Atomic Physics
One-loop self-energy using a numerical Green function
Hugo D. Nogueira, Maen Salman and Jean-Philippe Karr
We calculate the one-loop self-energy in hydrogenlike atoms using a numerical Green function obtained by solving the radial Dirac equation in an exponential basis set. The self-energy correction in the ground state of hydrogenlike uranium is obtained with about $10^{-5}$ relative uncertainty in the Feynman gauge. Using a convergence acceleration scheme, we extend our calculations to the region of low
nuclear charges. Our results allow calculating the self-energy correction for the hydrogen atom with $10^{-4}$ relative uncertainty. Calculations in the Coulomb gauge are also presented, improving the precision to $10^{-5}$. Present limitations and possible improvements of our method are discussed.
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Mesoscale and Nanoscale Physics
Raphael Ayache, Nilotpal Chakraborty, Manabendra Kuiri et al. (+11 more)
Although individual skyrmions are topologically protected objects, their cooperative crystalline order is fragile, easily disrupted by thermal fluctuations or other external perturbations. Probing the internal dynamics of such a
crystal is both compelling and challenging, as its intricate and delicate
spin texture must remain stable during measurement. Here, we engineer a nanoscale
graphene junction hosting a skyrmion Wigner
crystal, embedded between
magnon emitters and detectors. The skyrmion
crystal geometry leaves a striking imprint on
magnon transport: as the gate voltage is varied, near-periodic windows of sharp fluctuations in
magnon count are detected across the entire sample. We develop an interpretation that this results from skyrmions being added one by one to a quasi-one-dimensional array. Each burst of the fluctuations thus corresponds to the entry of an additional skyrmion, during which the
lattice stiffness reduces. The impinging
magnons induce and act as a probe of non-
equilibrium collective dynamics of the
crystal. These results establish a real-space probe of topological
spin textures in
quantum Hall-type insulating ground states via
magnon transport and open opportunities to explore correlated, topologically ordered phases in moire and multilayer
graphene systems.
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All authors Raphael Ayache, Nilotpal Chakraborty, Manabendra Kuiri, Quentin Benichou, Antonio Lacerda-Santos, Lilian Seyve, Himadri Chakraborti, Leo Pugliese, Kenji Watanabe, Takashi Taniguchi, Cosimo Gorini, Roderich Moessner, Benoit Doucot, Preden Roulleau
Quantum Physics
Tunable Families of Multiqubit Elegant Joint Measurements
Jef Pauwels and Nicolas Gisin
We give a closed-form construction of the $n$-
qubit Elegant Joint Measurement (EJM) proposed in [PRL 136, 190201 (2026)] and show that it is part of a tunable family of measurements with tetrahedrally arranged Bloch vectors. The construction is based on the interference pattern implied by a single phase
polynomial built from the elementary symmetric functions. It realises a regular tetrahedral measurement for every $n$, and the corresponding measurement
unitary lies at level $n{+}1$ of the Clifford hierarchy. Starting from this measurement, we ask whether the size of the local tetrahedron – and hence the
entanglement of the basis – can be varied while preserving its
symmetry. For every even $n$ the answer is yes, and remarkably the size follows the same one-parameter law that governs the known two-
qubit family, interpolating down to a $1$-uniform basis. For $n=3$ the EJM is locally isolated, while for odd $n\ge5$ we do not know an analogous closed-form family. We also give an analogous construction, valid for every $n \geq3$, with square local geometry.
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Astrophysics of Galaxies
Infrared spectroscopy of gas-phase hydrogenated and methylated pyrenes: from laboratory spectra to the simulated 3.4 $\mu$m emission band
Karine Demyk, Christine Joblin, Louan de Bentzmann et al. (+2 more)
Observations of the aromatic infrared emission band at 3.3 mic often reveal satellite emission features in the 3.4 - 3.6 mic range. While the 3.3 mic band is attributed to the CH stretching vibration of polycylic aromatic hydrocarbons (PAHs), the satellite bands - particularly its prominent 3.4 mic component - is assigned to aliphatic CH stretching vibrations in hydrogenated and methylated PAH-like species. Our aim is to derive state-of-the-art infrared emission spectra for aliphatic-containing pyrene derivatives and compare them with astronomical observations. This will help refine our understanding of the contribution of these species to the 3.4 mic emission band. Mid-infrared spectra (1.4-25 mic of gas-phase dihydropyrene, tehtrahydropyrene, hexahydropyrene methylated pyrene, and pyrene were recorded at temperatures ranging from 373 to 673 K, depending on the species. The band profiles were analyzed using a multi-component fitting tool, and empirical anharmonicity laws were derived to quantify the
evolution of the band positions and widths with temperature. The obtained spectral data was combined with the results of a Monte Carlo emission model to simulate the emission spectra following UV-
photon absorption, up to the dissociation limit (<6 eV). The resulting synthetic spectra were compared with James Webb Space
Telescope observations of the Orion Bar region (PDRs4All program). Based on these state-of-the-art simulated spectra, we show that 1,2,3,6,7,8-hexahydropyrene matches all the constrains to fit the red component of the 3.4 mic band observed at 3.403 mic. While 1-methylpyrene may also contribute to the underlying emission plateau, its lack of a strong infrared band complicates detection in observed spectra, unlike hexahydropyrene. All experimental spectra and their temperature-dependent analyses are available in the new cosmicPAH-IRDB database.
