High Energy Astrophysical Phenomena
Discovery of EP J175257.3-351923 as a Candidate Black Hole Low-Mass X-ray Binary
G. L. Huang, Q. C. Zhao, L. Tao et al. (+30 more)
We report the discovery of a new X-ray transient, EP J175257.3-351923 (EP250916a), by the Einstein Probe (EP) near the
Galactic plane. The outburst lasted for at least 250\,days, reached a peak 2–10 keV flux of $\sim 4 \times 10^{-10}$~erg~cm$^{-2}$~s$^{-1}$, and exhibited a fast-rise exponential-decay (FRED) profile typical of X-ray binary outbursts. The source remained in the hard state throughout the outburst, with only modest variations in the
photon index ($\sim 1.6$–$2.2$) and no evidence for a spectral state transition. Broadband spectral modeling suggests a truncated disk, a weak reflection component, and a high-energy cutoff at $\sim 217$~keV, consistent with hard-state
accretion in black-hole systems. No reliable optical or
radio counterpart is detected within the Swift/XRT error circle. The inferred X-ray-to-optical and X-ray-to-
radio flux ratios are consistent with a low-mass X-ray binary classification. Neither pulsations nor significant aperiodic variability are detected. Although the compact object cannot yet be firmly identified, the timing, spectral, and multiwavelength evidence favors EP~J175257.3–351923 as a black-hole low-mass X-ray binary candidate, highlighting EP's potential to uncover a faint, previously hidden population of X-ray binaries.
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All authors G. L. Huang, Q. C. Zhao, L. Tao, A. Coleiro, A. Rau, S. Brennan, C .Y. Dai, R. Soria, F. Cangemi, F. Coti Zelati, A. Marino, L. Zhang, S. Guillot, H. Q. Cheng, H. Feng, D. Götz, Y. Huang, Y. F. Huang, D. Y. Li, Z. S. Li, P. Maggi, R. C. Ma, X. Ma, H. W. Pan, N. Rea, J. Wang, Q. Y. Wu, L. P. Xin, W. M. Yuan, Z. H. Yao, G. B. Zhang, W. D. Zhang, S. N. Zhang
Superconductivity
Dichotomous electronic system in a bilayer Ni$^{1+}$ nickelate
Young-Joon Song, K.-W. Lee and W. E. Pickett
"Infinite layer" nickelates ${\cal R}$NiO$_2$ (${\cal R}$=rare earth), having empty apical O sites, become superconducting upon hole doping, stimulating research into the related sequence Nd$_{n+1}$Ni$^{+p}_n$O$_{2n+2}$, formal charge state $p$=1+$\frac{1}{n}$, $n$=2,3,4,...., with the $n$=5 member being found to be superconducting. The two layer system La$_3$Ni$_2$O$_{7-\delta}$, with $\delta$=0,$\frac{1}{2}$,1 ($p$=2.5,2,1.5) approaches the peak in the nickelate superconducting dome but shows no superconductivity. Newly reported La$_3$Ni$_2$O$_5$F reaches the Ni$^{1+}$ goal while, as we show, introducing a partially occupied electron band $E^*$, based on an interstitial density that extends over the three open "apical" layers and leads to a single cylindrical electron
Fermi surface giving self-doping. The commonly inert Ni $d_{xz},d_{yz}$ orbitals partner with interstitial $E^*$ to provide an incipient non-analytic Dirac point, with the critical point being reachable by pressure or further F insertion. The $E^*$ electron cylinder and the conventional Ni $dp\sigma$ hole carriers combine to provide a two-fluid dichotomy of hole and electron quasiparticles, affecting normal state properties that should verify the dichotomous aspect of transport.
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General Physics
MeV-GeV Gamma-Ray Astrophysics in the Multimessenger Era
Alessandro De Angelis
Gamma-ray astrophysics probes the most extreme particle accelerators and explosive transients in the Universe. From pioneering theoretical predictions in the 1950s and the first space-borne detections in the 1960s, mostly exploring the sub-MeV region, the field has evolved into a mature, multi-decade enterprise that spans nine orders of magnitude in
photon energy up to PeV energies and interfaces naturally with
neutrino and gravitational-wave astronomy. Yet the energy range from a few hundred keV to a few GeV – the "MeV gap", constraining progress on nucleosynthesis, positron annihilation, transient physics, dark-matter signatures, and electromagnetic counterparts to high-energy
neutrinos and gravitational waves - remains sensitivity-limited. In this paper, we survey the scientific motivations for gamma-ray astrophysics, sketch a concise history from the first ideas to key milestones in space- and ground- based gamma-ray astronomy, and discuss programmatic attempts to close the MeV gap.
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Classical Physics
The emergence of a new sound research methodology in the field of health: designo-therapy ?
Luc Perera and Pierre Jouvelot
Design fits in different fields, and it is given a plurality of titles: thinking, social, ecological, and graphic, space, etc. This discipline crosses the fields of research and engineering, which emancipate themselves from their historic fields and target other areas of public and private services. On the other hand, the sound sector, and more generally the acoustics, is more strictly categorized: musicology, psycho-acoustics or electro acoustics (see figure 1, which gives a relatively comprehensive overview) ). It is in this universe that evolves the discipline of sound design, with accents a priori industrial or environmental. But could it also allies, more unexpectedly, to health design and, if so, in what form\,? To answer this question, we try here, in a few lines, to explain the links between art (s) and health, links that aroused the interest to draw a parallel with the world of design, then to think about its integration. In the medical community. We will conclude, as an illustration, from our own research in sound design, in connection with Indian music.
