Atmospheric and Oceanic Physics
State transitions in land-vegetation systems emerge at Paris Agreement warming levels in CMIP6
Pouriya Alinaghi, Sybren Drijfhout, Joran Angevaare et al. (+2 more)
Using an automatic detection workflow applied to the Coupled Model Intercomparison Project Phase 6 (CMIP6) ensemble under future emission scenarios, we identify 47 abrupt and more gradually developing state transitions in the land-vegetation component of the Earth system, classified into 9 categories. Over the Amazon, we find state transitions via vegetation dieback alongside greening cases; the contrast between them is traced primarily to differences in precipitation: models showing dieback experience either a larger absolute decline in precipitation, or one that translates more efficiently into soil moisture loss, particularly near the surface, while in greening models the CO$_2$ fertilization effect wins out where the soil moisture loss remains weaker. The precipitation decline in dieback-prone models appears driven through a weakening of moist convection. Across these Amazon cases, models with dynamic vegetation undergo dieback, whereas greening is confined to models with prescribed vegetation distributions. African cases include greening over eastern-central Africa and the Congo basin, and an abrupt soil-moisture drying also over the Congo. At high latitudes, boreal forest expands, while permafrost thaws once the regional above-zero temperatures persist for more than half the year. Additional categories cover transitions to a reduced snow-cover state over northeastern North America, increased vegetation biomass near the Tibetan Plateau and southeastern Asia, and increased leaf-area index over the northeast Northern America. Of particular concern, a global warming of 2$^\circ$C or below, within reach of the Paris Agreement targets, is already enough to trigger the onset of the majority of the identified categories in CMIP6.
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All authors Pouriya Alinaghi, Sybren Drijfhout, Joran Angevaare, Chris Jones, Andy Wiltshire
Superconductivity
Onset of the transitional flux-avalanche regime in bulk NbTi controlled by the thermal boundary conductance
Irina Abaloszewa, Victor V. Chabanenko and Aleksander Abaloszew
Thermomagnetic avalanches in type-II
superconductors occur in two qualitatively different regimes, electromagnetically controlled in thin films and thermally limited in bulk samples, distinguished by the sign of the temperature derivative of the threshold field $H_\text{th}(T)$. The two regimes are separated by a critical thermal boundary conductance $h_c$, and a non-monotonic $H_\text{th}(T)$ has been predicted in the transitional region where the interface conductance $h$ approaches $h_c$. We approach this region in a bulk NbTi disk by raising the interface coupling above the pure-nonadecane baseline with a silver-filled interface layer. Whereas the pure interface gives a monotonically decreasing $H_\text{th}(T)$, the silver-filled interface produces a non-monotonic dependence not previously realized in a bulk
superconductor: a temperature interval of positive slope, $dH_\text{th}/dT > 0$, terminating in a maximum at $T^* \approx 6.1$–$6.4$~K. The effect is reproduced for two independent silver-filled compositions; in a third, with the highest loading, the low-temperature decrease is absent altogether and $H_\text{th}(T)$ is flat up to the same $T^*$, the
evolution expected for stronger coupling. The position of the maximum is set by the intrinsic properties of NbTi, independent of the silver content. The onset of the positive-slope interval coincides in temperature with a change of the avalanche morphology from narrow channeled fingers to broad fronts. The reversal of the sign of $dH_\text{th}/dT$ is a direct experimental signature of the onset of the transitional regime, in which heat removal during the instability becomes dynamically relevant.
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Strongly Correlated Electrons
Entwined lattice of atoms and anionic electrons in layered electride LaCl
Songyuan Geng, Xin Wang, Jianqi Zhong et al. (+14 more)
Controlling the
lattice geometry that governs electronic structure is a central theme in condensed-matter physics, yet in crystalline solids this geometry is usually fixed by the atomic framework. Electrides offer an alternative route to electronic structure design in which their excess electrons can organize into anionic electron
lattice (AEL) and provide a
lattice-like degree of freedom. Recent work has highlighted the standalone limit, where the AEL in YCl yields bands well described by the dice-
lattice model. Here, using angle-resolved photoemission spectroscopy (ARPES), we show that LaCl, although isostructural to YCl, realizes a qualitatively different regime where the AEL is entwined with the La cation framework, producing a fully reconstructed electronic structure. Combining the ARPES result with tight-binding model analysis, we demonstrate that this radical divergence stems from the activation of direct hopping channels between the AEL and the La atomic
lattice. This coupling reshapes the effective
lattice geometry, reconstructs the electronic states, and modifies the associated Chern band
topology, transforming the bipartite dice-
lattice network in YCl into a tripartite structure in LaCl. Our findings demonstrate that the coupling between the AEL and the atomic
lattice can actively shape the effective
lattice geometry that governs the electronic structure. This coupling can act as a powerful tuning knob for electronic structure design that is inaccessible in conventional materials.
