High Energy Physics (Experiment)
Improved limits on a new $Z'$ in $B-L$ scenarios with the NA64 experiment at CERN
The NA64 Collaboration: Yu. M. Andreev, A. Antonov, M. A. Ayala Torres et al. (+52 more)
Extensions of the Standard Model featuring an additional $U(1)_{B-L}$ gauge
symmetry provide a compelling framework linking the origin of
neutrino masses to possible dark matter candidates. The associated gauge
boson, $Z'$, couples directly to Standard Model
fermions and can be produced in fixed-target experiments through electron-
nucleus interactions. In this work, we present new constraints on the coupling constant $g_{B-L}$ obtained with the NA64 experiment using the full electron-beam
dataset collected between 2016 and 2022, corresponding to $(9.4\pm0.5)\times10^{11}$ electrons on target. The analysis includes the resonant $e^{+}e^{-}$ annihilation production channel, which enhances sensitivity in the mass range $m_{Z'}\in[200,300]$ MeV. The larger
dataset provides approximately three times the statistics of previous analyses, thereby improving sensitivity. For the unbroken $U(1)_{B-L}$ case, the new limits exceed those from dedicated
neutrino-scattering experiments, providing the most stringent laboratory bounds on $g_{B-L}$ for sub-GeV masses of the new
boson. In scenarios where the $Z'$ couples to dark matter, the decay width is dominated by invisible channels, and the corresponding exclusion limits can be directly derived from the NA64 invisible-mode analysis.
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All authors The NA64 Collaboration: Yu. M. Andreev, A. Antonov, M. A. Ayala Torres, D. Banerjee, B. Banto Oberhauser, V. Bautin, J. Bernhard, P. Bisio, A. Celentano, N. Charitonidis, P. Crivelli, A. V. Dermenev, S. V. Donskov, R. R. Dusaev, T. Enik, V. N. Frolov, S. V. Gertsenberger, S. Girod, S. N. Gninenko, M. Hösgen, Y. Kambar, A. E. Karneyeu, G. Kekelidze, B. Ketzer, D. V. Kirpichnikov, M. M. Kirsanov, V. A. Kramarenko, L. V. Kravchuk, N. V. Krasnikov, S. V. Kuleshov, V. E. Lyubovitskij, V. Lysan, A. Marini, L. Marsicano, V. A. Matveev, R. Mena Fredes, R. Mena Yanssen, L. Molina Bueno, M. Mongillo, D. V. Peshekhonov, V. A. Polyakov, B. Radics, K. Salamatin, V. D. Samoylenko, H. Sieber, D. Shchukin, O. Soto, V. O. Tikhomirov, I. Tlisova, A. N. Toropin, M. Tuzi, P. V. Volkov, I. V. Voronchikhin, J. Zamora-Sa'a, A. S. Zhevlakov
Strongly Correlated Electrons
II. Exploring the role of the Crystal Electric Field in the vicinity of a Quantum Critical Point
Julian G. Sereni, Ivan Curlik, Slavo Gabani et al. (+1 more)
Very low temperature thermodynamic properties of the Yb$M_{5-x}X_x$ (with $M$= Ni, Cu, and $X$= Cd, Mg, Au, Zn, Ag) cubic compounds are analyzed covering a broad range of behavior between
magnetic and
Fermi-
liquid ground states GS using the chemical doping: $\zeta$ as control parameter. This allows to gain insight into the
evolution of the GS behavior including a
quantum critical point QCP. Doniach-Lavagna phase diagram limitations are improved by taking into account
crystal electric field CEF splittings. Three regions are recognized as a function of $\zeta$: i) a
magnetic one with long range
magnetic order and $T_{ord}\propto T_N \approx 1$\,K, that weakens the interactions between $0.8\,K \geq T_m\geq 0.4$\,K, exhibiting very low Kondo temperature $T_K^{GS}$ in respective doublets GS. Then, for $T_Q\leq 0.4$\,K,
quantum fluctuations start to dominate the scenario with the specific heat $C_{4f}/T(T\geq T_Q)$ showing $T$ power law dependencies, and a very heavy-
fermion plateau below $T_Q$. ii) beyond the QCP the typical Non-
Fermi-
Liquid logarithmic $T$ dependence: $C_{4f}/T \propto \ln(T/T_0)$, with traces of
magnetic order. At the non-
magnetic limit: iii) the
alloys behave as valence-fluctuation systems with growing $T_K$ that overcomes the CEF splitting. With this experimental information, a realistic phase diagram can be drawn around the QCP where the scenario is dominated by low lying
quantum fluctuations, without $C_{4f}/T|_{Lim T\to 0}$ divergences but a clear drop entering into the non-
magnetic phase.
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All authors Julian G. Sereni, Ivan Curlik, Slavo Gabani, Mauro Giovannini
Earth and Planetary Astrophysics
Unraveling the Mystery of the Peculiar and Young Hot Jupiter CoRoT-2b II: Phase Resolved Emission Spectroscopy with VLT/CRIRES+ and Gemini-S/IGRINS
Aurora Y. Kesseli, Siddharth Gandhi, Lisa Dang et al. (+8 more)
Hot Jupiters are expected to be tidally locked and synchronously rotating due to their short orbital periods. These conditions create large day-night temperature contrasts and are thought to drive eastward super-rotating jets. Indeed, the majority of hot Jupiters are observed to have the hottest region of the
planet either at the substellar point or offset in the eastern direction. However, the full phase curve of CoRoT-2b, observed with the Spitzer Space
Telescope, exhibits robust evidence of a western hotspot offset. To determine the origin of this peculiar hotspot offset, we present phase-resolved high-resolution observations of CoRoT-2b from the CRIRES+ spectrograph on the Very Large
Telescope (VLT) and the IGRINS spectrograph on Gemini South, covering both pre- and post-eclipse phases (0.34–0.63). We detect the signal from the
planet (S/N$>$4) in both pre- and post-eclipse phases separately, and therefore perform separate cross-correlation and
retrieval analyses at the two epochs. The phase-resolved
retrievals show highly consistent abundances and C/Os, but prefer a hotter and more isothermal temperature-pressure profile at post-eclipse phases, consistent with the phase curve observations that indicated a western hotpsot offset. By testing multiple hypotheses invoked to drive a western hotspot offset, we find the most likely explanation to be sub-synchronous planetary rotation. We measure the
planet's rotational broadening to be $2.24\substack{+0.81\\-0.77}$ km s$^{-1}$, whereas the expectation from tidally locked rotation is $4.37\pm0.13$ km s$^{-1}$ (2.6-$\sigma$ discrepant). Other observations, such as high precision phase curves or eclipse mapping, would help to further confirm the western hotspot offset and sub-synchronous rotation.
