Optics
Angular displacement readout of a mechanical oscillator with a guided mode resonance
Diego Torres-Barajas, Oscar Angulo, Aman R. Agrawal et al. (+2 more)
Measuring the angular displacement of a mechanical oscillator is a ubiquitous task; however, the multimode nature of angular optomechanical coupling makes coherent signal enhancement challenging. Here we demonstrate coherently enhanced angular displacement readout with an integrated guided mode resonance (GMR) structure, applying it to precision readout of a nanomechanical oscillator. Specifically, we fabricate subwavelength gratings into 100-nm-thick Si$_3$N$_4$ membranes and record their vibration by direct transmission measurements. The narrow linewidth $\approx 2.5\;\text{mrad}$ of the GMR enables a shot-noise-limited displacement imprecision of $ 10^{-9}\;\text{rad}/\sqrt{\text{Hz}}$ with nanowatts of optical power, sufficient to resolve the thermal motion of a $Q\approx 10^6$ torsion mode with a signal-to-noise ratio of 47 dB. Control experiments based on polarization and wavelength detuning confirm that the measured signal arises from GMR-mediated transduction. These results establish guided-mode resonance as an on-chip approach to angular displacement readout in
quantum optomechanical sensors.
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All authors Diego Torres-Barajas, Oscar Angulo, Aman R. Agrawal, Mohamed ElKabbash, Dalziel J. Wilson
Fluid Dynamics
Data-driven modeling of hypersonic flows in chemical non-equilibrium with catalytic surfaces
Konstantinos Sarras, Louis Walpot, Thierry Magin et al. (+2 more)
Hypersonic flows involve extreme thermochemical non-
equilibrium, where strong energy dissipation leads to tightly coupled chemical reactions, radiation, and energy exchange. In this regime, surface chemistry, particularly catalytic wall reactions, can significantly affect boundary-layer composition and surface heat transfer. Accurate simulations of such flows may require repeated evaluations of detailed thermochemical libraries, which represent a major computational bottleneck in high-fidelity reactive-flow simulations. To mitigate this cost, we employ the data-driven reduced-order framework introduced by Scherding et al. (2023), which combines nonlinear dimensionality reduction, community clustering, and local surrogate models to efficiently approximate high-dimensional thermochemical mappings. In this work, this framework is extended for the first time to hypersonic reactive flows with localized catalytic surface discontinuities, introducing sharp variations in wall chemistry and heat transfer. To address the increased complexity of the thermochemical state space, the dimensionality reduction method is enhanced with a Sammon-type stress penalty that mitigates topological folding of the latent
manifold and improves the robustness of the clustering and surrogate stages. The resulting model accurately captures the effects of discontinuous catalytic properties, including sharp gradients in wall species mass fractions,
diffusion fluxes, and surface heat transfer, while reducing the overall simulation cost by 50% without compromising accuracy.
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All authors Konstantinos Sarras, Louis Walpot, Thierry Magin, Peter Schmid, Taraneh Sayadi
High Energy Physics (Phenomenology)
Understanding the enhanced $\phi \eta^{\prime}$ decay mode of the $\phi(2170)$ through strange-meson loops
Qin-Song Zhou, Jun-Zhang Wang and Dan Guo
The nature of the strangeonium-like $\phi(2170)$ remains controversial. Recent measurements of $e^+e^-\to\phi\eta^{(\prime)}$ reveal a striking puzzle: a broad $\phi(2170)$-like structure appears in the $\phi\eta^\prime$ channel but not in $\phi\eta$, despite the strong phase-space suppression of $\phi\eta^\prime$. We investigate this unexpectedly large $\phi\eta^\prime$ decay fraction within the excited-strangeonium assignment. A combined analysis of the $e^+e^-\to\phi\eta$ and $e^+e^-\to\phi\eta^\prime$ cross sections is performed by including short-distance amplitudes from
vacuum quark-pair creation and long-distance transitions mediated by strange-
meson loops. The short-distance mechanism predicts too small a $\phi\eta^\prime/\phi\eta$ strength ratio to explain the data. In contrast, strange-
meson loops naturally enhance this ratio because the SU(3)-
flavor factor at the $K^{(*)}K^{(*)}\eta^{(\prime)}$ vertex suppresses the transition to $\phi\eta$ relative to $\phi\eta^\prime$. The resulting overall description of both cross sections supports an important role for long-distance dynamics in hidden-strangeness decays of excited vector strangeonia. More intriguingly, although the excited strangeonium contributions have been included, the current high-precision $\phi\eta$ data still favor the existence of an extra narrow vector state near $2.15~\mathrm{GeV}$ with a width of about $25~\mathrm{MeV}$. If confirmed, it would be a promising exotic-
hadron candidate in the light-vector sector. Furthermore, we test $\Gamma(Y\to\phi\eta)/\Gamma(Y\to\phi\eta^\prime)=0.25$, $1$, and $4$ as fit inputs and obtain similarly good descriptions of the cross sections in all three cases. The present data therefore do not allow this ratio to discriminate among different internal configurations of the narrow state.
