Mathematical Physics · Cross-listed from math.PR
Directed distances in spanning-tree-decorated planar maps: exact exponent, scaling limit and universality
Jacopo Borga, Ewain Gwynne and Yuanzheng Wang
We define a natural orientation on a spanning-tree-decorated planar map whereby, roughly speaking, each directed edge in the map is oriented to match the direction of the contour exploration of the spanning tree. We study directed distances (lengths of shortest directed paths) with respect to this orientation. We construct the Busemann function which measures directed distances to $\infty$ along a natural interface in the uniform infinite spanning-tree-decorated map. We show that this Busemann function, re-scaled appropriately, converges in law to a $3/2$-stable Lévy process. We also show that in a uniform spanning-tree-decorated map with $n$ edges, directed distances are typically of order $n^{1/3}$. Using a strong coupling argument, we deduce analogous statements for directed distances in other random planar maps in the $\sqrt 2$-Liouville
quantum gravity (LQG) universality class, including uniform meandric systems and mated-CRT maps for $\gamma=\sqrt 2$. These results give the scaling dimension for a hypothetical directed version of the $\sqrt 2$-LQG metric. Our proof strategy is inspired by work of Borga and Gwynne (2025) on directed distances in bipolar-oriented triangulations.
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Materials Science
Experiments and Modeling of Defect Dynamics and BTI Behavior in Doped InO TFTs during $400^\circ$C Post-Processing Forming Gas Annealing
Yu-Hsin Kuo, Chengyang Zhang, Priyankka Ravikumar et al. (+13 more)
We investigate the impact of a monolithic three-dimensional (M3D) integration process-critical $400^\circ$C post-processing forming gas anneal (FGA) on the electrical performance, reliability, and defect
evolution of
oxide-channel thin-film transistors (TFTs), combining systematic experiments with density-functional-theory (DFT)-based
liquid-quench molecular-dynamics (MD) simulations. Indium tungsten
oxide (IWO) TFTs are employed as a model system and encapsulated with a thin 3 nm Al$_2$O$_3$ / 3 nm HfO$_2$ hybrid layer that effectively suppresses external hydrogen ingress. We reveal a non-monotonic
evolution of device behavior during FGA, governed by initial densification followed by partial crystallization. Short-duration FGA (10 min) induces channel densification and the formation of shallow, delocalized defect states, leading to pronounced positive bias temperature instability (PBTI) degradation and the emergence of a characteristic transfer-curve "kink." With prolonged annealing (>40 min), partial crystallization of the
oxide channel occurs, stabilizing hydrogen in deep, localized defect states, suppressing hydrogen mobility, and restoring device reliability. As a result, the PBTI shift is reduced to 10.4 mV after 2000 seconds of stress, accompanied by complete elimination of the transfer-curve kink. These findings provide a mechanistic understanding of hydrogen-defect interactions during high-temperature post-processing FGA and demonstrate that appropriate hydrogen-blocking encapsulation enables
oxide-channel TFT integration without compromising electrical performance or reliability.
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All authors Yu-Hsin Kuo, Chengyang Zhang, Priyankka Ravikumar, Sanghyun Kang, Taeyoung Song, Marco Villena, Luca Larcher, Hwan Kim, Minji Hong, Pilsang Yun, Gaurav Thareja, Shimeng Yu, Daewon Ha, Suman Datta, Julia Medvedeva, Asif Khan
Solar and Stellar Astrophysics
Inflated Supermassive Stars as Little Red Dots and Progenitors of Supermassive Black Holes
Wenbin Lu
JWST has uncovered an abundant population of compact, red sources at high
redshifts, termed little red dots (LRDs). We study whether they could be explained by thermally relaxed, hydrogen-burning, metal-enriched supermassive
stars (SMSs). We construct 1D models in hydrostatic and thermal
equilibrium, including a radiation-pressure-dominated, CNO-burning core and an outer envelope with
metallicity-dependent opacity, non-adiabatic convection, and an effective treatment of super-Eddington surface layers. The luminosity is close to the Thomson-scattering Eddington limit. The Fe-opacity bump drives the formation of a strongly inflated, low-mass envelope, while hydrogen recombination terminates the envelope at a bound photosphere. For M=$10^4$ to $10^6$ Msun and metal mass fractions $Z=10^{-4}$ to $10^{-2}$, we find that the most metal-rich models (Z ~ $10^{-2}$) develop highly inflated envelopes and reach Teff ~ 7000 K. We suggest that such enriched SMSs could instead be assembled through runaway
stellar collisions in compact
star clusters. The GR instability sets a maximum mass that depends on the core rotation rate. The nonrotating and rotating models have maximum masses $3\times10^5$ to $3\times 10^6$ Msun, and maximum luminosity of the order $10^{44}$ erg/s, comparable to the observed bright-end cutoff of the LRD luminosity function. Core hydrogen depletion can drive initially stable SMSs across the instability threshold after a lifetime of order 1 Myr. If each LRD leaves a black hole retaining most of its mass, the observed LRD abundance implies a present-day remnant density of order $10^{-2}\rm cMpc^{-3}$, consistent with the local abundance of supermassive black holes. Cool SMSs naturally produce weak X-ray and weak high-ionization lines. Non-LTE effects may significantly modify the Balmer features and the continuum opacity, and may lower Teff below our LTE value.
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High Energy Physics (Theory)
Tripartite Form Universality in Holographic Entropy Inequalities
Veronika E. Hubeny and Yu Liu
To elucidate the meaning of
holographic entropy inequalities (beyond subadditivity) which characterize the
entanglement structure of
geometric states in holography, arXiv:2309.06296 proposed the "tripartite form" for these inequalities, consisting of tripartite information and conditional tripartite information terms with unit coefficients. While this provides a compact and useful packaging of the inequalities, it is not a priori guaranteed that all inequalities can be recast in this form. Here we
conjecture that they can, and present substantial evidence, by proving that the two known infinite families of
holographic entropy inequalities found in arXiv:2309.15145 can indeed be written in the tripartite form. This is significant because such recasting is particularly nontrivial for these families. Apart from providing the explicit tripartite form expressions for every member of these two infinite families, we detail how we arrived at them, in the process deriving several useful identities which may serve as stepping stones to formulate further repackaging of the corresponding information quantities. We also illustrate the power of the tripartite form by proving a number of structural properties satisfied by any
holographic entropy inequality.