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Astrophysics of Galaxies
Hector Galaxy Survey: Linking the low- and high-mass ends of the initial mass function in star-forming galaxies
Diego Salvador, Andrew Hopkins, Matt Owers et al. (+30 more)
The
stellar initial mass function (IMF) is a fundamental ingredient in
galaxy evolution, linking observed integrated light to
galaxy properties. Constraining the full IMF shape beyond the Milky Way remains challenging, as most studies focus either on the low-mass end of quiescent
galaxies or the high-mass end of
star-forming
galaxies. Here we present the first simultaneous analysis of both ends of the IMF in 214
star-forming
galaxies from the Hector survey. We estimate the low-mass end slope using a
stellar population approach that fits IMF-sensitive absorption features with extended
star formation histories, while the high-mass end slope is derived via the Kennicutt diagnostic, which compares the observed H-alpha equivalent width and g-r colour with
stellar population synthesis model predictions. We find substantial diversity in IMF shapes and a weak but statistically robust correlation between the low- and high-mass IMF slopes. Both IMF slopes show significant correlations with
stellar mass,
star formation activity, and
stellar metallicity ([M/H]). In general, higher
stellar mass, stronger
star formation activity, and higher
metallicity are associated with both bottom-heavy and top-heavy IMFs. Partial correlation analysis reveals that the low-mass end slope is primarily driven by [M/H], whereas the high-mass end is mainly linked to
stellar mass and recent
star formation. Because the low-mass end slope traces the IMF over long-term averages and the high-mass end slope captures only recent
star formation, the processes shaping each end likely occur over different and possibly decoupled timescales. Our findings challenge the universality of the IMF and emphasise the need for
galaxy evolution and
stellar population models to incorporate a flexible IMF prescription. Accounting for these variations is essential to build an IMF-consistent picture of
galaxy evolution across
cosmic time.
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All authors Diego Salvador, Andrew Hopkins, Matt Owers, Ignacio Martín-Navarro, Gabriella Quattropani, Pratyush Kumar Das, Mina Pak, Scott Croom, Julia Bryant, Tereza Jerabkova, Karl Glazebrook, Andrei Ristea, Madusha Gunawardhana, Sarah Sweet, Kyuseok Oh, Jong Chul Lee, Joon Hyeop Lee, Caroline Foster, Tayyaba Zafar, Yifan Mai, Sujeeporn Tuntipong, Jesse van de Sande, Stefania Barsanti, Joss Bland-Hawthorn, Matthew Colless, Robert Content, Tony Farrell, Jon Lawrence, Seong-sik Min, Sree Oh, Naveen Pai, Ayoan Salim Sadman, Ross Zhelem
Astrophysics of Galaxies
Molecular Gas Structure and Star Formation Diversity in Stephan's Quintet Revealed by ACA CO(1-0) Mapping
Misaki Yamamoto, Fumiya Maeda, Kazuyuki Muraoka et al. (+10 more)
We present $^{12}$CO(1-0) mapping across the entire system of Stephan's Quintet, a well-known compact
galaxy group, observed by Atacama Compact Array (7\,m array + Total Power) of the Atacama Large Millimeter/submillimeter Array. These observations provide the first large-scale ($137\,\mathrm{kpc}\times119\,\mathrm{kpc}$), spatially resolved ($\sim$5.5\,$\mathrm{kpc}$) molecular gas map of a compact group. Our CO map revealed that most of the molecular gas resides in the disk of the member
galaxy NGC~7319 and in the intergalactic regions, including components along the shocked filament and the optically identified
tidal tail extending from NGC~7319. Along the
tidal tail and its surroundings, we found not only an extended molecular gas component but also four discrete CO clumps, with velocity dispersions of $\sim$10-30 $\mathrm{km\,s^{-1}}$ and molecular gas masses of order $10^7$-$10^8\,M_\odot$. Three of these clumps spatially overlap with H\,i, whereas the remaining clump shows no associated H\,i or counterparts at optical and infrared wavelengths. Using
star formation rates derived from H$\alpha$ luminosities of H\,ii regions, we found that
star formation efficiencies (SFEs) span $\sim$2.2\,dex ($\sim$0.02–4\,Gyr$^{-1}$) and negatively correlate with CO velocity dispersion. While regions with small velocity dispersion exhibit SFEs comparable to those of nearby disk
galaxies, those with large velocity dispersion ($\sim$50-150$\,\mathrm{km\,s^{-1}}$) around the shocked filament show strongly suppressed
star formation. These results suggest that
turbulence plays a significant role in regulating
star formation in interacting systems.
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All authors Misaki Yamamoto, Fumiya Maeda, Kazuyuki Muraoka, Fumi Egusa, Shinya Komugi, Bunyo Hatsukade, Hiroyuki Kaneko, Masato I.N. Kobayashi, Kotaro Kohno, Ayu Konishi, Kana Morokuma-Matsui, Kouichiro Nakanishi, Kouji Ohta
Quantum Physics
Non-Hermitian scattering in SSH superconducting waveguides: exact Green-function reduction and dimerization-sensitive microwave functionalities
Jie Zhou, Xiao-Xue Zhang and Xi-Zheng Zhang
We formulate an exact Green-function theory for non-Hermitian single-microwave-
photon scattering by finite superconducting
circuit subsystems embedded in an SSH waveguide. The structured SSH environment is integrated out exactly and enters the local scattering problem as an energy-dependent
matrix self-energy, reducing the full open system to a finite-dimensional effective non-Hermitian
Hamiltonian. This reduction places scattering amplitudes, exceptional-point diagnostics, coherent-perfect-absorption conditions, and lasing thresholds within one unified framework. Within this approach we analyze two superconducting devices. A flux-controlled two-
qubit interferometric scatterer exhibits a broad bright branch and a narrow quasi-dark branch whose interference is reshaped by the SSH environment and changes qualitatively across the two dimerizations. A mediator-assisted two-
qubit scatterer generates an additional energy-dependent complex coupling, reorganizes the dressed spectrum, and produces clearer dimerization-sensitive transparency-versus-absorption windows together with a pronounced separation between zero-like and pole-like scattering branches. In the active regime, near-exceptional-point hybridization enhances the pole-dominated response while deepening the singular-value valley associated with near-coherent perfect absorption. These results show how structured topological waveguides can be used not only to host scattering, but also to design non-Hermitian superconducting microwave functionalities.