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Chaotic Dynamics · Cross-listed from eess.SY
Reduced Arc-Weight Heterogeneity for Master Stability Analysis of Directed Networks
Aandrew Baggio Sahaya Arokiadoss and G. Arunkumar
Master stability analysis can be applied to directed networks even when their
Laplacian matrices are not diagonalizable. Nevertheless, a diagonalizable
Laplacian is easier to analyse because the perturbations governing synchronization separate into independent modes. This paper asks how many different positive coupling strengths are needed to obtain this simplification without adding or removing any directed connections. We first give an elementary construction showing that suitable positive weights exist for every weakly connected directed network and explain its relationship to stronger genericity results in the literature. We then introduce a measure of the smallest number of distinct coupling strengths required for diagonalizability. If a common coupling strength already produces a diagonalizable
Laplacian, only one value is needed. For directed acyclic networks, we give a constructive upper bound based on the length of the longest directed path from a source. This bound is exact for rooted outward directed trees. Consequently, an outward
star requires only one coupling value, whereas a directed path requires a different value on every arc. These results reduce coupling heterogeneity while retaining the simpler modal form of master stability analysis. Diagonalizability is treated as an analytical convenience, not as a sufficient condition for synchronization.
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Mathematical Physics
A semiclassical limit of reduced Hartree-Fock theory at positive temperature
Dominic Shillingford
It is established that the reduced Hartree-Fock grand potential at positive temperature converges in the semiclassical limit to a Thomas-
Fermi grand potential. In particular, a density-potential dual representation of the limiting functional is proposed for a general class of fermionic
entropy functions. The corresponding dual problem has no duality gap and admits a maximizer. The resulting grand potential converges to the established zero-temperature grand potential as the temperature tends to zero and, for the
Fermi-Dirac
entropy, agrees with the standard positive-temperature Thomas-
Fermi free-energy functional. The proof also establishes a semiclassical trace formula that is uniform over locally precompact families of potentials subject to a common confinement condition.
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Soft Condensed Matter
Surface Roughness and Filler Restructuring in Magneto-Active Elastomers: Magnetically Hard versus Magnetically Soft Particles
Júlio P. A. Santos, Mehdi Hasanzade, Chaitanya Doifode et al. (+5 more)
Magneto-active elastomers (MAEs) – composites of
magnetic nano-/micro-particles embedded in a soft
polymer matrix – are promising for soft robotics, as their shape and mechanical properties can be controlled by an applied
magnetic field. Most MAEs are filled with magnetically soft (MS) micro-particles, such as carbonyl iron powder (CIP). We employ molecular dynamics to study the differences between thin MAE layers with MS and magnetically hard (MH) filler particles having the same saturation magnetization. We find that both MH and MS elastomers converge to the same high-field state – a labyrinth of bundled, field-aligned chains – but do so through distinct pathways: MH MAEs break their zero-field chains, which lie parallel to the MAE layer plane (in-plane), and rotate them into
alignment with an external
magnetic field, whereas MS MAEs gradually build up field-aligned chains from neighboring particles. We show that the MS model reproduces the magnetization curves and surface roughness of CIP-based MAEs for
magnetic fields close to saturation, while maintaining the observed qualitative features at lower field strengths. The mismatch between simulation and experimental results at low fields suggests the need for a MS model that accounts for the multi-domain nature of carbonyl iron microparticles.
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All authors Júlio P. A. Santos, Mehdi Hasanzade, Chaitanya Doifode, Raphael Kriegl, Alexander Kovalev, Mikhail Shamonin, Stanislav N. Gorb, Sofia Kantorovich
Cosmology and Nongalactic Astrophysics
How X-rays heat the IGM in different 21-cm simulation codes: a comparison between Licorice and Beorn
Romain Meriot, Jonathan R. Pritchard and Timothée Schaeffer
Any interpretation of the 21-cm signal of neutral hydrogen using
Bayesian inference methods can only be as accurate as the underlying simulation code used to model the state of the intergalactic medium (IGM). 3D radiative transfer (RT) simulation codes may capture complex physics, but are computationally expensive and, therefore, faster, more approximate codes have been developed. To improve our understanding of the convergence of simulation codes in the 21-cm science community, we present a comparison of the X-ray heating of the IGM modelled in Licorice, a 3D RT simulation code, and Beorn, a 1D RT code. We use Beorn to process sources extracted from Licorice simulations, using the same physics of the sources, in order to obtain two versions of the temperature of the IGM heated by X-rays. We observe a good agreement between the luminosity fields, mean temperatures, and global 21-cm signal of the two setups, but discrepancies in the distribution of temperature and 21-cm signal, which result in a $\sim 30\%$ difference in the 21-cm power spectrum. We attempt to isolate the approximations that lead to these differences and find that common approximations used in 1D RT codes produce effects of that magnitude. Using an emulator of the Licorice power spectra in an MCMC pipeline, we translate these differences between power spectra into differences between posterior distributions over the astrophysical parameters. We observe a typical bias between 1D posteriors of $\gtrsim 1 \sigma$ (with a noise level corresponding to 100h of SKA observations).
