Papers

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Physics

Friday 3 July

Astrophysics of Galaxies

Direct Evidence for Outflow Driven by Wolf-Rayet Stars in the Nearby Galaxy PGC44685

Qian Huang, Zhengyi Chen, Min Bao et al. (+3 more)

Wolf–Rayet (WR) stars are evolved massive stars which can drive strong stellar winds, injecting energy and momentum into the interstellar medium (ISM). However, the geometry and kinematics of WR-dominated outflows, specially in low-metallicity environments, is still poorly constrained by observations. We present a spatially resolved spectroscopic study of a WR region in a nearby dwarf galaxy, PGC\,44685, using high-resolution MEGARA IFU data from the Gran Telescopio Canarias (GTC). After decomposing the [O iii]~$\lambda5007$ emission line with narrow and broad components, we verify a WR-driven outflow with a velocity reaching up to $20\,\mathrm{km\,s^{-1}}$ relative to the systemic velocity. By use of the velocity and flux of the [O iii] broad component, we estimate an outflow mass of $(8.25 \pm 3.03)\times10^{3}\,M_\odot$ and a mass-loss rate of $(9.47 \pm 3.48)\times10^{-4}\,M_\odot\,\mathrm{yr}^{-1}$. The corresponding kinetic power and momentum injection rate are $(4.77 \pm 1.77)\times10^{41}\,\mathrm{erg\,s^{-1}}$ and $(8.20 \pm 3.02)\times10^{28}\,\mathrm{g\,cm\,s^{-2}}$, respectively. The inferred low energy-loading efficiency ($\sim0.35\%$), together with the low metallicity of the WR region ($\sim0.1\,Z_\odot$), suggests that the system is observed in an early feedback phase in which stellar winds have not yet efficiently coupled their energy into the ISM. These results support the ability of WR feedback to shape the ISM on sub-kiloparsec scales, while these winds fail to launch galactic-scale outflows.

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All authors Qian Huang, Zhengyi Chen, Min Bao, Qiusheng Gu, Shiying Lu, Yulong Gao

General Relativity and Quantum Cosmology

Distinguishing wormholes via Einstein rings and global curvature

M. B. Cruz, C. R. Muniz, R. M. P. Neves et al. (+1 more)

In this work, we investigate the gravitational lensing properties of a static Ellis-Bronnikov wormhole embedded in a curved Friedmann-Lemaître-Robertson-Walker (FLRW) universe. By employing curvature-dependent cosmological distances, we derive the corresponding weak-field lens equation and demonstrate that the wormhole Einstein ring radius follows a characteristic cubic scaling with cosmological distances, in sharp contrast to the square-root behavior found for Schwarzschild black holes. This distinct scaling leads to a qualitatively different redshift evolution of the lensing signal, providing a model-independent geometric diagnostic to discriminate between wormhole and black hole lensing scenarios. Numerical analysis reveals that the interplay between the local wormhole geometry and the FLRW background produces an asymmetric response to spatial curvature that inverts at intermediate redshifts, exhibiting a non-negligible sensitivity even under tight modern constraints such as those from DESI 2024. We also find that Ellis-Bronnikov wormholes are substantially less efficient gravitational lenses than Schwarzschild black holes of comparable physical scale, implying that microarcsecond-scale Einstein rings require macroscopic throat radii. These results suggest that, should a population of cosmological wormholes exist, their lensing signatures could provide a sensitive, complementary probe of both exotic spacetime topology and the global geometry of the Universe.

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All authors M. B. Cruz, C. R. Muniz, R. M. P. Neves, Jonathan A. Rebouças

Quantum Physics

Accuracy, Decision Risk, and Sampling Cost in Quantum Error Mitigation

Vicenzo Scavino Alfaro

Quantum error mitigation estimates expectation values that are often used to select or rank candidates. We study how estimation accuracy, decision risk and sampling cost are related in these tasks. The joint law of residual differences determines the risk of a shift-invariant decision; in Gaussian regimes, effective margins and their covariance provide a computable representation. This connects mitigation maps, shared measurement records and shot allocation, and yields an extrapolation design criterion under certified margins. Finite-shot QAOA-MaxCut controls illustrate two forms of this relationship: a positive affine CDR correction reduces mean-squared error while preserving rankings, whereas signed PEC sampling reduces mean-squared error and increases selection failures at equal evaluation cost. A retrospective, oracle-assisted study of 48 landscapes compares Gaussian-risk and MSE-based method selection using separate fitting, selection and evaluation samples. At the primary total shot budget, with learning amortized over 20 decisions per landscape, failure rates are $0.3083$ for Gaussian-risk selection, $0.4719$ for MSE selection and $0.2333$ for unmitigated estimation. These comparisons describe how uncertainty in candidate differences and the allocation of measurements between learning and evaluation jointly enter the assessment of mitigation.