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Materials Science
Optical-like interference control polar-phonons dispersions in 2D materials
Benoit Van Troeye and Geoffrey Pourtois
It has been argued that the polar
phonon modes of two-dimensional (2D) materials should show a linear dependence close to the Brillouin zone center due to the reduced problem dimensionality compared to a three-dimensional
crystal, leading to a vanishing LO-TO splitting. Revisiting this question using a mirror-charge framework derived from classical electrostatics, we show that it is not always true: with perfectly-reflective dielectric interfaces, it is possible to recover a LO-TO splitting, or an equivalent phenomenon for the out-of-plane modes. Effectively, the dispersion of polar
phonon modes is governed by optical-like constructive and destructive interferences of the source potential with its reflection at the dielectric interfaces. This work highlights the critical role of dielectric boundary conditions to understand
phonon-related properties in 2D materials.
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Strongly Correlated Electrons
Interaction-driven dynamics in graphene flakes as a benchmark for quantum simulation
Fabian Eickhoff, Satoshi Ejima, Lukas Windgätter et al. (+4 more)
We study interaction-driven ultrafast dynamics in finite
graphene flakes following an optical pump quench in an interacting tight-binding model. By comparing exact real-time
evolution with simulations restricted to particle-hole excitation subspaces, we assess when relaxation can be captured by low-order many-body processes and when this is not sufficient. The single-particle orbital
entropy provides a compact diagnostic for dynamic correlation growth. For the systems studied here, periodic
graphene flakes are well described by low-order excitations, whereas confined geometries require substantial higher-order contributions even for relatively small interaction strengths. The quench protocol combines simple initial-state preparation with strongly correlated dynamics, identifying a promising
benchmark problem for future
quantum-computing simulations.
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All authors Fabian Eickhoff, Satoshi Ejima, Lukas Windgätter, Florian G. Eich, Hannah Rittich, Sebastian Zanker, Peter Schmitteckert
Materials Science · Cross-listed from eess.IV
Unsupervised Deep Learning for Limited-Angle STEM-EDX Tomography – Application to 3D Chemical Analysis of Phase-Change Memory Devices
Daniel del Pozo Bueno, Serge Brosset, Theo Monniez et al. (+3 more)
Energy Dispersive X-ray (EDX)
tomography in Scanning Transmission Electron Microscopy (STEM) enables 3D compositional and elemental mapping at the nanoscale, but its use is limited by restricted tilt ranges and low-dose conditions required to avoid beam damage. Limited-angle acquisition introduces missing-wedge artefacts such as elongation and anisotropic resolution, while noisy low-dose data further degrade reconstruction quality and quantitative reliability. Here, we introduce an unsupervised deep learning framework based on Deep Image Prior with total variation regularization (DIP-TV) for limited-angle STEM-EDX
tomography. We extend it to a multi-channel formulation (DIPm-TV) that jointly reconstructs multiple elemental maps by exploiting spatial correlations. Using a synthetic 3-channel phantom, we show that the method compensates for severe missing-wedge artefacts corresponding to approximately $100^\circ$ of missing angular range under moderate noise, outperforming simultaneous iterative reconstruction technique and compressed sensing approaches. We apply the method to 3D chemical analysis of Ge-Sb-Te (GST)
memory devices in virgin (as-fabricated) and SET (crystalline) operational states. Samples were prepared as cross-sectional focused ion beam lamellae and acquired under a limited-angle tilt range from $-40^\circ$ to $+40^\circ$ with $5^\circ$ steps and a dose of $2.0\times10^5$ $e^-/Ang^2$. The multi-channel approach enables voxel-by-voxel elemental reconstruction using only EDX signals without external structural priors such as high-angle annular dark-field imaging. The reconstructed volumes show near-isotropic spatial resolution and reveal compositional heterogeneities associated with device operation. This approach enables 3D chemical characterization in experimentally accessible sample geometries where conventional methods fail due to severe angular limitations.
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All authors Daniel del Pozo Bueno, Serge Brosset, Theo Monniez, Gabriele Navarro, Philippe Ciuciu, Zineb Saghi
Classical Physics
A phase-field modeling approach to sea-ice fracturing
Laetitia Drumare, Vidar Skogvoll, François Renard et al. (+2 more)
The thin ice that covers the polar oceans is a complex geomaterial that is constantly stressed and fractured by winds and ocean currents. In the central Arctic, this forcing produces deformations in the form of shear bands, within which individual ice plates detach, locally generating a granular medium. Capturing this transition from a continuous to a granular sea-ice cover has implications for the adequate representation of the mechanical and dynamical behavior of sea-ice in regional and large-scale models used for operational and
climate prediction purposes. Our work investigates the feasibility of a phase-field approach to capture this granularization processes and focuses on fracture propagation in the material. The model combines a double-well free-energy formulation with an overdamped displacement response. The governing equations are solved using a spectral method in
Fourier space. The implementation accounts for body forces, representative of the main forcings on sea-ice, and remains computationally tractable despite the highly nonlinear character of the double-well energy formulation. We first validate the framework against a
benchmark problem: the opening of an inclusion embedded into an elastic
matrix under tensile loading. Then, additional simple shear configurations are investigated: an inclusion solicited under plane shear and a cylindrical Couette experiment, for which the analytical solution of the displacement field is known. The resulting fracture patterns and displacement fields demonstrate that our phase-field framework captures key features of tensile and shear fracture propagation, including the linear scaling between crack speed and applied load predicted by the Griffith's theory.