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All authors Aurora Y. Kesseli, Siddharth Gandhi, Lisa Dang, Alexis Lavail, Alejandro Sanchez-Lopez, Ying Shu, Emily Rauscher, Hayley Beltz, Romain Allart, Stefan Pelletier, Vatsal Panwar
Materials Science
Dislocation-templated antiferromagnetic domains in epitaxial NiO
Alexandra Fonseca Montenegro, Justin Michel, Fengyuan Yang et al. (+1 more)
Controlling
antiferromagnetic domains is essential for spintronics, yet predictable manipulation remains challenging due to their lack of net magnetization. Here, we utilize scanning electron microscopy electron channeling contrast imaging (ECCI) to observe the formation of nanoscale
antiferromagnetic domains in epitaxial NiO/MgO(001) at interface dislocations. Thermal cycling across the Néel temperature reveals that while domain contrast vanishes in the paramagnetic phase, the features re-emerge at identical spatial locations upon cooling. Diffraction-vector-dependent ECCI imaging, governed by a relative tilt contrast model, indicates that the domains stem from localized rhombohedral distortions of volumetric twin-type $T$-domains. These $T$-domains are stabilized by the long-range shear stress field of interface misfit dislocations (MDs). By tracking a film thickness series from 23 to 46~nm, we resolve a transition in
oxide relaxation mechanics from primary $60^\circ$ interface MDs along $\langle110\rangle$ to a cross-slipped network of pure edge $90^\circ$ MDs deviated toward $\langle100\rangle$. We demonstrate that ECCI identifies the Burgers vector and line direction of these MDs via strict $\vec{g} \cdot (\vec{b} \times \vec{u})$ invisibility criteria, and an Eshelby interaction energy model accurately predicts the asymmetric nucleation of specific $T$-domains along MD flanks. Quantitative image analysis shows $T$-domain volume fractions track the spatial configuration of the evolving MD networks, providing a framework for defect-engineering
antiferromagnetic textures using one-dimensional defects.
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All authors Alexandra Fonseca Montenegro, Justin Michel, Fengyuan Yang, Roberto C. Myers
Quantum Physics
Induced Resource Theories and Harvesting via Quantum Probes
Ron Nyström, Simone Cepollaro, Nicola Pranzini et al. (+3 more)
We consider scenarios in which a
quantum system with a well-defined resource theory is used as a probe to interact with an environment, such as a
quantum field, for which a resource-theoretic description is absent or incomplete. We clarify if and how the harvesting of a resource in the probe can tell us about the state of the environment. This is particularly ambiguous when the probe-environment interaction is not a free operation, or the concept of such free operations cannot be defined altogether. We propose a framework and precise conditions under which it becomes possible to interpret resource generation on the probe as evidence of resources in the environment, thereby introducing an effective notion of resources for the latter. Our results clarify in which sense resources can be said to be harvested from the environment and provide a systematic way to analyse such processes beyond fully controlled resource-theoretic settings. More generally, this work may provide a step towards a more general understanding of the interplay of different
quantum resources.
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All authors Ron Nyström, Simone Cepollaro, Nicola Pranzini, Stefano Cusumano, Alioscia Hamma, Esko Keski-Vakkuri
General Relativity and Quantum Cosmology
Shadow, Emission, and Strong-Field Lensing of Dilatonic Black Holes
Kuantay Boshkayev, Ainur Urazalina, Aidana Kurmanbek et al. (+2 more)
We study the shadow and strong-field optical properties of a static, spherically symmetric dyon-like dilatonic black hole. The
photon sphere radius, critical impact parameter, and shadow radius are obtained and analyzed in terms of the charge $Q$ and the dilatonic coupling parameter $a$. We show that increasing these parameters decreases the
photon sphere and shadow radii, leading to a smaller apparent shadow. The predicted angular diameter is compared with the observational data for M87$^{*}$ and SgrA$^{*}$. We explicitly show that the Sgr A* data do not constrain the model parameters, whereas the results for M87* depend on the adopted mass estimates from
stellar and gas dynamics. We also estimate the high-frequency energy emission rate in the
geometric-optics approximation and derive the leading Bozza coefficient $\bar{a}$, which characterizes the logarithmic behavior of the deflection angle in the strong-field regime. Astrophysical implication of the obtained outcomes are discussed.
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All authors Kuantay Boshkayev, Ainur Urazalina, Aidana Kurmanbek, Manas Khassanov, Daniya Utepova
Mesoscale and Nanoscale Physics
Room-temperature tuning and probing of Fermi polarons in atomically thin semiconductors on a plasmonic metasurface
Tingting Wu, Francesca Maria Marchetti, Antonio Tiene et al. (+9 more)
The
Fermi polaron, arising from interactions between a mobile
impurity and a degenerate
Fermi sea, is a many-body quasiparticle that provides a sensitive probe of strongly correlated electronic phases in atomically thin
semiconductors. In doped transition-metal dichalcogenides, the attractive and repulsive polaron branches are well established in monolayers. However, extending active control and quantitative, branch-resolved probing to stacked geometries has remained elusive because spectral quenching and weak optical contrast restrict access to
Fermi polaron signatures. Here, we integrate electron-doped WS$_2$ flakes from monolayer to quadrilayer with a strain-tunable plasmonic metasurface, enabling high-contrast scattering readout at room temperature through coupling between
Fermi polaron resonances and surface plasmons. This platform enables quantitative extraction of polaron branch spectral weights and coupling strengths across different layer numbers. We uncover a systematic thickness dependence of the spectral-weight distribution and demonstrate continuous and fully reversible spectral-weight transfer between attractive and repulsive branches in
bilayers and quadrilayers, with near-complete transfer achieved in
bilayers. By identifying layer number and strain as complementary control parameters for
Fermi polarons, our results establish metasurface-enabled scattering spectroscopy as a practical route to resolve and manipulate many-body resonances in stacked van der Waals
semiconductors, bridging idealized monolayer polaron physics and device-relevant architectures.