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All authors Karine Demyk, Christine Joblin, Louan de Bentzmann, Dominique Toublanc, Giacomo Mulas
Mesoscale and Nanoscale Physics
Negative quantum friction in nanoscale water flows: the Wigner picture
Adriano Tiribocchi, Marco Lauricella, Efthimios Kaxiras et al. (+1 more)
We explore the phenomenon of "
quantum" friction based on a single-particle model patterned after the Wigner equation describing electrons flow in a solid wall confining nanoscale water flows. The numerical simulations show a clear signature of negative
quantum friction, namely a net momentum transfer from the electrons in the solid wall to the flowing water molecules. Such net momentum transfer results into a sizeable reduction of the water friction, up to forty percent, depending on the strength of the coupling between classical and
quantum fluctuations. Our results offer the prospect of a theoretical framework bridging classical and
quantum description by using continuum kinetic theories and particle-based simulations.
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All authors Adriano Tiribocchi, Marco Lauricella, Efthimios Kaxiras, Sauro Succi
Mathematical Physics
Variational modeling adapted to the medium with gradient properties
Azdine Nait-Ali and Sami Ben Elhaj Salah
This study aims to develop a numerical homogenization method that can be applied to a heterogeneous stratified medium. Traditional scale transition methods are inadequate in capturing the essential gradient properties of some materials. Therefore, the focus of this work is to construct a homogenized model that considers the material property gradient. To achieve this, a two-step homogenization scheme is proposed. Firstly, the 3D model is decomposed into multiple 2D heterogeneous layers, and the behavior of each layer is estimated using a micro-mechanical model such as the Hashin-Shtrikman bounds. Secondly, a variational sum method is used to rebuild the behavior of the 3D environment. Finally, the method is applied to homogenize a thin plate with a porosity gradient.
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Superconductivity
Drosophila of phonon-mediated superconductivity: Full Eliashberg theory of the jellium model
Christophe Berthod, Louk Rademaker and Dirk van der Marel
We present a full numerical solution of the Migdal–Eliashberg equations for the jellium model of
phonon-mediated superconductivity. We find very low critical temperatures below 1~K, in contrast to earlier claims that the jellium model for hydrogen solids might reach room-temperature superconductivity. Our results suggest that full momentum and frequency dependence of the gap function and normal self-energy should be taken into account for accurate $T_c$ estimates.
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Mesoscale and Nanoscale Physics
Qubit encodings in the p-orbital-valley spectrum for enhanced coherence and tunable two-qubit interaction
John H. Caporaletti and J. P. Kestner
We propose encoding a
qubit in a two-level subspace spanned by the lowest $p$-orbital state in the excited valley of an anisotropic
quantum dot and the excited $p$-orbital in the ground valley, which we dub the $pOv$
qubit. There is an avoided crossing between these states due to valley-orbit coupling (VOC) induced by
alloy disorder, enabling complete single-
qubit control using baseband electrical control of the dot anisotropy. We find that `sweet spots' exist at specific dot orientations where the instantaneous eigenstates are first-order insensitive to charge noise. Using a phenomenological two-level fluctuator (TLF) dipole noise model, we estimate an average dephasing time of $T_2^*\approx 10\,\mu\text{s}$ and a quality factor of $Q\sim 10^4$. Alternatively, encoding in the $p$-orbital states in the ground valley near the isotropic dot point, we show that one can induce a similar sweet spot via an out-of-plane
magnetic field. Finally, we find that two-
qubit gates for the $pOv$
qubit are mediated by the quadrupole-quadrupole Coulomb interaction and can be electrically tuned from zero to $\sim 1~\text{GHz}$ by adjusting the relative orientation of the anisotropic dots, providing a novel pathway towards scalable
quantum computation.
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Mesoscale and Nanoscale Physics
Phase-controlled quasi-bound states in the continuum and thermoelectric enhancement in Majorana-quantum-dot nanostructures
Alejandro Garrido, David Zambrano, Hishan Farfán-Bachiloglu et al. (+3 more)
We investigate how the interplay between Majorana zero modes (MZMs) and bound states in the continuum (BICs) governs the electronic thermoelectric response of a crossbar-shaped
quantum dot (QD) coupled to two topological-
superconductor nanowires. Using the Green-function formalism, exact linear-response energy integrals, and their low-temperature Sommerfeld expansion, we analyze the spectral and thermoelectric properties of the system. We show that
symmetry breaking converts BICs into quasi-BICs, allowing them to contribute to electrical and thermal transport and thereby generate a finite thermoelectric response. While unequal nanowire lengths, reflected in different intra-Majorana coupling strengths, produce only a modest enhancement of $ZT_{el}$, detuning the QD level increases $ZT_{el}$ by approximately one order of magnitude. Superconducting-phase control produces a much stronger enhancement, reaching $ZT_{el} \simeq 0.75$ through a quadratic transmission zero and a pronounced violation of the Wiedemann-Franz law. The low-temperature values $ZT^{max}_{el} \simeq 0.755$ and $\mathscr{L} /\mathscr{L}_{0} = 21/5$ are universal consequences of this quadratic antiresonance. Our results establish phase-tunable thermoelectric signatures of the Majorana-coupled interference structure and identify superconducting-phase control as an efficient means of engineering the electronic response of topological hybrid nanostructures.