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Quantum Physics
Spin-Boson Mappings in the Formalism of $f$-Deformations
Vladimir A. Orlov, Liubov A. Markovich, Andrey V. Mikheyenkov et al. (+1 more)
We develop a unified algebraic approach to
spin-
boson transformations based on the formalism of $f$-deformed oscillators. In the single-mode case, we show that the Holstein-Primakoff and Dyson-Maleev transformations, together with the interpolating $\alpha$-family, arise as different factorizations of the same algebraically determined object. The standard
spin-
boson mappings can thus be interpreted as realizations of a common structure, which makes it possible to clearly separate the exact algebraic content on the physical subspace from effects associated with non-Hermiticity, the choice of metric, and extensions beyond the physical subspace. In the two-mode case, the same approach yields both deformed versions of the Jordan-Schwinger transformation and new exact two-mode realizations. Our results provide a unified description of known
spin-
boson transformations and naturally lead to new bosonic representations.
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All authors Vladimir A. Orlov, Liubov A. Markovich, Andrey V. Mikheyenkov, Vladimir I. Man'ko
Quantum Physics
Gravitationally Induced Entanglement of Matter in Quadratic Curvature Gravity and Constraints on Ghost Mass
Linda M. van Manen, Tim Blankenstein and Anupam Mazumdar
We investigate gravitationally generated
entanglement in two
quantum harmonic oscillators induced by quadratic (Stelle)
gravity, including corrections up to $1.5$ post-Newtonian order. Starting from the quadratic action, we derive the effective two-body
Hamiltonian for two harmonically trapped masses, incorporating the contributions of the massive
spin-$2$ ghost ($m_2$) and massive
spin-$0$ ($m_0$) degrees of freedom of the gravitational field. For two quantised oscillators prepared in their ground state, we compute the von Neumann and Rényi
entropies of the reduced state and identify a frequency at which the gravitationally-induced
entanglement vanishes due to cancellation between relativistic momentum squeezing and
quantum-delocalisation-induced position squeezing. We further analyze the cancellation frequency and derive the approximate constraint $m_0 < \sqrt[3]{4}\, m_2$ for the
spin-$2$ and
spin-$0$ modes. This relation follows from demanding a stable harmonic oscillator description. Finally, we study gravitationally-induced concurrence in a non-Gaussian setup and show how quadratic
gravity modifies the
entanglement generated between two spatial superpositions. The concurrence can approach $\mathcal{O}(1)$ for certain choices of mass, spatial superposition, particle distance, and
spin-$2$ and
spin-$0$ modes. The concurrence will deviate from Newtonian
gravity at certain particle separations, depending on the energy of the
spin-$2$ and
spin-$0$ modes. For example,
spin modes as low as $0.0197$ eV become distinguishable from Newtonian
gravity at a distance $d \sim 40 \mu$m. This allows us to constrain the
spin-$2$ and
spin-$0$ masses in experiments.
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Chaotic Dynamics
Dynamics tuning with reservoir computer control
Krithikesh Ravishankar, Juan G. Restrepo and Per Sebastian Skardal
We present an equation-free method for maintaining a dynamical system operating in a desired regime, even as system parameters are disturbed in such a way that qualitatively different dynamics would emerge. This method allows for real-time identification of changes made to a system's
evolution equations induced by the parameter changes. If the equations governing the original system's dynamics are known, our method can allow one to determine the values of the parameters in real time. We illustrate our method with numerical examples using a reservoir computer control implementation.
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High Energy Physics (Phenomenology)
Heavy-quark spin precession as a magnetic field chronometer
Dushmanta Sahu and Captain R. Singh
The lifetime of the strong
magnetic field generated in relativistic heavy-ion collisions remains one of the major open questions in the study of the
quark–
gluon plasma. We propose heavy-
quark spin precession as a probe to quantify the
magnetic field and its profile in such collisions. We investigate the Larmor
evolution of polarized charm and bottom
quarks propagating through an expanding
quark–
gluon plasma in the presence of the
magnetic field. We show that realistic
magnetic-field strengths and lifetimes generate measurable accumulated precession phases prior to hadronization, leading to characteristic charge-dependent polarization splittings between $\Lambda_c^+$ and $\bar{\Lambda}_c^-$, as well as between $\Lambda_b^0$ and $\bar{\Lambda}_b^0$, through the mixing of transverse and longitudinal polarization components. The predicted signals exhibit distinctive transverse-momentum and
quark-mass dependence, providing complementary sensitivity to the
magnetic-field lifetime in the charm and bottom sectors. Our results suggest heavy-
flavor polarization, especially in the charm sector, as a quantitative probe for the space–time
evolution of
magnetic fields in relativistic heavy-ion collisions.
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Chemical Physics
XC100: A Wavefunction-Derived Exchange-Correlation Energy Dataset for Atomic and Molecular Species
Vaibhav Khanna and Paul M. Zimmerman
A workflow is introduced for constructing accurate, wavefunction-derived Kohn-Sham (KS) exchange-correlation (XC) energies across atomic and molecular species. Correlated total energies and densities are obtained from configuration interaction wave functions in a polarized triple-
zeta basis, cc-pVTZ, and each wavefunction density is then mapped onto a KS determinant. A composite correction adds valence and core basis functions (cc-pVQZ and cc-pCVTZ), plus a two-point Riemann extrapolation to approach the complete-basis-set limit. The workflow is applied to 100 closed-shell atomic and molecular species composed of main group elements to form the XC100 data set. The resulting KS densities closely reproduce the correlated densities, with a median L2/Ne difference of 1.42 X 10^{-5}, while the composite corrections recover substantial correlation energy beyond the cc-pVTZ reference. Comparison with conventional and machine-learned density functional approximations gives insight into the quality of Exc across different types of models for XC. In all, this paper's workflow demonstrates a practical route for generating XC reference data for the assessment and development of density functionals.