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Medical Physics · Cross-listed from eess.IV
UMPIRE-Net: Unrolled Magnitude-Phase Regularization Network for Accelerated MRI
Mahdi Saberi, Toygan Kiliç and Mehmet Akçakaya
MRI reconstruction from undersampled k-space measurements is an ill-posed inverse problem. Physics-driven deep learning (PD-DL) methods have shown strong performance for this task by combining the MRI forward model with learned image regularization within
algorithm-unrolling frameworks. However, most existing PD-DL methods reconstruct complex-valued images directly, thereby implicitly coupling magnitude and phase within a single learned representation. This coupled regularization may be suboptimal in reconstruction settings where accurate phase modeling plays an important role, such as partial
Fourier (PF) imaging, where recovery of the omitted asymmetric k-space measurements depends on the underlying image phase. In such scenarios, explicit modeling of magnitude and phase as separate components may reduce the reliance on externally estimated or predefined phase information. To this end, we propose UMPIRE-Net (Unrolled Magnitude-Phase In REgularization Network), a PD-DL method that introduces separate learned regularizers for magnitude and phase components, together with a novel data-fidelity formulation that enforces measurements consistency. We evaluate UMPIRE-Net for accelerated MRI with PF across different
datasets and acceleration factors. Experimental results demonstrate that our proposed method improves reconstruction quality compared with a conventional complex-valued PD-DL baseline, yielding sharper images and reduced artifacts. Code available at: https://github.com/MahdiSaberii/UMPIRE-Net
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High Energy Physics (Phenomenology)
NNLO QCD corrections to $WW\gamma$ production at the LHC
Paolo Garbarino, Massimiliano Grazzini and Stefan Kallweit
Triboson production processes are crucial to study quartic gauge-
boson couplings. We present the computation of the radiative corrections to $WW\gamma$ production at the next-to-next-to-leading order (NNLO) in QCD. The leptonic decays of the $W$
bosons and off-shell effects are fully included. The calculation is exact, apart from the finite part of the two-loop amplitudes, which is evaluated in a soft-
photon approximation. We validate our approach by using $Z\gamma$ production as a reference process, where we take advantage of the availability of the exact two-loop amplitudes to derive a conservative error estimate for our approximation, and then apply it to $WW\gamma$ production. For typical selection cuts, at the centre-of-mass energy $\sqrt{s}=13$ TeV, the NNLO corrections increase the next-to-leading order (NLO) result by about $16\%$, and the perturbative uncertainties are reduced to the $\pm4\%$ level. The uncertainty from the soft approximation turns out to be at the few per mille level, largely subdominant compared to the residual perturbative uncertainties, both for the fiducial cross section and the most relevant differential distributions.
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Disordered Systems and Neural Networks · Cross-listed from q-bio.PE
Extinction drives emergent metastability in complex ecosystems
Jong Il Park, Tim Rogers and Joseph W. Baron
Extinction is inevitable; every species eventually dies out, impacting the ecosystem it is part of. Over the past few decades, extensive research stemming from the stability-diversity debate has addressed how species diversity contributes to the stability of large ecosystems. However, conventional stability criteria often rely on deterministic frameworks, overlooking the intrinsic population fluctuations that allow any species to go extinct by chance. In this paper, we incorporate demographic stochasticity into large complex ecosystems with a rule-based model. We demonstrate that such demographic fluctuations rapidly prune the low-abundance species from the ecological community, thereby securing higher systemic stability. By developing a bottom-up theory to characterise the statistics of extinction dynamics, we discover that the fraction of surviving species exhibits an anomalous heavy-tailed decay over time, revealing the emergence of remnant communities with robust metastability. Our results highlight that when demographic fluctuations are accounted for, ecosystems self-stabilise by reducing their diversity even when they are predicted to be chaotic in the deterministic limit.
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High Energy Astrophysical Phenomena
XRISM reveals sloshing-driven gas motions in the core of Abell 2029
Yuusuke Uchida, Yuna Saito, Naomi Ota et al. (+13 more)
We investigate the velocity structure of the intracluster medium (ICM) in the core of the relaxed cool-core cluster Abell 2029 using XRISM Resolve spectroscopy. We analyze combined XRISM Resolve observations and divide the central region into several subregions. To account for
photon mixing caused by the XRISM point spread function, we perform a spatial-spectral mixing analysis. We detect an ordered line-of-sight bulk-velocity gradient across the cluster core: the northern regions are blueshifted relative to the brightest cluster
galaxy (BCG), while the southern regions are close to zero velocity or slightly redshifted. The maximum velocity difference is about $280~{\rm km\,s^{-1}}$. In contrast, the turbulent velocity dispersion is smaller, with measured values and upper limits of $\lesssim150~{\rm km\,s^{-1}}$, implying a non-thermal pressure fraction below $\sim2.5\%$. The velocity pattern is consistent with gas sloshing associated with the spiral structure seen in Chandra X-ray images. Averaged over all regions, the inferred turbulent heating rate is below the radiative cooling rate, indicating that turbulent dissipation alone is insufficient to offset cooling in the entire core. These results reveal that A2029 is not kinematically featureless: sloshing-induced bulk motions are present, while the observed line-of-sight velocity dispersion indicates only a limited contribution to pressure support and core heating.