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All authors Tingting Wu, Francesca Maria Marchetti, Antonio Tiene, Antonio I. Fernández-Domínguez, Miao Qi, Zhe Wang, Lin Liu, Lei Wei, Francisco J. Garcia-Vidal, Mengxiao Chen, Qi Jie Wang, Yu Luo
Superconductivity
Tunable Superconductivity in 1313-La$_3$Ni$_2$O$_7$: Suppressed under Compression and Possible $s^{\pm}$ Pairing under Tension
Yang Zhang, Ling-Fang Lin, Adriana Moreo et al. (+2 more)
Motivated by recent progress in the 1313-La$_3$Ni$_2$O$_7$ nickelate thin films (Nie et al., Nature 652, 628 (2026)), we systematically investigate the effects of both compressive and tensile strain in this system. Self-doping effects between the single-layer (SL) and trilayer (TL) blocks are observed in our studies in both cases, but are most pronounced under tensile strain. We find that superconductivity is unlikely to emerge in the 1313 film on the LSAO substrate even with further hole doping. Remarkably, within the random-phase approximation, under tensile strain, a robust $s^{\pm}$-wave pairing state emerges in the TL subsystem with sign changes between the small electron-like $\sigma$ pocket at the $\Gamma$ point and the small hole-like $\gamma$ pocket at the M point. These pockets are connected by a wave vector close to $(\pi,\pi)$. Our calculations also suggest that superconductivity in 1313-LNO requires an optimally sized $\gamma$ pocket, because an oversized $\gamma$ pocket suppresses pairing formation. Overall, our results predict strain-dependent electronic reconstruction in 1313-La$_3$Ni$_2$O$_7$ and provide guiding principles for engineering superconductivity under ambient pressure conditions.
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All authors Yang Zhang, Ling-Fang Lin, Adriana Moreo, Thomas A. Maier, Elbio Dagotto
Solar and Stellar Astrophysics
Pre-nova Observations of T CrB: A view from the CHARA Array
Ryan Norris, Narsireddy Anugu, Thomas Gaudin et al. (+38 more)
T CrB is a symbiotic recurrent nova consisting of a red
giant and white
dwarf with recent eruptions in 1866 and 1946 and an anticipated eruption in the mid 2020s. We report CHARA Array observations obtained with MIRC-X (H -band) and MYSTIC (K-band) in 2022-2025. We fit limb darkened disk models constrained with literature limb darkening coefficients to the squared visibilities as only the first visibility lobe is sampled. The average limb darkened diameter of the
star across these epochs is $0.70\pm0.04$ mas in H-band and $0.72\pm0.07$ mas in K-band. Adopting a distance of $914^{+24}_{-22}$ pc, the
stellar radius is $69\pm5~R_{\odot}$ in H-band and $71\pm8~R_{\odot}$ in K-band. This is consistent with filling a Roche lobe volume radius of $71~R_{\odot}$ inferred from published orbital solutions. These measurements provide a pre-eruption angular diameter and support a Roche lobe filling donor.
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All authors Ryan Norris, Narsireddy Anugu, Thomas Gaudin, Magdalena Otulakowska-Hypka, Fabian Kaczmarek, Cameron Caruso, Cody Gustafson, Andrew Kotowski, Rebecca Proni, Nirupam Roy, Fabien Baron, Dipankar P.K Banerjee, Dana K. Baylis-Aguirre, Michelle J. Creech-Eakman, Justin Linford, Alexandre Gallenne, Joanna Mikołajewska, John D. Monnier, Denis Mourard, Ulisse Munari, Nicolas Nardetto, Rachael M. Roettenbacher, Jennifer L Sokoloski, Montana Williams, C. E. Woodward, Stefan Kraus, Jean-Baptiste Le Bouquin, Sorabh Chhabra, Isabelle Codron, Jacob Ennis, Tyler Gardner, Mayra Gutierrez, Noura Ibrahim, Cyprien Lanthermann, Benjamin R. Setterholm, Christopher D. Farrington, Olli Majoinen, Norm Vargas, Douglas R. Gies, Gail H. Schaefer, Theo ten Brummelaar
Astrophysics of Galaxies
Black Hole Stars Across the Universe: Identifying Central Engine Dominated Little Red Dots at $z\sim1.5-9.5$
Andrea Weibel, Rohan P. Naidu, Pascal A. Oesch et al. (+16 more)
Photometric selections of Little Red Dots (LRDs) largely rely on identifying their “V-shaped” spectral energy distribution (SED). Recent work suggests this V-shape stems from a combination of a central engine – also referred to as a Black Hole
Star (BH*) – and a
star-forming host
galaxy. We present a new and highly complementary photometric selection that is based on incorporating BH* templates in the eazy
redshift fitting code. Selecting compact sources where a BH* template contributes $>80$% to the best fitting SED in the rest-optical, we compile a sample of 241 BH*-dominated candidates from $\sim1000\,{\rm arcmin}^2$ of legacy and pure parallel JWST imaging. Our selection does not require a blue UV-component, and it successfully identifies objects that resemble the paradigmatic sources “MoM-BH*-1” and “The Cliff”. We find that BH*-dominated sources exist across a wide range of
redshifts ($z\sim1.7-9.3$) and optical luminosities (log$(L_{5100}/{\rm erg}\,{\rm s}^{-1})\sim42-44.5$), and we measure a median Balmer break strength of $\sim3$, with some breaks reaching values $>10$. We estimate bolometric luminosities in the range log$(L_{\rm bol}/{\rm erg}\,{\rm s}^{-1})\sim42-45$, which, assuming
accretion at the Eddington-limit, would translate to black hole masses of $M_{\rm BH}\sim10^4-10^7{\rm M_\odot}$, spanning the intermediate mass black hole to the
quasar regime. The number density of BH*-dominated candidates peaks at $z\sim5-6$ ($\sim10^{-5}\,{\rm Mpc}^{-3}$) and it declines by an order of magnitude down to $z\sim2$. Tentatively, comparing to V-shaped LRD samples suggests that the fraction of BH*-dominated sources among the broader LRD population does not decrease towards lower
redshift. Crucially, our work demonstrates that BH*-dominated sources are not merely an early-Universe phenomenon but rather persist at least until
cosmic noon.