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Solar and Stellar Astrophysics
The Last Gasps of a Dying Star: ALMA Observations of the Pre-Planetary Nebula IRAS 06530-0213
Raghvendra Sahai, Wouter Vlemmings, Guillermo Quintana-Lacaci et al. (+16 more)
We present high angular-resolution ($\sim 0.{''}1 - 0.{''}5$) ALMA observations of millimeter-wave line and continuum emission (at $\sim0.44$ and $0.88$ mm) in the pre-planetary nebula IRAS 06530–0213 (IRAS 06530). These data show the presence of an extended circular ring – first evidence of the last thermal-pulse preceding the post-AGB phase in a carbon
star – and a central bipolar nebula (CBN) and
torus. The mass-loss rate of IRAS 06530's AGB progenitor decreased immediately after the thermal pulse, then rose again just before the post-AGB phase as evidenced by the presence of filamentary arc structures around the CBN. The arc stuctures are likely part of a 3-D Archimidean spiral structure generally attributed to the presence of a binary companion. But we do not find a compact continuum source at the location of IRAS 06530's central
star, such as that associated with the compact dusty disks typically found in disk-prominent post-AGB objects known to have binary companions. The expansion ages derived for the
torus and CBN imply that IRAS 06530's progenitor transitioned to a post-AGB
star $\lesssim700$ yr ago. The molecular mass of the ejecta in IRAS 06530 is dominated by the filamentary arc region with a mass $M_{H_2}=(0.12-0.25) M_{\odot}$. Compared with
solar values, the
torus of IRAS 06530 appears to be significantly (modestly) enriched in $^{13}$C and $^{17}$O ($^{15}$N) as well – a pattern of rare-isotope enrichment inconsistent with standard nucleosynthesis models. From the luminosity of IRAS 06530 and the age of its detached shell, while it was still on the AGB, we infer that the mass of IRAS 06530's progenitor was $(1.6-3.4) M_{\odot}$.
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All authors Raghvendra Sahai, Wouter Vlemmings, Guillermo Quintana-Lacaci, Hyosun Kim, Javier Alcolea, Bruce Balick, Eric G. Blackman, Arancha Castro-Carrizo, Orsola de Marco, Joel H. Kastner, Eric Lagadec, Chin-Fei Lee, Miguel Santander-García, Carmen Sánchez Contreras, Toshiya Ueta, Albert A. Zijlstra, Valentin Bujarrabal, Laurence Sabin, Daniel Tafoya
Astrophysics of Galaxies
CECILIA: Using Flexible Photoionization Models to Accurately Measure Abundances without Auroral Lines
Nathalie A. Korhonen Cuestas, Allison L. Strom, Yijia Li et al. (+6 more)
JWST has facilitated the detection of faint, auroral emission lines needed to directly measure the electron temperature and elemental abundances in high-
redshift galaxies. However, such measurements still require substantial observational investment, potentially making self-consistent, population-level studies of direct-method
metallicity scaling relations across multiple epochs of
Cosmic time prohibitively expensive. Photoionization modeling could allow us to measure
metallicity using more routinely-observed emission lines across larger
galaxy samples with shallower spectra. We use $z\sim 2$
galaxies from the CECILIA survey and local
galaxies and H II regions from the LBT $Y_P$ Project to compare abundance measurements made via the $T_e$ method to abundances estimated using the novel photoionization modeling code, Cue. Based on the results, we explore the viability of, biases introduced by, and the best practices for measuring gas-phase
metallicity with photoionization modeling. We show that Cue can be used to accurately measure O/H while remaining agnostic to the ionizing spectrum and that accurate recovery of O/H can be achieved with relatively bright oxygen and sulfur lines, demonstrating that Cue could be used to measure
metallicity in large samples that lack the depth necessary for direct measurements of O/H. However, using sulfur emission lines can also severely bias the results of photoionization modeling in high-
redshift galaxies, where non-
Solar abundance patterns are common. We make recommendations regarding the use of photoionization models to measure
metallicity in local and high-
redshift samples and future developments to photoionization modeling methods.
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All authors Nathalie A. Korhonen Cuestas, Allison L. Strom, Yijia Li, Noah S. J. Rogers, Caroline von Raesfeld, Gwen C. Rudie, Ryan F. Trainor, Menelaos Raptis, Zhuyun Zhuang
High Energy Physics (Phenomenology)
Machine Learning for Invisible Dark Boson Searches at the Electron-Ion Collider
Rojae Mighty and Ankush Reddy Kanuganti
We investigate whether adding $t$, the positive magnitude of the squared
nuclear four-momentum transfer, enables boosted decision trees (BDTs) to improve invisible-dark-
boson selection relative to optimized rectangular cuts at the Electron-Ion
Collider. We model coherent exclusive scalar and vector production at generator level in electron-gold collisions at 18 GeV by 100 GeV per nucleon. Both methods use identical weighted samples, inputs, preselection, and optimization objectives. Using only electron information, the BDT provided no consistent advantage over optimized cuts for signal selection across 11 masses for each
boson type. When both methods also use $t$, the BDT distinguishes signal from background slightly better than optimized cuts at 10 GeV for both
boson types. These results motivate further investigation of machine learning in EIC dark-
boson searches through exclusive processes where $t$ can be reconstructed.