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All authors Songyuan Geng, Xin Wang, Jianqi Zhong, Risi Guo, Fangjie Chen, Qun Wang, Kangjie Li, Keyu An, Teng-Fei Ying, Chen Qiu, Hanpu Liang, Zhengtai Liu, Mao Ye, Sungsoo Hahn, Balasubramanian Thiagarajan, Benjamin T. Zhou, Haoxiang Li
Astrophysics of Galaxies
CO Structures with Narrow Lines in Nearby Quiescent Regions
Ruilin Xia, Yang Su, Shiyu Zhang et al. (+13 more)
Using CO data from Phase I of the Milky Way Imaging Scroll Painting (MWISP) survey, we present a systematic study of molecular structures with narrow lines. We identify 57 CO structures, most of which exhibit low densities and subsonic/transonic
turbulence. Among them, structures with large projected areas and diffuse, sheet-like geometries are identified as veil clouds. The low LSR velocities and the concentration of these CO structures toward both the
Galactic center (e.g., Ophiuchus, Aquila) and anticenter (e.g., Cepheus, Taurus) regions suggest a local origin for the sample, as supported by distance measurements of about 200–300pc for a subset with relatively large angular extents. These nearby structures likely arise from large-scale compression driven by past
supernova activity within the Local Bubble. The observed low-velocity-dispersion emission may trace quiescent regions where
turbulence has decayed due to a lack of sustained energy injection. For diffuse veil clouds with an assumed
magnetic field of ~10uG, ion-neutral friction may provide an additional mechanism for turbulent dissipation on sub-parsec scales corresponding to their thickness of 0.1–0.3pc. Tracing the atomic-to-molecular transition, veil clouds provide a unique window into the diffuse, quiescent precursor state of dense gas. They likely represent a widespread but previously overlooked component of the
Galactic molecular gas reservoir, with significant implications for cloud formation and
evolution, the total mass budget and spatial distribution of molecular gas, and the initial conditions of
star formation as a related consequence.
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All authors Ruilin Xia, Yang Su, Shiyu Zhang, Xuepeng Chen, Ji Yang, Yan Gong, Yuehui Ma, Yan Sun, Min Fang, Fujun Du, Shaobo Zhang, Xin Zhou, Lixia Yuan, Qing-Zeng Yan, Li Sun, Jiancheng Feng
Materials Science
Surface Equilibration Mechanism Controls the Stability of a Model Co-deposited Glass Mixture of Organic Semiconductors
Shinian Cheng, Yejung Lee, Junguang Yu et al. (+2 more)
While previous work has identified the conditions for preparing ultrastable single-component organic glasses by physical vapor deposition (PVD), little is known about the stability of co-deposited mixtures. Here, we prepared binary PVD glasses of organic
semiconductors, TPD (N,N-Bis(3-methylphenyl)-N,N-diphenylbenzidine) and m-MTDATA (4,4,4-Tris[phenyl(m-tolyl)amino]triphenylamine), with 50:50 mass concentration over a wide range of substrate temperatures (Tsub). The enthalpy and kinetic stability are evaluated with differential scanning calorimetry and spectroscopic ellipsometry. Binary organic
semiconductor glasses with exceptional thermodynamic and kinetic stability comparable to the most stable single-component organic glasses are obtained when deposited at Tsub=0.78-0.90Tg (where Tg is the conventional glass transition temperature). When deposited at 0.94Tg, the enthalpy of m-MTDATA/TPD glass equals that expected for the
equilibrium liquid at that temperature. Thus, the surface equilibration mechanism previously advanced for single-component PVD glasses is also applicable for these co-deposited glasses. These results provide an avenue for designing high-performance organic electronic devices.
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All authors Shinian Cheng, Yejung Lee, Junguang Yu, Lian Yu, M. D. Ediger
General Relativity and Quantum Cosmology
Gravitational caloric theory: From early dark energy to a wide variety of gravitational phenomena
S. X. Tian
We propose gravitational caloric theory (GCT) — an extension of general relativity that features a vector field $S_\mu$ sourced by and non-minimally coupled to the fluid sector while preserving covariant conservation of the standard fluid energy-momentum tensor. Our initial motivation is to trigger early dark energy (EDE) using the total fluid equation of state that encodes the
cosmic radiation-matter transition. This mechanism provides a natural resolution of the EDE coincidence problem. The cosmological background dynamics are analyzed in detail by casting the
evolution equations into dynamical-system form and, in relevant reduced cases, using Poincaré compactification to uncover the corresponding global phase-space structure. Beyond EDE, GCT admits two novel cosmological applications associated with critical points at infinity. Both arise from a class of energy-cancelling solutions in which conventional energy components preferentially excite $S_\mu$ rather than source spacetime
curvature. One is a $\Lambda$-cancelling solution that realizes the self-tuning mechanism for the old cosmological constant problem. Yet it remains incomplete. The other is a fluid-cancelling solution that serves as the basis for our proposed early static hot Universe. In this scenario, $S_\mu$ offsets the gravitational effect of ordinary hot gas, yielding quasi-static expansion with a decreasing comoving Hubble radius that can address the horizon problem. This offers an alternative to inflation. Furthermore, its hot ingredient distinguishes this scenario from other quasi-static early Universe models and may leave observable signatures in
primordial fluctuations. To probe the viability of GCT beyond cosmology, we further analyze linear perturbations about Minkowski spacetime and investigate static spherically symmetric (strong-field) systems. (Abstract abridged to meet arXiv limits.)
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Cosmology and Nongalactic Astrophysics
Conformal Killing Gravity: New Constraints from DESI DR2 BAO datasets
Himanshu Chaudhary, Salvatore Capozziello, Carlo Alberto Mantica et al. (+3 more)
We investigate a
geometric approach referred to as the Conformal Killing
Gravity (CKG), in which the dark energy sector emerges naturally from the conformal Killing
symmetry of the Robertson–Walker space-time. Within this framework, the divergence-free conformal Killing tensor behaves as an effective perfect fluid, giving rise to a dynamical dark-energy component whose density, pressure, and equation of state are uniquely determined by the underlying geometry, without introducing any empirical dark-energy parametrization. The resulting CKG model extends the standard $\Lambda$CDM cosmology through a single additional parameter while recovering the $\Lambda$CDM limit in the absence of the
geometric contribution. We constrain the model using Planck PR4 (NPIPE) CMB temperature, polarization, and
lensing observations, ACT DR6 CMB
lensing, DESI DR2
baryon acoustic oscillation measurements, and the Pantheon$+$, DES-Dovekie, and Union3 Type Ia
supernova compilations. The analysis shows that the CKG favors a quintessence-like dark-energy
evolution with no evidence for phantom crossing, while the reconstructed equation of state rapidly approaches the cosmological constant at earlier
cosmic times. Furthermore, the model predicts a future critical
redshift in the range $-0.8 \lesssim z_c \lesssim -0.7$, indicating that the present
cosmic expansion eventually reaches a turning point before the formal singular limit at $z=-1$. Since the
geometric contribution modifies only the post-recombination expansion history, the sound horizon remains essentially unchanged and the model does not provide a complete solution to the $H_0$ tension. Our results demonstrate that the CKG provides a simple, physically motivated, and observationally favored framework for describing the late-time accelerated expansion of the Universe.