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All authors Alejandro Garrido, David Zambrano, Hishan Farfán-Bachiloglu, Juan Pablo Ramos-Andrade, Vladimir Juričić, Pedro Orellana
Physics and Society
Diffusion-induced instabilities promote cooperation in eco-evolutionary networks
Sourav Roy, Md Sayeed Anwar, Timoteo Carletti et al. (+2 more)
Understanding how cooperation persists despite the advantage of selfish behavior remains a central challenge in evolutionary dynamics. Classical models of public goods dilemmas predict dominance of defectors, yet natural and social systems often sustain cooperation. We study an eco-evolutionary public goods game on complex networks where cooperators and defectors diffuse at different rates. When the isolated system is in a defector-dominated coexistence regime, faster dispersal of defectors than cooperators leads to a
symmetry-breaking transition that produces localized clusters of cooperators. In heterogeneous networks, nodes with higher connectivity become significantly more likely to exhibit cooperative dominance. A degree-based mean-field reduction supports this result by showing that network connectivity controls an effective coupling strength proportional to node degree, thereby producing a bifurcation that separates defector-dominated and cooperative states. We also address why not all hubs become cooperative by means of a multistability analysis. These results reveal how asymmetric mobility and heterogeneous connectivity jointly promote cooperation in structured populations.
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All authors Sourav Roy, Md Sayeed Anwar, Timoteo Carletti, Matjaz Perc, Dibakar Ghosh
Soft Condensed Matter
Fast temperature up steps as a test of the Tool-Narayanaswamy formalism
Armand Rykner, François Ladieu and Marceau Hénot
We investigated the aging dynamics of a glass-forming
liquid triethyl-2-acetylcitrate (TEAC), following fast temperature up steps with amplitudes ranging from 0.3 to 13.6 K. The initial states were either at
equilibrium or prepared at increasing levels of out-of-
equilibrium through a prior down step experiment. Our goal was to test the predictive power of the Tool-Narayanaswamy (TN) formalism which assumes that the non-linear re-equilibration of a
liquid can be linked to its linear response to a small perturbation. We determined the TN parameters for steps with small to moderate amplitude ($\leq 3.3$~K) and crucially took advantage of down step aging experiments below the glass transition temperature to constrain the determination of the
equilibrium relaxation time. We tested the TN predictions and found very good agreement for differences in fictive temperature characterizing the distance from
equilibrium as high as 10~K. For larger steps, however, the prediction progressively fails to capture the aging dynamics. This likely indicates that the re-equilibration mechanism is no longer related to the
equilibrium dynamics. Finally, we discuss the possibility of obtaining a general criterion for the limit of validity of the TN formalism, which we compare to other systems from the literature.
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High Energy Physics (Phenomenology)
Gluon Saturation
Alfred H. Mueller
This is a review on
gluon saturation. Sec. 1 gives a general introduction to the subject while Sec. 2 has a brief discussion of
quark saturation. Sec. 3 covers
gluon saturation in a semiclassical limit and the much more general context of QCD
evolution. Surprisingly
gluon occupancies in a high energy
hadron can become arbitrarily large, much larger than $1/\alpha$. Sudakov effects are introduced in Sec. 4 and reduce the maximum
gluon occupancies to less than or equal to $(1/\alpha)^{3/2}$ in both fixed coupling and running coupling QCD. In Sec. 5 the role of saturation in coherent states in QCD is reviewed as well as brief discussions on
nuclear shadowing, heavy ion collisions and Drell-Yan like processes are given.
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Nuclear Theory
The anomalous long lifetime of $^{14}$C revealed by ab initio nuclear lattice EFT
Teng Wang, Serdar Elhatisari, Xu Feng et al. (+2 more)
The 5730-year half-life of $^{14}$C, the physical basis of radiocarbon dating, is anomalously long compared to typical
nuclear-physics expectations. Its origin has remained a subject of debate for many decades. Here we report an ab initio
nuclear lattice effective field theory (NLEFT) calculation of $^{14}$C $\beta$ decay. Using systematically optimized interactions and transition operators consistently derived from
chiral effective field theory, We obtain a result consistent with the Gamow-Teller
matrix element $M_\text{GT}^\text{exp}\simeq 2\times 10^{-3}$ measured with the current uncertainty of $O(10^{-2})$. We first show that
chiral interactions and weak currents beyond leading-order are essential for quenching the GT
matrix element to the physical value, among which the optimization of three-nucleon forces is indispensable. We then illustrate that the quenching is deeply rooted in the ground-state structure of $^{14}$N as found in the
nuclear shell model, where the competition between $S$- and $D$-wave components exists, sensitive to the interaction employed. The physical $^{14}$N ground state is found to be dominated by $D$-wave configurations, which constitutes the key factor for the quenching. The sensitivity of the decay
matrix element to the fine-tuning of low-energy-constants is explored, revealing the prominent role of the $^3S_1$-channel two-nucleon contact force and the one-pion-exchange three-nucleon force. This work eliminates the gap between shell-model and ab initio studies of $^{14}$C $\beta$ decay, provides a valid and straightforward explanation for the anomalous long lifetime of $^{14}$C, and turns NLEFT into a practical tool for the systematic study of
nuclear transitions.