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General Relativity and Quantum Cosmology
Charged particles and fields in bumblebee gravity: Periodic orbits and superradiance
Marco A. A. de Paula, Renan B. Magalhães, V. B. Bezerra et al. (+1 more)
We investigate the dynamics of charged particles and fields in the background of a charged black hole in bumblebee
gravity, aiming to better understand the role played by the Lorentz-violating parameter $l$. We first review the derivation of the charged bumblebee black hole and investigate its main physical and geometrical properties. We then obtain the circular and bound trajectories of charged particles and find that the innermost stable circular orbit increases with $l$. By using a numerical approach, we compute the total absorption cross section for arbitrary values of the scalar wave frequency $\omega$. Since the spacetime is not asymptotically flat, we construct the total absorption cross section by taking into account the modified asymptotic momentum and flux. Analytical approximations are derived in the low- and high-frequency regimes. The low-frequency expression displays a transition velocity that separates two distinct asymptotic branches and generalizes the corresponding Reissner-Nordström result. Our numerical results for the cross section agree with the analytical approximations in their corresponding limits, and the absorption parameter space can be divided into three regions: Unbounded absorption, bounded absorption, and bounded superradiance. In particular, superradiance occurs whenever $\omega<\omega_{c}$, where $\omega_{c}$ is the threshold for superradiance. Moreover, the superradiance amplification decreases as we increase $l$, and charged bumblebee black holes with $l < 0$ lead to greater superradiant scattering than in the Reissner-Nordström case. We also note that although increasing $l$ lowers the potential barrier, it reduces the total absorption cross section because of the geometrical factor $1/(1+l)$ present in the cross section formula.
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All authors Marco A. A. de Paula, Renan B. Magalhães, V. B. Bezerra, A. A. Araújo Filho
High Energy Astrophysical Phenomena
Importance of the Resonant Cosmic-Ray Streaming Instability Upstream of Collisionless Shocks
Bricker Ostler, Benedikt Schroer and Damiano Caprioli
Cosmic rays (CRs) escaping collisionless shocks form a dilute, relativistic population whose current amplifies the upstream
magnetic field, a process widely attributed to the non-resonant (Bell) instability. Solving the dispersion relation for both cold and finite-spread CR distributions, we show that for the maximum-energy escaping population, the resonant mode can outgrow the non-resonant mode. At slower shocks, this dominance persists for broader CR distributions, and sufficient pitch-angle broadening can even stabilize the non-resonant mode while leaving the resonant mode unstable. Relativistic hybrid particle-in-
cell simulations confirm the cold-beam linear theory predictions and, in the nonlinear regime, saturate at $\delta B/B_0 \sim 1$ with significant pitch-angle redistribution. Neglecting the resonant instability thus underestimates
magnetic field growth at the very scale needed to confine the highest-energy escaping CRs.
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Earth and Planetary Astrophysics
Tectonics on early Earth driven by Earth's changing shape during tidal recession of the Moon
Simon J. Lock
Few fragments of Earth's earliest crust have survived, and so this formative period of our
planet's history is shrouded in mystery. To leverage the limited data available, it is important to understand all the processes that could have shaped our young
planet. Here, I explore a previously neglected aspect of early-Earth dynamics: rotation. Earth after the Moon-forming impact was rapidly rotating with its rotation rate slowing significantly during the first tens of millions of years after the impact as the Moon tidally receded. Using planetary structure and
tidal evolution calculations, I show that the initially distorted structure of Earth would likely have led to significant latitudinal variations in primary crustal thickness. Further, the subsequent changes in Earth's shape in response to its slowing rotation rate could have driven extensive tectonic activity and modulated the response of the crust to other forces. There was extension of the crust in polar regions and convergence in the equatorial regions at rates potentially comparable to those forming the Himalayas today in high-angular momentum scenarios. Depending on the rheology of the earliest crust, such motions could have led to burial of hydrated and weathered surface material, extensive volcanism, and degassing of Earth's interior. Phase changes due to increases in internal pressure could have led to delamination of parts of the crust, producing early mantle heterogeneities. Hydrated secondary melting of the crust and the production of evolved magmas could explain the emergence of a diversity of rock types within tens of millions of years of Earth's formation.
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Solar and Stellar Astrophysics
The "Other" Centuries-Long Record of Solar Magnetic Activity Cycles: Lessons From the Stars
Jason T. Wright, Travis S. Metcalfe, Kristof Petrovay et al. (+1 more)
Studies of space
climate and
solar magnetic activity and studies of
stellar dynamos and
magnetic cycles are separated by discipline and by the quality of the data we have to work with: the Sun gives us detailed knowledge of a single
star, while the
stars give us comparatively sparse data across a range of (sometimes poorly known) masses and ages. This review, a collaboration among scientists with expertise in
stellar astronomy, space
climate, and
solar physics, seeks to provide a guide to what the Sun's and
stars'
magnetic activity records can tell us about how
stellar dynamos operate on decadal, millennial, and
stellar-evolutionary timescales. It reviews the historical
Solar sunspot record, terrestrial cosmogenic isotope records, and decades-long chromospheric activity measurements of dozens of sun-like
stars across a range of masses, ages, and
metallicities near the
solar value. Particular emphasis is placed on the Maunder minimum, and the hunt for similar events in the
stellar record, especially the recently discovered grand minimum event ongoing in the
star HD 166620. These records show that
solar-like dynamos are a common feature of Sun-like
stars, and
magnetic grand minimum events akin to the Maunder minimum might be very rare, with only one identified in 3,000
star-years of
magnetic activity records. Together,
solar and
stellar dynamo studies are bringing a still-fuzzy picture into focus in which
stellar magnetic activity weakens as
stars spin down over billions of years towards a critical Rossby number near the
solar value, at which point
stellar cycles begin to be frustrated. These periods of frustration manifest as
magnetic grand minima, and increase in frequency until they become permanent and
stars enter a period of very low and constant
magnetic activity.