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Solar and Stellar Astrophysics

Improving Solar EUV Irradiance Modeling with Differential Emission Measure Informed Spectra

Courtney L. Peck, Shah M. Bahauddin, Daniel B. Seaton et al. (+3 more)

Solar extreme ultraviolet (EUV) irradiance predominantly originates from the chromosphere and corona, and variations in EUV irradiance are a significant driver of space weather at Earth, causing increased satellite drag, radio communication disruptions, and reduced GPS accuracy. Since solar EUV irradiance measurements are intermittent and inhomogeneous, models are used to fill spectral and temporal gaps, typically relying on proxy-based methods that utilize linear correlations between emission originating from similar heights or temperatures in the solar atmosphere. Proxy methods can struggle to capture dynamic irradiance variations of the solar corona during flares in part due to the relative infrequency of flares on which to derive correlations and the steep temporal temperature gradients experienced during flares. This paper presents a hybrid method for modeling solar EUV irradiance utilizing forward-modeled physics-informed solar differential emission measures (DEMs) to capture the optically-thin coronal emission coupled with traditional proxy-based correlation methods to capture the chromospheric and continuum emission. The model is trained and tested using inputs from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) and EUV Variability Experiment (EVE) and compared against a proxy-only method. The results demonstrate that including information from DEMs into a EUV irradiance model improves accuracy for flaring conditions, particularly for high-temperature coronal lines, where the model error is reduced by up to a factor of 3 for M- and X-class flares compared to a proxy-only model trained on the same data.

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All authors Courtney L. Peck, Shah M. Bahauddin, Daniel B. Seaton, Janet L. Machol, Ed Thiemann, Mark Cheung

High Energy Physics (Phenomenology)

Revisiting $\bar B^0 \rightarrow \Lambda_c^+ \bar p$ decay with higher twist corrections

Zhi-Tian Zou, Ying Li and Zhou Rui

We investigate the single-charmed baryonic decays $\bar B^0 \to \Lambda_c^+ \bar p$ and $\bar B^0 \to \bar\Lambda_c^- p$, which receive contributions from both $W$-emission and $W$-exchange topologies, within the framework of perturbative QCD (PQCD). Higher-power corrections associated with the hadronic light-cone distribution amplitudes (LCDAs) of both the initial- and final-state hadrons are systematically taken into account. We find that these higher-twist contributions play an important role in baryonic $B$ decays and cannot be neglected. A sizable destructive interference between the $W$-emission and $W$-exchange amplitudes is observed, which significantly reduces the predicted branching fraction of $\bar B^0 \to \Lambda_c^+ \bar p$ and leads to improved agreement with experimental measurements. The doubly Cabibbo-suppressed decay $\bar B^0 \to \bar\Lambda_c^- p$ is studied for the first time. Its branching fraction is predicted to be of order $10^{-8}$, placing it within the reach of future high-luminosity experiments. We further present the first theoretical predictions for the decay asymmetry parameters of both channels, which provide additional observables for testing the underlying decay dynamics and can be confronted with future experimental data.

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Optics

Second-harmonic generation from an optically levitated KTP nanocrystal in vacuum

Yuanbin Jin, Chenli Gao, Jiayu Feng et al. (+3 more)

The optically levitated system in vacuum has emerged as a powerful platform for studies of fundamental physics and precision measurements. Although various nanoparticles have been successfully levitated in vacuum, they typically lack the capability to support optical nonlinear processes. Here, we experimentally demonstrate the stable levitation of a potassium titanyl phosphate (KTP) nonlinear nanocrystal in vacuum and investigate its second-harmonic generation (SHG) properties. This levitated system intrinsically provides a pristine dark-background environment with a high signal-to-noise ratio. The trapping laser simultaneously serves as a fundamental light for efficient SHG. Moreover, the polarization of the collected SHG signal is correlated with that of the fundamental laser, providing clear evidence of the optical torque enabling controllable alignment of the nanocrystal with the driving field. Our work establishes a new route, to our knowledge, toward exploring nonlinear optical processes in vacuum levitation systems and designing novel nanodevices with high manipulation agility in a fully contact-free environment.