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All authors Teng Wang, Serdar Elhatisari, Xu Feng, Bing-Nan Lu, Ulf-G. Meißner
Quantum Physics
Parameter Estimation in a Continuously Monitored Non-Markovian Quantum System
Erik L. André, Pharnam Bakhshinezhad, Patrick P. Potts et al. (+2 more)
Continuous monitoring is a powerful tool for analyzing
quantum systems and is increasingly used as a non-demolition technique in
quantum metrology. In this context, noisy data acquired through continuous monitoring can be used to precisely pinpoint unknown parameters of the system. However, extending the theoretical framework that connects these data to the underlying parameters beyond Markovian dynamics is notoriously difficult, primarily because such dynamics cannot be expressed as completely positive divisible maps. To overcome this, we propose a method based on the reaction coordinate mapping to extend these parameter-estimation techniques beyond the Markovian regime. Our approach specifically targets linear systems with non-Markovian dynamics undergoing Gaussian continuous measurements, such as homodyne detection. Within this framework, we analyze
Bayesian estimation and provide an analytical expression for the Fisher information, alongside the asymptotic scaling of the estimation precision for arbitrary parameters. Finally, we demonstrate the efficacy of our method through the example of thermometry of a bosonic bath.
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All authors Erik L. André, Pharnam Bakhshinezhad, Patrick P. Potts, Luis A. Correa, Mohammad Mehboudi
Atomic Physics
A coherent quantum interface between a neutral atom and a polar molecule
Daniel K. Ruttley, Tom R. Hepworth, Juan M. García-Garrido et al. (+4 more)
Arrays of trapped neutral atoms and polar molecules have separately emerged as powerful and complementary platforms for
quantum science. Neutral atoms enable fast, programmable interactions through excitation to Rydberg states, whereas polar molecules possess long-lived rotational states that are attractive for
quantum memories and qudits. Combining these platforms would create new possibilities, but requires a coherent interface between individual atoms and molecules, which so far has not been realised. Here, we establish such an interface between a single neutral atom and a single polar molecule. By tuning atomic and molecular transitions into resonance, we realise strong state-dependent dipolar interactions at micrometre separations in an optical tweezer platform with single-particle control. We exploit this interface to perform
quantum operations between the two particles, demonstrating atom-mediated readout of a molecular
qubit, coherent
spin exchange, and
entanglement using a blockade-based controlled-NOT operation. These results establish a new hybrid
quantum platform at the intersection of atomic and molecular physics, in which long-lived molecular
quantum information can be rapidly mapped onto an atom for readout or onward coherent transfer. The platform provides a route to hybrid
quantum processors utilising atom-mediated readout and
entanglement of molecular
qubits, mixed-species
quantum simulators of dipolar systems, and macroscopic entangled molecular states for
quantum-enhanced metrology and precision sensing.
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All authors Daniel K. Ruttley, Tom R. Hepworth, Juan M. García-Garrido, Caleb J. H. Rich, Rosario González-Férez, Alexander Guttridge, Simon L. Cornish
Soft Condensed Matter · Cross-listed from q-bio.CB
A phenomenological multiscale framework for orientational interactions and viscoelasticity in migrating epithelial monolayers
Ivana Pajic-Lijakovic, Milan Milivojevic and Peter V.E. McClintock
Collective migration of epithelial monolayers emerges from the interplay between mechanical interactions and biochemical signalling. Here, we present a phenomenological mechanobiological framework linking
cell-scale orientational interactions to tissue-scale mechanics. We distinguish reversible and irreversible head-on and glancing collisions, showing that reversible interactions store orientational mechanical energy while preserving collision geometry, whereas irreversible interactions dissipate energy and alter
cell orientation. The balance between energy storage and dissipation governs collective migration, mechanical feedback, and density-dependent processes including
cell jamming and live
cell extrusion. These interactions regulate
cell elasticity, contractility, and adhesion, thereby modifying epithelial surface tension and the effective viscoelastic response of the monolayer. We quantify these effects using orientational interaction potentials, an effective second virial coefficient, and dimensionless measures of stored and dissipated orientational energy. The relative contribution of these mechanisms increases with
cell packing density, becoming dominant near the jamming transition. This framework provides a constitutive interpretation connecting collision-induced orientation dynamics with emergent epithelial rheology and suggests how density-dependent interaction regimes shape collective migration and tissue viscoelasticity.