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All authors Jason T. Wright, Travis S. Metcalfe, Kristof Petrovay, Hisashi Hayakawa
Materials Science
Revealing epitaxial relationships at Ga$_2$O$_3$ interfaces with p-type oxides
Anna Sacchi, Krishna Acharya, Michelle A. Smeaton et al. (+5 more)
p-type
oxide contact layers such as Cr$_2$O$_3$ and NiO are attracting increasing interest in pn-heterojunctions with n-type monoclinic $\beta$-Ga$_2$O$_3$ for high-power electronic devices and other extreme environment applications. However, scientific understanding of their epitaxial relationships remains incomplete. In this work we investigate the epitaxial relation of Cr$_2$O$_3$ and NiO layers to (001) and ($\bar{2}$01) out-of-plane oriented Ga$_2$O$_3$ substrates. Surprisingly, we find that, for the most commercially relevant (001)-orientation of the Ga$_2$O$_3$ substrate, the epitaxial relationships are Cr$_2$O$_3$ (0001) and NiO (111) $\parallel$ Ga$_2$O$_3$ (101), both at the non-intuitive $\chi$ = 22.5 $^\circ$ angle with respect to the substrate normal. We explain this unusual discovery by the interfacial atomistic bonding dominated by oxygen sublattice equivalence of these Cr$_2$O$_3$ and NiO polar surface orientations to the tilted Ga$_2$O$_3$ (101), rather than Ga$_2$O$_3$ (001) substrate surface planes. Furthermore, we assign the in-plane orientation for Cr$_2$O$_3$ on ($\bar{2}$01)-oriented Ga$_2$O$_3$ as: Cr$_2$O$_3$ $[12\bar{3}0]$ $\parallel$ Ga$_2$O$_3$ $[010]$ with two in-plane rotational domains. Interface modeling confirms the in-plane orientation for Cr$_2$O$_3$/$(\bar{2}01)$ Ga$_2$O$_3$ and shows that strained O-terminated Ga$_2$O$_3$ $(\bar{2}01)$ surfaces have the lowest interfacial energy with Cr$_2$O$_3$ (0001). Beyond establishing the specific epitaxial relationships for Cr$_2$O$_3$ and NiO on Ga$_2$O$_3$, this work provides a systematic methodology for the unambiguous structural characterization of heterointerfaces involving materials with markedly different
crystal symmetries.
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All authors Anna Sacchi, Krishna Acharya, Michelle A. Smeaton, Renae N. Gannon, Vladan Stevanovic, Steven R. Spurgeon, M. Brooks Tellekamp, Andriy Zakutayev
Cosmology and Nongalactic Astrophysics
Stress-testing the spatially flat Universe: nonparametric spatial curvature determination from DESI DR2
Hannah C. Turner, Suhail Dhawan, Sunny Vagnozzi et al. (+2 more)
We present a nonparametric determination of spatial
curvature using only late-time geometrical probes. Under a Gaussian Process smoothness prior, we jointly constrain the dimensionless expansion history and $\Omega_K$, combining three Type Ia
Supernovae (SNeIa) samples with either DESI DR2 line-of-sight
baryon acoustic oscillations (BAO) or
cosmic chronometers (CC) data. From our baseline SNeIa+BAO analyses we find $\Omega_K=0.219^{+0.110}_{-0.111}$, $\Omega_K=0.330^{+0.098}_{-0.150}$ and $\Omega_K=0.260^{+0.124}_{-0.127}$ for the PantheonPlus, DES Dovekie and Union3 SNeIa samples respectively. These nonparametric results mildly favour an open Universe, supporting recent hints in this direction, and improve on the sensitivity of a previous application of the method by up to a factor of $\sim 2.5$. We find consistent constraints combining SNeIa and CC, whereas restricting SNeIa data to the
redshift range covered by BAO somewhat weakens the constraints and shifts the PantheonPlus central value to $\Omega_K<0$. Our results depend only on late-time relative distances and expansion rates, making them insensitive to the absolute distance scale calibration, while relying neither on
Cosmic Microwave Background data nor on a parametric dark energy model.
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All authors Hannah C. Turner, Suhail Dhawan, Sunny Vagnozzi, Alice Townsend, Peter Massey
Computational Physics
TubeLab: Interactive inverse design of wind instrument bores with hard spectral constraints
Carlo Andrea Rozzi and Andrea Ferroni
We present TubeLab, a browser-based acoustic simulator and inverse design tool for wind instrument bores without tone holes. The direct problem is solved by a Transfer
Matrix Method. Inverse design - finding a bore correction that shifts selected resonance frequencies toward specified musical targets - is formulated as a Tikhonov-regularized least-squares problem whose Jacobian is computed by a single adjoint backward pass per mode. Modes whose frequencies must be preserved are handled by a saddle-point formulation that enforces hard equality constraints regardless of the regularization strength. Resonance frequencies agree with state-of-the-art finite-element calculations to within 1.21 cent over eleven geometries and 132 mode pairs. Experimental validation against tap-tone measurements of 16 numerical control-machined didgeridoos spanning six distinct bore designs yields 9.6 cent RMS deviation over 189 matched mode pairs. Replicate specimens of the same nominal bore disagree with each other by 4.5 cent RMS, so about 36% of the residual variance is fabrication scatter.
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Materials Science
Mobility-lifetime relation links photodegradation in spin-coated and gravure-printed organic solar cells
Maria Saladina, Paul Weitz, David Holzner et al. (+24 more)
The degradation mechanisms of organic
solar cells (OSCs) have been studied primarily in
spin-coated, laboratory-scale devices, whereas scalable processing modifies the device architecture, active-layer morphology, and underlying charge-transport and recombination properties. Whether these changes also alter how
solar cells degrade remains unclear. Here, we compare
spin-coated and fully roll-to-roll-compatible gravure-printed PM6:Y12
solar cells during $\sim$1000 h of continuous illumination. Despite distinct initial properties and degradation signatures, the loss of power-conversion efficiency systematically follows the mobility-lifetime product $\mu\tau$. Remarkably, ageing of the printed devices increases the recombination lifetime while strongly reducing charge-carrier mobility, showing that a longer lifetime alone does not imply improved device performance. The mobility reduction is accompanied by decreased PM6 lamellar order, whereas the additional open-
circuit voltage loss originates predominantly from increased non-radiative recombination. Dark recovery further reveals a metastable contribution specific to the printed architecture. These results identify the mobility-lifetime product as a unifying physical descriptor for photodegradation, linking ageing-induced microscopic changes to macroscopic performance loss across
spin-coated and scalable printed OSCs.