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All authors Andrea Weibel, Rohan P. Naidu, Pascal A. Oesch, Anna de Graaff, Raphael E. Hviding, Zhaoran Liu, Jorryt Matthee, Christina C. Williams, Gabriel Brammer, Alba Covelo Paz, Jenny E. Greene, Christian Kragh Jespersen, Zhiyuan Ji, Michael V. Maseda, David J. Setton, Wendy Q. Sun, Alberto Torralba, Callum Witten, Mengyuan Xiao
Astrophysics of Galaxies
Dust in the Average Galaxy: Attenuation, Emission, and Opacity from $0<z<7$
Caitlin M. Casey, Hollis B. Akins, Andrew J. Battisti et al. (+43 more)
We present constraints on the
dust emission and attenuation properties of
galaxies across 0<z<7 using JWST imaging from the COSMOS-Web Survey combined with deep FIR/(sub)millimeter data from Spitzer, Herschel, SCUBA-2, NIKA-2 and ALMA. We analyze over 500,000
galaxies to independently constrain attenuation in the rest-frame UV/optical as well as
dust emission from stacked FIR SEDs, enabling a direct comparison between the two. We find UV/optical attenuation systematically underpredicts IR luminosity by a factor of ~3x at 0.5<z<7 and up to an order of magnitude for $M_\star>10^{10.5}M_\odot$. We derive empirical relationships for the effective attenuation,
dust temperature, fraction of
star formation that is unobscured, and
dust-to-
stellar mass ratio as functions of
redshift and
stellar mass. We separate the first order effect of
star/
dust geometry from
dust grain properties by combining constraints on the IR SED, UV SED, and
dust mass surface density. Importantly, we measure over an order of magnitude decrease in $\kappa_{UV}/\kappa_{FIR}$–the ratio of
dust mass absorption coefficients in the UV at 1600Å\ and FIR at 500$\mu$m–from z~0 to z~7. A depressed $\kappa_{UV}/\kappa_{FIR}$ is consistent with a deficit of small
dust grains, possibly attributable to the intense radiation fields of high-$z$
star formation; indeed, we find a
redshift-invariant inverse relationship between $\kappa_{UV}/\kappa_{FIR}$ and $\Sigma_{SFR}$. Most
evolution in the
dust-to-
stellar ratio is at $z<1$, the product of mild downward
evolution in the
dust-to-gas ratio combined with steep
evolution in the gas-to-
stellar ratio. The significant
evolution and dynamic range of $\kappa_{UV}/\kappa_{FIR}$ and prevailing disconnect between the UV/optical and FIR regimes emphasize that direct
dust constraints are irreplaceable for the majority of
star-forming
galaxies at z<7, not just the most extreme
star-formers.
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All authors Caitlin M. Casey, Hollis B. Akins, Andrew J. Battisti, Jed McKinney, Ezequiel Treister, Jorge A. Zavala, Hiddo Algera, Manuel Aravena, Yingjie Cheng, Nicole E. Drakos, Andreas L. Faisst, Maximilien Franco, Seiji Fujimoto, Ghassem Gozaliasl, Ali Hadi, Santosh Harish, Michaela Hirschmann, Olivier Ilbert, Kohei Inayoshi, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Claudia del P. Lagos, Erini Lambrides, Ronaldo Laishram, Daizhong Liu, Arianna S. Long, Georgios E. Magdis, Sinclaire M. Manning, Crystal L. Martin, Felix Martinez III, Richard Massey, Jacqueline E. McCleary, Henry Joy McCracken, Lauro Moscardini, Desika Narayanan, Louise Paquereau, Jason Rhodes, Brant E. Robertson, Rasha M. Samir, Claudia Scarlata, Marko Shuntov, Laura Sommovigo, Aswin P. Vijayan, Wuji Wang, Can Xu, Dhruv Zimmerman
Quantum Physics
Breaking the bicycle frame: Coset-based quantum LDPC codes
Arda Aydin, Itzhak Tamo and Alexander Barg
Generalizing the construction of two-block group
algebra (2BGA) codes, we introduce a family of two-block
quantum LDPC codes constructed using the action of a group on the cosets of its subgroup. This replaces the regular group actions of the earlier two-block constructions and significantly expands the search space, yielding new
quantum LDPC codes outside the 2BGA family. Through a computer search, we identify several new
quantum LDPC codes, including weight-6 codes with parameters $[[48,8,6]]$, $[[96,8,10]]$, and $[[224,12,16]]$, as well as weight-8 codes with parameters $[[84,16,8]]$, $[[112,16,10]]$, $[[128,16,12]]$, and $[[168,16,15]]$. Furthermore, we introduce a maximally packed syndrome extraction schedule of depth $w+2$, including initialization and measurement steps, for any code with a maximum stabilizer weight of $w$ from our family. Under a standard
circuit-level noise model, our codes, when decoded using BP-OSD, perform competitively with BB codes, achieving thresholds of $\approx0.65\%$ for the weight-6 family and $\approx0.35\%$ for the weight-8 family. Finally, we introduce a group-theoretic framework to generate sequences of graph-based covers of 2BGA codes, recovering and extending recent results on code constructions of this type.