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Instrumentation and Methods for Astrophysics
Coherence differential imaging using gradient-boosted decision trees for the direct detection of exoplanets
Johan Mazoyer, María J. Mellado-Tenorio, Axel Potier et al. (+4 more)
Coronagraphic imaging of
exoplanets is limited by residual speckles that mimic
planets. Advanced post-processing is essential for current and future instruments on the ground or in space. Current techniques are time-intensive and limited. ADI requires long sequences and is limited at small separations. RDI is also time-consuming and sensitive to speckle
evolution, leading to imperfect subtraction. Coherence Differential Imaging (CDI), which we successfully demonstrated on SPHERE, offers a faster alternative by using the light incoherence between speckles and
planets. However, its reliance on accurate instrumental models limits its performance. In this work, we introduce EPICX, an enhanced CDI method using gradient-boosted decision trees. EPICX models the differential signal as a high-dimensional regression problem, optimizing the discrimination between coherent speckle noise and incoherent
planet signal. We validate this enhanced CDI method using simulated data for different coronagraphs, including those aboard JWST and Roman.
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All authors Johan Mazoyer, María J. Mellado-Tenorio, Axel Potier, Christian Wilkinson, Lukas Delaye, Raphaël Galicher, Iva Laginja
Astrophysics of Galaxies
Radio-detected Lya emitters at 1.88 < z < 3.52: AGN fraction and Lya emission
Sai Zhai, Huub Röttgering, Anniek J. Gloudemans et al. (+10 more)
Lya emitters (LAEs) are
galaxies with strong Lya emission, tracing early
star formation and ionizing radiation. Their connection to active
galactic nuclei (AGNs) is key to understanding the mechanisms behind (extended) Lya emission. In this work, we measure the fraction of LAEs identified as
radio-emitting AGN (fAGN,
radio) and the fraction of
radio sources that exhibit Lya emission (fLya) to investigate the connection between
radio AGN activity and Lya emission at 1.88 < z < 3.52. We identify 928 sources detected in both the Hobby-Eberly
Telescope Dark Energy Experiment (HETDEX) and the LOw Frequency ARray (LOFAR) surveys. These matches are drawn from 55,109 spectroscopically confirmed LAEs and 27,625
radio sources. After applying completeness corrections, we obtain fAGN,
radio = 1.77 $\pm$ 0.04% and fLya = 18.15 $\pm$ 0.14%. The fraction fAGN,
radio increases from 0.4 $\pm$ 0.1% to 9.7 $\pm$ 1.3% with increasing Lya luminosity, while fLya rises from 0.7 $\pm$ 0.1% to 55.8 $\pm$ 14.5% with
radio luminosity. `LAEs with
radio AGN' and `optical AGN with Lya emission' show similar
radio luminosities above the AGN threshold, although optical AGN have higher Lya luminosities. We find no significant correlation between Lya luminosity and either
radio luminosity or spectral index. Lya line width increases with Lya luminosity but shows no correlation with
radio size. Our results show that most Lya emission at 1.88 < z < 3.52 is powered by
star formation, with
radio AGN activity confined to a small luminous subset (1.77 $\pm$ 0.04%). The absence of correlations between Lya and
radio properties suggests that Lya emission is governed primarily by host-
galaxy gas properties rather than direct AGN jet coupling.
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All authors Sai Zhai, Huub Röttgering, Anniek J. Gloudemans, Erin Mentuch Cooper, Maya H. Debski, Gregory Zeimann, Matt J. Jarvis, Leah K. Morabito, Donald P. Schneider, Daniel J. Farrow, Gary J. Hill, Caryl Gronwall, Yuming Fu
Physics and Society
Sociocultural Influences on Opinion Formation: Word of Mouth Dynamics, Mass Media and Behavioural Development
Elpida Tzafestas
We study a society of
agents belonging to a number of occupational or cultural groups that form opinions about others' situation in the same or different group. Opinions develop either by observation within own group or by directly interacting with members of other groups, therefore by word of mouth (WoM). Additionally, global mass media (MM) may be available that inform indirectly about the situation of the various groups. The sociocultural interplay of these processes and the degrees of relative exposure to each of the sources has diversified effects on final opinion and social attitude formation. In large and complex societies and groups where not everyone can physically interact by WoM with everyone about everything, these processes show potential for mass control and social automation engineering. Our model can also represent and be generally informative about segmented societies that consist of groups with different occupational and cultural characteristics and it can offer insights into social issues such as the generation gap, social cleavages and so on.
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Materials Science
Nonuniform pressure helps structural superlubricity
Melisa M. Gianetti, Viet Hung Ho, Bjørn Haugen et al. (+2 more)
Structural superlubricity, nearly vanishing friction between two structurally incommensurate crystalline surfaces, is a promising avenue for reducing friction in applications, but requires very specific and well-controlled conditions. One of those conditions is perfectly uniform atomically flat surfaces. Real-world surfaces are generally rough, leading to nonuniform pressure distributions. We investigate the effects of nonuniform pressure distributions on structural superlubricity, using analytical calculations for rigid contacts as a basis, and molecular-dynamics simulations for a simple model to include the crucial effects of elasticity. We show that a key ingredient is the vanishing pressure at the edge of the contact, and that this leads to improved scaling depinning and scaling behaviour, leading to lower friction. We thus show that nonuniform pressure distributions actually help structural superlubricity, rather than hinder it.
