Materials Science
Capturing Nuclear Quantum Effects in Hydrogen Diffusion through MoS2 via Machine-Learning-Enhanced Path-Integral Simulations
Ismail Eren, Ege Yigit Erbil, Maria-Judith Caisachana-Lozada et al. (+3 more)
Hydrogen transport through layered two-dimensional (2D) materials is central to technologies such as hydrogen storage, fuel
cells, and isotope separation. Among these materials, MoS2 exhibits tunable interlayer
diffusion properties, whose accurate theoretical description requires accounting for
nuclear quantum effects (NQEs), including zero-point motion and tunneling. Here, we present a machine-learning-enhanced atomistic study of hydrogen and deuterium
diffusion in layered MoS2 based on interatomic potentials trained on r2SCAN+rVV10 density-functional-theory data. Combining well-tempered metadynamics with path-integral molecular dynamics, we investigate
diffusion across multiple MoS2 polytypes and twisted
bilayer structures while explicitly incorporating NQEs. Our simulations show that NQEs substantially lower free-energy barriers for hydrogen
diffusion at 300 K, significantly increasing the hydrogen self-
diffusion coefficient compared to classical
nuclei simulations. We further identify a pronounced kinetic isotope effect, with a 35 meV difference between hydrogen and deuterium
quantum free-energy barriers. In twisted
bilayer MoS2, hydrogen transport exhibits strong spatial variations governed by the local stacking environments within the moiré superlattices. These results highlight the critical role of NQEs in hydrogen transport through layered materials and provide atomistic insight intoisotope-selective
diffusion in structurally complex 2D systems.
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All authors Ismail Eren, Ege Yigit Erbil, Maria-Judith Caisachana-Lozada, Hossein Mirhosseini, Thomas D. Kühne, Agnieszka B. Kuc
High Energy Physics (Phenomenology)
Stefan Antusch, Jan Hajer and Bruno M. S. Oliveira
Symmetry-protected low-scale seesaw models can account for the observed
neutrino flavour oscillations without fine-tuning, while yielding
collider-accessible signatures through pseudo-Dirac heavy neutral
leptons (HNLs). Seesaw frameworks generically predict
lepton number (LN) violation, which provides a powerful discovery channel. In
symmetry-protected realisations, however, the amplitudes for LN violation are strongly suppressed by destructive interference between the contributions of the two quasi-degenerate HNLs within the usual QFT plane-wave treatment. We demonstrate that damped heavy
neutrino-antineutrino oscillations significantly alleviate this suppression. We compare the sensitivities to pseudo-Dirac HNLs in both LN-blind and LN-violating channels at the LHC and future
hadron colliders such as the FCC-$hh$ and the S$pp$C. We find that, although searches for LN violation outperform their LN-blind counterparts, small mass splittings in the pseudo-Dirac HNL pair can drastically reduce the sensitivities in these channels. We further show that combining LN-blind and LN-violating searches can distinguish a pseudo-Dirac HNL pair from the double-Majorana limit in the intermediate regime where LN violation is observable but not yet saturated.
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Optics
Exact modes, hybridization and polarization rotation of electromagnetic fields propagating in topological insulating slab
Sebastián Filipini, Mauro Cambiaso, Alberto Martín-Ruiz et al. (+1 more)
We study electromagnetic waves in slab waveguides with a topological
insulator core characterized by a topological magnetoelectric parameter (ME). TIs are electrically insulating in the bulk with robust conducting states at their boundaries. Their electromagnetic response is described by an
axion-like $\Theta$ term that modifies Maxwell's electrodynamics, leading to rich and unconventional phenomena, as the topological ME effect. All supported modes are exact hybrid modes with nonvanishing longitudinal field components. This hybridization is a consequence of the boundary conditions produced by the $\Theta$ term and is absent in topologically trivial, reciprocal and non-
chiral slab waveguides. Modifications to the propagation condition and modes are shown for the asymmetric slab. The detailed solution of the exact modes, coupling of modes and the dispersion relations is made for the symmetric slab. By solving the full $\Theta$-electrodynamics nonperturbatively, we derive the modal dispersion relations and explore polarization rotation and power transfer between modes. Our approach reveals qualitative and quantitative deviations from standard coupled-mode theory and captures new signatures of the topological ME response. Due to the smallness of the $\Theta$-effects, we perform a perturbative analysis of mode propagation, based on writing a general solution as a superposition of exact modes of $\Theta$-ED but expanding to first non-vanishing order. Also, we apply coupled-mode theory, that is predicated on building solutions as superpositions of modes of ordinary electrodynamics that fail to satisfy the boundary conditions imposed by the $\Theta$-term but compensate at the expense of modifying the field profiles. These findings provide a comprehensive framework for light control in topological photonics and potential routes to experimentally probe the ME effect in guided settings.
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All authors Sebastián Filipini, Mauro Cambiaso, Alberto Martín-Ruiz, Luis F. Urrutia
High Energy Physics (Phenomenology)
Factorization of the Energy-Energy Correlation in the two-jet limit in the massive case
Ugo Giuseppe Aglietti, Giancarlo Ferrera and Lorenzo Rossi
We consider non-logarithmic heavy-
quark mass effects in the factorization and resummation of the Energy-Energy-Correlation (EEC) function, in the two-jet limit. We define a new, "partial" event fraction, restricted to the two-jet region and excluding the forward region, whose calculation at first order requires to consider real emission diagrams only, in $D=4$ space-time dimensions (no need to consider virtual diagrams or take $D \ne 4$). In order to determine explicitly the next-to-leading order coefficient function and the remainder function (both entering the standard resummation formula), we evaluate numerically the EEC spectrum at first-order in $\alpha_S$, finding good agreement with previous calculations. To have a smooth massless limit, a new, improved factorization scheme is proposed, in which the coefficient function also depends on the correlation angle $\chi$.