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All authors Yuusuke Uchida, Yuna Saito, Naomi Ota, Erwin T. Lau, Ming Sun, Eric D. Miller, Tommaso Bartalesi, Stefano Ettori, Kotaro Fukushima, Caroline Kilbourne, Lorenzo Lovisari, Kyoko Matsushita, Brian R. McNamara, Arnab Sarkar, Kazunori Suda, Irina Zhuravleva
High Energy Astrophysical Phenomena
Optical Spectroscopy of TeV-emitting BL Lac Candidates
Cassidy Metzger, Ryan C. Hickox and John R. Thorstensen
TeV-emitting BL Lacertae (BL Lac) blazars have important implications for the study of jet phenomenology, particle acceleration, and ultra high-energy
cosmic ray production. They also allow for indirect studies of the extragalactic background light,
cosmic magnetic fields, and
axion-like particles. The upcoming Cherenkov
Telescope Array (CTA), a ground-based gamma-ray observatory, will expand the observed TeV-emitting BL Lac population and enhance the aforementioned fields of study. However, reliable
redshifts are crucial for planning and interpreting observations with CTA and only about 50% of gamma-ray BL Lacs have spectroscopic
redshifts. We performed medium resolution optical spectroscopy of 16 TeV-emitting BL Lac candidates with the SALT and MDM
telescopes. We measured spectroscopic
redshifts for the full sample, ranging from 0.059 to 0.4, including 5 new spectroscopic
redshift measurements.
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General Relativity and Quantum Cosmology · Cross-listed from math.DG
One-sided type-D Ricci-flat multi-centre metrics
Yu Chen
We employ a simplified form of Tod's ansatz—which is built on the LeBrun–Tod ansatz—to construct one-sided type-D
Ricci-flat multi-centre metrics. These metrics are Hermitian non-Kähler and conformally Kähler, and they are determined by a pair of generating potentials: an axisymmetric harmonic function (different from the one originally proposed by Tod) in an auxiliary 3D flat space and its harmonic conjugate. We carry out a systematic study of these multi-centre metrics, including their rod structure, asymptotic structure and recovering from them various known closed-form examples. In particular, we show that, when fitted into the scheme of multi-
soliton solutions on flat space constructed by the present author using the inverse-scattering method, these metrics, with number of centres $n\le 3$, have a free-
soliton number 2 or 3 greater than their phantom-
soliton number; we
conjecture that this is true for general $n$.
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Instrumentation and Detectors · Cross-listed from cs.RO
Effect of Twisted-Yarn Architecture on Pressure and Proximity Sensing Characteristics of Textile Capacitive Sensors for Robotic Skin
Ishtia Zahir, Eslam Saleh, Maryam Rezayati et al. (+2 more)
Textile-integrated capacitive sensors offer flexible and conformable tactile sensing for wearable electronics and human-
robot interaction; however, the influence of yarn-level architecture on capacitive transduction characteristics remains insufficiently quantified. This work presents a textile capacitive sensing platform based on silver-coated yarns coated with polydimethylsiloxane and assembled into one-, two-, and four-layer twisted configurations. The influence of effective electrode overlap area and inter-fiber separation on the capacitive response is systematically investigated, enabling architecture-dependent tuning of pressure and proximity sensing characteristics. Pressure was calculated using the localized single-fiber contact area, corresponding to stresses of 0.4-3.9 MPa. Increasing the layer number improved mechanical strength and sensing performance: elongation at break increased from 37.5% to 62.5% and 85.0%, while the maximum load increased from 23.3 to 42.7 and 89.7 N. Sensitivity increased with layer number and frequency, reaching 0.1331 MPa$^{-1}$ for the four-layer sensor at 100 kHz. The four-layer configuration also exhibited low hysteresis, minimal thermal drift from 25 to 90 $^\circ$C, and stable operation over 15,000 cycles. Proximity detection ranges of 60, 50, and 40 mm were obtained for the one-, two-, and four-layer sensors, respectively, revealing an architecture-dependent sensitivity-range trade-off. A 4$\times$4 textile sensing array enabled spatial contact mapping, while robotic-arm integration demonstrated real-time touch and proximity detection with an end-to-end robotic system latency (from detection to
robot reaction) of 403 ms. The results establish yarn architecture as a tunable design parameter governing the measurement characteristics of textile-integrated capacitive sensing systems.