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All authors Melisa M. Gianetti, Viet Hung Ho, Bjørn Haugen, Graham Cross, Astrid S. de Wijn
High Energy Physics (Phenomenology)
Portal Matter and Scotogenic-like Dirac Neutrino Masses
Thomas G. Rizzo
Loops of portal matter (PM) fields, carrying both Standard Model (SM) and dark charges, can generate the necessary kinetic mixing (KM) between the ordinary and dark
photons (DP) in vector portal scenarios thus allowing for interactions between visible and dark sector fields. Here we show that the field content of a previously considered model based on a partial $E_6$-like UV-completion of such setups can generate light Dirac
neutrino masses in the interesting range, $\sim 0.05$ eV, at the one-loop level similar to what happens in scotogenic dark matter (DM) scenarios. While general $E_6-$like PM scenarios have been shown to be easily probed at
colliders, such as the HL-LHC, uniquely testing this specific subclass of these setups in a direct fashion is found to be somewhat more challenging.
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High Energy Physics (Theory)
Hanbury-Brown Twiss effect, squeezed gravitons and the photon correlations
Massimo Giovannini
Unlike the gravitational waves classically generated by moving macroscopic masses, the diffuse backgrounds of gravitons originate most likely from zero-point fluctuations of the gravitational field amplified by the
evolution of the space-time
curvature. The resulting entangled states lead to specific second-order correlation effects that could be eventually detected. For a quantitative analysis of this empirical expectation we scrutinize the interactions between the
cosmic gravitons and the fundamental mode of a quantized electromagnetic field confined inside a closed optical resonator with perfectly-reflecting walls. We show that the Hanbury-Brown Twiss correlations of the
photons are insensitive to the degrees of second-order coherence of the gravitons even barring for the exceedingly small couplings of the problem. Since the degree of second-order coherence of the
photons does not reflect the correlation properties of the gravitons, the statistical properties of the gravitons (and their super-Poissonian statistics) cannot be inferred, even in principle, from the intensity correlations of the cavity modes.
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High Energy Astrophysical Phenomena
Non-thermal emission from the vicinity of the magnetar CXOU J171405.7-381031
Manoel F. Sousa and Rita. C. Anjos
Magnetars are
neutron stars with ultra-strong
magnetic fields ($B \sim 10^{14}$-$10^{15}$ G) and are promising candidates for high-energy particle acceleration. We present a multiwavelength analysis of the region surrounding CXOU J171405.7-381031, a magnetar associated with the
supernova remnant (SNR) CTB 37B. The broadband spectral energy distribution spanning
radio to TeV energies is modeled using leptonic and lepto-hadronic scenarios, with particle populations constrained using Markov Chain Monte Carlo techniques. Within an SNR framework, both scenarios provide acceptable descriptions of the gamma-ray data. The purely leptonic model reproduces the overall spectral shape but slightly underestimates the highest-energy flux measured by H.E.S.S., whereas a lepto-hadronic interpretation offers an improved description above $\sim 10$ TeV, with inverse-Compton scattering dominating the GeV emission and neutral-pion decay contributing at the highest energies. The required
proton energy ($W_{\rm p} \gtrsim 10^{51}$ erg) can be substantially reduced if the remnant interacts with a dense ambient medium. A magnetar wind nebula scenario can reproduce the broadband spectrum but is strongly disfavored by the observed source morphology. Simulated Cherenkov
Telescope Array Observatory (CTAO) observations indicate that exposures of $\sim 50$ h will constrain the
proton cut-off energy, enabling a decisive test of hadronic emission in this region.
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Strongly Correlated Electrons
Altermagnetism without a long-range order
V. E. Valiulin, A. V. Mikheyenkov and K. I. Kugel
The Kugel-Khomskii
spin-pseudospin model, originally developed for transition-metal compounds with orbital degrees of freedom, has recently been reinterpreted in the context of altermagnetism. In this work, we theoretically investigate the emergence of altermagnetic behavior in the absence of long-range
magnetic or orbital order. Using the rotation-invariant Green's function method for the SU(2) x SU(2) symmetric model on a square
lattice and on a linear chain, we analyze
spin-
spin and
spin-pseudospin correlation functions, excitation spectra, heat capacity, and susceptibilities. We show that beyond a critical intersubsystem exchange Kc(T), a composite state arises with nonzero
spin-pseudospin correlations, even though the average
spin and pseudospin at each site are zero. The excitation spectrum splits into acoustic and optical branches, with nodal lines along qx = qy - a direct signature of altermagnetic
symmetry. A peak in heat capacity and a jump in susceptibility are observed at the phase boundary. In 1D, the phase boundary is nonmonotonic and demonstrates reentrant transition. These results establish the concept of an "altermagnetic paramagnet" or "altermagnetic
liquid" without long-range order, relevant for low-dimensional and strongly fluctuating systems.