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All authors Yuanbin Jin, Chenli Gao, Jiayu Feng, Yuxuan Hao, Xudong Yu, Jing Zhang

Quantum Physics

Photon Squeezing and Its Signatures of Quantum Phase Transitions in the Open Quantum Rabi-Stark Model

Tian Ye, Xinghan Chen and Chen Wang

As a hallmark of nonclassical light, squeezed light is of profound theoretical interest and holds broad practical promise for emerging quantum technologies. In this work, we investigate steady-state optical quadrature squeezing in the open quantum Rabi-Stark model by employing the quantum dressed master equation. Both numerically and analytically, we find that positive (negative) Stark coupling tends to enhance (suppress) the squeezing effect. The quadrature squeezing exhibits distinct signatures associated with both first- and second-order quantum phase transitions (QPTs). Notably, a sharp vanishing of squeezing is observed across the first-order QPT, suggesting its potential as a sensitive probe of such transitions. In the vicinity of the second-order QPT, we further demonstrate that the squeezing factor displays finite-size scaling behavior, indicating a promising route toward the realization of near-perfect squeezing. Moreover, we establish a quantitative criterion for the disruption of quantum criticality induced by thermal fluctuations, which may offer valuable guidance for future experiments. These findings contribute to a deep understanding of nonclassical light in light-matter interacting systems and provide useful insights for the design of strong optical squeezing states.

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High Energy Physics (Phenomenology)

Studying baryon number transport dynamics via hyperon-kaon correlations in $p + \mathrm{Au}$ collisions at $\sqrt{s_{_{\rm NN}}}=20$, $39$ and $62$ GeV

Siyuan Ping, Xiaozhou Yu and Long Ma

The observation of positive net hyperon baryon numbers at mid-rapidity in heavy-ion collisions indicates that baryon numbers from incident nucleons can be transported across a large rapidity gap to hyperons where strange quarks of $s-\bar{s}$ are pair-produced. Consequently, hyperons and kaons are expected to be correlated, providing a sensitive probe of both baryon number transport mechanism and strange quark pair correlation. Such correlation may be used to test the gluon-junction interaction mechanism where a $Y$-shaped gluonic field may carry the baryon number and be responsible for the baryon number transport to hyperons over a large rapidity gap. We present hyperon-kaon correlations as a function of their relative rapidity in $p + \mathrm{Au}$ collisions at $\sqrt{s_{NN}} = 20$, $39$, and $62$ GeV using a multiphase transport ($\texttt{AMPT}$) model and Ultra-relativistic Quantum Molecular Dynamics ($\texttt{UrQMD}$) models where hyperon-kaon pairs are originated from fragmentation scheme. We quantify the correlation function using the Wasserstein distance method and systematically investigate the correlation dependence on the beam energy, hyperon emission direction and detector acceptance. Our simulation results provide a baseline without the baryon junction mechanism for future experimental measurements.

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Optics

Fluctuation – dissipation physics of stimulated light scattering from laser-driven density gratings

Aleksei Zheltikov

The fluctuation - dissipation theorem (FDT) is shown to provide a powerful resource for the analysis of stimulated light scattering from laser-driven density gratings, including stimulated Brillouin scattering (SBS) and its kinetic-regime extension. In the physical setting of stimulated light scattering by density gratings, the FDT establishes that the dynamics of disturbances induced in a medium by a laser-driven electrostrictive force unfolds via the same physical pathways as the dynamics of internal, spontaneous fluctuations in this medium at equilibrium. When integrated into a suitable kinetic framework, the FDT leads to a significant simplification of the analysis of stimulated light scattering, allowing the stimulated gain/loss spectrum to be found directly from the spectrum of spontaneous density fluctuations without the need to solve kinetic equations with an external-field term. Such FDT-based framework enables an accurate description of stimulated light scattering within a vast parameter space, recovering all the signature properties of sound-wave-mediated Stokes amplification in the hydrodynamic regime, providing a continuous crossover from the hydrodynamic to kinetic regime of stimulated scattering, and explaining distinctly different properties of kinetic stimulated scattering from density gratings, consistent with experiments on stimulated scattering in moderate-pressure gases. As important physical benchmarks, in the limits of vanishingly low and very high collision frequencies, this solution for the SBS gain recovers the FDT-transformed solutions of, respectively, the Vlasov and Navier - Stokes equations.