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Quantum Physics
Tensor network characterization and mitigation of readout errors
Yuchen Guo and Shuo Yang
Readout errors are a major bottleneck to extracting reliable information from near-term
quantum processors, especially when spatial correlations are non-negligible. We present a unified tensor-network framework that models the readout process as a
matrix product operator (MPO), enabling efficient characterization and mitigation beyond uncorrelated approximations. The MPO model is trained via likelihood optimization on calibration data and applies to multiple tasks, including nonlocal observable estimation, random
circuit sampling, and random-measurement protocols, such as classical shadows and learning-based
tomography. Experiments on a superconducting processor and numerical simulations up to 20
qubits show that the MPO model captures correlated readout errors that uncorrelated models miss, with a sample cost that grows only near-linearly with system size. When extended to two-dimensional systems, the framework can also be integrated with tensor-network
quantum error-correction decoders by performing joint inference over data and readout errors. These results establish tensor-network readout error mitigation as a scalable and versatile approach for noise-aware
quantum data processing.
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General Relativity and Quantum Cosmology
Radial Perturbations of Black Holes in DHOST Theories
Christos Charmousis, Simon Iteanu, David Langlois et al. (+1 more)
We study radial perturbations of static black holes with primary hair in a subfamily of degenerate higher-order scalar-tensor (DHOST) theories. We recast the equation of motion for the monopole degree of freedom into a flat radial wave equation and show that the associated operator can be extended, through appropriate boundary conditions, to a positive self-adjoint operator which ensures the stability of the radial mode. Remarkably, the coordinate choice that leads to the flat wave equation corresponds to the
unitary gauge, in which the scalar field is uniform. As a result, the radial coordinate extends beyond the event horizon, into the black hole interior, in contrast with the tortoise coordinate in General Relativity. The same wave equation with the same coordinate choice applies to all solutions that are connected by disformal transformations. We also examine stealth black hole solutions, with either a constant or non constant kinetic term. In the former case, we find, to linear order, the absence of a propagating degree of freedom. In the latter case, we identify a stable radial degree of freedom, except for special values of the theory coupling constants.
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All authors Christos Charmousis, Simon Iteanu, David Langlois, Karim Noui
Cosmology and Nongalactic Astrophysics
HI Simulations for Cosmology with the SKA Observatory
Tommaso Ronconi, Gabriella De Lucia, Marta Spinelli et al. (+15 more)
We present a comparative overview of state-of-the-art methods for modelling the distribution of neutral hydrogen (HI) in the post-reionization Universe, developed in preparation for upcoming SKAO cosmological surveys. Our aim is to assess how different physical and empirical assumptions reflect into predictions for key observables such as the
cosmic HI density, the HI mass function, and the HI-
halo mass relation. We consider both: (i) semi-analytical approaches that self-consistently evolve baryonic components within dark matter merger trees through physically motivated prescriptions and (ii) empirical schemes tailored to different observables and based on fast approximations designed for large ensemble studies. By comparing the predictions from the different methods considered, we find overall consistency in integrated quantities such as $\Omega_{\mathrm{HI}}$, yet systematic differences in the detailed shape and scatter of the HI–
halo mass relation and its
redshift evolution. Semi-analytical models offer physically grounded predictions but depend on assumed prescriptions, while empirical methods provide flexibility and computational efficiency at the expense of robustness in extrapolated regions of the parameter space. The increasing number of HI measurements from SKA precursors and pathfinders (including surveys with MeerKAT, ASKAP, and FAST) will provide critical observational constraints to refine and calibrate current simulation methodologies. In turn, increasingly realistic HI simulations play a key role in interpreting these data, guiding survey design and analysis strategies, in preparation for the advent of SKAO data.
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All authors Tommaso Ronconi, Gabriella De Lucia, Marta Spinelli, Pascal Hitz, Fabio Fontanot, Francesco Sinigaglia, Lizhi Xie, Robert M. Yates, José Luis Bernal, Anna Bonaldi, Stefano Camera, Isabella P. Carucci, Steven Cunnington, Francisco-Shu Kitaura, Joël Mayor, Rajesh Mondal, Giulia Piccirilli, Digvijay Wadekar
Strongly Correlated Electrons
Fractional phase slips across the charge-density-wave domain walls in 1-T TiSe2
Haotian Zhang, Zihao Song, Zhongchen Xu et al. (+9 more)
The microscopic origin of the charge density wave (CDW) in 1T-TiSe$_2$ remains controversial, with competing scenarios based on
phonon-driven
lattice instability and electronically driven excitonic correlations. Here, we combine low-temperature scanning tunneling microscopy with two-dimensional lock-in phase analysis to directly resolve the local CDW phase in real space and track its
evolution across individual domain walls. In homogeneous regions, the CDW phase remains uniform; by contrast, across domain walls we uncover a robust and reproducible $2\pi/3$ phase shift that occurs collectively in all three
symmetry-related CDW components. This nontrivial and correlated phase-slip configuration places stringent constraints on the order-parameter
manifold and challenges the simplest purely
phonon-driven commensurate lock-in picture, which would instead predict a $\pi$ phase shift. A minimal free-energy model incorporating both electron-
phonon and electron-hole interactions reproduces the observed phase behavior and indicates that electronic interactions play an important role in shaping the local phase structure of the CDW order. These results establish domain walls as direct real-space probes of the microscopic interactions underlying multicomponent order and provide a general phase-resolved framework for constraining competing ordering mechanisms in correlated materials.