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All authors Maria Saladina, Paul Weitz, David Holzner, Chen Wang, Robert Eland, Svitlana Taranenko, Christopher Wöpke, Toni Seiler, Fabian Eller, Doyoung Sun, Alexander Ehm, Bekcy Joseph, Peli̇n Çi̇loğlu, Carmen Tretmans, Andreas Willert, Harald Kuhn, Roderick C. I. Mackenzie, Jan-Frederik Pietschmann, Martin Stoll, Yana Vaynzof, Dietrich R. T. Zahn, Safa Shoaee, Eva M. Herzig, Arved Carl Hübler, Thomas Heumüller, Christoph J. Brabec, Carsten Deibel
Cosmology and Nongalactic Astrophysics
Model-Independent Measurement of Baryon Gas Fractions through Galaxy-Galaxy Lensing and the Kinematic Sunyaev-Zel'dovich Effect
R. Henry Liu, Uroš Seljak, Simone Ferraro et al. (+52 more)
Baryon feedback is a leading source of systematic uncertainty for cosmology from weak
lensing, but measurements of the gas distribution around
galaxies have largely relied on parametric profile models or simulation-calibrated frameworks. We present model independent measurements of the radial gas fraction profile around
galaxies, combining
galaxy-
galaxy lensing and kinematic Sunyaev-Zel'dovich (kSZ) effect. We introduce a method that applies the same radial $\Delta\Sigma$ aperture filter to both the
galaxy-
galaxy lensing shear field and the velocity-weighted kSZ temperature maps; their ratio directly yields $\Delta\Sigma$ filtered gas fraction $f_{\rm gas}(R)$, the ratio of ionized gas to total matter as a function of projected radius. We apply this approach to DESI DR2 Bright
Galaxy Survey (BGS, $\bar{z} \approx 0.26$) and Luminous Red
Galaxy (LRG, $0.4 < z < 1.1$) samples, using ACT DR6 component-separated CMB maps for kSZ, and the HSC Year 3 shear catalog for weak
lensing. After correcting for ACT beam suppression using a simulation-calibrated compensation factor, we detect
baryon depletion relative to the
cosmic mean
baryon fraction at SNR = 17.2 (BGS) and SNR = 13.8 (LRG bin 1). Comparison with six hydrodynamical simulations from the Illustris, IllustrisTNG, SIMBA, and FLAMINGO suites shows that the fiducial FLAMINGO run most closely tracks the observed radial gas distribution in both samples, with Illustris-1 and TNG300-1 bracketing the data from below and above at small radii. We find a mild discrepancy between the kSZ measurements in the South and North
Galactic Caps in one LRG
redshift bin, which may indicate residual systematics. We show that the ratio is robust to splits by
stellar mass and to the removal of close pairs. These results establish $\Delta\Sigma$ filtering of kSZ versus weak
lensing signal as a model-independent probe of the
baryon distribution around
galaxies.
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All authors R. Henry Liu, Uroš Seljak, Simone Ferraro, Boryana Hadzhiyska, Frank J. Qu, Bernardita Ried Guachalla, Emmanuel Schaan, Jessica Nicole Aguilar, Steven Ahlen, Anton Baleato Lizancos, Florian Beutler, Davide Bianchi, David Brooks, Aurelio Carnero Rosell, Francisco Javier Castander, Todd Claybaugh, Andrei Cuceu, Axel de la Macorra, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Klaus Honscheid, Dragan Huterer, Mustapha Ishak, Stephanie Juneau, Tanveer Karim, David Kirkby, Anthony Kremin, Ofer Lahav, Martin Landriau, Laurent Le Guillou, Martine Lokken, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Seshadri Nadathur, Jeffrey A. Newman, Hernan Enrique Noriega, Will Percival, Ignasi Pérez-Ràfols, Francisco Prada, Corentin Ravoux, Graziano Rossi, Lado Samushia, Eusebio Sanchez, Christoph Saulder, David Schlegel, Michael Schubnell, Hee-Jong Seo, Małgorzata Siudek, Gregory Tarlé, Benjamin Alan Weaver, Rongpu Zhou
Materials Science
Laser-Ablated Au Electrodes with Preferred Orientation and Flat Interface on Oxides
Ambrose Seo, Richard Lai, Sujan Shrestha et al. (+5 more)
Gold (Au) thin-film electrodes deposited on
oxides by pulsed
laser deposition (PLD) exhibit distinctive structural properties compared with thermally evaporated Au films. While thermally evaporated Au forms polycrystalline films with randomly oriented grains, PLD-grown Au films show a strong preferred [111] orientation perpendicular to the substrate surface, likely due to the energetic nature of the
laser-ablated Au plume. High-resolution transmission electron microscopy reveals atomically flat interfaces between the PLD-grown Au electrodes and epitaxial
oxide thin films, separated by nanometer-scale gaps comparable to interlayer spacings in van der Waals materials. The highly ordered microstructure and flat interfacial morphology result in enhanced adhesion of the Au films to
oxide surfaces. These results demonstrate that PLD can produce both high-quality Au electrodes and
oxide thin films within a single deposition platform, offering improved interfacial control and potential benefits for a wide range of
oxide electronic and functional devices.