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All authors Himanshu Chaudhary, Salvatore Capozziello, Carlo Alberto Mantica, Luca Guido Molinari, Dhruba Jyoti Gogoi, Ghulam Mustafa
General Relativity and Quantum Cosmology
Spotlight searches for continuous gravitational waves triggered on radiometer candidates in LIGO O4a data
Alan M. Knee, Keith Riles and Ling Sun
We report on a follow-up search for continuous gravitational waves (CWs) targeting sub-threshold candidates from the O4a LIGO-Virgo-KAGRA (LVK) all-sky all-frequency (ASAF) directed radiometer analysis. We analyze a total of $562$ ASAF candidates using Advanced LIGO data from the first part of the fourth LVK observing run. Each candidate comprises a narrow $1/32$ Hz frequency band paired with a ${\sim}13$ deg$^2$ sky pixel, defining the search parameter space for our analysis. Our search pipeline leverages the $F$-statistic matched filter equipped with a hidden Markov model to enable tracking of a potentially frequency-wandering CW signal. Of the 562 initial candidates, we obtain $21$ outliers with false alarm probability less than $5\%$ that survive all instrumental vetoes. None of the outliers are recovered at comparable statistical significance in the second part of the fourth observing run, from which we conclude that no convincing CW signals are detected. We estimate the sensitivity of our analysis by recovering simulated signals added to real detector data. Across the $20\text{--}1726$ Hz frequency band, our search achieves $95\%$ detection efficiency for strain amplitudes in the range of $h_0\sim (0.63\text{--}6.3)\times10^{-25}$ with respect to isolated
neutron stars (NSs), and $h_0\sim (0.82\text{--}7.1)\times10^{-25}$ with respect to NSs in long-period ($>1$ yr) binary systems. The large range in sensitivity is due to the strong frequency dependence of detector noise, particularly at low frequencies.
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General Relativity and Quantum Cosmology
Oscillations of Dissipative Neutron Stars: The Impact of Hyperonic Reaction Rates
Suprovo Ghosh, Alexander Haber, Nils Andersson et al. (+1 more)
Tidal excitations of
stellar oscillation modes during binary
neutron-
star inspirals offer a powerful probe of the composition of dense matter at supranuclear densities. Chemical equilibration plays a crucial, but often neglected, role in
stellar perturbation calculations. If the chemical equilibration timescale is comparable to the oscillation timescale, then viscous effects can damp the modes. If the reactions are fast, some modes can completely disappear since their restoring force vanishes. Typically, these calculations, however, assume either instantaneous chemical
equilibrium or no equilibration (frozen composition). Motivated by this, we investigate the effects of finite reaction rates on the oscillation spectrum of
neutron stars containing hyperonic matter. We calculate the dominant non-leptonic weak interaction rates and incorporate them into the relativistic perturbation equations through a complex, frequency-dependent dynamical sound speed. We show that finite-rate effects naturally manifest as bulk-viscous dissipation, modifying the properties of both the fundamental ($f$) and
gravity ($g$) modes. We further examine the impact on the
tidal response by matching
stellar perturbations to near-zone boundary conditions, demonstrating how viscous dissipation gives rise to a
tidal lag. These results provide a consistent framework connecting microscopic reaction rates and the resulting bulk viscosity to the
tidal dynamics of compact binaries, and represent a step towards incorporating viscous dissipation into gravitational-wave models of binary
neutron-
star inspirals.
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All authors Suprovo Ghosh, Alexander Haber, Nils Andersson, Andrew Rhys Counsell
Soft Condensed Matter
Overaging with stress in polymer glasses? Faster segmental dynamics despite larger yield stress!
Masoud Razavi, Enran Xing and M.D. Ediger
It is well known that physical aging of
polymer glasses increases their yield stress and affects their failure behavior. Studies indicate that application of moderate levels of stress during aging results in higher yield stress compared to aging in the absence of stress (quiescent aging). This has been interpreted to indicate that stress accelerates physical aging, and has been described as overaging. In this study, we age PMMA glasses under stress, and carry out direct measurement of segmental dynamics during and after aging by using a probe reorientation technique. We observe that samples aged under stress, despite having higher yield stress, have faster segmental dynamics after stress release than quiescently aged samples. This contradicts the overaging interpretation, for the range of conditions explored here. Our results indicate that yield stress is not a simple function of structural relaxation time and theoretical models based on this understanding need to be revised.
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Optics
Dynamically reconfigurable THz quantum walk comb laser through subharmonic excitation
Valerio Digiorgio, Robert Matthew Gray, Marco Raffa et al. (+5 more)
On-chip frequency combs are increasingly relevant to both
laser science and applications. Broad bandwidths and flat-top spectral envelopes are especially desirable for precision spectroscopy and dense wavelength-division multiplexed communications. Toward these goals, active microwave modulation has emerged as a powerful strategy for generating, stabilizing, and reconfiguring frequency combs at the source. However, practical challenges associated with high-frequency modulation imposes an upper bound on the accessible cavity free spectral ranges. Here, we demonstrate a subharmonic locking scheme in a
quantum walk comb
laser, a recently introduced platform for broadband and highly controllable comb states. Using a THz ring
quantum cascade
laser, we realize
quantum walk comb formation under strong microwave injection at successive subharmonics of the cavity round-trip frequency, tuning the comb spacing from 15.8 to 1.58 GHz. The resulting states arise from fast-gain dynamics and nonlinear microwave mixing in the
laser cavity. Through two-tone injection, we exploit this mixing to dynamically control the comb bandwidth and spectral shape. These results establish subharmonic excitation as a route to broadband, reconfigurable
semiconductor comb generation in high-FSR cavities.