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All authors Ishtia Zahir, Eslam Saleh, Maryam Rezayati, Güunter Grabher, Gaffar Hossain
Physics and Society
Absorbing phase transition in a queueing model of coupled adaptive agents
Alexei Vazquez
What decides whether people do things together or separately? Many activities cannot be carried out alone, and an individual must rank them against the private tasks competing for the same time. We address this within the priority-queue description of human activity by letting each
agent choose the priority of a shared task rather than drawing it from a fixed distribution: the value of the joint activity, discounted by the estimated risk that the partner will not take part. Participation becomes strategic, and the model acquires a phase transition. A coupled phase, in which joint activity is sustained, is separated from an absorbing solitary phase by a saddle-node bifurcation that we obtain in closed form. The transition is discontinuous and the solitary phase is absorbing, so collapse is irreversible unless an
agent persists unilaterally for of order one
memory time, a cost we also compute. The heavy-tailed interevent statistics that motivate queueing models of human dynamics survive only in a narrow window at the transition, and there the exponent is fixed by the fraction of time spent coupled rather than by queue length: the universality classes of the non-strategic model do not survive the introduction of choice. On a network,
attention divides as $1/(k+a)$ and fixes a critical degree beyond which no coupled state exists, so the solitary phase percolates according to the Molloy–Reed criterion with the second moment truncated at that degree — formally an attack on hubs, with no attacker. For group activities the critical degree falls as the $(m-1)$th root, implying a maximum group size. The transition organises two quantities already measured in communication records: a finite capacity for keeping ties active, and the decay of ties whose rhythm is interrupted.
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Quantum Physics
Linearised quantum signal processing
Marek Arsenault and Hlér Kristjánsson
Quantum functional programming has been developed through two distinct paradigms in the last few years:
Quantum Signal Processing (QSP)-based methods, including the
Quantum Singular Value Transformation (QSVT), and methods based on higher-order
quantum transformations, such as the Universal
Hamiltonian Eigenvalue Transformation (UHET). While UHET performs functional transformations of
Hamiltonian dynamics, its relationship to QSP-based techniques has remained unclear despite evident structural similarities. In this work, we resolve this gap by establishing a connection between UHET and QSP-based frameworks; specifically, we show that UHET can be interpreted as a (randomised) linearisation of Generalised QSP (GQSP). Building on this result, we introduce a linearised variant of (
Hamiltonian-based) QSVT, which we call Universal
Hamiltonian Singular Value Transformation (UHSVT), that enables the efficient transformation of the singular values of any arbitrary
matrix $A$ encoded in a block of a
Hamiltonian, whose dynamics is accessible as a black box, by any sufficiently differentiable complex-valued function $f$. Our
algorithm requires the sole condition that $f$ vanishes at the origin, in contrast to previous QSVT-based approaches that assumed either a lower bound on the singular values of $A$ or the ability to perform $X$-rotation gates on the induced two-dimensional 'qubitised' subspace.
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High Energy Physics (Theory)
Large lumps
D. Bazeia, I. Bezerra, M.A. Marques et al. (+1 more)
We introduce a procedure to obtain lump solutions via the formation of a kink-antikink pair, consisting of the superposition of kinks whose distance from the origin is controlled by a single parameter $a$. For large values of $a$, a wide plateau appears in the solution, which we call a large lump. The procedure involves the use of a first-order equation that allows the construction of the potential associated with the lump solution. We then investigate several known scalar field models where the parent kinks are capable of giving rise to novel lumps. The lump inherits the tails of the parent kink, allowing for either short-range exponential profiles or long-range profiles characterized by distinct power-law decays. We also show how to verify if an arbitrary lump solution can be obtained via our method and illustrate this possibility with a novel vacuumless lump.
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All authors D. Bazeia, I. Bezerra, M.A. Marques, R. Menezes
Mesoscale and Nanoscale Physics
Floquet Superlattices and Edge States in Graphene Nanoribbons
Siam Sarower, Jonathon Dvorscak, Nancy P. Sandler et al. (+1 more)
Structured light provides a route to imprint spatially patterned Floquet potentials onto
quantum materials. As a particular example, we study a zigzag
graphene nanoribbon driven by two coherent tilted beams, whose interference creates a periodic polarization pattern that gives rise to a photo-induced superlattice. The matching between the periodicity of the optical field and the nanoribbon width leads to two regimes in the quasienergy spectrum: matched profiles preserve degenerate edge branches, while mismatched profiles yield a boundary-induced gap that survives in wide ribbons. We propose a two-edge model that captures this splitting through residual hybridization and the boundary-sampled optical field. The quasienergy gap reverses between valleys, leading to a valley-selective boundary response. Our results establish light-induced superlattices as a flexible method for valley selectivity in finite-size Dirac-like materials through tunable edge-state quasienergy splitting.
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All authors Siam Sarower, Jonathon Dvorscak, Nancy P. Sandler, Mahmoud M. Asmar
High Energy Physics (Phenomenology)
Jet functions for next-to-leading power factorization
Robin van Bijleveld, Jaco ter Hoeve, Eric Laenen et al. (+3 more)
We discuss the factorization of scattering processes near partonic threshold at next-to-leading power (NLP) in the threshold variable $1-z$, with $z \equiv q^2/\hat{s}$. We review the general structure of power-suppressed contributions both in Soft-Collinear Effective Theory (SCET) and in a direct QCD approach, and discuss the definition of NLP jet functions as gauge-invariant operator
matrix elements in QCD. As a controlled check of the resulting factorization formula, we verify it explicitly at one and two loops for the massive electromagnetic form factor in the limit $m^2 \ll s$, using the method of regions. We conclude by outlining the two challenges that remain for a systematic resummation of NLP logarithms: the treatment of endpoint divergences in SCET convolutions, and the extension of jet functions to radiative processes capable of describing an arbitrary number of soft-
gluon emissions – the latter being the last missing ingredient for exponentiation, given that the purely soft sector is already understood in terms of generalised webs via the replica trick.