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All authors Haotian Zhang, Zihao Song, Zhongchen Xu, Jun Shu, Zhongxu Wei, Zunming Lu, Jun Liu, Zengyi Du, Jinxing Zhang, Youguo Shi, Ge He, Jun Shen
Applied Physics · Cross-listed from cs.RO
From Rubble Simulation to Active Magnetic Mapping: Quantum Sensing for Disaster Response
Samuel Tovey, Stefan Prestel and Hiroshi Yamauchi
Locating survivors of building collapses within the first 72 hours is a critical challenge in disaster response, and existing sensing modalities provide only partial information about the structure beneath the rubble. This paper proposes drone-based
quantum magnetometry as a complementary modality and develops a simulation pipeline spanning rubble physics, sensor-array deployment, and active spatial reconstruction. We use Unreal Engine to generate a steel-reinforced concrete parking-garage collapse and compute the induced
magnetic field via a per-triangle dipole approximation, establishing that meaningful
magnetic structure is recoverable in the sub-pT to sub-nT range from roughly 1 m above the roofline. Then, we feed sparse multi-sensor samples into a Gaussian Process Regression back-end driven by
Bayesian active sampling and validate the pipeline across multiple independent collapse realizations; a three-sensor array optimizes the trade-off between gradient resolution and
UAV payload constraints, and active sampling reaches peak structural correlation in roughly $100$ samples. Together, these results indicate that
quantum-grade sensing could become a useful tool for drone-based structural analysis and potentially void detection in collapsed buildings.
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Cosmology and Nongalactic Astrophysics
Single-dish HI Intensity Mapping with the SKAO: Precursor Progress with MeerKAT's Large Area Synoptic Survey (MeerKLASS)
Steven Cunnington, Jingying Wang, Mario G. Santos et al. (+16 more)
Using the SKAO to map the intensity of neutral hydrogen's 21cm emission line will be a golden opportunity to constrain models of cosmology. To access the largest cosmological scales, wide-sky surveys should ideally reach thousands of square degrees, requiring SKA-Mid's dishes to scan the sky in auto-correlation mode, so-called single-dish observations. In this chapter, we overview the latest results from MeerKAT's Large Area Synoptic Survey (MeerKLASS), which has been pioneering this single-dish observing strategy, and motivating its continuation with the SKA-Mid AA4 deployment. MeerKLASS, operating on the same Karoo site where the SKA-Mid is being built, has now achieved multiple cosmological detections from single-dish observations, including high-significance cross-correlations with optical
galaxy surveys and continually improving measurements of the HI auto-power spectrum. These results demonstrate that stable calibration, effective foreground mitigation, and statistical recovery of cosmological signal are all achievable with a large multi-dish
telescope in total-power mode. The success of MeerKLASS therefore validates the observational strategies required for SKA-Mid and marks a key milestone in demonstrating the viability of single-dish HI intensity mapping for cosmology. Looking ahead, SKA-Mid's increased sensitivity and Band 1 coverage (350-1050 MHz) will allow the same methodology to probe
redshifts up to $z\,{\sim}\,3$, mapping volumes several orders of magnitude larger than currently accessible. The techniques refined with MeerKLASS thus form the operational and scientific foundation for a large portion of the SKAO's cosmology programme.