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All authors Valerio Digiorgio, Robert Matthew Gray, Marco Raffa, Paolo Micheletti, Alexander Dikopoltsev, Mattias Beck, Jérôme Faist, Giacomo Scalari
Earth and Planetary Astrophysics · Cross-listed from math.DS
GPU-Accelerated Orbit Propagation with High-Fidelity Solar Radiation Pressure Modeling
Leandro Zardaín, Ariadna Farrés, Anna Puig et al. (+2 more)
Solar Radiation Pressure (SRP), the force exerted by
photons emitted by the Sun, is one of the main non-gravitational perturbations affecting spacecraft trajectories, making its accurate modeling essential for high-fidelity orbit propagation. While physically-based ray-tracing models improve SRP accuracy, their computational cost becomes a limitation during numerical integration, where the SRP force must be evaluated repeatedly throughout the trajectory propagation. This paper investigates the integration of high-fidelity SRP models into orbit propagation through two complementary contributions: a Vulkan-based GPU implementation that accelerates direct SRP evaluation, and an extension of the SRP model to account for the dynamic orientation of
solar panels. These contributions are evaluated independently through orbit propagation experiments, while a precomputed SRP interpolation strategy (SPAD) is included as an alternative approach for reducing computational cost through offline sampling and interpolation. Numerical validation shows that the Vulkan implementation preserves the accuracy of the original OpenGL-based method, showing relative differences below $5\times10^{-4}$ while achieving speed-ups of up to 9.4 for individual SRP computations and up to 15.2 for complete orbit propagation, particularly for geometrically complex spacecraft. The movable
solar panel model shows that neglecting panel motion can produce significant long-term propagation errors, especially for spacecraft with large articulated
solar panels, while introducing only a moderate computational overhead. Based on the experimental evaluation, this work concludes with practical guidelines for integrating high-fidelity SRP models into orbit propagation frameworks, identifying the scenarios under which interpolation-based methods are sufficient and when online high-fidelity SRP computation is justified.
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All authors Leandro Zardaín, Ariadna Farrés, Anna Puig, Kevin Muntal, Albert Mir
Quantum Physics
Flip-chip integrated superconducting qubits using electroplated bump bonds
Yen-An Shih, Rebecca Gharibaan, Barka Khan et al. (+9 more)
Flip-chip integration offers a promising route toward scalable superconducting
quantum processors and hybrid
semiconductor-
superconductor quantum devices. We develop a three-dimensional transmon architecture using electroplated indium in which the
qubit electric field is shared nearly equally between two bump-bonded substrates while maintaining low participation at the indium-bump interface. The resulting geometry is well suited for future hybrid
qubits, enabling the integration of distinct material platforms while minimizing sensitivity to bump-interface loss. Using this platform, we evaluate electroplated indium interconnects for superconducting
quantum circuits. Flip-chip transmons incorporating electroplated indium bumps exhibit
qubit quality factors around $10^6$. In addition, a systematic study of coplanar-waveguide resonators is used to identify losses associated with the electroplating process. In particular, we find that surface losses associated with the gold-layer, used to enable good electric contact with the indium, is likely the primary contributor to the
qubit decay rate. These results demonstrate the compatibility of electroplated indium technology with high-coherence superconducting
circuits and establish a promising platform for three-dimensional hybrid
quantum integration.
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All authors Yen-An Shih, Rebecca Gharibaan, Barka Khan, Dhananjay Joshi, Siddharth Singh, Martijn F. S. Zwanenburg, Eugene Y. Huang, Nataliia Zhurbina, Figen Yilmaz, Lukas Johannes Splitthoff, Srijit Goswami, Christian Kraglund Andersen
Materials Science
Fractional Spin Ferroelectric and Sliding Spin Current in Magnetic Sliding Ferroelectrics
Yilin Han, Lei Li, Chaoxi Cui et al. (+3 more)
We investigate the fractional
spin ferroelectric (FSFE) in
magnetic sliding ferroelectrics (SFEs), where ferroelectric switching is characterized not only by the reversal of the out-of-plane electric polarization but also by a variation of fractional in-plane
spin electronic polarization. We show that interlayer sliding in FSFEs can naturally lead to a
symmetry-protected pure
spin current, termed the sliding
spin current here. The underlying mechanism is that, during switching, the contributions of valence electrons and ions to the in-plane charge transfer cancel each other, whereas the in-plane
spin transfer, which stems solely from valence electrons, persists, leading to a pure
spin current. We demonstrate our ideas in various material candidates, including $H$-stacked
bilayer CrI$_3$, whose few-layer form has been experimentally confirmed to be a
magnetic SFE, and $R$-stacked
bilayers $2H$-V$X_2$ ($X=$ S, Se, Te), which have been experimentally synthesised. For a typical switching time of about $1$ ns, the estimated
spin-current densities for
bilayer CrI$_3$ and V$X_2$ reach $10^9 (\hbar/2e)\mathrm{A/m^2}$ and $10^8 (\hbar/2e)\mathrm{A/m^2}$, respectively. This means that by applying a periodic out-of-plane electric field, a significant alternating
spin current can be generated in
magnetic SFEs. Thus, our findings propose a compelling new mechanism for the all-electrical generation of pure
spin current, and predict concrete realistic materials for experimental verification.