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All authors Robin van Bijleveld, Jaco ter Hoeve, Eric Laenen, Coenraad Marinissen, Leonardo Vernazza, Guoxing Wang
Astrophysics of Galaxies
The Galactic Centre G+0.633-0.0604 Molecular Cloud: A New Gold Mine for Astrochemistry
D. San Andrés, V. M. Rivilla, L. Colzi et al. (+4 more)
Astrochemistry is living a golden age, with more than a quarter of the ~350 molecules in the current interstellar census having been detected over the last three years. One of the sources driving this progress is the G+0.693-0.027 cloud, located in the northern part of the
Galactic Centre Sgr B2 complex. In this contribution, we present the astrochemical characterisation of G+0.633-0.0604, a newly discovered chemically rich molecular cloud at the southern edge of Sgr B2. With an inventory of >120 species, G+0.633 provides robust second detections of several prebiotic molecules only reported towards G+0.693, establishing it as the first confirmed astrochemical twin of G+0.693 while demonstrating that the extraordinary chemistry of this cloud is not unique. Furthermore, G+0.633 offers an observational advantage over G+0.693 since it displays half narrower linewidths. Together, G+0.633 and G+0.693 form a unique
benchmark pair for unveiling molecular complexity and prebiotic chemistry in the interstellar medium.
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All authors D. San Andrés, V. M. Rivilla, L. Colzi, M. Sanz-Novo, S. Martín, I. Jiménez-Serra, S. Zeng
History and Philosophy of Physics
Scientific understanding across disciplines: in varietate concordia?
Henk W. de Regt, Milo D. Cornelissen, Vincent Coumans et al. (+7 more)
Understanding is a generally acknowledged aim of science, but the way in which understanding is pursued and criteria for when it is achieved differ widely across scientific disciplines. This paper offers a comparative analysis of this disciplinary variation, aimed at revealing differences as well as commonalities in methods and criteria for achieving understanding. Starting point is the contextual theory of scientific understanding (De Regt 2017), which was developed to accommodate contextual variation in criteria for understanding. While this work focused on historical variation and used mainly case studies from the history of physics, the current paper applies the contextual theory to disciplinary variation. We present brief descriptive accounts of how understanding figures in nine scientific disciplines: mathematics, theoretical physics, astrophysics, chemistry, geoscience, biology, neuroscience, psychology, and the engineering sciences. Subsequently, we compare and evaluate these accounts in light of the contextual theory of scientific understanding.
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All authors Henk W. de Regt, Milo D. Cornelissen, Vincent Coumans, Nina S. de Boer, Sebastian De Haro, Paul H. W. Disberg, Kristian González Barman, Maarten G. Kleinhans, Daniel Kostić, Ludo L. J. Schoenmakers
Atmospheric and Oceanic Physics
Characterizing the Evolution of Tropical Cyclone Thermal Structure: A Tropical Cyclone Thermal Phase Space
Jimin Liu, Yaoming Ma, Jeremy Cheuk-Hin Leung et al. (+4 more)
Current understandings of the tropical cyclone (TC) warm core primarily relies on statistical averages from soundings and satellite products, which provide a climatological thermal state but cannot adequately characterize the continuous three-dimensional
evolution of the warm core throughout the TC life cycle. In this study, Empirical Orthogonal Function (EOF) analysis was applied to three-dimensional temperature anomalies of Western North Pacific (WNP) TCs derived from the ERA5 reanalysis
dataset for the period 1979-2024. We found that the three leading EOF modes effectively capture the primary characteristics of the TC thermal structure: the first mode represents the typical warm core structure; the second mode characterizes vertical baroclinicity; and the third pattern captures the horizontal asymmetry of the temperature anomalies. Using the first three principal components (PCs), we established a three-dimensional Cartesian coordinate system. Within this framework, two phase parameters define a thermal phase space to visualize the TC's three-dimensional thermal structure: one diagnoses the vertical barotropic or baroclinic structure, and the other quantifies the horizontal asymmetry of the thermal field. The results demonstrate that the trajectory in the phase diagram effectively captures the observed intensity changes and thermal structural
evolution. The EOF-based phase diagrams offer promising insights and provide a novel, objective tool for analyzing and diagnosing structural thermodynamic characteristics and intensity
evolution by quantifying key thermal features and their dynamic relationships with TC intensity. This capability thereby holds substantial potential for advancing both theoretical understanding and operational
forecasting of TCs.