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High Energy Physics (Theory)

Learning Effective Bulk Fields from Fermionic Spectra: Application to an Extended Power-Law Liquid Model for Cuprate Strange Metals

Hong-Zhi Xiao, Zhan-Zhi He, Zhuo-Yu Xian et al. (+1 more)

We develop a Neural-ODE framework to infer effective bulk metric functions and the charge-weighted gauge potential from boundary fermionic spectra within a static, planar black-hole ansatz. Controlled benchmarks recover the known bulk profiles of the Einstein–Maxwell and Gubser–Rocha models. We then use normalized interaction self-energy targets generated from an extended power-law liquid model with parameters calibrated by angle-resolved photoemission measurements to test the proposed geometric explanation of cuprate strange-metal spectra in a semi-holographic setting. For this application, we use a massless probe in backgrounds with conformal-to-$\mathrm{AdS}_2\times\mathbb{R}^2$ asymptotics and derive a spectral extraction formula from the conserved radial Dirac flux. We identify coordinate/Weyl redundancy and a degeneracy in the scaled Hawking temperature of the normalized inverse problem. The conformal factor remains undetermined, so bulk entropy and the associated contribution to electronic specific heat require independent input. Low-temperature targets are fitted accurately across the studied doping range. In the high-temperature test, however, the present ansatz and optimization search have not yielded a refined geometry that accurately reproduces the thermal spectral shape while preserving frequency symmetry. These results may guide the further development of semi-holographic models for cuprates, and the framework may also find applications in other strongly correlated electron systems.

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All authors Hong-Zhi Xiao, Zhan-Zhi He, Zhuo-Yu Xian, Shao-Feng Wu

High Energy Astrophysical Phenomena

Evidence for Asymmetric Ejecta and Circumstellar Material in SN 2023ixf Inferred from Extensive Nebular-phase Observations

Brian Hsu, Nathan Smith, K. Azalee Bostroem et al. (+34 more)

We present extensive optical and near-infrared (NIR) observations of the nearby Type II supernova (SN II) 2023ixf in the nebular phase from +89 days to +749 days after explosion, supplemented with NIR and mid-infrared (MIR) spectroscopy from the James Webb Space Telescope. The H$\alpha$ emission profile shows complex evolution, with the emergence of high-velocity components consistent with the outer ejecta interacting with extended, low-density circumstellar material (CSM). We find that the H$\alpha$ profile at an intermediate epoch (around +375 d) can be reconstructed by scaling an earlier decay-powered component and a later-phase shock-powered component, which revealed an additional intermediate-width component. This is consistent with the ejecta crashing into the initially aspherical dense CSM that has been swept-up by the forward shock. In the NIR, we find double-peaked emission from Mg I $1.504\ {\rm \mu m}$, Na I $2.206\ {\rm \mu m}$, and [Ni I] $3.12\ {\rm \mu m}$ between +200 d and +374 d, consistent with an asymmetric distribution of Ni-rich material that heats the ejecta inhomogeneously. We posit a disk-like CSM geometry and an ejecta geometry in which at least two large Ni-rich plumes lead to the observed line-profile diversity.

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All authors Brian Hsu, Nathan Smith, K. Azalee Bostroem, Jeniveve Pearson, David J. Sand, Lindsey A. Kwok, Jennifer E. Andrews, Bhagya M. Subrayan, Griffin Hosseinzadeh, Manisha Shrestha, Conor Ransome, Moira Andrews, Collin T. Christy, Yize Dong, Joseph Farah, Alexei V. Filippenko, Noah Franz, Jared A. Goldberg, Estefania Padilla Gonzalez, Claudia P. Gutiérrez, Emily Hoang, D. Andrew Howell, Saurabh W. Jha, Réka Kőnyves-Tóth, Michael Lundquist, Curtis McCully, Darshana Mehta, Nicolas E. Meza Retamal, Megan Newsome, Aravind P. Ravi, Jeonghee Rho, Giacomo Terreran, Stefano Valenti, Sergiy Vasylyev, X.-F. Wang, Kathryn Wynn, Yi Yang

Quantum Physics

Tunable M-Ary Quantum Secure Direct Communication via Correlation-Histogram Modulation