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All authors Laetitia Drumare, Vidar Skogvoll, François Renard, Luiza Angheluta, Véronique Dansereau
Materials Science
Probing Spin Configurations in Exchange-Coupled Magnetic Bilayers with Orthogonal Anisotropies via Anomalous Hall and Nernst Effects
Sebin Jung, Hiroki Koizumi, Hiroaki Sukegawa et al. (+1 more)
When two
ferromagnetic thin films with different
magnetic easy axes are coupled via the exchange interaction, the magnetization process becomes nontrivial. In this paper, we demonstrate that three-dimensional magnetization information in such a
bilayer system can be accessed electrically by combining measurements of the anomalous
Hall effect (AHE) and anomalous Nernst effect (ANE). Specifically, we investigate a CoFe$_2$O$_4$(001)/Fe
bilayer, where the insulating nature of CoFe$_2$O$_4$ ensures that these transport measurements selectively probe only the conductive Fe layer. By combining the AHE and ANE results and comparing them with a simple micromagnetic simulation, we probe the
magnetic configuration of antiferromagnetically coupled Fe layer and suggest the emergence of a twisted
magnetic structure near the interface.
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All authors Sebin Jung, Hiroki Koizumi, Hiroaki Sukegawa, Hideto Yanagihara
High Energy Astrophysical Phenomena
Updating the PATH framework with FRB host galaxy models
C. W. James, N. Loudas, M. Woodland et al. (+5 more)
Over a hundred fast
radio burst (FRB) host
galaxies have now been identified, enabling both comparisons of host
redshift with FRB dispersion measure to study the cosmological distribution of ionised gas, and analyses of host properties in order to identify FRB progenitors. The standard method for determining the most likely FRB host
galaxy in an optical image is the
Bayesian framework Probabilistic Association of Transients to their Hosts (PATH), which accounts for uncertainties in the
radio localisation, and simplified prior distributions on the host being observable. In this work we extend PATH, incorporating physically-motivated priors that are based on expectations about FRB host
galaxy magnitudes. We develop three different models for the apparent r-band magnitude distribution based on an FRB's expected host
galaxy redshift, $P(m_r|z)$ and combine these with expectations for
redshift based on an FRB's dispersion measure, $P(z|DM)$. We fit the parameters of these prior models using host
galaxy candidates for 32 FRBs detected by the Australian SKA Pathfinder (ASKAP) in incoherent sum (ICS) mode by the Commensal Real-time ASKAP Fast Transients (CRAFT) survey. Employing PATH with the new priors on the host magnitudes, we find increased confidence in the most probable hosts of all ASKAP ICS FRB host
galaxies. All three models predict similar distributions of FRB host magnitudes at low
redshift $(z \sim 0.1)$, and we confirm previous results that the true FRB host
galaxy distribution is fainter than expected for a
star-formation-weighted distribution (p-value of 0.12%). However, a mass-weighted distribution provides an even worse fit (p-value of $10^{-9}$). Tests against more FRBs in the $z > 0.5$ range, where the models differ, and extensions of the models to account for e.g. host
metallicity, may help to resolve these uncertainties in the FRB host distribution.
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All authors C. W. James, N. Loudas, M. Woodland, B. C. Andersen, J. X. Prochaska, J.L. Hoffmann, L. Marnoch, S. D. Ryder
Optics
Intrinsic plasmon canalization in the biaxial van der Waals crystal MoOCl$_2$
Farid Aghashirinov, Andrea Mancini, Lin Nan et al. (+4 more)
Anisotropic polaritons in low-
symmetry crystals allow for subwavelength confinement and directional routing of light. The most extreme form of such anisotropy arises at the topological transition between elliptical and
hyperbolic dispersion, where the isofrequency contours collapse into parallel lines and polaritons propagate in a diffractionless, beam-like fashion. This canalization regime has previously been accessed through twisted
heterostructures or engineered metasurfaces. Here we show that natural canalization can be achieved without any fabrication or structuring by exploiting the intrinsic elliptical-to-
hyperbolic transition in the van der Waals
crystal MoOCl$_2$ at room temperature. Using near-field imaging, we directly visualize plasmon-polariton canalization emerging at the low-loss Drude crossing point along the [010]
crystal axis. Owing to the moderate slope of the Drude permittivity, the resulting polaritons remain highly directional across a broad spectral window. This weak dispersion also enables robust thickness-dependent tuning, and we demonstrate, both experimentally and theoretically, that the canalization wavelength can be adjusted by more than 1 {\mu}m simply by varying the flake thickness. This work brings canalized polariton propagation into the 4.5 - 6 {\mu}m range, beyond the frequency limits of
phonon-polariton platforms and overlapping with important molecular vibrations, opening new opportunities for mid-IR nanophotonics and sensing.