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All authors Ambrose Seo, Richard Lai, Sujan Shrestha, Tina Tong, Joseph W. Brill, Menglin Zhu, Chris Chae, Jinwoo Hwang
Astrophysics of Galaxies
The ALMA View of High-Redshift Galaxy Formation
Renske Smit and Rebecca A.A. Bowler
The advent of routine operations with the Atacama Large Millimeter/submillimeter Array (ALMA) in the last decade has led to a revolution in the direct study of the interstellar medium (ISM) in `normal' high-
redshift galaxies in the rest-frame far-infrared (FIR). This review summarizes the observational literature on z>6.5 sources observed with ALMA and NOEMA (NOrthern Extended Millimeter Array). The main findings are as follows: Cool gas consistently scales with
star-formation in a wide range of
galaxy environments, similar to local relations, suggesting fundamental processes of
star-formation stay relatively constant over 13 billion years of
cosmic time. Significant metal enrichment is present in
galaxies just 300-400 million years after the Big Bang. There is a trend to higher obscured fraction of
star formation with
stellar mass and SFR already in place at z~7, with measurements of the
cosmic SFR density showing that >10 percent of the SFR density is obscured at this epoch. The estimated
dust masses compared to the
stellar mass suggest that rapid
dust enrichment occurs, likely from
supernova with little
dust destruction and/or rapid growth in the ISM, which is in agreement with maximal predictions from models. In individual sources cold disks are already in existence, with their gas disks being more extended and smooth than their observed
stellar counterparts.
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Computational Physics
Stochastic consensus dynamics for decentralized decision systems
André L. M. Vilela, Caio B. L. Silva, Kenric P. Nelson et al. (+2 more)
A fundamental mechanism underlying collective phenomena in social, technological, and economic systems is decentralized decision-making, in which the behavior of individual
agents follows from local interactions in the absence of central coordination. Consensus formation is a central feature of such systems, with relevance to blockchain networks, distributed artificial intelligence, autonomous multi-
agent systems, distributed control, and collective decision networks. We investigate consensus formation using a
stochastic consensus model on random networks and examine how initial conditions, network connectivity, and system size shape the emergence of unanimous states. We show that the
stochastic dynamics strongly amplify small initial majorities, progressively suppress the competing state, and drive the system toward a predictable collective outcome. Network connectivity primarily controls the efficiency of this process: increasing connectivity accelerates the propagation of local agreement and reduces the likelihood that fluctuations reverse the initially dominant state, although these gains gradually saturate in highly connected networks. System size produces a complementary effect. Larger networks require more individual updates to reach unanimity, but they are also increasingly reliable in selecting the state favored by the initial majority. Finite-size analysis shows that the range of initial conditions associated with uncertain outcomes becomes progressively narrower as the network grows, decreasing approximately with the inverse square root of the system size. These results reveal a collective amplification mechanism by which weak initial asymmetries become increasingly decisive in large decentralized networks, and they provide a simple framework for understanding the efficiency, predictability, and reliability of consensus formation in distributed decision systems.
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All authors André L. M. Vilela, Caio B. L. Silva, Kenric P. Nelson, Emilio Cobanera, Gaogao Dong
Nuclear Theory
Evidence for a Continuous Hadron–Quark Transition in Cold Dense Matter
Yong-Jia Huang and Bikai Gao
Statistical evidence for a continuous
hadron-
quark transition is found in this work. Confronting microscopic descriptions connecting the Parity Doublet Model and the Nambu–Jona-Lasinio model with observationally constrained non-parametric equations of state,
Bayesian model comparison decisively favors a boundary-free crossover over the conventional first-order Maxwell construction ($\Delta\ln\mathcal{Z} \sim +7.20$) and fixed-boundary crossover ($\Delta\ln\mathcal{Z} \sim +5.16 $). The preferred crossover decouples the intermediate stiffening from the intrinsic stiffness of each phase, allowing both sectors to exhibit physical self-consistency. The
chiral-invariant nucleon mass is large, $M_0 = 834^{+28}_{-92}\text{ MeV}$, as expected for a substantial
baryon mass surviving
chiral restoration. While the
quark sector accommodates a small pairing gap $\Delta_{\rm CFL} = 88^{+83}_{-59}\text{ MeV}$ consistent with perturbative QCD limits, avoiding the excessively large gaps $\Delta_{\rm CFL} \gtrsim 200\text{ MeV}$ required by the other constructions. These results demonstrate that a realistic unified description represents a continuous transition deviating substantially from isolated effective models of
hadrons and
quarks. Exploring genuine phase boundaries is therefore necessary through the emergence of spinodal instabilities within unified frameworks.
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Astrophysics of Galaxies
LoTSS of dual AGN: enhanced detectability and prospects for a systematic search
Q. D'Amato, F. Mannucci, E. De Rubeis et al. (+25 more)
Context: Dual active
galactic nuclei (DAGN) - systems of two accreting supermassive black holes at kpc-scale separations - trace
galaxy mergers and are the progenitors of gravitational-wave sources targeted by
pulsar timing arrays and the upcoming
Laser Interferometer Space
Antenna. However, their
radio properties remain poorly constrained, particularly at high
redshift. Aims: We demonstrate the detectability of high-
redshift DAGN at 144 MHz through sub-arcsec imaging of the LOFAR Two-metre Sky Survey (LoTSS) and characterize their low-frequency
radio properties. Methods: We cross-matched 92 spectroscopically confirmed DAGN (z > 0.3, projected separation r_p < 30 kpc) with the LoTSS DR2 catalog and reprocessed international LOFAR
telescope (ILT) data for three systems (0.59 < z < 2.39), achieving ~0.3 arcsec resolution at 144 MHz. Multi-frequency analysis and brightness-temperature diagnostics were used to investigate the
radio emission. Results: We obtained high-quality ILT images for all three systems. In one source at z = 1.49, both AGN are detected at >5 sigma, making it one of the highest-
redshift and faintest
radio-detected DAGN. Brightness temperatures confirm AGN-powered emission even in sub-mJy sources. In the other two systems only one AGN is detected; for one, the new data constrain the low-frequency spectrum of a compact steep-spectrum source, indicating that its morphology is driven by jet-ISM interaction rather than the companion
galaxy. For the 92 objects sample, the LoTSS detection rate is ~24%, significantly higher than for matched single AGN (~9-10%), suggesting an enhanced detectability of DAGN in the LoTSS. Conclusions: Low-frequency sub-arcsec
radio observations provide an efficient,
dust-unbiased method to detect and characterize DAGN. This pilot study establishes a
benchmark for the forthcoming all-sky ~0.3 arcsec iLoTSS survey and future SKA observations.