Todd M.W. Hodges

We propose a two-way entanglement-based quantum secure direct communication (QSDC) protocol in which information is encoded as the value of a continuously tunable parameter and decoded from empirically estimated joint-outcome histograms over windows of detected pairs. The protocol uses a fixed two-qubit polarization Hilbert space and only standard coincidence-based polarization measurement at the receiver, with the symbol alphabet enlarged not by increasing the carrier Hilbert-space dimension but by exploiting temporal integration over a window of pairs to resolve distinguishable joint-outcome probability distributions. Under an idealized model in which the source is maximally entangled, the encoding operation is strictly local, and the channel imprints no parameter-dependent signature on the traveling photon, the reduced state of the traveling photon is maximally mixed and independent of the encoded parameter. Consequently, passive interception of the in-flight subsystem alone yields no information about the encoded message. We further develop a quantitative trace-distance framework for bounding any parameter-dependent leakage that may arise from non-ideal channel and device effects in practical implementations. The protocol introduces protocol-level design parameters not available in fixed-alphabet two-way QSDC, specifically a runtime-tunable alphabet size and native support for continuous-time analog modulation, which may be advantageous in operating environments where channel conditions vary on protocol-relevant timescales.

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Optics

Electron-beam Writing of Spectrally Uniform Green Single-photon Emitters in Hexagonal Boron Nitride

Qingsong Tao, Fuyi Zhou, Zhijie Li et al. (+16 more)

Scalable quantum photonic technologies require single-photon emitters whose positions and emission energies can be engineered simultaneously. Hexagonal boron nitride (hBN) is an attractive room-temperature host, but deterministic creation of spectrally reproducible emitters remains challenging. Here, we use a standard scanning electron microscope as a direct-writing tool to activate bright green single-photon emitters in hBN at predefined sites, without ion implantation or post-fabrication thermal annealing. The written emitters exhibit reproducible zero-phonon-line emission centered near 536 nm, room-temperature antibunching with g(2)(0) as low as 0.08, high brightness, strong linear polarization, and stable emission. Thickness-dependent activation, stacking experiments, cathodoluminescence spectroscopy, and first-principles calculations support a carbon-related defect complex as the most plausible origin of the emission. As a proof of nanophotonic compatibility, we further activate emitters in a nanoparticle-on-mirror plasmonic nanocavity and observe photoluminescence enhancement accompanied by shortened emission lifetimes. These results establish electron-beam direct writing as a practical route to site-selective, spectrally uniform green quantum emitters in hBN, offering a promising basis for integrated room-temperature quantum photonic architectures.

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All authors Qingsong Tao, Fuyi Zhou, Zhijie Li, Yihao Yan, Shuangyue Li, Yuelan Gao, Zijing Wu, Yizhou Liu, Tao Liang, Shuai Yuan, Dakun Wu, Hongzhi Zhou, Qi Zhang, Zhenyi Ni, Chunlei Yu, Pan Wang, Fei Yu, Lili Hu, Ning Zhou

Mathematical Physics

A new PBW basis for the alternating central extension of the $q$-Onsager algebra

Haoran Zhu

We establish a new PBW basis for $\mathcal A_q$, the alternating central extension of the $q$-Onsager algebra. Terwilliger showed that the alternating generators form a PBW basis in the block order $\mathcal G<\mathcal W^-<\mathcal W^+<\widetilde{\mathcal G}$. We prove that they also form a PBW basis in the different block order $\mathcal W^-<\mathcal G<\widetilde{\mathcal G}<\mathcal W^+$. Consequently, multiplication induces a vector-space isomorphism \[ \mathcal W^-\otimes\mathcal G\otimes\widetilde{\mathcal G}\otimes\mathcal W^+ \longrightarrow \mathcal A_q, \] thereby confirming a conjecture of Terwilliger.

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Materials Science

Crystal structure and basic properties of dirhenate quantum materials

Danrui Ni, Xianghan Xu, Stephen Zhang et al. (+3 more)

The anhydrous divalent 3d-metal dirhenate quantum materials, M(ReO$_4$)$_2$,were synthesized using solid-state methods for M = Mn through Zn. Previously unreported Mg(ReO4)2 is also described. Their layered crystal structures, which feature an in-plane triangular lattice of M$^{2+}$, were refined using single crystal X-ray diffraction, and their optical absorption and several other physical properties were characterized. Their magnetism and heat capacity reveal long-range magnetic order at low temperatures in many of the M(ReO$_4$)$_2$ phases. Notably, many of these ordered states are sensitive to applied magnetic fields and can be readily suppressed by relatively small fields, suggesting competing magnetic interactions in a low-dimensional framework, which appear worthy of further study.