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Materials Science
General Method for Evaluation of Stop-Bands of Periodic Structures with Symmetric Unit Cells
Alexander Hvatov, Mariia Krasikova, Aleksandra Pavliuk et al. (+1 more)
The mirror
symmetries of a periodic unit
cell are exploited to decompose the standing-wave eigenproblem at the high-
symmetry vertices of the Brillouin zone into four independent sub-problems on a quarter-
cell, each governed by Neumann (sound-hard) or Dirichlet (sound-soft) boundary conditions. Sorting and pairing the resulting eigenfrequencies by index along each segment of the irreducible Brillouin zone boundary yields an explicit formula for the stop-band intervals without computing the full dispersion diagram. The decomposition is exact, following directly from the representation theory of the little group at each high-
symmetry point. It applies to any unit
cell whose material distribution is invariant under the mirrors normal to the
cell faces. The method is validated on two configurations: a phononic
crystal of lead cylinders in an epoxy
matrix, analyzed using the plane-wave expansion, and a
lattice of coupled C-shaped Helmholtz resonators, analyzed using finite-element analysis. For both systems, the reconstructed stop-band boundaries agree with the full Floquet dispersion calculation to within 1% for the lowest bands, requiring
eigenvalue solutions at only three discrete wavevectors. Avoided crossings within a Brillouin zone segment can cause bands to exhibit non-monotone behavior, rendering the pairing rule approximate; the spectral conditions for this are identified. Flat bands common to both boundary-condition types are identified as bound states in the continuum.
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All authors Alexander Hvatov, Mariia Krasikova, Aleksandra Pavliuk, Steffen Marburg
Applied Physics
Coupled-Mode Equations with Arbitrary Mode Combinations for Kinetic-Inductance Superconducting Traveling-Wave Parametric Devices: Theory and Experimental Validation
F. Patricio Mena, Camilo Espinoza, Ryan O. Berriel et al. (+2 more)
The coupled-mode equations (CMEs) have proven very successful in describing parametric processes in nonlinear optics. More recently, the same formulation has been used to model microwave superconducting parametric amplifiers and frequency multipliers. However, when applied to the microwave regime, not all assumptions remain valid and losses play a more dramatic role. Here, we revisit the CMEs applied to traveling-wave superconducting amplifiers to include losses and provide a formulation that enables their systematic derivation for any combination of traveling waves. As examples, we discuss the impact of unwanted harmonics and intermodulation products on parametric amplification, as well as harmonic generation. We verify that, if not properly accounted for, device performance can deviate considerably from the ideal case. Furthermore, using a superconducting CPW-based artificial transmission line and combining an independent experimental determination of its nonlinear parameter $I'_*$ with simulations of its linear properties, we obtain a parameter-free validation of this formulation. The nonlinear parameter was determined to be $I'_* \approx 27$ mA which, surprisingly, scales with the theoretical depairing current and not with the much smaller critical current of the device. For the validation, we measured multiple-harmonic generation and found excellent agreement between theory and experiment. The fact that $I'_* \gg I_C$ has direct implications for device design.
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All authors F. Patricio Mena, Camilo Espinoza, Ryan O. Berriel, Ricardo Finger, David J. Thoen
Astrophysics of Galaxies
Dust-Embedded Star Formation: Bridging Magellanic Cloud Studies of Massive Young Stellar Objects to Nearby Spiral Galaxies
M. Jimena Rodríguez, Rémy Indebetouw, Janice C. Lee et al. (+13 more)
We use JWST NIRCam and MIRI imaging at 2, 4, 10, and 21 um to study young, dusty compact sources in four nearby
galaxies at distances of ~ 1-5Mpc (M33, NGC300, NGC7793, and NGC5068). This work bridges well-characterized massive young
stellar objects (MYSOs) in the Magellanic Clouds from the Spitzer SAGE survey to new studies of embedded clusters in more distant
galaxies with JWST. Guided by the SAGE-LMC catalog, we define JWST color-magnitude selection criteria (F1000W versus F1000W-F2100W) and test them using resolution-degradation experiments. We identify 216, 32, 80 and 139 dusty young objects in the four
galaxies, respectively. The selected population spans sources from systems dominated by a single MYSO to compact marginally resolved sources hosting multiple MYSOs. The color selection remains stable across 1-5 Mpc, and the 10um luminosity function retains a slope of alpha~ -2. However, blending and surface-brightness dilution remove fainter sources, leading to incompleteness of up to ~ 50% at 5.2 Mpc and biasing the sample toward brighter objects (F1000W < 19 mag). The sample spans approximate
stellar masses of ~10-2 X 10^5 Mo. Spatial resolution affects the interpretation of mid-infrared emission: clustering increases the fraction of emission attributed to compact sources in active regions, while blending into diffuse emission dominates in quiescent environments. Comparisons with PAH-selected young clusters in the PHANGS
galaxy NGC5068 show that our selection recovers ~ 80% of the PAH-selected sources. We show that the practical limit for studying individual MYSOs with JWST is ~3 Mpc. The resulting catalog provides a foundation for future resolved studies of
star formation rates and early cluster
evolution.