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All authors Farid Aghashirinov, Andrea Mancini, Lin Nan, Giacomo Venturi, Bettina Frank, Harald Giessen, Antonio Ambrosio
Quantum Physics
Precision measurements at the interface between unitary and non-unitary encoding
Peng Xu
We investigate precision scaling at the interface between
unitary and non-
unitary encoding under generalized noise including single-particle and collective dephasing and decay. Using linear response theory and the error propagation formula, we derive analytic precision expressions for both the
unitary parameter $\Omega$ and the dissipation strength $\gamma$. For
unitary encoding, when the observable commutes with a Hermitian noise operator, the optimal encoding time is independent of $N$, yielding the Heisenberg limit $\Delta \Omega \propto 1 / N$; otherwise the precision degrades to the standard
quantum limit or ceases to improve with $N$. For non-
unitary encoding, when $[\hat{A}, \hat{O}] = 0$, the precision is insensitive to intrinsic dynamics and encoding time, scaling as $\Delta \gamma \propto \sqrt{\gamma / \expval*{\hat{L}^\dagger \hat{L}}}$. Notably, for collective decay, the Dicke state reaches the Heisenberg limit $\Delta \gamma \propto 1 / N$, demonstrating that
entanglement can enhance non-
unitary estimation. Our results provide a unified framework and practical guidance for designing
quantum metrology protocols in noisy environments.
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High Energy Astrophysical Phenomena
Circular polarization effects induced by photon-axion mixing in astrophysical environments
Meng Wang, Nan Ding, Qiusheng Gu et al. (+2 more)
Axions and
axion-like particles (ALPs) are compelling candidates for dark matter and new physics beyond the Standard Model.
Photon-
axion mixing in external
magnetic fields modifies the
photon energy spectrum and linear polarization state, and also induces circular polarization signals. Compared to spectral and linear polarization methods, circular polarization benefits from lower astrophysical background contamination, providing an independent probe for
axion searches. In this work, we study the circular polarization induced by
photon-
axion mixing within the
chiral basis framework. By analytically solving the
evolution equations under the single-domain approximation, we derive an expression for the circular polarization degree $P_C$, applicable in the resonant, strong coupling, and weak coupling regimes. Within single-domain
magnetic field models, we compare the energy-dependent circular polarization in four astrophysical environments (AGN jets, intracluster medium, intergalactic medium, and
Galactic magnetic fields). We find that the X-ray to MeV band represents the most sensitive observational window. Using the blazar S4 0954+65 as a case study, phase accumulation in random
magnetic domains causes the circular polarization degree to fluctuate with
redshift and exhibit pronounced energy structures. Using the optical circular polarization upper limit $P_C < 0.184\%$ (measured in the z-SDSS band) from this source, we statistically constrain $g_{a\gamma\gamma} \lesssim 3\times 10^{-11}\,\mathrm{GeV}^{-1}$ (95% confidence level) for $m_a \sim 10^{-16}$–$10^{-10}\ \mathrm{eV}$, with the strongest constraint reaching $g_{a\gamma\gamma}\sim6\times10^{-12}\,\mathrm{GeV}^{-1}$ near $m_a \sim 10^{-14}\,\mathrm{eV}$. These results establish circular polarization as a complementary
axion probe.
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All authors Meng Wang, Nan Ding, Qiusheng Gu, Yunyong Tang, Rui Xue
High Energy Physics (Phenomenology)
Tensor Decomposition for Energy-Momentum Correlation Functions
Guy D. Moore and Jonas Winter
We establish the general functional form of the energy-momentum-tensor two-point function in Euclidean coordinate space at zero and finite temperature. The full correlation function is first decomposed into its fundamental tensorial structures based on the remaining rotational
symmetry. We use energy-momentum conservation to derive differential relations between the resulting component functions. Using these constraints, the full set of component functions of the correlator can finally be represented in the form of a smaller set of spectral functions. Finally, we show how to use these techniques for more efficient future
lattice investigations.
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High Energy Astrophysical Phenomena
Gamma-Ray Emission from the Crab Pulsar: A 17-Year Fermi-LAT Reanalysis
Liancheng Zhou, Yun-Lu Gong, Jun Fang et al. (+1 more)
We present a reanalysis of 17 years of
Fermi Large Area
Telescope (LAT) observations of the Crab
pulsar obtained between 2008 August and 2025 August. Using monthly Jodrell Bank
radio ephemerides, we assigned pulse phases to the LAT events and aligned the phase zero across the full data set. From this phase-aligned data set, we derived pulse profiles over 100 MeV to 300 GeV. The pulsed emission remains clearly detectable in the 10 to 20 GeV and 20 to 30 GeV bands, with H-test significances of 32.36 sigma and 11.59 sigma, respectively, but is not significantly detected in the 30 to 300 GeV band. Phase-resolved likelihood analysis was performed over 100 MeV to 30 GeV using 14 phase bins with comparable pulsed statistics. The fixed-window fractional fluxes show that the contribution of Peak 1 (P1) decreases steadily with energy, while those of Peak 2 (P2) and the Bridge increase, with P2 exceeding P1 above 10 GeV. Finally, the same phase-assignment framework also enables an off-pulse analysis from 100 MeV to 1 TeV, confirming the synchrotron and inverse-Compton components that dominate the emission in the selected off-pulse interval.