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All authors Danrui Ni, Xianghan Xu, Stephen Zhang, N.P. Ong, Sanfeng Wu, R. J. Cava

Physics and Society · Cross-listed from eess.SY

Overload-Based Cascades in Multiplex Flow Networks with Partial Functionality

Orkun İrsoy and Osman Yağan

Cascading failures driven by load or flow redistribution arise in networked systems such as power grids, supply chains, and cloud computing centers. Most flow-network models assume that a node either functions or fails as a whole. In many real systems, however, a node supports several distinct flows that share node-level resources, and failure in one of them does not necessarily imply failure in the others. We study this setting through multiplex flow networks with partial functionality, where a node can remain operational in some functionalities while failing in others. A heavy load on one functionality reduces the capacity available to the others, as quantified by cross-layer influence factors. When a node fails in one layer, its load is redistributed among surviving nodes in that layer, while the node may continue to operate in the others. Using mean-field analysis, we derive recursive equations for the final system sizes, namely the fraction of surviving nodes in each layer after the cascade stops. We validate the analysis through simulations for several load-capacity distributions. We then examine key features of the cascade dynamics, including non-monotone robustness curves, different cascade-outcome regimes, and their relation with cross-layer influence. We map the outcomes to distinct steady-state regimes, including single-layer survival phases absent in joint-functionality models, and show that partial functionality can increase robustness relative to the joint-functionality case. Finally, we study robustness maximization under a fixed total capacity budget by comparing several capacity allocation strategies. We propose a strategy that combines cross-layer influence with local neighborhood information on load and degree, and show that it gives the strongest robustness performance across the configurations considered.

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Earth and Planetary Astrophysics

Revisiting the dynamics of the Prometheus-Pandora system

Demétrio Tadeu Ceccatto, Nelson Callegari Jr. and Gabriel Teixeira Guimarães

This study revisits the dynamics of Prometheus and Pandora. The analysis focuses on their current orbits and considers mutual perturbations and the non-spherical shape of Saturn. Numerical integrations of the full equations of motion were performed in the context of the N-body problem using a dense set of initial conditions. Spectral analysis of these orbits, together with an interpretation of the dynamical maps, revealed several resonance domains of various orders between Prometheus and Pandora, including the 121:118 resonance domain. Resolving the secular equations for eccentricity and inclination revealed the absence of a forced component in both cases. The period associated with the precession rate, $\Delta\varpi$, corresponds to the anti-alignment period. Chaos was quantified by analysing the diffusion of independent frequencies, which indicates dynamics governed by weak chaos. Minor perturbations caused by the Janus-Epimetheus pair on the orbits of Prometheus and Pandora were also considered. Finally, we investigated the dynamical history of the Prometheus Pandora system, accounting for Pandora's migration due to tidal interactions with Saturn. This revealed several past cross-resonances with a low probability of capture, as well as a scenario in which the Prometheus-Pandora pair exhibited a co-orbital configuration.

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Medical Physics

Geometry-Consistent Discretization of Local Correlation Equations for the Radon Transform in Clinical CT

Xuanqing Mou, Jiayu Duan and Yang Mou

In this work, we extend the local correlation equation (LCE) framework of the 2D Radon transform to clinical computed tomography (CT) geometry and propose a set of geometry-consistent discretization schemes. Building upon the dual-center-of-rotation formulation, the 1st and 2nd LCEs are reformulated under circular fan-beam geometry and discretized using finite difference methods aligned with clinical acquisition configurations. The numerical validity of the proposed discretized circular LCEs (cLCEs) is evaluated using projection data generated from clinical CT datasets. Quantitative analysis based on residual error, mean absolute error (MAE), and mean percentage error (MPE) demonstrates strong consistency between both sides of the equations, with the 2nd cLCE exhibiting the highest accuracy. Furthermore, the proposed cLCE framework is applied to sparse-view sinogram interpolation. By refining interpolated projections using a gradient-descent-based scheme without additional regularization, improved reconstruction quality is achieved. Experimental results show that the cLCE-refined projections significantly enhance image quality compared to sparse-view reconstruction and can outperform clinical complete view (CCV) reconstruction under certain conditions. These results demonstrate that the proposed cLCE discretization provides an effective tool for exploiting projection redundancy in clinical CT and has strong potential for sparse-view reconstruction applications.

