C/2022 E3 (ZTF) carried out on UT 2023 February 28 and March 1 at a heliocentric distance (rH) of 1.33 au. These measurements of H2O, HCN, CH3OH, C2H6, CH4, CO, CO2, 13CO2, and OCS sampled post-perihelion molecular chemistry in C/2022 E3. A suite of near to mid-infrared OH (prompt emission) transitions were also detected. This work presents nucleus-centered spectra for all detected species, spatial-spectral maps of column density and rotational temperature as a function of distance from the nucleus for all except C2H6, HCN, and OH, and maps of co-measured continuum. The spatial distributions of both quantities were anisotropic for all mapped molecules; however, H2O showed distributions distinct from the remaining species. Coma-averaged values of the ortho-to-para ratio (OPR) for H2O and the 12CO2/13CO2 ratio derived from these maps were consistent with the statistical equilibrium value of 3 and the terrestrial value of 89, respectively. The modeled mass fraction of the sub-micron dust grains is dominated by amorphous carbon (56%) followed by amorphous Mg:Fe pyroxene (28%), crystalline olivine (10%), and amorphous Mg:Fe olivine (5%) with a crystalline mass fraction of 0.2385(0.0008). We compare the volatile and dust composition of C/2022 E3 (ZTF) against comets measured to date, including those surveyed by JWST.
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All authors Stefanie N. Milam, Nathan X. Roth, Geronimo L. Villanueva, Dominique Bockelee-Morvan, Jacques Crovisier, David E. Harker, Michael S.P. Kelley, Kiernan D. Foster, Ian Wong, Davide Farnocchia, Marco Micheli, Heidi B. Hammel

Soft Condensed Matter

Highly organized smectic-like packing in vapor-deposited glasses of a liquid crystal

Ankit Gujral, Jaritza Gomez, Jing Jiang et al. (+6 more)

Glasses of a model smectic liquid crystal-forming molecule, itraconazole, were prepared by vapor deposition onto substrates with temperatures ranging from Tsubstrate = 0.78 Tg to 1.02 Tg, where Tg = 330 K is the glass transition temperature. The films were characterized using x-ray scattering techniques. For Tsubstrate near and below Tg, glasses with layered smectic-like structures can be prepared and the layer spacing can be tuned by 16% through choice of Tsubstrate. Remarkably, glasses prepared with Tsubstrate above Tg exhibit much higher structural organization than a thermally annealed film. These results are explained by a mechanism based upon preferred molecular orientation and enhanced molecular motion at the free surface, indicating that molecular organization in the glass is independent of the anchoring preferred at the substrate. These results suggest new strategies of optimizing molecular packing within active layers of organic electronic and optoelectronic devices.
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All authors Ankit Gujral, Jaritza Gomez, Jing Jiang, Chengbin Huang, Kathryn A. OHara, Michael F. Toney, Michael L. Chabinyc, Lian Yu, M.D. Ediger