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All authors Yilin Han, Lei Li, Chaoxi Cui, Run-Wu Zhang, Zhi-Ming Yu, Yugui Yao
Mathematical Physics
Toward a Rational Extended Thermodynamics of dispersive elastic media
Tommaso Ruggeri and Giuseppe Saccomandi
We develop a one-dimensional theory of dispersive elasticity within Rational Extended Thermodynamics, taking local first-order balance laws rather than higher spatial gradients as the fundamental description. A supplementary mechanical-energy law and the Ruggeri–Strumia main-field principle determine the admissible stress, internal fluxes and production. A canonical two-field hierarchy is symmetric
hyperbolic under explicit convexity conditions and contains nonlinear elasticity and a generalized-stress theory as principal subsystems. For the reversible linear singular two-field class, elimination of the fast stress mode yields the Love–Rosenau equation exactly, together with a necessary and sufficient realizability condition. Nonlinear elastic stresses and non-quadratic higher-field energies are compatible with the same RET architecture; for the exact nonlinear Love–Rosenau reduction we retain quadratic higher-field inertia while allowing nonlinear elastic stress. The reduced equation admits a travelling-wave first integral. For the leading cubic elastic correction we obtain an exact parametric smooth solitary pulse in a supersonic velocity window, while the truncated-cosine compacton is excluded. Direct simulations of the
hyperbolic parent system show finite-time pulse persistence in the reversible regime and slow decay under weak dissipation. The local parent energy flux is kept distinct from interstitial working in the reduced theory.
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High Energy Physics (Theory)
Critical dynamics of a scalar field near four spatial dimensions
Laura Batini and Eduardo Grossi
The critical dynamics of a non-conserved order parameter is generally expected to become overdamped at long distances, even when propagating modes occur at microscopic or intermediate scales. We investigate the critical dynamics of a scalar field theory in thermal
equilibrium which, in addition to local friction and noise, also contains a time-dependent second-order kinetic term. We show how to build a supersymmetric field-theory formulation. Using a two-loop expansion about four spatial dimensions, we show that the propagating and strictly overdamped limits share the same static Gaussian and Wilson-Fisher fixed points but realize distinct dynamical scaling regimes. The overdamped limit reproduces Model A. On the surface where local friction and noise vanish, the theory instead supports an interacting propagating fixed point whose dynamic exponent receives corrections at two loops. We demonstrate that coarse-graining does not generate a local dissipative operator on this surface, which therefore remains invariant under the RG flow. Local dissipation is nevertheless relevant at the propagating fixed point: an arbitrarily small
equilibrium friction-noise perturbation drives the flow away from propagating scaling. Propagating critical dynamics thus defines a consistent but fine-tuned regime that is unstable to local
equilibrium dissipation.
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Astrophysics of Galaxies
Testing dark matter models and modified gravity theories with spatially resolved HI observations
Federico Lelli, Antonino Marasco, Timothy A. Davis et al. (+8 more)
Understanding the nature of dark matter (DM) is one of the most pressing questions of modern physics. The flat rotation curves of
galaxies, especially the extended HI rotation curves from
radio observations at 21 cm, played a key historical role to establish the DM problem and continue to be a major tool to test different
galaxy formation models, particle DM models, and modified
gravity theories. The SKA observatory will revolutionize the study of HI rotation curves thanks to its unprecedented angular resolution, sensitivity, and survey speed. In combination with optical and near-infrared ancillary data, HI surveys with SKA-Mid AA4 will allow us to (1) obtain HI data at spatial resolutions of 1"-2", probing the inner
galaxy dynamics with unprecedented details (e.g., the cusp-core problem); (2) move from representative samples of a few hundreds of objects to statistical samples of tens of thousands of objects, allowing us to study the dynamical scaling laws of
galaxies and their DM properties with unprecedented statistical power across different
cosmic environments; (3) move from
galaxies at z~0 to
galaxies at z~1, probing DM
halos at earlier
cosmic epochs and exploring the
redshift evolution of the dynamical laws across about 8 Gyrs. The massive SKA data, however, will pose important technical challenges for the derivation of HI rotation curves with automated kinematic software. Developing such kinematic software in the SKA era will be crucial to reach major scientific goals, such as discriminating between different solutions to the DM problem.
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All authors Federico Lelli, Antonino Marasco, Timothy A. Davis, Nathan Deg, Jonathan Freundlich, Gyula I. G. Jòzsa, Peter Kamphuis, Pavel E. Mancera Piña, Stacy S. McGaugh, Amidou Sorgho, Kristine Spekkens
High Energy Astrophysical Phenomena
Multi-dimensional NLTE radiative transfer for a double detonation Type Ia explosion model in the photospheric phase
F. P. Callan, L. J. Shingles, S. A. Sim et al. (+7 more)
Previous radiative transfer calculations have shown that both multi-dimensionality and NLTE (non local thermodynamic
equilibrium) effects impact the synthetic observables predicted for Type Ia
supernova explosion models. Here we carry out a 2D NLTE radiative transfer simulation in the photospheric phase for a double detonation model with a 1 M$_{\odot}$ carbon-oxygen core and 0.02 M$_{\odot}$ helium shell. The predicted observables demonstrate that departures from both spherical
symmetry and local thermodynamic
equilibrium are significant on scales relevant to comparisons with observations. The NLTE treatment leads to a bluer spectral energy distribution, more slowly declining optical-band light curves, changes to the near-infrared light curve shapes, and differences in the
evolution of key spectral features. Although substantial viewing-angle variation is predicted for the model, the scale of the variation is not significantly impacted by NLTE effects up to peak. However, after peak, our 2D NLTE simulation retains a strong viewing-angle dependence in its spectra whereas our simulation of the same ejecta model using an approximate NLTE treatment predicts significantly reduced spectroscopic viewing-angle variation. The NLTE treatment leads to improved agreement with normal Type Ia
supernovae, primarily due to the increased ionisation state of the simulation, although the absence of a secondary near-infrared maximum suggests that the ejecta remain over-ionised relative to observations after peak. Despite the improved agreement, many viewing angles still show excessive line blanketing, suggesting that the 0.02 M$_{\odot}$ helium-shell mass of the current model is too large to reproduce normal Type Ia
supernovae over the majority of lines of sight.