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All authors Liancheng Zhou, Yun-Lu Gong, Jun Fang, Li Zhang
Strongly Correlated Electrons
SANS and magnetometry study of the magnetic phase diagram of the B20 helimagnet FeRhSi
E. V. Altynbaev, A. V. Guseva, D. O. Skanchenko et al. (+5 more)
This manuscript reports the first direct
neutron-scattering evidence for long-period helimagnetism in the newly identified 4d-substituted B20 compound Fe0.5Rh0.5Si. By combining SANS with low-field magnetometry, we establish the
magnetic modulation, construct a field-temperature phase diagram, and identify a candidate A-phase region supported by an independent structural signature. The work is important beyond this single compound because it expands the family of
chiral B20 helimagnets into Rh-substituted materials, where
spin-orbit coupling, disorder, and Dzyaloshinskii-Moriya interactions can be tuned. It will interest researchers in
chiral magnetism, topological
spin textures,
magnetic neutron scattering, and
quantum materials, and provides a foundation for future studies of emergent
magnetic phases and
topology-driven phenomena in chemically tuned
chiral magnets.
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All authors E. V. Altynbaev, A. V. Guseva, D. O. Skanchenko, V. N. Krasnorussky, A. V. Bokov, D. A. Salamatin, V. A. Sidorov, A. V. Tsvyashchenko
Mathematical Physics
Contact Tulczyjew Geometry for Continuous and Discrete Dissipative Dynamics on Skew Algebroids
Leonardo Colombo and Manuel de León
We develop a contact Tulczyjew formalism for dissipative dynamics on skew algebroids. Starting from the Tulczyjew morphism of an skew algebroid, we identify its contact extension in a local line-bundle trivialization. The local representative is obtained by adding to the ordinary Tulczyjew morphism the Euler vector field contribution on $E^*$. This gives an intrinsic explanation of the contact term appearing in the local contact Tulczyjew morphism. For a contact generating object, the construction produces an implicit dissipative dynamics on the contact phase side. In local coordinates, the matching condition gives the Euler-Lagrange-Herglotz equations on the skew algebroid. In the hyperregular case, the corresponding contact
Hamiltonian equations are recovered by Legendre transformation. We also develop the discrete counterpart of the construction. After fixing a discrete admissibility relation, a discrete contact generating object defines a discrete contact Tulczyjew relation on the contact phase space. Discrete Herglotz extremals are obtained by matching consecutive contact momenta, with the usual conormal interpretation in the constrained case. In the regular tangent-bundle case, this recovers standard contact variational integrators, while in the singular or skew algebroid setting the same construction remains meaningful as an implicit discrete relation rather than an a priori update map.
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Atomic Physics
Ytterbium lattice clock with systematic uncertainty of $1.3\times 10^{-18}$ and instability at the $10^{-19}$ level
Qiang Zhu, Jingran Shi, Yuechen Zhang et al. (+8 more)
We report an optical
lattice clock based on $^{171}$Yb atoms with a total systematic uncertainty of $1.3\times 10^{-18}$. An in-
vacuum buildup cavity was employed to enhance the
lattice light power. Differential frequency measurement between two identical clocks facilitates the evaluation of systematic shifts. Synchronous comparison of the two clocks reached a stability level of $2.7\times 10^{-19}$ in an averaging time of 216,000~s. The blackbody radiation (BBR) shield which is placed in
vacuum provides a well-characterized BBR environment, enabling an uncertainty contribution of $8.7\times 10^{-19}$ from the BBR Stark shift.
Lattice light shifts were measured at different
lattice depths $U$, and fitted with a fourth-order
polynomial of $U$. The zero-linear-shift frequency $\nu_{\mathrm{zero}}$ was determined to be 394 798 260.6(3) MHz. The
lattice light shift can be controlled at an uncertainty level of $6.3\times 10^{-19}$ under typical operating conditions. Other systematic shifts have also been evaluated. The two clocks will be used for remote frequency comparisons between Shanghai and Wuhan.
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All authors Qiang Zhu, Jingran Shi, Yuechen Zhang, Xiatian Xu, Bing Wang, Dezhi Xiong, Zhuanxian Xiong, Pengcheng Fang, Qunfeng Chen, Lingxiang He, Baolong Lyu
Soft Condensed Matter
Moving backward to go faster: Diatom-inspired sliding reveals efficient modes of locomotion
Julien le Dreff and Blaise Delmotte
Across biological scales, from sperm
cells to whales, locomotion commonly relies on undulatory gaits, in which traveling deformation waves interact with the surrounding fluid to generate thrust opposite to the direction of wave propagation. In viscous environments, microorganism locomotion is classically understood in terms of undulatory bending of slender filaments such as flagella, with optimal propulsion achieved when the deformation wavelength is comparable to the swimmer length. Inspired by diatom colonies, we identify a fundamentally different swimming mechanism based on sliding between neighboring elements within a chain. We show that sliding between stacked elongated
cells generates internal shear that drives propulsion opposite to classical undulatory swimming, while achieving higher speeds and greater energetic efficiency. Remarkably, optimal performance occurs at wavelengths much larger than the chain length and at
cell aspect ratios consistent with those observed in natural diatom colonies, suggesting that hydrodynamic efficiency may constitute an evolutionary selective pressure in diatom chains. Together, these results identify sliding as a previously overlooked mode of locomotion in multicellular assemblies and suggest new design principles for efficient bio-inspired microswimmers and swarm robotic systems.