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All authors Q. D'Amato, F. Mannucci, E. De Rubeis, I. Prandoni, A. De Rosa, M. Scialpi, M. Kunert-Bajraszewska, A. Janiuk, A. Krauze, L. Battistini, E. Bertola, C. Bracci, A. Chakraborty, M. Ceci, C. Cicone, G. Cresci, A. Marconi, C. Marconcini, E. Nardini, M. Parvatikar, A. Peca, K. Rubinur, P. Severgnini, C. Spingola, L. Ulivi, G. Venturi, C. Vignali, M. V. Zanchettin
Fluid Dynamics
Applications of a moving surface drag model: From Stokes waves to offshore wind farms
Manuel Ayala, Zein Sadek, Raul. B Cal et al. (+2 more)
Offshore wind farms operate within the marine atmospheric boundary layer, where ocean waves can modify air-sea momentum transfer, turbine inflow, and wake recovery. Wave-resolved simulations can capture phase-dependent wind–wave interactions, but their computational cost and implementation complexity limit their use in large atmospheric and wind-farm domains. This study describes applications and tests of the recently proposed moving surface drag (MOSD) model, a flat-bottom wall-stress formulation for horizontally resolved moving waves, to a sequence of increasingly complex wind–wave and offshore wind-energy applications. The model is first evaluated for turbulent flow over Stokes-like waves using laboratory measurements, where it reproduces mean velocity profiles and captures the qualitative structure of wave-induced motions, although their amplitude is underpredicted. MOSD is then applied to broadband wave spectra fields and offshore wind-farm boundary layers, showing good agreement with mean velocity profiles from wave-resolved simulations across different wave ages, grid resolutions, and turbine spacings. Finally, exploratory offshore wind-farm simulations using MOSD under conventionally neutral conditions demonstrate its application at wind-farm scale. Large-scale waves leave detectable signatures in near-surface velocity spectra, but these signatures decay with height and do not produce clear peaks in temporal spectra of aggregate turbine power. Overall, the results demonstrate that the MOSD model provides a tractable framework for incorporating resolved wave effects in wind-wave and offshore wind-farm simulations.
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All authors Manuel Ayala, Zein Sadek, Raul. B Cal, Dennice. F Gayme, Charles Meneveau
Quantum Physics
A Near-Optimal Joint Lower Bound for Sparse Quantum Linear System Solvers
Dhrumil Patel
Quantum linear system solvers form one of the central algorithmic primitives in
quantum computing, with applications ranging from differential equations and optimization to machine learning. Their cost is commonly measured through query complexity, which counts the number of oracle calls needed to access the input
matrix. In the sparse-access model, this complexity is governed by three parameters: the condition number $\kappa$, the sparsity $s$ of the input
matrix, and the target precision $\varepsilon$. The dependence on $\kappa$ and $\varepsilon$ is already well understood through the lower bound $\Omega(\kappa\log(1/\varepsilon))$, which matches the best known scaling in these parameters. Once the sparsity $s$ is included, however, the expected lower bound has long been conjectured to be $\Omega(\kappa\sqrt{s}\log(1/\varepsilon))$. Recent work by Mori et al. [
Quantum Sci. Tech. 11 035063 (2026)] made an important step towards this goal by establishing the lower bound $\Omega(\kappa\sqrt{s})$ for constant error $\varepsilon$. In this work, we complete the picture and prove the full joint lower bound $\Omega(\kappa\sqrt{s}\log(1/\varepsilon))$ in the sparse-access model, thereby establishing the anticipated dependence on all three parameters simultaneously.
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Quantum Physics
Extracting Electromagnetic Bare Mode Couplings in Large Superconducting Quantum Processors
Reza Molavi, Ebrahim Forati, Yaxing Zhang et al. (+9 more)
High-fidelity control of superconducting
quantum processors requires accurate characterization of electromagnetic coupling strengths among the device's constituent elements. Accurately extracting these couplings across large-scale architectures, presently featuring hundreds of
qubits, poses a challenging multi-scale modeling problem. This requires resolving scales from the nanometer-scale geometry of Josephson junctions and their leads to the centimeter-scale size of the enclosing metallic packages. We present four numerical coupling extraction methods based on the avoided level crossing, the energy participation ratio, the induced electromotive force, and the impedance
matrix. These methods are tailored to work with commercially available 3D electromagnetic solvers. We
benchmark these techniques on a $10\times10$ array of transmon
qubits, extracting their couplings to standing package modes. Our results show that these methods yield consistent coupling strengths with a maximum relative difference of less than 5%.
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All authors Reza Molavi, Ebrahim Forati, Yaxing Zhang, Andrey R. Klots, Juan Atalaya, Brandon W. Langley, Dogan A. Timucin, Moein Nazari, Ghazi Khan, Zlatko K. Minev, Alexander N. Korotkov, Michel H. Devoret
Materials Science
A low-symmetry ground state of dense two-dimensional hydrogen
Cesare Cozza, Chris J. Pickard and Guglielmo Mazzola
Hydrogen under pressure is an extremely complex system featuring molecular dissociation, metallization, and anomalous melting. While bulk hydrogen has been studied for nearly a century, its two-dimensional counterpart remains unexplored. Using first-principles structural searches and relaxations in supercells containing up to 512 atoms, we identify ground-state structures of dense two-dimensional hydrogen showing no evidence of long-range crystalline order over the simulated length scales. Within density functional theory, these structures have lower enthalpy than all crystalline candidates considered over an intermediate pressure interval between molecular and atomic
crystals. This preference already emerges with classical
nuclei and persists as the supercell size increases, while the dominant structure-factor peaks grow substantially more slowly than in the crystalline reference phases. Although
crystals with very large primitive
cells cannot be rigorously excluded, these findings support the possibility of a disordered ground state and identify dense two-dimensional hydrogen as a promising setting for investigating competition between crystallization and structural disorder.
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