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All authors Steven Cunnington, Jingying Wang, Mario G. Santos, Matilde Barberi-Squarotti, Philip Bull, Stefano Camera, Isabella P. Carucci, Zhaoting Chen, Brandon Engelbrecht, José Fonseca, Karin Fornazier, Keith Grainge, Wenkai Hu, Melis O. Irfan, Yichao Li, Alkistis Pourtsidou, Marta Spinelli, Amadeus Witzemann, Laura Wolz
High Energy Physics (Phenomenology)
Forward Searches for Heavy Neutrinos and $Z'$ Bosons at FCC-hh
ShivaSankar K.A., Souvik Das, Arindam Das et al. (+1 more)
The discovery of
neutrino masses strongly motivates extensions of the Standard Model containing heavy neutral
leptons and additional gauge interactions. We investigate the prospects for probing these states at the proposed Forward Physics Facility (FPF) of the 100 TeV Future Circular
Collider (FCC-hh) within a broad class of anomaly-free
chiral $U(1)$ gauge extensions. These models predict a new neutral gauge
boson, $Z'$, together with right-handed
neutrinos responsible for generating light
neutrino masses through the seesaw mechanism. We study long-lived particle signatures arising from both heavy
neutrinos and the $Z'$
boson produced in the far-forward region. In particular, we analyze heavy
neutrino production from
meson decays, visible decays of long-lived $Z'$
bosons produced through
meson decays and
proton bremsstrahlung, long-lived $Z'$
bosons decaying into heavy-
neutrino pairs, and
prompt $Z'$ decays yielding long-lived heavy
neutrinos. The expected event rates are evaluated for the proposed FPF detector configurations, taking into account realistic detector geometry, decay probabilities, and visible final states. We derive projected sensitivities to the heavy
neutrino mass and active-sterile mixing as well as to the $Z'$ mass and gauge coupling for several representative $U(1)$ charge assignments. Our results demonstrate that the FPF at FCC-hh can substantially extend the discovery reach for light long-lived heavy
neutrinos and light $Z'$
bosons beyond existing and proposed experiments, providing a powerful and complementary probe of
neutrino-mass models and hidden gauge sectors. https://github.com/SouvikPhD/RHN-Detection-with-FASER-2-
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All authors ShivaSankar K.A., Souvik Das, Arindam Das, Sanjoy Mandal
Mesoscale and Nanoscale Physics
High-Performance Nanophononic Resonators in Self-Suspended WSe$_2$ Domes and Drums
Jens-Christian Drawer, Bo Han, Edson Rafael Cardozo de Oliveira et al. (+7 more)
Van der Waals materials are ideally suited for the implementation of high-frequency nanophononic resonators with atomically flat interfaces. Here, we present two versatile van der Waals-based nanophononic architectures: First, we introduce self-supporting nano-domes of WSe$_2$ as a scalable platform for the simultaneous generation of hundreds of high-quality nanoacoustic resonators with resonance frequencies in the 100 GHz range. Second, we engineer self-supporting nano-drums that reach record-high working frequencies for 2D-
semiconductor transducers beyond 1 THz. Through optical pump-probe spectroscopy experiments and photoelastic linear chain model calculations, we gain a detailed understanding of the intricate interplay between phononic mode hybridization across
heterostructures, the differences between modes close to the center and edge of the acoustic Brillouin zone, and the temporal structure of the photoelastic response. Both architectures have potential applications in low-cost nanoacoustic probing and the ultrafast modulation of
quantum emitters in two-dimensional
semiconductors. While nano-drums surpass the THz frequency barrier, nano-domes appear as an accessible, low-cost alternative for developing scalable nanophononic technologies.
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All authors Jens-Christian Drawer, Bo Han, Edson Rafael Cardozo de Oliveira, Chushuang Xiang, Vita Solovyeva, Kenji Watanabe, Takashi Taniguchi, Norberto Daniel Lanzillotti-Kimura, Christian Schneider, Martin Esmann
Accelerator Physics
Dispersion Suppression for Wedge-Based Final Cooling at a 10 TeV Muon Collider
Inci Karaaslan, Karri DiPetrillo, David Neuffer et al. (+2 more)
Achieving a luminosity of $\gtrsim 10^{34} cm^{-2} s^{-1}$ in a $10 \text{ } TeV$
Muon Collider, given the short lifetime of a
muon, requires reducing the 6D emittance of the
muon beam through a process known as ionization cooling. In the final stage of this cooling process, the transverse emittance must be reduced to $22 \text{ } \mu m$, typically by allowing longitudinal emittance growth up to downstream acceptance limits. While the current International
Muon Collider Collaboration designs involve $40 \text{ } T$ solenoids to reach the transverse emittance target, such high-field solenoids come with several challenges, including mechanical stress management, quench protection, and potential limitations in relying on High Temperature
Superconductor technology. Designed as an alternative to using such solenoids while simultaneously reaching target transverse emittance, the previously proposed wedge-based, reverse emittance-exchange cooling scheme requires excellent dispersion suppression. In this study, we design and simulate a dispersion suppressor channel for the wedge-based final cooling design that reduces dispersion in the target direction to a target value of $D_x \sim 0.001 \text{ } m$.
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All authors Inci Karaaslan, Karri DiPetrillo, David Neuffer, Diktys Stratakis, Katsuya Yonehara
Mathematical Physics · Cross-listed from math.DG
Boundary Rigidity in a fixed conformal class for Asymptotically Hyperbolic Manifolds
Tristan Humbert and Sebastián Muñoz-Thon
Given two conformal asymptotically
hyperbolic metrics which are either both simple or both negatively curved, we show that if their (marked) renormalized boundary distances coincide for some choices of conformal representatives in their conformal infinities, then the two metrics are equal.
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Atmospheric and Oceanic Physics
Event-Aware Loss Design for Forecasting of Convective Precipitation and Lightning
ChangJae Lee, Heecheol Yang and Byeonggwon Kim
Accurate
forecasting of high-impact weather, specifically extreme precipitation and lightning, remains a significant challenge in numerical weather prediction (NWP) due to the complexity of atmospheric microphysics. While deep-learning models have shown promise in large-scale
forecasting, they often suffer from systematic under-prediction of rare, high-intensity events and localized convective showers when optimized with conventional loss functions like Mean Squared Error (MSE). This study proposes an Event-Aware multi-task deep-learning post-processing framework designed to improve the representation of convective processes by leveraging lightning observations. The model jointly predicts precipitation amount, rainfall probability, and lightning occurrence using a shared-backbone Patch-cGAN (Conditional Generative
Adversarial Network) architecture. To address the rare event problem, we introduce a lightning-informed loss-weighting strategy that element-wisely multiplies the MSE component by a spatial weight map derived from observed lightning strikes, forcing the model to prioritize accuracy in convective regions during training. Evaluations conducted over the Korean Peninsula during the 2025 Summer demonstrate that our framework outperforms standard AI
benchmarks and conventional NWP models, particularly at intense rainfall thresholds (40 mm/6 h). Furthermore, the model exhibits superior skill in predicting lightning compared to conventional lightning parameterization and instability-index-based methods. These results indicate that integrating physical event indicators into the loss formulation effectively guides models to learn the meteorological signatures of deep convection, offering a pathway toward more reliable extreme weather
forecasting.