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Biological Physics
Cauchy-Paul wavelet transforms revisited: A framework for intermittent non-sinusoidal oscillations
P. Argoul, J. Taillard and F. Argoul
This paper revisits the continuous wavelet transform framework by establishing a rigorous physical and dimensional formulation of the Cauchy-Paul mother wavelet, tailored specifically for intermittent, non-sinusoidal electrophysiological oscillations. Departing from conventional, purely mathematical definitions, we introduce a characteristic time scale $\tau$ into the frequency-domain formulation of the mother wavelet. This parameter ensures strict dimensional consistency by maintaining dimensionless functional arguments, thereby confining the physical dimension solely to the multiplicative normalization constant under both $L^1(\mathbb{R})$ and $L^2(\mathbb{R})$ norms. A sharp dimensional and structural analysis of the resulting wavelet is conducted. We demonstrate that the spectral asymmetry inherent to the Cauchy-Paul wavelet dictates a strict mathematical hierarchy between three alternative reference frequencies: the peak ($L^\infty$), the centroid ($L^1$), and the energy-weighted ($L^2$) frequencies. Each frequency definition yields distinct quality factors ($Q$) and time-bandwidth characteristics that govern the time-frequency localization trade-off. To track multi-component
EEG sleep pattern signals, a phase-based algebraic
estimator is deployed alongside an advanced ridge-extraction method. The robust tracking performance and morphological adaptability of the proposed Cauchy-Paul framework are first numerically validated on synthetic transients, harmonics, and chirps, and subsequently applied to real, non-stationary
EEG recordings to successfully isolate and decipher the non-sinusoidal signatures of sleep spindles.
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Quantum Physics
Conditional Euclidean-Hamiltonian reductions for sign-problem toy models
Tsogtgerel Gantumur
Euclidean Monte Carlo methods are effective when the path-integral weight is real and nonnegative, but finite-density
fermion systems often produce sign-changing or complex scalar weights after the fermionic sector is traced out.
Hamiltonian formulations avoid this complex-weight sampling problem but face rapid
Hilbert-space growth. This paper studies a conditional Euclidean-
Hamiltonian (CEH) reduction that combines these two descriptions. The calculation is organized around a Monte Carlo-tractable reference problem and a residual active sector. Instead of tracing the active sector into a determinant or scalar weight, CEH keeps it operator-valued and uses the reference calculation to determine projected correlation or transfer
matrices. These
matrices define a finite effective
Hamiltonian, with the remaining finite-density dependence introduced after projection. At finite rank, the result is an effective model whose accuracy must be tested through basis enlargement, metric conditioning,
stochastic matrix-element errors, and number-sector diagnostics. The construction is examined in three finite
benchmarks. A two-channel oscillator tests conditional basis compression; a positive-measure
stochastic calculation tests correlation-
matrix harvesting and GEVP extraction, including a comparison with a PDMS-style
estimator; and a four-site Hubbard ring combines a finite-budget determinant-sign stress test with finite-density continuation in non-target active spaces. The
benchmarks support the proposed trade from scalar sign reweighting to a monitored active-space approximation in structured finite models, but they do not provide an end-to-end
stochastic CEH treatment of the Hubbard sign problem or establish favorable scaling. Usefulness requires both low-rank approximability and efficient extraction of the required projected
matrix data.
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Quantum Physics
Beyond the Positive Partial Transpose Squared Conjecture: The Qutrit Case
Junhyeong An and Soojoon Lee
Entanglement swapping is a fundamental operation in
quantum repeaters for establishing
entanglement between distant parties. The positive partial transpose (PPT) squared
conjecture asks whether two PPT entangled links can generate terminal
entanglement through
entanglement swapping, or equivalently, whether the composition of two PPT maps is always
entanglement breaking. Motivated by this
conjecture, we investigate the map-composition problem beyond the PPT setting. For qutrit completely positive (CP) maps, we prove that the composition of any CP map whose Choi
matrix is $1$-undistillable with any CP map whose Choi
matrix has Schmidt number at most two is
entanglement breaking in either order. Moreover, we show that the cone of $1$-undistillable CP maps is exactly the largest qutrit cone of CP maps whose composition with every CP map whose Choi
matrix has Schmidt number at most two is
entanglement breaking in both orders. Finally, although map composition captures only the standard maximally entangled outcome in
entanglement swapping, we prove that any $1$-undistillable two-qutrit state and any state of Schmidt number at most two cannot generate terminal
entanglement under an arbitrary selective measurement on the intermediate systems.