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All authors F. P. Callan, L. J. Shingles, S. A. Sim, C. E. Collins, J. M. Pollin, R. Pakmor, S. Gronow, F. K. Roepke, A. Holas, I. R. Seitenzahl
Instrumentation and Methods for Astrophysics
WST, the Wide-field Spectroscopic Telescope: dispersing elements
Andrea Bianco, Michele Frangiamore, Anna Brucalassi et al. (+7 more)
The Wide-field Spectroscopic
Telescope (WST) is a proposed 12-m class facility entirely dedicated to spectroscopic surveys, combining a high-multiplex multi-object spectrograph operating at low (MOS-LR) and high (MOS-HR) spectral resolution with a
giant panoramic integral-field spectrograph (IFS), all three operating in parallel. Diffraction gratings are the key dispersing elements of all three instruments and, given the very large number and size of the units required, drive critical trade-offs in throughput, feasibility and production cost. This paper reviews the two grating technologies under consideration for WST, Volume Phase
Holographic Gratings (VPHG) and binary (lithographic, surface-relief) gratings, summarizing their working principles and the parameters that control their diffraction efficiency. We then present the current baseline grating parameters and vendor results for each instrument: low-dispersion, VPHGs for the IFS; a four-arm GRISM layout for MOS-LR; and two competing high-resolution disperser architectures (8M16D and 16M4D) for MOS-HR, where binary gratings show a promising path to diffraction efficiencies beyond what is achievable with VPHGs. We conclude with the main open challenges, chiefly the mass production of hundreds of grating units within cost and schedule and the next steps foreseen to consolidate the disperser baseline for WST.
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All authors Andrea Bianco, Michele Frangiamore, Anna Brucalassi, Dimitri Buffat, Corentin Cudennec, Kjetil Dohlen, Alexandre Jeanneau, David Lee, Will Saunders, Andrea Tozzi
Quantum Physics
Demonstration of an LLO CV-QKD system over 12 km of optical fiber
Christiano M. S. Nascimento, Artur A. Matoso, Gustavo C. Amaral et al. (+1 more)
Continuous-variable
quantum key distribution (CV-QKD) promises high rates and seamless integration with classical beams within a single optical fiber. Over the years, implementations have been performed by transmitting a local oscillator reference along with the
quantum channel, opening security loopholes for eavesdroppers and limiting potential applications. Here, we report on a Gaussian CV-QKD implementation using fully independent transmitter and receiver
lasers (local-oscillator sources) over a 12 km fiber spool. The system was experimentally evaluated using logical frames containing approximately $10^7$ coherent states, each composed of ten independently processed subframes of approximately $10^6$ states, and security was assessed in both asymptotic and finite-size regimes under a trusted-device model. The full-fledged classical post-processing is capable of recovering the channel parameters and extracting secret key rates of 5.11 Mbit/s in the asymptotic regime and 4.67 Mbit/s in the finite-size regime, showing good agreement with theoretical predictions. This work establishes the foundation for metropolitan fiber deployment of CV-QKD under strict security constraints.
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All authors Christiano M. S. Nascimento, Artur A. Matoso, Gustavo C. Amaral, Guilherme P. Temporão
Mathematical Physics · Cross-listed from math.AP
Unique continuation at infinity for potentials with arbitrary radial growth
Henrik Ueberschaer
Let $G$ be any given continuous positive function on $\mathbb{R}_+$. Let $V$ be radial with $|V(x)|\leq G(|x|)$. We prove a Landis-type
theorem for any real-valued solution of $\Delta u=Vu$ on $\mathbb{R}^n$. We construct a decay threshold $e^{-g(r)}$, where $g$ is a strictly increasing function which can be computed explicitly in terms of $G$. Under suitable assumptions the exponent in the decay threshold is proportional to the Agmon distance associated with $G$.
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High Energy Physics (Theory)
Magnetic Catalysis and Fermion Mass Generation in de Sitter Spacetime
Kohei Fujikura, Toshifumi Noumi and Shintetsu Yamazaki
We consider the dynamics of a charged
fermion in de Sitter space in the presence of a uniform background
magnetic field, and discuss
magnetic catalysis of
chiral symmetry breaking using the Nambu–Jona-Lasinio (NJL) model. We evaluate the mode functions of the charged
fermion field in this background by imposing the Bunch–Davies
vacuum condition. The gap equation is solved in the mean-field approximation. We derive analytic expressions for the gap in several limiting regimes, such as the large-
magnetic-field and large-
curvature limits. We find that the
curvature effect restores
chiral symmetry, whereas the
magnetic field enhances
chiral symmetry breaking through the conventional mechanism of
magnetic catalysis. The phase structure associated with
chiral symmetry breaking is revealed by numerical calculations.
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High Energy Physics (Theory)
Tilting Mutations and Quiver-Invariant Dualities in Brane Tilings
Seong-Jin Lee, Rak-Kyeong Seong and Benjamin Suzzoni
Quiver-invariant dualities relate distinct 4d N=1 supersymmetric gauge theories that arise as worldvolume theories on a D3-brane probing the same toric Calabi-Yau 3-fold. These dual theories share an identical quiver and differ only in their superpotentials. We show that quiver-invariant dualities are realized by tilting mutations on the brane tilings that realize these theories. Among the 42 toric phases of the H1121 model, we identify three general families of tilting mutations, all characterized by the reversal of the orientations of zig-zag paths within the mutation region of the brane tiling. We present new examples of quiver-invariant dualities, given by five doublets and one triplet of toric phases with identical quivers, for which we verify that the brane tilings related by the tilting mutations correspond to the same toric Calabi-Yau 3-fold H1121.