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Earth and Planetary Astrophysics

Uniform Metallicity Measurements of M Dwarf Planet Hosts Support Metallicity-Dependent Sub-Neptune Formation

Emma V. Turtelboom, Steven Giacalone, Rebecca Gore et al. (+6 more)

M dwarfs are the most common sites of planet formation in the Milky Way. Planet occurrence and composition are closely linked with the availability of metals in protoplanetary disks, which can be probed by measuring planet host star metallicities. In this work, we measure the metallicities ([M/H] and [Fe/H]) of 59 M dwarfs hosting 76 planets and candidates using medium-resolution near-infrared spectra collected with IRTF/SpeX. We combine these results with literature metallicity measurements for planet-hosting cool dwarfs, and present 86 stars hosting 142 candidate, validated, and confirmed planets with homogeneously derived stellar parameters. Using our updated stellar radii, we calculate planet radii from TESS transit depths for both the confirmed (N = 51, 0.6 - 12.5 R$_\oplus$, median $R_p$ = 1.8R$_\oplus$) and candidate (N = 25, 0.6 - 7.2 R$_\oplus$, median $R_p$ = 2.1R$_\oplus$) planets. We compare the metallicity distributions of super-Earth and sub-Neptune host stars, finding that M dwarfs hosting sub-Neptunes are statistically more metal-rich than those hosting super-Earths. This result is robust to the radius valley prescription used, and is likely not due to differences in the stellar samples considered. This result supports the hypothesized formation pathway whereby sub-Neptunes form beyond the water ice line where they can accrete volatiles before migrating inwards to their observed locations. The enhanced inventories of refractory elements throughout the disk and of volatiles beyond the ice line in metal-rich disks around low-mass stars may contribute to the preference seen in the observed planet sample for sub-Neptunes to orbit metal-rich M dwarfs.

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All authors Emma V. Turtelboom, Steven Giacalone, Rebecca Gore, Courtney D. Dressing, Ryan Cloutier, Karina Kimani-Stewart, Aida Behmard, C.M. Lisse, M.L. Sitko

Thursday 2 July

Astrophysics of Galaxies

Tracing gas outflows in molecular gas-rich galaxies with the SKA

Mamta Pandey-Pommier, Ramya Sethuram, Chiranjib Konar et al. (+4 more)

Active galactic nuclei with powerful radio jets play a key role in galaxy evolution through their ability to regulate the cold gas reservoirs that fuel star formation. Jet-driven feedback can heat, compress, or expel atomic and molecular gas, thereby reshaping the interstellar medium and altering star formation efficiency. However, the physical coupling between AGN activity and the multi-phase interstellar medium remains poorly constrained, particularly in radio-loud systems where mechanical feedback and multiphase outflows are expected to dominate. SKA will provide major advances in the study of cold gas in AGN host galaxies through sensitive observations of H~i emission and absorption, together with access to selected low-frequency molecular transitions within the SKA~1 frequency range, including OH, H$_2$CO, CH$_3$OH, and, at high redshift, low-$J$ transitions of CO, HCN, and HCO$^{+}$ in rare bright systems. Combined with radio continuum measurements, these tracers will provide direct constraints on gas mass, kinematics, turbulence, and inflow/outflow signatures, enabling detailed studies of feedback-regulated cold gas reservoirs in AGN environments. In this chapter, we examine how SKA1 observations of neutral hydrogen, complemented by molecular-line and radio continuum studies, can be used to quantify multiphase gas flows and feedback energetics in molecular-gas-rich radio galaxies. SKA surveys will enable population-level studies of AGN-driven feedback, providing a new framework for understanding how radio jets regulate the cold interstellar medium and star formation across cosmic time.