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All authors M. Jimena Rodríguez, Rémy Indebetouw, Janice C. Lee, Bradley C. Whitmore, David A. Thilker, J. Peltonen, Erik Rosolowsky, Thomas G. Williams, Eric W. Koch, Bruce Elmegreen, Ralf S. Klessen, Roberta Paladini, Sumit Sarbadhicary, Daniel A. Dale, Kelsey E. Johnson, Aida Wofford
Disordered Systems and Neural Networks
Stochastic Thermodynamics of Score Matching in Diffusion Models
Xuehao Ding, H. T. Quan and Yuhai Tu
Score-based
diffusion models are a powerful class of generative AI systems capable of sampling from complex, high-dimensional probability distributions. Their dynamics consist of a forward
diffusion process that transforms data into noise and a learned reverse process that reconstructs data by reversing the probability flow. Here, we develop a
stochastic thermodynamic framework for
diffusion models and their score-matching objective. We introduce a trajectory-dependent quantity, time-asymmetry
entropy production (TAEP), defined from the forward and reverse
diffusion dynamics, and show that it obeys exact fluctuation
theorems. Remarkably, Hyvärinen's implicit score-matching kernel emerges naturally as a fluctuating component of TAEP, while the average TAEP is exactly proportional to the score-matching objective. We further show that fluctuations of TAEP quantify sampling unevenness and provide a thermodynamic measure of data-
manifold coverage. These results yield a quantitative explanation for the superior sampling diversity of
diffusion models and reveal a thermodynamic mechanism by which
stochastic gradient descent favors flatter, more generalizable solutions. By uncovering the entropic nature of score matching, our work establishes fundamental statistical-mechanical principles underlying
diffusion-based generative AI.
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Quantum Physics
Post-Selection Probability and Fidelity of Bidirectional Teleportation
Ning Sun, Lei Feng and Pengfei Zhang
Understanding the scrambling of
quantum information is central to many areas of
quantum physics, including
quantum thermalization,
entanglement growth, and
quantum information processing. Insights from these studies have, in turn, inspired the development of novel
quantum protocols and
algorithms. Recently, a bidirectional teleportation protocol was proposed to implement a digital SWAP operation between
qubits by leveraging chaotic
Hamiltonian evolution combined with measurement and post-selection. In this work, we provide a comprehensive study of two central quantities that characterize the protocol, the post-selection probability and the fidelity, taking into account possible errors in time-reversed dynamics. We show that these quantities can be expressed in terms of standard diagnostics in
quantum dynamics, including the Loschmidt echo and its subsystem variant. The results unveil (1) the initial-state dependence of the fidelity and (2) the stability of the post-selection probability in integrable models. Our findings offer practical guidance for the implementation of the protocol on realistic
quantum devices.
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Quantum Gases
Spin effects in the particle current of Bose-Einstein condensates in synthetic gauge fields
Hugo Bencomo Martín and Antonio Muñoz Mateo
Spin reveals the rotational features of a system independently of its state of motion. Hence, it is not a relativistic quantity, despite giving rise to effects that emerge naturally from relativistic equations only. Within a non-relativistic framework these effects are not inherently captured, and have to be added by resorting to
symmetry principles or to the asymptotic limit of the corresponding relativistic framework. We report on one of these effects: the divergenceless
spin term in the particle current density of spinor Bose-Einstein condensates. It could be observed in the setup of a synthetic
Hall system made with non-relativistic pseudospin-1/2 bosonic particles. By tuning the interaction strength, the system can show how the
spin term in the particle current is needed for the local matching of classical drift velocity in the ground state of the non-interacting system, whereas for increasing interparticle interactions the
spin-to-orbital current ratio decreases. In either case, since the overall particle velocity changes with the
spin term contribution, so does its circulation in a loop, which in turn has physical consequences for its relationship with the Aharonov-Bohm phase shift.
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Strongly Correlated Electrons
Antisite-disorder driven tuning of magnetic properties and exchange-bias in Nd$_{2-x}$Sr$_{x}$CoMnO$_{6-\delta}$ $(0 \leq x \leq 1)$ ($\delta \sim 0.5$) double perovskites
Kazi Parvez Islam, Jayjit Kumar Dey, Sourav Chowdhury et al. (+8 more)
We demonstrate precise control of exchange bias (EB) in the Nd$_{2-x}$Sr$_x$CoMnO$_{6-\delta}$ ($0 \leq x \leq 1$) double-perovskite series through Sr$^{2+}$ induced hole doping, unveiling a remarkable transition between normal and inverse EB states. Employing
neutron powder diffraction and X-ray absorption spectroscopy, we reveal a structural
evolution from a B-site-ordered monoclinic ($P2_1/n$) phase to a disordered rhombohedral ($R\overline{3}c$) phase with increasing $x$, accompanied by a shift in the effective Co valence from +2 toward +3, while the Mn valence remains essentially unchanged. DC magnetization measurements indicate a gradual suppression of ferromagnetism with hole doping, whereas AC susceptibility measurements at $x = 0.75$ reveal pronounced cluster-glass behavior and the highest EB field of $\sim 4$ kOe at 8 K under a 6 T cooling field. After correcting for minor-loop effects, we identify robust inverse EB at $x = 0.75$, persisting even under a cooling field of 6 T. We attribute this phenomenon to competing
ferromagnetic–
antiferromagnetic and
ferromagnetic–glassy interfaces, governed by strong
magnetic frustration and the magnetocrystalline anisotropy associated with rare-earth 4$f$ electrons. These findings elucidate the pivotal role of doping-induced structural and
magnetic competition in tailoring EB behavior in rare-earth double perovskites, providing new insights for the design of advanced
magnetic materials.
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All authors Kazi Parvez Islam, Jayjit Kumar Dey, Sourav Chowdhury, Samyabrata Paria, Flora Banerjee, Suryakanta Mishra, Suman Kalyan Samanta, Moritz Hoesch, Robert Dankelman, Indu Dhiman, Debraj Choudhury
High Energy Physics (Phenomenology)
Quantum decoherence of hyperon spin correlations in QCD hadronization
Feng Liu and Zhoudunming Tu
Hadronization, the transition of
quarks and
gluons into
hadrons, lies beyond the reach of perturbative
quantum chromodynamics (QCD) and is commonly described by the semiclassical Lund string model. Yet this very success raises a fundamental question: where does the quantumness go during hadronization? In this Letter, we propose an approach inspired by
quantum information science, in which (i)
quark-antiquark pairs excited from the QCD
vacuum inherit its
quantum numbers, giving rise to
spin entanglement at their creation, and (ii) subsequent string breaking generates environmental degrees of freedom that induce
quantum decoherence of the
spin state. This framework simultaneously describes the $\Lambda$ hyperon
spin-correlation data measured at RHIC [Nature 650, 65-71 (2026)] and at the LHC, establishing a quantitative connection between the QCD
vacuum,
spin entanglement and decoherence, and hadronization.