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High Energy Physics (Phenomenology)
Chiral Doubling of Heavy-Light Hadrons and the New Beauty–Strange $B_{s0}^*(5700)^0$ Candidate
Maciej A. Nowak and Ismail Zahed
The recent observation by the LHCb Collaboration of a new beauty–strange
meson $B_{s0}^*(5700)^0$~\cite{LHCb:2026Bs0
star}, under the conditional assignment $J^P=0^+$ provides an important new test of the
chiral organization of heavy-light
hadrons. More than three decades ago it was proposed that the coexistence of heavy-
quark spin symmetry and spontaneously broken
chiral symmetry implies that every heavy-light
spin multiplet should possess an opposite-parity partner separated by a nearly universal mass gap determined primarily by the dynamics of the light degrees of freedom~\cite{Nowak:1993vc,Bardeen:1993ae}. This
chiral doubling scenario was later developed into a quantitative heavy-
hadron effective theory and extended to the complete charm and beauty spectra. In particular, the strange beauty sector was predicted to exhibit a parity splitting closely related to that of the strange charm sector, with only small $1/m_Q$ corrections. We briefly review the
symmetry origin of
chiral doubling, derive the universal parity splitting through the heavy-
hadron chiral effective theory, and discuss the new LHCb observation in the context of the original theoretical predictions. Taken together with the established charm spectrum, if the new beauty-strange state is confirmed to have $J^P=0^+$, its mass is consistent with its interpretation as the
chiral partner of the ground state $B_s^0$. Finally, we stress that the above confirmation of the
spin and parity imposes in the
chiral doubling scenario an existence of yet unobserved, very narrow beauty-strange
meson with assignment $1^+$ at 5747 $\pm$ 2 MeV. This work is dedicated to the
memory of our friend and collaborator Mannque Rho (1936–2026).
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Materials Science
Homojunction-induced thermopower enhancement in polymer films
Zhen Xu, Hui Li, Guangzheng Zuo et al. (+7 more)
It has been more than twenty years since conductive
polymers began to receive
attention as an emerging thermoelectric material. However, the trade-off between electrical conductivity ({\sigma}) and thermopower (S) has proven to be a major challenge that has obstructed their use in actual devices. Here we report the discovery that the thermopower of the p- and n-type legs of organic thermogenerators can be substantially enhanced, without significant deterioration of {\sigma}, by constructing an in-plane segmented structure consisting of a homojunction with different doping levels on either side. In such segmented layers, the S is abnormally higher than the average value of the constituent parts when applying a forward temperature gradient (heating the heavily doped counterpart), while it is lower upon a reverse temperature gradient. Typically, for a two-stage segmented film of p-type PDPP-Se, an abnormally large S of 210 uV K-1 and {\sigma} of 2.5*10^4 S m-1 are obtained, resulting in a large power factor (PF) of 1100 uW m-1 K-2 and a record ZT of 1.36 at room temperature. The enhanced thermopower is attributed to an additional voltage developed at the homojunction under heating as explained by kinetic Monte Carlo simulations. This finding provides a breakthrough approach to the modulation of thermoelectric transport properties of conductive
polymers.
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All authors Zhen Xu, Hui Li, Guangzheng Zuo, Xiaojuan Dai, Jincheng Liao, Guofeng Cheng, Jian Song, Wenqing Zhang, Martijn Kemerink, Lidong Chen
Cosmology and Nongalactic Astrophysics
Tensor-Induced Backreaction in Ultra-Slow-Roll Inflation
Alessandro Ciaiolo and Giovanni Marozzi
We discuss the impact of tensor-induced backreaction at second order in perturbation theory on
primordial black holes production in single-field inflationary models, where the comoving
curvature power spectrum is amplified by a transient ultra-slow-roll phase. Although the leading perturbative correction is mostly negligible in standard slow-roll
evolution, it becomes important in non-attractor regimes, going in the direction of limiting the suppression of the first slow-roll parameter $\varepsilon$ and reducing the enhancement of the scalar power spectrum. We then go beyond the standard perturbative analysis by considering the background parameters as effective quantities with
evolution self consistently determined by a closed system of backreaction equations. This analysis, which leads to a partial resummation of the effect beyond the perturbative treatment, confirms the limitation of the suppression of $\varepsilon$ by consistently showing how the effect remains important even after accounting for the effective
evolution of the background in the evaluation of the backreaction itself. Finally, we discuss how, taking into account the tensor-induced backreaction, the fine-tuning associated with the value of the peak amplitude of the scalar power spectrum is strongly reduced.
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Atomic Physics
Quantum sensing of radiofrequency fields using cold Rydberg atoms in a super-molasses trap
Romain Granier, Anthony El Bekai, Miguel Angel Cifuentes Marín et al. (+12 more)
We demonstrate the
quantum sensing of radiofrequency fields based on cold Rydberg atoms in a super-molasses trap, without the need for
magnetic coils. Our approach combines the metrological advantages of cold atoms with a metal-free dielectric sensor head minimizing perturbations to the electromagnetic environment, a feature that was previously restricted to vapor-
cell-based devices. Moreover, the absence of inductive loads allows to rapidly alternate between the cooling phase and the Rydberg excitation, leading to trap-loss spectroscopy signals one order of magnitude narrower than for conventional magneto-optical traps. This enables self-calibrated microwave power measurements with an unprecedented dynamic range of 43dB, opening the door to new perspectives of applications in calibration measurements. We also report a scale factor linearity better than 1%, the absence of drifts over several tens of minutes leading to a 3$\mu$V/cm resolution, and the possibility to retrieve the ellipticity of the applied microwave field. By demonstrating a cold-atom metrological platform in a compact dielectric sensor head, this work paves the way for new applications in the field of radiofrequency measurements with Rydberg atoms, and in other fields of
quantum sensing based on cold atoms such as magnetometry, gravimetry or inertial
navigation.