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High Energy Physics (Phenomenology)
Complementary probes of bilinear R-parity violating SUSY models with a winolike LSP via neutrino oscillations and at the LHC
Arghya Choudhury and Arpita Mondal
In this work, we explore the bilinear R-parity violating Supersymmetry model's parameter space by performing a Markov Chain Monte Carlo scan with
neutrino oscillation data,
Higgs mass and its coupling strengths, and
flavor observables such as $B$-
hadron decay branching ratios. From the allowed parameter space, we analyze the decay patterns of wino-like lighter charginos and lightest neutralinos and demonstrate how the branching ratios to different
neutrino and charged
lepton flavors depend on the
neutrino mass hierarchy. Furthermore, we investigate the impact of current LHC bounds and projected future sensitivities from trilepton resonance searches on the allowed parameter space. We show that considering the branching ratio $\mathrm{Br}(\widetilde{\chi}_1^{\pm} \to Zl^\pm; l= e,\mu,\tau) \sim$23%, obtained at the best-fit point, the wino-like mass degenerate $\widetilde{\chi}_1^{\pm}/\widetilde{\chi}_1^0$ are excluded upto 565 GeV from LHC Run-II data. The projected exclusion reach with a similar branching ratio at High-Luminosity LHC (HL-LHC) is around 950 GeV. For a simplified scenario where $\widetilde{\chi}_1^{\pm} / \widetilde{\chi}_1^0$ decays via a $Z$
boson with branching ratios of 1%, 50%, and 100%, wino masses can be excluded up to approximately $600~\mathrm{GeV}$, $1185~\mathrm{GeV}$, and $1350~\mathrm{GeV}$ respectively. Our analysis shows that the HL-LHC can probe a significant portion of the 1$\sigma$ allowed parameter space by
neutrino oscillation measurements and other experimental constraints.
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Quantum Physics
From spectral structure to sensing limits in quantum thermometry
Youssef Aiache, Simone Cavazzoni, Abderrahim El Allati et al. (+2 more)
The precision of a
quantum thermometer is fundamentally constrained by the spectral structure of the probe itself, and a systematic mapping between the configurations of energy levels and thermometric performance provides relevant information to design optimized devices. In this work, we establish such a mapping by analyzing a broad class of
quantum systems, ranging from finite
spin ensembles and degenerate atoms to confining potentials,
quantum walks, and continuous-spectrum models. We derive exact scaling laws for the
quantum Fisher information, revealing two distinct high-temperature universality classes: finite-spectrum probes exhibit a $T^{-4}$ decay, while unbounded or continuous spectra yield a slower $T^{-2}$ decay. At low temperatures, we show that sensitivity, though universally exponentially suppressed, can be enhanced arbitrarily by engineering degenerate excited states or a
quantum walk on a fully connected
topology. By contrast, specific
quantum walk
topologies provide a distinct enhancement mechanism based on gap engineering, whereby an optimal network size yields an optimized $T^{-2}$ low-temperature scaling. Furthermore, power-law spectra enable tunable scaling of thermometric performance with system size, offering a design principle for optimal probes in specific temperature windows. Our results contribute to transform spectral information into a resource for
quantum thermometry, providing both fundamental bounds and practical guidelines to tailored temperature sensing.
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All authors Youssef Aiache, Simone Cavazzoni, Abderrahim El Allati, Paolo Bordone, Matteo G. A. Paris
High Energy Astrophysical Phenomena
Using SKA-Low to Detect PeV Gamma-rays from Galactic Sources
Anna Nelles, Philipp Laub, Haoning He et al. (+28 more)
Detecting so called PeVatrons is considered one of the
prime goals of $\gamma$-ray astronomy. PeVatrons are astrophysical objects in the
Galaxy that are sources of
cosmic rays exceeding PeV ($10^{15}$ eV) energies, the highest in our
Galaxy. Their nature is unknown as of now, with some candidates reaching barely above PeV energies just having been identified. Serendipitously, the energy threshold of air shower detection using
radio emission, has been proven at 50 PeV. There is a case to be made that SKA-Low with its unprecedented number of
antennas, can reach lower in energy, while the size of the core is sufficiently large provide a significant effective area to measure PeV fluxes. While this promises a novel angle towards understanding the
cosmic ray accelerators in our
Galaxy, it also would be the first detection of $\gamma$-ray air showers using
radio emission.