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All authors Jimin Liu, Yaoming Ma, Jeremy Cheuk-Hin Leung, Hong Huang, Shaojing Zhang, Zeyong Hu, Banglin Zhang
Disordered Systems and Neural Networks · Cross-listed from math.PR
Non-Shattering at and Above the Dynamical Temperature in the Spherical Pure p-Spin Model
Taegyun Kim
We consider the notion of shattering introduced by Ben Arous and Jagannath for spherical pure $p$-
spin glasses with overlap $q$. For every $p\geq 3$ and $0<\beta\leq\beta_{\mathrm{sh}}(p)$, we rule out shattering whenever $q\leq2^{-1/2}$ or $q>\sqrt{(p-2)/(p-1)}$. The proof combines a deterministic $N+1$ bound for disjoint bands in the first range with a general-$p$ sign law showing that their total marked weight has subdominant free energy in the second. A spherical-code bound and Hölder's inequality give an additional $q$-dependent obstruction; in particular, they rule out every fixed overlap for $0<\beta\leq\sqrt{\log2}$. For $p=3$, the first two ranges already exhaust every fixed $q\in(0,1)$, so the landscape is not shattered at any $T\geq T_{\mathrm{sh}}$. For $p\geq4$, the cases not covered by our criteria are confined to $2^{-1/2}<q\leq\sqrt{(p-2)/(p-1)}$ and $\sqrt{\log2}<\beta\leq\beta_{\mathrm{sh}}(p)$. In particular, this paper partially resolves
Conjecture 1 of the paper above and also suggests new methods to show non-shattering.
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Materials Science
Unraveling the Roles of Shallow, Deep and Auger Trapping in Charge Carrier Recombination in Triple-Cation Perovskites
Jitendra Kumar, Thomas Kirchartz, Alexandr Marunchenko et al. (+7 more)
Understanding charge-carrier recombination in metal halide perovskites is essential for accurately identifying the factors limiting
solar cell efficiency, yet it remains challenging due to the interplay of multiple competing processes. Here, we combine time-resolved photoluminescence and excitation dependent photoluminescence
quantum yield measurements over a wide range of fluences and repetition rates to investigate recombination dynamics in triple-cation perovskite thin films. By jointly analyzing these multidimensional
datasets, we develop a unified model that quantitatively reproduces both photoluminescence decays and absolute
quantum yields across all excitation conditions. Our results reveal the coexistence of deep and shallow traps, as well as a second-order nonradiative recombination pathway attributed to Auger-assisted trapping. Importantly, this mechanism dominates under one-sun illumination, making it a critical limiting factor for photovoltaic performance. These findings provide a comprehensive framework for understanding recombination in perovskites and highlight the importance of higher-order defect-mediated processes in determining their efficiency.
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All authors Jitendra Kumar, Thomas Kirchartz, Alexandr Marunchenko, Alexander Kiligaridis, Shraddha M. Rao, Shivam Singh, Ankur Yadav, Monojit Bag, Yana Vaynzof, Ivan G. Scheblykin
Mathematical Physics
Form factors of field exponentials in the 1+1 dimensional Sine-Gordon model
Karol K. Kozlowski and Alex Simon
This work provides explicit expressions, in all sectors of the Fock space:
soliton, antisoliton and breather, for the fundamental building blocks -the form factors- of the generalised integral kernels which represent the exponential of the field operator in the 1+1 dimensional Sine-Gordon
quantum field theory. The obtained form factors reproduce the various results obtained earlier in the literature using, in particular, the free field approach.
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High Energy Astrophysical Phenomena
The Evolution of the ACIS Contamination Layer on the Chandra X-ray Observatory from 2010 to 2026
Paul P. Plucinsky, Peter W. Ratzlaff, Akos Bogdan et al. (+1 more)
The Chandra X-ray Observatory (CXO) was launched over 27 years ago and has been delivering spectacular science over the course of its mission. The Advanced CCD Imaging Spectrometer (ACIS) is the
prime instrument on the satellite, conducting over 90% of the observations. The CCDs operate at a temperature of $-$120$^\circ$C and the optical blocking filter (OBF) in front of the CCDs is at a temperature of approximately $-$60$^\circ$C. The surface of the OBF has accumulated a layer of contamination over the course of the mission, as it is the coldest surface exposed to the interior to the spacecraft. We have been characterizing the thickness, chemical composition, and spatial distribution of the contamination layer as a function of time over the mission. The contamination model has required several revisions over the course of the mission as the properties of the contamination layer have changed and our understanding of the layer has improved. In this paper, we evaluate the performance of the current contamination model (N0016 released in CalDB 4.12.3 on 16 December 2025) using the most recent calibration observations conducted from 2023 to 2026 by using the standard model spectrum for the
supernova remnant 1E 0102.2-7219 (E0102) developed by the International Astronomical Consortium for High Energy (IACHEC), spectral data from the cluster of
galaxies known as Abell 1795, and high resolution X-ray spectra of Mrk 421. This evaluation has been complicated by the decreasing observed counts at low energies, especially the O VII He$\alpha$ line complex and the O VIII Ly$\alpha$ line from E0102 which are no longer useful for this purpose. The analyses of the E0102, Abell 1795, and Mrk 421 data show that the current model of the contamination adequately predicts the additional absorption through mid-2026.