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All authors Romain Granier, Anthony El Bekai, Miguel Angel Cifuentes Marín, Cédric Blanchard, Nassim Zahzam, Yannick Bidel, Alexandre Bresson, Vilius Atkočius, Chester Camm, Florence Concepcion, Konstantinos Karakostas, Matt Himsworth, Alexander Jantzen, Alexis Bonnin, Sylvain Schwartz
High Energy Physics (Theory)
Spectral Topology and Universal Krylov Dynamics
Jeff Murugan, Hendrik J. R. Van Zyl and Masataka Watanabe
The leading asymptotic growth of Lanczos coefficients is controlled by spectral tails and furnishes a coarse classification of Krylov dynamics. We show that the global
topology of the spectral measure, specifically the number of connected components, the gap structure, and the behaviour at gap-closing transitions, encodes a finer hierarchy of dynamical invariants invisible to tail-based arguments. Using the Riemann-
Hilbert formulation of orthogonal
polynomials and Deift-Zhou steepest descent, we recover the Freud growth laws $b_n\sim n^{1/\beta}$ for single-cut measures and determine their sub-leading corrections from endpoint data. Gapped spectra produce quasiperiodic Lanczos oscillations at a frequency fixed by the filling fraction of the spectral bands alone, and hence predictable from the band edges. We verify this in the SSH chain and its next-nearest-neighbour deformation. At a gap-closing transition the oscillation amplitude is governed by the Hastings-McLeod solution of Painlevé II, decaying as $n^{-1/3}$ at criticality and interpolating between the gapped and merged phases, so that the
topology change of the spectral curve is realised as a Krylov phase transition. We also demonstrate that, while in the conformal limit of SYK the operator scaling dimension is invisible in the leading rate $\alpha = \pi T$, it can be extracted from the subleading offset $b_0 = \pi T(\Delta - \frac{1}{2})$. These results establish a refined notion of universality in operator growth, classified by spectral
topology rather than spectral tails alone.
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Quantum Physics
The small effect of graviton-induced decoherence
Guri K. Buza and Marko Toroš
We derive and investigate the reduced dynamics of a nonrelativistic
quantum matter system interacting with quantized gravitational waves. Because gravitational radiation couples tidally to the mass quadrupole moment, we emphasize that the leading interaction is quadratic in the mechanical displacement. Rather than treating it as a complication to be removed by linearization, we retain this full quadratic dependence, which gives rise to two-
phonon rather single-
phonon processes typical in dipolar interactions. We clarify its relation to the effective linear coupling that often appears in optomechanical literature, but which conceals the delicate
quantum signatures of the full quadratic coupling. Using the Born-Markov and secular approximations, we microscopically derive Lindblad master equations for the matter dynamics induced by graviton baths in multi-mode
vacuum, coherent, number, thermal, and squeezed states. We treat the ultraviolet-divergent Lamb-shift
Hamiltonian by an explicit renormalization procedure, with the mechanical frequency identified as the physical frequency. Remarkably, owing to the nature of the interaction, the matter
Hilbert space decomposes into even- and odd-parity sectors for all bath states considered. For a coherent graviton bath, the decoherence is identical to that of the
vacuum, while the bath one-point function produces a coherent-shift
Hamiltonian that exactly reproduces the
tidal interaction with a classical gravitational wave. For a
vacuum graviton bath, we recover the coherence protection between the two lowest mechanical number states, while number and thermal graviton baths remove this protection and enhance decoherence, although the effect remains small for realistic parameters. By contrast, a squeezed graviton bath enlarges the coupled coherence structure, and gives rise to a novel, coherence-protected sector spanned by dressed dark states.
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Quantum Physics
Theory of Deterministic Photon-Loss Subspaces for Quantum Interferences
Yadi Niu, Haoyang Zhang, Zihan Mo et al. (+2 more)
Quantum coherence,
quantum decoherence, and
photon number reduction are coexistent in linear lossy optical systems. However, how these three elements combine together to determine the
evolution of the
quantum light remains unclear. Here, based on singular value decomposition (SVD), we propose the theory of deterministic
photon-loss subspace (DPLS) for
quantum interferences in lossy systems. By performing an SVD of scattering
matrices with singular values either 0 or 1, a series of completely lossy and lossless input modes are first defined. According to n_1,...,n_i
photons in the first,..., i-th lossy modes, the
Hilbert space of the input states can be decomposed into a set of orthogonal subspaces H_((n_1,...,n_i ))^in, i.e., deterministic
photon-loss subspaces (DPLSs). When the concept of DPLS is established, the input state can be projected onto these DPLSs. In each DPLS, the
photons in lossy modes will be completely dissipated, while those in lossless modes experience a
unitary evolution. The output state is a statistical mixture of the evolved outcomes of all projections, since decoherence is a concurrent process. Then, based on the DPLS theory, we not only revisited Anti-HOM interference and the
distillation of
quantum states, but also demonstrate a robust W-state generation for various input states in a three-port lossy system with one-dimensional DPLSs. Through investigating the loss-induced subspace structure of the system, our general theory for analyzing
quantum state
evolution in lossy systems explicitly reveals the interplay among
quantum coherence,
quantum decoherence, and
photon number reduction. By engineering the loss, the constructed DPLSs can be used to precisely control
quantum interferences in dissipative systems, with potential applications in
quantum state preparation,
quantum logic operations, and other
quantum information processes.
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All authors Yadi Niu, Haoyang Zhang, Zihan Mo, Nuo Wang, Ying Gu