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All authors Anna Nelles, Philipp Laub, Haoning He, Felix Schlüter, Sjoerd Bouma, Justin Bray, Stijn Buitink, Arthur Corstanje, Vital De Henau, Edwin Dickinson, Brian Hare, Jörg Hörandel, Tim Huege, Clancy James, Xingyu Li, Hermann-Josef Mathes, Katharine Mulrey, Subhadip Saha, Olaf Scholten, Ralph Spencer, Christopher Sterpka, Karen Terveer, Satyendra Thoudam, Gia Trinh, Paulina Turekova, Darko Veberic, Keito Watanabe, Hiroaki Yamamoto, Chao Zhang, Pengfei Zhang, Yi Zhang
Materials Science
Impact of sintering conditions on the dielectric properties of TiO2 ceramics for metamaterialsapplications at terahertz frequencies
Djihad Amina Djemmah, Delphine Gourdonnaud, Faycal Bouamrane et al. (+3 more)
Titanium dioxyde (TiO2) is a promising dielectric material for the realization of metamaterials operating in the terahertz (THz) range. Indeed, these necessitate a high permittivity and low loss material. In this paper, we compare the processes of fabrication and the results of characterisation of bulk TiO2 pellets. From the results of this characterization, we have numerically designed 2D all dielectric metamaterials (ADM) showing that they may exhibit negative or near-zero effective index. Our previous simulations show that the relative permittivity epsilon has to be around 100, while the loss tangent has to be lower than 0.02. We have thus compared conventional sintering (CS) vs spark
plasma sintering (SPS), and investigated the effect of post-sintering annealing on the loss to satisfy these two criteria. The samples were characterized by THz Time Domain Spectroscopy (THz-TDS). One of the samples exhibits a loss tangent as low as 0.006, with a permittivity epsilon = 103. These results highlight the importance of the fabrication process on the EM properties of bulk TiO2, and demonstrate that it is a promising material for the development of metamaterial in the THz band.
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All authors Djihad Amina Djemmah, Delphine Gourdonnaud, Faycal Bouamrane, Jean-Francois Roux, Pierre-Marie Geffroy, Eric Akmansoy
Quantum Physics
Klein–Gordon Dynamics from Intrinsic Phase Periodicity
Emiliano Puddu
This work develops a phase-based formulation of relativistic wave dynamics, demonstrating that the Klein–Gordon equation emerges naturally from the foundational assumption of intrinsic phase periodicity in material fields. Mapping the phase directly onto the classical action, we postulate that localized excitations possess an invariant rest-frame oscillation governed by a proper frequency $\omega_0$. This physical condition establishes an operational mass-frequency relation, $m = \hbar \omega_0 / c^2$, without requiring rest energy as an independent, axiomatic input. We show that the Klein–Gordon equation arises as the minimal local, linear, Lorentz-invariant field equation compatible with this internal phase structure. Within this framework, mass acts as an intrinsic frequency scale governing wave propagation, and relativistic kinematics is fully recovered as a structural consequence of phase coherence. This approach provides a unified wave-mechanical interpretation where particle dynamics maps onto the group velocity of dispersive wave packets, offering an intuitive account of free propagation, dispersion, and tunneling across potential barriers.
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High Energy Physics (Phenomenology)
Electroweak corrections to Higgs boson pair production: The quark channel
Marco Bonetti, Gudrun Heinrich, Philipp Rendler et al. (+1 more)
We present the mixed QCD-electroweak corrections to
Higgs boson pair production in the
quark-antiquark channel. The virtual amplitudes are computed fully analytically using the method of differential equations. We determine the integration constants by matching our expressions to the large mass expansion limit of the canonical integrals. We implement the results in the POWHEG-BOX framework for phenomenological studies. The corrections are found to have a significant impact on the shapes of differential cross sections, reaching up to +10% for the invariant mass distribution of the
Higgs boson pair near the production threshold. This channel has not been considered before in calculations of the next-to-leading order electroweak corrections to
Higgs boson pair production.
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All authors Marco Bonetti, Gudrun Heinrich, Philipp Rendler, William J. Torres Bobadilla
Disordered Systems and Neural Networks
Spectral properties and phase diagrams of sparse antagonistic random matrices with diagonal disorder and Jacobian-like structure
Luca Giammanco, Pietro Valigi and Chiara Cammarota
Complex interacting systems are often modelled by random
matrices whose spectral properties dictate stability. In sparse antagonistic
matrices without diagonal disorder, low connectivity gives rise to a characteristic reentrance effect in the spectral boundary near the real axis, which disappears via a continuous transition as the connectivity increases. The reentrance effect implies the presence of a complex leading
eigenvalue, which suggests the existence of a phase characterized by oscillatory dynamics around
equilibrium. Here, we expand the investigation to
matrices featuring diagonal disorder and a Jacobian-like structure. In these settings, the spectrum also develops a segment of
eigenvalues accumulating on the real axis, which can trigger a discontinuous jump of the complex leading
eigenvalue to a purely real value. The interplay between connectivity and disorder produces a rich variety of spectral behaviours. Employing the cavity method and a an adaptation of the Population Dynamics
algorithm, we map a phase diagram with five distinct spectral phases. Finally, we show that the
algorithm underestimates the spectral support under strong disorder, motivating future technical developments to handle this limit.