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All authors Paul P. Plucinsky, Peter W. Ratzlaff, Akos Bogdan, Herman L. Marshall
Strongly Correlated Electrons
Tuning crystal-fields by He-irradiation and orbital Widom line in SrVO$_3$ films
Matthias Pickem, Karsten Held and Jan M. Tomczak
Helium-ion irradiation of epitaxial SrVO$_3$/SrTiO$_3$ films causes a metal-
insulator transition, so far attributed to a Mott localization driven by a reduced kinetic energy. Using density-functional theory plus dynamical mean-field theory, we show that the driving mechanism is instead the
crystal-field splitting generated by the irradiation-induced tetragonal expansion, not the interaction-to-bandwidth ratio. The resulting $c$-axis vs. temperature phase diagram mirrors that of the one-band Hubbard model, but its critical end-point spawns an orbital Widom line, rooted in an anomalous compressibility of orbital, rather than charge occupation. At an effectively quarter filling, superexchange-like processes favor orbital over
magnetic long-range order. Our results semi-quantitatively reproduce the fluence-dependent spectral gaps and transition thresholds reported experimentally, establishing ion implantation as a route to chemically expand correlated materials.
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Quantum Physics
Native multi-qubit gates on a single-junction unimon circuit
Sasu Tuohino, Mikko Möttönen and Matti Silveri
Quantum processors with native multi-
qubit gates may offer very efficient implementations of near-term
quantum algorithms on noisy hardware. Here, we introduce the multiunimon, a superconducting multimode
circuit that encodes multiple
qubits and enables native multi-
qubit gates in a device consisting of a single Josephson junction embedded in a coplanar waveguide structure. Closely related to the unimon
qubit, it inherits properties such as high anharmonicity, full protection against low-frequency charge noise, and partial protection against flux noise. By designing such a three-
qubit device with Josephson-to-inductive energy ratio above unity and using a leakage-aware encoding scheme for the computational states, we simulate all twelve different controlled-controlled-NOT gates with a mean fidelity of 99.5% with simple sine-squared pulses of comparable length to single-
qubit gates. The performance is limited by incoherent errors dominated by dielectric loss. With improvements in noise protection, design, and pulse shaping, the simulations suggest that fidelities approaching 99.99% are within reach. Our results demonstrate the potential of the multiunimon as a highly connected multi-
qubit unit for larger superconducting
quantum processors.
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Materials Science
Orbital Hall Effect in Weyl Semimetals from quantum geometric band interference
Chiara Pacella, Maximilian Ünzelmann, Ahmed Osman et al. (+4 more)
Orbital angular momentum (OAM) transport in solids, prominently manifested in the orbital
Hall effect, has emerged as a fundamental phenomenon that can decisively exceed its
spin-based counterparts. However, the microscopic mechanisms governing OAM dynamics remain only partially understood. In particular, the role of band geometry in orbital transport is still largely unresolved. Here we address this question in the TaAs family of Weyl semimetals, TaAs, TaP, NbAs, and NbP, whose well-established
topology and associated OAM textures make them an ideal platform in this context. Using ab initio density functional theory, complemented by a minimal Weyl model based on adiabatic perturbation theory, we establish — both numerically and analytically — a direct link between OAM transport, band geometry, and topological electronic structure.
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All authors Chiara Pacella, Maximilian Ünzelmann, Ahmed Osman, Tim Figgemeier, Friedrich Reinert, Angel Rubio, Domenico Di Sante
Chemical Physics
Multidimensional Design of Metal-Nitrogen-Carbon Electrocatalysts for Direct Propylene Epoxidation
Songbo Ye, Qingyuan Han, Jingwen Chi et al. (+6 more)
Propylene
oxide is a major industrial chemical whose production currently relies on hazardous chlorine- or peroxide-based oxidants. Direct electrochemical epoxidation using water as the oxygen source offers a sustainable alternative, but controlling oxygen-atom transfer against the competing oxygen
evolution reaction remains a fundamental challenge. Here, we show that propylene epoxidation selectivity cannot be described by oxygen binding energy alone, but is jointly governed by oxygen adsorption, the potential of zero charge, and applied potential. By combining theoretical calculations with pH-field-coupled microkinetic modeling across 41 metal-nitrogen-carbon single-atom catalysts, we first identified an optimal oxygen-binding window and Co as the most favorable metal center. We then found that peripheral substituents can tune the PZC while largely preserving the optimal oxygen adsorption energetics, thereby providing an independent design dimension to further optimize the already favorable Co active site. This sequential, multidimensional design strategy identified CoPc-NH2-CNT as the optimal catalyst, delivering a record PO Faradaic efficiency of 70-80 percent for direct propylene epoxidation in aqueous electrolyte under ambient conditions. These results establish interfacial electrostatics as an independently tunable design dimension for controlling selective oxygen-atom transfer in electrocatalysis.
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All authors Songbo Ye, Qingyuan Han, Jingwen Chi, Yuan Huang, Heng Liu, Di Zhang, Hitoshi Shiku, Li Wei, Hao Li