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Mesoscale and Nanoscale Physics
Disentangling topological and anomalous Hall contributions of skyrmions using Kerr microscopy and thermal transport measurements
H.Heyen, M. Vogel, F. Gossing et al. (+4 more)
The topological
Hall effect is a valuable tool to indicate the presence of topologically protected
magnetic structures. In this work, we present topological
Hall effect measurements originating from topologically protected skyrmions in Ta/CoFeB/MgO single-layer thick films with a one nanometer thick
magnetic layer. The simultaneous occurrence of the small topological
Hall effect and the dominating anomalous
Hall effect in this material system makes direct detection challenging as compared to bulk or multilayer systems. In electronic transport measurements, both effects' contributions impact electron trajectories in the same way, overlapping in the measurement signal, and require disentanglement. Magneto-optical Kerr microscopy was used to image the surface magnetization, enabling the separation of the topological
Hall effect from other
Hall effect contributions. These measurements reveal a topological
Hall resistivity of $249(18)\,$\si{\pico\ohm\meter} for Ta/CoFeB/MgO layer stacks at room temperature. Magneto-optical Kerr effect (MOKE) measurements also allow tracking skyrmion formation during external
magnetic field sweeps to confirm their occurrence when measuring the topological
Hall effect. We verify this outcome by comparing the results with thermal and electrical transport measurements from which we calculate the overall topological quantity that gives rise to the topological Nernst and
Hall effect, respectively.
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All authors H.Heyen, M. Vogel, F. Gossing, J. Walowski, K. Dahmen, J. McCord, M. Münzenberg
Instrumentation and Detectors
A Hydrogenated Amorphous Silicon Photodiode indirect flexible device for radiation flux measurements at low intensities
Mauro Menichelli, Aishah Bashiri, Marco Bizzarri et al. (+46 more)
The objective of the Photo-HASPIDE experiment is the construction and test of an indirect a-Si:H (Hydrogenated Amorphous Silicon) photo-detector plus scintillator device on a flexible substrate for the detection and measurement of particles fluxes (X-rays, electrons and
protons) and for dosimetric measurements. The idea behind this experimental project lies in the utilization of Hydrogenated Amorphous Silicon (a-Si:H) as photodiode material; owing to its notable attributes of radiation hardness, light detection capability and mechanical flexibility. After the implementation of the HASPIDE experiment, which explored direct radiation detection using a-Si:H devices on a polyimide (PI) substrate, we aim to delve into indirect detection by employing these devices in conjunction with flexible and rad-hard scintillators like polysiloxane. The indirect detector design holds promise for improved responsiveness to low radiation fluxes compared to direct detection methods. The indirect a-Si:H detector should be composed of arrays of small (about 5 x 5 mm2) scintillator
crystals read by a-Si:H photodiodes. Through optimization of the scintillator and detector thicknesses, we expect to achieve a better performance for low minimum detectable fluxes compared to direct detection methodologies. This new detector will find application in in-vivo dosimetry during radiotherapy or
hadron-therapy and also, due to its expected fast response, in FLASH therapy. Another important application will be also in
Solar Physics using these devices to measure particle fluxes in
solar energetic particle events.
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All authors Mauro Menichelli, Aishah Bashiri, Marco Bizzarri, Lucio Calcagnile, Mirco Caprai, Domenico Caputo, Anna P. Caricato, Sara M. Carturan, Massimo Cazzanelli, Andrea Cesarini, Marco Cinausero, Federico Cittadini, Tommaso Croci, Sylvain Dunand, Michele Fabi, Giorgia Franchin, Benedetta Gianfelici, Antonella Giuri, Catia Grimani, Hamza Hasnaoui, Giacomo Insero, Maria Ionica, Keida Kanxheri, Nicola Lovecchio, Gianluigi Maggioni, Giuseppe Maruccio, Anna G. Monteduro, Arianna Morozzi, Augusto Nascetti, Stefania Pallotta, Andrea Papi, Daniele Passeri, Maddalena Pedio, Marco Petasecca, Pisana Placidi, Matteo Polo, Marta Ponzecchi, Alberto Quaranta, Gianluca Quarta, Walter Raniero, Silvia Rizzato, Aurora Rizzo, Federico Sabbatini, Rabia Sandhu, Leonello Servoli, Cinzia Talamonti, Alberto Verdini, Mattia Villani, Nicolas Wyrsch
Earth and Planetary Astrophysics
Features in the visible spectra of the Enceladus particle plume and E ring: Potential evidence of organic materials and/or missing sub-micron particles
M.M. Hedman and S.M. MacKenzie
Visible spectra of the Enceladus particle plume and E ring contain evidence for a change in spectral slope around 0.5 micron. This feature can be seen in data obtained by both the Visual and Infrared Mapping Spectrometer (VIMS) and Imaging Science Subsystem (ISS) onboard the Cassini Spacecraft, and is consistent with the slope change seen in the surface spectra of Saturn's rings and moons that has been attributed to either organics or iron compounds. The observed spectral features in the plume and E ring could represent either a non-ice contaminant in the plume particles or a deficit of sub-micron particles, so this spectral feature provides a new tool for assessing variations in the plume particle's composition and/or size distribution with time and space. The observed strength of this feature is consistent with the plume particles having an organic fraction similar to that measured by in-situ measurements, so there are good reasons to expect that this feature can be used to quantify the organic content of the plume particles. There are also hints of a potential absorption band around 0.45 micron in these spectra. If this feature can be confirmed, it could provide further constraints on the plume particles' composition.
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