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Optics · Cross-listed from eess.IV
Improving Richardson–Lucy Deconvolution with Diffusion Priors for Fluorescence Microscopy
Hao Chen and Scott S. Howard
Richardson–Lucy (RL) deconvolution improves fluorescence microscopy images by recovering details lost to diffraction. It estimates the fluorescence signal most likely to have produced the measured
photon counts under a Poisson imaging model. However, deconvolution remains ill-posed, especially at low
photon counts, when weak biological structures become difficult to distinguish from shot noise and the prior strongly influences the reconstruction. RL recovers structure in early iterations but can amplify noise and become unstable, while regularizers such as total variation (TV) reduce these artifacts at the cost of oversmoothing. Instead, we learn a prior from real fluorescence microscopy images and use its gradient within an inverse-problem framework. The prior is estimated using an unconditional score-based
diffusion model trained on a large microscopy
dataset. At each step, the learned prior guides RL toward plausible specimen structures, while RL enforces Poisson consistency with the measured counts. Across diverse biological samples and cellular morphologies, the framework reduces RL noise amplification while better preserving weak structures at low
photon counts.
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Physics and Society
Exact Solution of Granovetter's Threshold Model for a Finite Population
José F. Fontanari
The Granovetter threshold model formalizes collective behavior by assuming that individual
agents face a binary decision to join a movement, doing so only when the number of already active participants reaches or exceeds an intrinsic, personal threshold. In this work, we derive an exact analytical expression for the probability that a cascade halts with precisely $k$ active
agents in a finite population of size $N$ triggered by a single initial instigator, and use this result to obtain the scaling corrections that govern the system near its critical boundaries. By parameterizing individual threshold heterogeneity via a Beta distribution with shape parameters $\alpha$ and $\beta$, we map how these micro-level predispositions aggregate into macro-level collective outcomes. Here, a small $\alpha$ represents a high proportion of low-threshold, highly susceptible
agents, while a small $\beta$ marks a significant density of high-threshold, conservative individuals. In the infinite-population limit, a phase transition occurs at the critical parameter $\alpha = 1$, which separates an inactive phase from a regime of widespread mobilization. For a power threshold distribution ($\beta = 1$), the system exhibits a discontinuous, first-order phase transition where the active fraction jumps abruptly from 0 to 1, and the finite-size critical scaling window contracts as $N^{-1/2}$. In stark contrast, when the population features a persistent density of high-threshold
agents ($\beta < 1$), the system undergoes an infinite-order phase transition characterized by an exceptionally smooth, continuous onset of collective activity, causing the finite-size critical region to contract at a drastically slower rate proportional to $(\ln N)^{-1}$. These analytical findings establish a mathematical
benchmark for finite-size effects in behavioral cascades.
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Quantum Physics
Finite-Shot Sensitivity for Moment Estimation in Quantum Metrology
Shaowei Du, Shuheng Liu, Weidong Li et al. (+3 more)
The
quantum Cramér-Rao bound can be saturated only asymptotically and does not specify how many measurements are needed for a concrete
estimator to approach it. We develop a finite-measurement theory for method-of-moments estimation, where the parameter is inferred from the sample mean of a calibrating observable rather than from the full likelihood. For general
quantum statistical models, the expansion is written in terms of the calibration curve and the central moments of the measured observable. Nonlinear calibration curves make the usual moment
estimator biased at finite measurement number; we construct a bias-corrected
estimator with bias $O(\nu^{-3})$. This gives sensitivity corrections beyond the leading error-propagation term of the chosen moment protocol. We identify a general density-
matrix condition under which the full $1/\nu^2$ correction vanishes. In
unitary examples, the leading residual correction appears at order $1/\nu^3$, is governed by calibration
curvature, and can be reduced or cancelled by higher-rank components of the same measured observable. The resulting thresholds quantify how many measurements are needed before the asymptotic sensitivity of a moment-estimation protocol is operationally visible.
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All authors Shaowei Du, Shuheng Liu, Weidong Li, Luca Pezzè, Augusto Smerzi, Qiongyi He
Statistical Mechanics
Macroscopic Fokker-Planck equation from microscopic Glauber dynamics for the Nagle-Kardar model
Jean-François de Kemmeter, Stefano Ruffo and Stefano Gherardini
In the companion Letter we have highlighted the dynamical universality class of the Nagle-Kardar model, where a mean-field interaction is added to the one-dimensional nearest-neighbor Ising model. Starting from the microscopic Glauber dynamics, this paper provides a complete derivation of the Fokker-Planck equation that describes the time
evolution of the macroscopic variables (magnetization and defect density) appearing in the model's
Hamiltonian. The study of the Langevin equation, associated with the Fokker-Planck equation, allowed us to prove that the model belongs to the universal class of systems with diffusive dynamics and non-conserved order parameter (model A). To this goal, we used several features of the model at
equilibrium, including the phase diagram and the fluctuations of macroscopic variables, which are here discussed for completeness. The derivation of the Fokker-Planck equation requires the solution of some combinatorial problems that appear in the counting of configurations at an intermediate level between the microscopic Glauber dynamics and the macroscopic Fokker-Planck one. Finally, we apply both the Glauber and the Langevin dynamics to the study of the average first passage time between local
equilibrium states. We confirm that this time obeys an exponential Arrhenius law in terms of system's size, offering a direct link between microscopic energy landscapes and macroscopic relaxation mechanisms.