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Biological Physics
Cell sensing: from physical limits to active behaviors
Andrew Mugler and Maria Rose
Physics sets the information contained in the signals that
cells sense. But
cells are active, not passive, sensors. They shape and reshape both the environment and themselves. These active behaviors allow
cells to amplify, redistribute, share, and prioritize sensory information, often surpassing or obviating passive physical limits. Here, we review recent results on active sensing. After describing classic and more recent limits to sensory precision, we focus on four ways that
cells implement active sensing: coordinating with other
cells, reshaping their environment, dynamically updating themselves, and discriminating signals. We conclude with potential future directions.
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Exactly Solvable and Integrable Systems
Vector peakon equations and isospectral flows in Clifford algebras
Andrew N.W. Hone, Vladimir S. Novikov and Jacek Szmigielski
Starting from a spectral problem posed in a Clifford
algebra with $d$ generators and Euclidean signature, we study an integrable, coupled system of PDEs that can be viewed as a vector perturbation of the Camassa–Holm equation with residual orthogonal
symmetry. In the two-component case $d=2$, we show that the travelling wave solutions correspond to a Liouville integrable
Hamiltonian system with two degrees of freedom, making use of a reciprocal transformation linking the coupled PDEs to a
symmetry of the Hirota–Satsuma system. We also present a
symmetry classification of all integrable two-component perturbations of Camassa–Holm, and find that besides the $d=2$ system analyzed here, the coupled 2CH system studied by Olver and Rosenau (as well as by Chen, Liu and Zhang, and Falqui), and equations related to either of those systems by Miura transformations, we also obtain a new system that (to the best of our knowledge) has not been reported previously. For the case of an arbitrary number of components $d$, we additionally investigate the short-pulse (high-frequency) regime, in which the limiting dynamics are governed by a vector-valued Hunter-Saxton type system. Furthermore, we provide a detailed analysis of the corresponding measure-valued (weak) solutions associated with this system.
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Plasma Physics
Time-dependent Trapped Plasmas: Nonlinear Dynamics, Symmetries and Invariants
Thonimar V. Alencar, Luiz Gustavo Ferreira Soares and Ronaldo Thibes
We investigate the nonlinear dynamics of a single-component
plasma confined in a time-dependent harmonic trap regarding aspects of
symmetry and invariant functions. The system is described as a fluid in an isentropic adiabatic regime by a system of partial differential equations. A convenient change of variables, with a Gaussian ansatz for the number density distribution, allows a consistent mathematical description in terms of ordinary differential equations, from which we follow up with an analysis concerning the corresponding differential operators algebraic structure and Noether
symmetries in specific physical regimes. For each studied case, proper invariants are identified. The obtained conserved quantities capture an interplay between the internal
plasma dynamics and the time modulation of the trap, resulting in a sharp restriction for the system
evolution.
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Lattice Field Theory
Precision renormalisation and improvement of $N_{\rm f}=3$ lattice QCD with Wilson fermions
Patrick Fritzsch, Jochen Heitger, Simon Kuberski et al. (+2 more)
We renormalise (and improve) the flavour non-singlet axial current, pseudo-scalar density, vector current and tensor current, as well as
quark masses, in O(a) improved
lattice QCD with three massless flavours and
lattice spacings down to 0.01 fm. To this end, we tune a number of
lattices with Schrödinger functional boundary conditions and resolutions $8\leq L/a\leq 64$ to lines of constant physics with massless
quarks and fixed gradient flow coupling $\bar{g}_\mathrm{GF}^2(L_i),\; i=0,1,2$, corresponding to $L_0 \approx 0.25$ fm, $L_1=2L_0$ and $L_2=4L_0$. We further renormalise and improve the
quark mass of additional heavy
quarks for use in the B-physics programme of the collaboration (arXiv:2312.09811). Our somewhat technical results enable first-principles strategies for solving multi-scale problems involving, e.g., the b-
quark mass (arXiv:2312.10017) or a large temperature (arXiv:2501.11603). Comparing also to other determinations of the axial current renormalisation constant $Z_{\rm A}$, we have a precise confirmation of how renormalisation and the restoration of
chiral symmetry work out with Wilson
fermions at small $a$. In particular, the accurate restoration of
chiral symmetry and the exact flavour
symmetry lead to practically negligible uncertainties in observables determined from Ward identities: four to five significant digits are achieved for $Z_{\rm A},Z_{\rm V}$. We provide an explanation for the strong suppression of their statistical variances.
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All authors Patrick Fritzsch, Jochen Heitger, Simon Kuberski, Hubert Simma, Rainer Sommer
Materials Science
Physics-Informed Attention Mechanism and Generalization Capability of Deep Learning-Based Grain Growth Evolution Prediction
Pungponhavoan Tep and Marc Bernacki
Machine Learning (ML) models for grain growth prediction are typically trained on idealized synthetic data, yet practical applications require generalization to conditions outside the training distribution. This study evaluated the Out-Of-Distribution (OOD) generalization capability of the trained model from our previous study across three test cases, including experimental microstructures, microstructures characterized by a bimodal grain size distribution, and abnormal grain growth. To further probe whether physics-informed architectural design could improve robustness under these different conditions, a boundary-masked
attention mechanism was proposed specifically for grain growth, constraining
attention to grain boundary pixels. Both the baseline and the proposed physics-informed
attention model were evaluated without retraining or fine-tuning on the OOD data. Both models successfully generalized to all three test cases, yet the boundary-masked
attention mechanism provided substantial improvements, with the most notable gains for microstructures characterized by a bimodal grain size distribution, where Structural Similarity Index Measure (SSIM) improved from \num{0.6221} to \num{0.7609} and mean grain size ($\overline{R}$) error decreased from \SI{8.75}{\percent} to \SI{3.57}{\percent}. The
attention heatmap analysis revealed that the boundary-masked
attention model learned to concentrate
attention on large grain boundaries in a manner consistent with
curvature-driven grain growth physics, emerging from training without being explicitly encoded into the architecture. These results indicate that models trained on synthetic data can generalize to diverse OOD conditions without retraining, and that physics-informed
attention may improve accuracy when the boundary morphology matches the training domain.