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Solar and Stellar Astrophysics
Turbulent Diffusion of Magnetic Field Lines in the Heliosphere
J.V.A. Joubert, R.D. Strauss, J. Light et al. (+2 more)
Due to
solar wind
turbulence, Parker spirals are
stochastic. The dispersion of
magnetic field lines is described by a convection-
diffusion equation for the field line density distribution which is a function of the two heliographic angles in addition to the radial distance. Taking into account the radial
evolution of the
turbulence, the three-dimensional convection-
diffusion equation is transformed into a set {of}
stochastic differential equations which is solved numerically using both a forward and backward formulation. By tracing a large number of
stochastic Parker spirals, the field line density distribution is constructed at any point in the heliosphere. It is shown that the angular part of the distribution function can be well-fitted by a two-dimensional Gaussian with standard deviation close to $ 25^{\circ}$ at 1 AU. The simulations also confirm that the
magnetic field lines are underwound, on average, for strong enough
turbulence intensity. Applying the backward approach,
magnetic field lines are traced from an observer at 1 AU back to the Sun, quantifying the probability of
magnetic connection when interplanetary
turbulence is accounted for. It is shown that the angular uncertainty of $\sim 25^{\circ}$ is sharply reduced to $\sim 4^{\circ}$ when the field lines are traced back to the
solar wind source surface from 0.25 AU.
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All authors J.V.A. Joubert, R.D. Strauss, J. Light, N.E. Engelbrecht, N.H. Bian
Quantum Physics
Single-photon scattering in a dissipative superconducting-qubit–SSH lattice hybrid
Xiao-Xue Zhang, Jie Zhou and Xi-Zheng Zhang
We study single-
photon scattering in a Su–Schrieffer–Heeger (SSH) photonic
lattice locally coupled to a superconducting
qubit with tunable loss or gain. Working in the single-excitation sector, we derive an explicit real-space scattering formulation for the full energy-dependent scattering
matrix $S(E)$ and identify how its
eigenvalues encode coherent perfect absorption, amplification, and spectral singular behavior. The analytical results are benchmarked against time-domain wave-packet simulations, which reproduce the stationary scattering probabilities with high accuracy. We show that the SSH dimerization, the
qubit-induced non-Hermitian self-energy, and the synthetic gauge phase cooperate to reshape the reflection and transmission spectra in a highly selective way. In particular, changing the dimerization can switch the system between transmission-dominated and reflection-dominated regimes, while the flux provides a direct handle on interference and
symmetry-controlled response. We also find a robust loss–gain correspondence in the reflection landscape and show that the linewidth broadening is governed predominantly by the magnitude $|\gamma|$ of the non-Hermitian coupling. These results establish a compact and experimentally relevant framework for topological scattering in superconducting
quantum networks.
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Solar and Stellar Astrophysics
Phase-drifting with emitting plasma temperature in the quasi-periodic pulsations of an X-class solar flare
Libo Fu, Valery M. Nakariakov, Ding Yuan et al. (+3 more)
Recent multi-wavelength observations of
solar flares have provided new constraints on the physical origin of quasi-periodic pulsations (QPPs). In an X-class
flare, we detect a short-lived $\sim$5-minute QPP simultaneously in hard X-rays, extreme-ultraviolet (EUV), and soft X-ray emissions, exhibiting a clear phase-drifting behavior with emitting
plasma temperature. Based on phase-resolved timing analysis, it is found that (i) the QPPs in all diagnostics share nearly identical oscillation periods, (ii) a systematic temperature-dependent phase drifting is present, with the phase delay relative to the hard X-ray emission increases systematically from the hottest to cooler EUV channels, and (iii) the QPP persists for only a few cycles during the impulsive phase. These properties imply that periodic
magnetic reconnection, possibly triggered by the leakage of 5-minute oscillations from the lower atmosphere, modulates the non-thermal electrons responsible for the leading Hard X-ray QPPs. Subsequently,
plasma heating and cooling processes manifest sequentially across passbands with different temperature responses, resulting in the observed temperature-dependent phase drifting. These results provide novel observational evidence supporting the use of multi-temperature, multi-wavelength phase relationships to constrain the temporal
evolution of
flare energy release and the origins of QPPs.
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All authors Libo Fu, Valery M. Nakariakov, Ding Yuan, Suraj Sahu, Song Feng, Ehsan Tavabi
Solar and Stellar Astrophysics
Solar flare ribbons structured by uncombed chromospheric loops
L. P. Chitta, E. R. Priest, David Orozco Suárez et al. (+33 more)
A part of the
magnetic energy released during a
flare is transported to the lower atmosphere. High-resolution observations show that
flare ribbons, sites of energy deposition at the footpoints of flaring loops which appear bright in the chromosphere and transition region, are structured on small spatial scales on the order of 100 km. Based on idealized numerical models of
flares it is suggested that the ribbon fine-structures could originate from a tearing instability and the development of plasmoids in current sheets. Here we report on Fe I 5250.6 Å and Mg I b2 5173 Å spectral observations of a
solar flare from the Tunable Magnetograph onboard the SUNRISE III balloon-borne mission that reveal an intricate link between the
flare ribbon structure and the ambient chromosphere. We identified uncombed chromospheric loops and non-flaring fine-structures that are interspersed among brighter
flare ribbon threads. These loops remain stable on timescales of minutes. Spectral lines from these regions show reduced emission or self-reversal in the line core compared with the immediately adjacent
flare ribbons. We discuss the potential role of these structures in the onset of a
flare. Furthermore, we suggest that irrespective of the complexities in the flaring current sheet, uncombed chromospheric loops and nonflaring fine-structure might play a role in spatially modulating the
flare energy deposition in the lower atmosphere.