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Biological Physics
Density-dependent growth emerges from Bayesian adaptation of phenotype
Manish Kumar Gupta, Arnab Barua and Haralampos Hatzikirou
Classical models often describe early tumor expansion as exponential growth, yet experimental and clinical evidence shows that tumor populations can deviate systematically from this behavior, exhibiting density dependent proliferation, cooperative low-density growth, intermediate growth optima, and finite upper growth bounds before resource limitation or spatial crowding dominate. These observations raise a common question: why should the per capita growth rate depend on population size? Here, we propose that sensing mismatch provides a mesoscopic link between environmental change and density dependent proliferation. We model the
cell as a
Bayesian adaptive
agent whose coarse grained phenotype evolves on an intrinsic regulatory landscape, while environmental sensing reweights phenotypic states according to how well they account for the extracellular signal statistics generated by the population. In the weak phenotype signal correlation regime, the stationary phenotype distribution is Gaussian, with its mean displaced from the proliferative optimum by a population size-dependent baseline information mismatch. This displacement produces a quadratic penalty in the per capita growth rate. Coupling the framework to a receptor ligand decoding model, we show that basal readout error and nonlinear receptor saturation make the mismatch nonmonotonic in population size. This single structure gives rise to an intermediate proliferation optimum, an Allee survival threshold, a tissue specific capacity, and superlinear scaling at low density. A phase diagram in the phenotype signal coupling and readout-error plane partitions growth into regulated, uncontrolled, and arrested regimes. Thus, density dependent proliferation need not be imposed phenomenologically, but can emerge from cellular sensing and inference.
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Computational Physics · Cross-listed from math.NA
A fast scheme for the homogeneous Boltzmann equation based on lifting and tensor train approximation
Kun Huang, Yingda Cheng and Irene M. Gamba
We propose a fast deterministic scheme for the space-homogeneous Boltzmann equation that exploits the low-rank structure of the velocity distribution. This paper consists of two independent contributions. The first is a lifting-projection (LP) scheme, inspired by the approach in the recent theoretical breakthroughs \cite{guillen2025landau, imbert2026monotonicity, guillen2025landau2} on the well-posedness of the Landau and Boltzmann equations. In particular, the approach lifts the nonlinear 3D Boltzmann equation to the 6D linear Kac master equation, advanced over a single time step, and projected back to its marginal in 3D. The second contribution is a low-rank tensor method for evaluating the collision operator, in which the lifted solution is represented in tensor train (TT) format and computed via a TT cross approximation
algorithm with interpolation, complemented by a TT-friendly conservation correction that enforces conservation of mass, momentum, and energy. When the solution is low-rank in velocity, the method scales linearly in $n$ when cubic interpolation is used (and quadratic in $n$ when spectral interpolation is used), where $n$ is the number of grid points in each velocity direction. Therefore, our methods offer significant computational savings over existing deterministic solvers in such cases. Numerical experiments on 2D and 3D
benchmarks, including the BKW exact solution and anisotropic initial data, confirm the computational scaling, the expected order of accuracy and verify the effectiveness of the conservation correction.
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Medical Physics
On the link between optoacoustic imaging and selective photothermolysis
Sergio Contador, Rodrigo Rojo, Alvaro Jimenez et al. (+1 more)
Selective photothermolysis (SP) is widely used in clinical and cosmetic dermatology to remove unwanted skin structures. Careful
laser parameter selection results in safe and effective target removal. Nevertheless, parameter selection relies on a trial-and-error process based on visual inspection of the immediate skin response. This process is highly dependent on the practitioner experience and can be time-consuming. SP and optoacoustic imaging (OI) share many physical principles. However, the possibility of using OI to improve
laser parameter selection in SP has not been studied before. Here, we explore the relationship between OI and SP theoretically and through clinical in-human trials with a focus on tattoo removal. Our results demonstrate a strong correlation between OI signals acquired before and after treatment with the immediate clinical endpoint, suggesting that OI could be used as a tool for optimal parameter selection and reduced treatment duration in tattoo removal and other SP treatments.
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All authors Sergio Contador, Rodrigo Rojo, Alvaro Jimenez, Juan Aguirre
Materials Science
Orientation Mapping via Dictionary Indexing of AC-STEM Kikuchi patterns using Open-source Software
Shamail Ahmed, Johannes Haust, Felix Gruber et al. (+5 more)
The properties of polycrystalline materials are strongly influenced by the spatial arrangement and orientations of individual grains within the microstructure, making nanoscale characterization of grain orientation essential. This is also often the case for small grains in the nm regime explored using scanning transmission electron microscopy (STEM). Automated
crystal orientation mapping (ACOM) is traditionally performed using spot-like diffraction patterns. In contrast, orientation mapping based on transmission Kikuchi diffraction (TKD) using an aberration-corrected (AC) convergent STEM probe remains relatively underexplored, despite its superior orientation sensitivity and higher spatial resolution. In this work, we present an open-source software-based template-matching approach for orientation mapping using AC-STEM TKD. A master pattern (a simulated angular distribution of Kikuchi band intensities on the unit sphere) is first generated through a dynamical simulation implemented in open-source software. This resulting pattern is subsequently imported into another open-source package for
geometric simulations and orientation indexing. We demonstrate the capability of the proposed method by applying it to orientation mapping in BaZr0.4Ce0.4Y0.1Yb0.1O3-{\delta} (BZCYYb4411) fuel-
cell material and LiNiO2 (LNO) lithium-ion battery cathode material. The best-matched simulated patterns exhibit strong agreement with experimental data, even under the challenging conditions with limited diffraction space available for matching.
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All authors Shamail Ahmed, Johannes Haust, Felix Gruber, Celina Becker, Juergen Belz, Andreas Beyer, Laura-Alena Schaefer, Kerstin Volz