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High Energy Astrophysical Phenomena
Can a slow and strong phase transition in neutron stars relieve major compact-star observation tensions?
Chen Zhang
Recent anomalous compact-
star observations challenge the conventional
neutron-
star interpretation in complementary ways: HESS J1731–347 and XTE J1814–338 favor unusually small radii at low mass, while the secondary component of GW190814 appears too massive for an ordinary
neutron star under GW170817-based maximum-mass inferences. We examine whether
neutron stars with a strong first-order
hadron-
quark phase transition can address these tensions via the extended stable hybrid branches that arise when the phase conversion is slow compared to radial oscillations, while remaining consistent with GW170817 and NICER constraints. Using a piecewise-polytropic (PP)
benchmark, supplemented by an independent speed-of-sound (CS) parametrization comparison, we find two viable scenarios after a general parameter scan over both the hadronic and hybrid branches. Scenario 1 realizes an all-at-once solution: the same equation of state has a pure hadronic branch compatible with both the GW190814-scale mass and HESS J1731–347, while its slow stable hybrid branch reaches XTE J1814–338. Scenario 2 retains the GW190814-scale hadronic branch but reaches XTE J1814–338 and HESS J1731–347 on slow stable hybrid branches in very different transition-strength regimes.
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High Energy Astrophysical Phenomena
The properties of tidal disruption event infrared counterparts produced by dust rings and inference of the observing angle
Rob A. J. Eyles-Ferris
A substantial fraction of
tidal disruption events (TDEs), resulting from a black holes's disruption and
accretion of a
star, exhibit infrared (IR) counterparts thought to arise from spherical shells of
dust reprocessing the TDE emission. Some modelling of TDEs also predicts an angular dependence in their observed properties with more X-ray emission on-axis and more optical emission at higher angles. However, there is growing evidence that X-ray rich TDEs are more likely to exhibit IR counterparts, contradicting the spherical shell model that predicts no significant variation in IR luminosity with angle. Here, I demonstrate that this result naturally follows for
dust arranged in a ring instead of a spherical shell. I present a toy model of this scenario and show that on-axis angles result in a brighter counterpart. I also show that on-axis angles result in a delay in the initial rise and off-axis angles may display a double-peaked structure. Crucially, this model also allows the observing angle of the TDE to be constrained. Finally, I demonstrate that this model reproduces the properties of two IR counterparts, including constraining their observing angles and independently inferring an optical plateau, and briefly comment on its application to quasi-periodic eruption counterparts.
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Optics
220-GBd optical coherent waveform generation using temporal unitary transforms
Callum Deakin, Xi Chen and Di Che
We use temporal
unitary transforms to generate 16-QAM up to 220 GBd using only 50-GHz electrical bandwidth. The technique is theoretically lossless and can generate arbitrary optical waveforms beyond the bandwidth of the constituent modulators.
Optics
All-optical analogue of anti-skyrmions and anti-merons in difference-frequency-generation process
Arannya Ghosh, Mukesh K Shukla and Ritwick Das
In the paraxial domain, a difference-frequency generation (DFG) process provides a versatile platform for exploring non-Hermitian dynamics in an all-classical interaction. This letter aims to show the existence of topologically non-trivial optical analogues of anti-Skyrmionic states in an 'anti' parity-time (anti-PT)
symmetry-broken dynamical interaction in a DFG process. A practical DFG set-up, which is constituted by a periodically-poled lithium tantalate (PPLT)
crystal and pumped by a visible (green) pump
laser, is considered for ascertaining the non-Hermitian dynamics. In the anti-PT
symmetry broken phase, a negatively phase-mismatched interaction gives rise to a topologically non-trivial pseudo-magnetization texture that could support anti-skyrmion-like quasi-particles in signal and idler modes. The analysis also reveals the existence of anti-meron like pseudo-magnetization texture for a phase-matched DFG.
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High Energy Physics (Theory)
Effective-metric formulation of Casimir energies in nonlinear scalar and electromagnetic theories
C. A. Escobar
We study the Casimir effect in nonlinear field theories through the effective geometries that \mbox{govern} their linearized fluctuations. Previous analyses of Lorentz-violating scalar fields showed that a constant kinetic background modifies the parallel-plate Casimir energy by a rescaling of the plate separation and an overall determinant factor. We show that this structure is not merely a consequence of diagonalizing the reduced Green function. It follows from a common Schur-complement structure: after
Fourier reduction parallel to the plates, the same reduced quadratic form controls the spectral denominator of the reduced Green function and the numerator generated by the energy-density insertion. This observation allows the Lorentz-violating scalar result to be used as an effective-metric prescription for regular fluctuation sectors arising from the linearization of nonlinear theories around constant backgrounds. In nonlinear scalar theories, the effective tensor is the Hessian of the Lagrangian evaluated on a constant-gradient background. In nonlinear electrodynamics $\mathcal{L}(\mathcal{F})$, a constant
magnetic background splits the fluctuations into an ordinary Maxwell branch and an extraordinary optical branch. For this electromagnetic sector, we compute the parallel-plate Casimir energy both by direct mode summation and by applying the effective-metric formula branch by branch, finding exact agreement. The resulting energy depends on the orientation of the
magnetic background relative to the plates, providing a concrete anisotropic Casimir response in a regular nonlinear electromagnetic sector.
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