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All authors L. P. Chitta, E. R. Priest, David Orozco Suárez, Azaymi L. Siu-Tapia, Jose Carlos del Toro Iniesta, Francisco Javier Bailén, Julian Blanco Rodríguez, Alberto Álvarez-Herrero, Maria Balaguer Jiménez, Esteban Sanchis Kilders, Ignacio Torralbo, Christoph Kuckein, Sami K. Solanki, Andreas Lagg, Achim Gandorfer, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alex Feller, Tino L. Riethmüller, Masahito Kubo, H. N. Smitha, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Juan Sebastián Castellanos Durán, Edvarda Harnes, Johannes Hoelken, Francisco A. Iglesias, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Hanna Strecker, Dušan Vukadinović
Strongly Correlated Electrons
Microscopic evidence for a Zhang-Rice triplet state in the van der Waals antiferromagnet, NiPS$_3$
Beom Hyun Kim, Youjin Lee, Junik Hwang et al. (+3 more)
Quantum-entangled states underpin many emergent phenomena in
quantum materials, yet their direct experimental identification remains a challenge. NiPS$_3$, a van der Waals antiferromagnet exhibiting a resolution-limited
magnetic exciton in its ordered phase, has been proposed to host a many-body entangled Zhang-Rice triplet state. Here, using $^{33}$S
nuclear magnetic resonance (NMR) on $^{33}$S-enriched NiPS$_3$ single
crystals, we provide microscopic evidence for this charge-transfer state. The $^{33}$S and $^{31}$P Knight shifts as a function of temperature reveal a unified
spin-triplet configuration arising from strong hybridization between a self-doped hole in the S $3p$ orbitals and a hole in Ni $3d$ orbitals. Furthermore, the $^{33}$S
nuclear spin-
lattice relaxation rate exhibits a power-law divergence as it approaches the Néel temperature $T_N=155$ K, indicating critical slowing down of collective charge fluctuations consistent with
spin-nematic correlations. These results reveal a
spin-charge-intertwined ground state and establish the microscopic foundation for the exceptional coherence of the
magnetic exciton in NiPS$_3$.
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All authors Beom Hyun Kim, Youjin Lee, Junik Hwang, Junghyun Kim, Je-Geun Park, Seung-Ho Baek
Mathematical Physics · Cross-listed from math.PR
Dimension lower bounds in random geometry via Lipschitz functions
Manan Bhatia, Ewain Gwynne and Brin Harper
We prove lower bounds for the Hausdorff dimensions of various natural sets associated with the Liouville
quantum gravity (LQG) metric. We prove that the set of 3-
star points (i.e., starting points of three disjoint geodesics) has Hausdorff dimension at least two with respect to the LQG metric, which is conjectured to be optimal. Our proof works for a general class of planar length metrics which also includes, e.g., Kendall's Poisson roads metric. We additionally prove a dimension lower bound of one for the set of 2-
star points intersected with the boundary and for the metric net intersected with the boundary, as well as a dimension lower bound of two for the intersection of two metric nets. In the particular setting of LQG, we obtain sharper lower bounds for the Hausdorff dimensions of the set of 2-
star points and the LQG metric net, with respect to both the Euclidean metric and the LQG metric. Our proofs are primarily topological. The key idea is to express the sets of interest in terms of non-constancy sets of Lipschitz functions.
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General Relativity and Quantum Cosmology
Stability and Physical Properties of Compact Stars Beyond Einstein Gravity
M. Sharif and Adeeba Arooj
This manuscript discusses feasible features of anisotropic celestial sphere within the framework of $f(\mathbb{Q},\mathcal{L}_{m})$
gravity, where $\mathbb{Q}$ represents non-metricity scalar and $\mathcal{L}_{m}$ is the matter Lagrangian. The
geometric configuration of static spherical symmetric structure is examined using a specific non-singular solution (Krori-Barua solution). A particular model of this theory is considered to derive explicit field equations. The Darmois matching conditions are used to evaluate unknown constants in the metric coefficients. To verify plausible existence of compact objects in this gravitational framework, we analyze their fundamental physical properties including fluid parameters, gradients, surface
redshift, mass-radius relation, anisotropy measure, compactness factor, energy conditions and equations of state. The stability of the considered
stellar objects is verified by adiabatic index and sound speed. Our results demonstrate that all required physical conditions are satisfied, confirming the existence of physically stable anisotropic celestial objects within this modified
gravity.
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Plasma Physics
Systematic comparison of VMEC and HINT equilibrium calculations for finite-beta LHD plasmas
Albert Civit-Bertran, Yasuhiro Suzuki and Shimpei Futatani
A systematic comparison between VMEC and HINT
equilibrium calculations has been carried out for Large Helical Device
plasmas to clarify the influence of the assumption of the nested flux surfaces at finite beta. Three
vacuum magnetic-axis configurations, $R_{\rm axV} = \SI{3.53}{\, m}$, $\SI{3.60}{\, m}$, $\SI{3.85}{\, m}$, are examined for the beta values on the axis in the range $\beta_0 \in [0.0\%, 5.0\%]$. The
magnetic-axis position, the rotational transform on the axis, and the
plasma volume enclosed by the last closed flux surface are compared between the two codes. At low-$\beta_0$, VMEC and HINT give consistent
equilibria, indicating that the nested flux surfaces are largely preserved. Above a configuration-dependent critical $\beta_0$, however, the two solutions begin to diverge, indicating that the nested flux surfaces assumption is compromised. In HINT, the enclosed
plasma volume decreases at higher beta because the
stochastic magnetic field evolves near the
plasma edge, whereas VMEC cannot represent this flux surface breaking due to its assumption of nested flux surfaces. These results show that the 3D
equilibrium responses in LHD
equilibria become increasingly important from inward- to outward-shifted configurations, mainly through Pfirsch-Schlüter current-driven perturbations of the
magnetic field and the resulting edge stochasticity.
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