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All authors Mamta Pandey-Pommier, Ramya Sethuram, Chiranjib Konar, Chinnathambi Muthumariappan, Subhashis Roy, Nirupam Roy, Alexandre Marcowith

Computational Physics · Cross-listed from cs.LG

Scale-Aware Learning of Chaotic Dynamics on Unstructured Meshes via Binned Spectral Losses

Kanad Sen and Romit Maulik

Surrogate modeling for high-dimensional nonlinear dynamical systems that exhibit chaos requires mechanisms that preserve not only pointwise accuracy but also the scale-dependent structure of physical fields. Bandwise spectral power losses, such as the binned spectral loss function, provide such supervision on structured grids, where Fourier modes define a standard frequency decomposition. On irregular meshes, however, no canonical Fourier basis exists, and spectral representations must be constructed from graph operators induced by mesh connectivity and geometry. In this study, we extend the binned spectral power loss for application to unstructured-mesh surrogate modeling of nonlinear dynamical systems. This is obtained by replacing Fourier bands with graph-Laplacian frequency bands, and we provide scalable Chebyshev and multilevel approximations for improving long-horizon rollout fidelity. In its full-spectrum form, our approach uses graph Laplacian eigenspaces to provide a graph analogue of Fourier band-power matching, but incurs the high cost of spectral decomposition. As a scalable approximation, we replace exact band projectors with sparse Chebyshev polynomial graph filters, avoiding explicit eigendecomposition. When utilizing multilevel graph architectures, we introduce Graph Laplacian Energy Alignment for Meshes (GLEAM), which applies retained-subspace scale-aware supervision across graph hierarchies so that coarse and fine representations are regularized during autoregressive rollout. Our results show that the proposed spectral losses improve long-horizon rollout fidelity and preserve statistical invariants for the forecasting of turbulent flows on unstructured meshes, compared to deterministic baselines.

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Quantum Physics

Relativistic bound-state solutions for a non-central Schiöberg-type hyperbolic potential with double ring-shaped angular terms

Shakir.M. Nagiyev and Vatan H. Badalov

Singular interactions can reshape quantum spectra by changing admissible wavefunction domains. In this study, we investigate this mechanism in the Klein–Gordon equation for a non-central Schiöberg-type hyperbolic potential with double ring-shaped angular barriers. Equal scalar and vector couplings separate the radial and angular dynamics. We solve the angular equation exactly on each hemisphere with principal boundary conditions and treat the radial equation with the Greene–Aldrich approximation, obtaining Jacobi-polynomial wavefunctions and an implicit relativistic quantization condition. With this boundary realization, the equatorial inverse-square singularity splits configuration space into reflection-related sectors with identical angular spectra. Reducing the barrier to zero while retaining the equatorial wall selects the odd-reflection spectral branch of the regular full-domain problem; a single hemisphere has no intrinsic parity. The nonrelativistic limit recovers the corresponding Schrödinger formulation. State-resolved nonrelativistic and relativistic benchmarks quantify the centrifugal error. In a dimensionless relativistic example, the relative error in the remaining binding exceeds unity near threshold although the absolute energy error decreases. For NaH and Na$_2$, low-lying central-radial vibrational energies agree reasonably with spectroscopic reference values, whereas the global radial shape limits near-dissociation accuracy and gives an incorrect NaH bound-state count.

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Plasma Physics

Integrated 3D fully kinetic simulation of field-reversed-configuration formation with embedded coils

Bowen Zhu and Jian Wu

We present an integrated, three-dimensional, fully kinetic particle-in-cell simulation of field-reversed-configuration (FRC) formation at the device scale. To our knowledge, this is the first fully kinetic model of whole-device FRC formation. The model embeds the drive coils directly inside the computational domain as physical conductors, advancing them self-consistently with the plasma on a single explicit grid and coupling them in closed loop to an external circuit. We apply this unified framework to the Yingguang-1 $\theta$-pinch. Unlike the magnetohydrodynamic and hybrid models used previously, our framework advances the electrons as kinetic particles rather than a fluid, capturing fast magnetic reconnection and electron heating from first principles. The simulation reproduces the complete formation sequence, from reversed-bias lock-in through reconnection to the emergence of a closed-flux FRC, reaching a peak ion density ${\sim}2.2\times10^{22}\,\mathrm{m^{-3}}$ consistent with experiment. The compressed core is electron-dominated, with $T_e\approx1.7\,$keV exceeding $T_i\approx1.2\,$keV, and is pinched to a separatrix radius $r_s\approx1\,$cm, several times below the equilibrium-inferred value, indicating that the plasma never relaxes to a pressure-balanced equilibrium within the microsecond pulse. The model further reproduces a non-axisymmetric, four-fold ($m=4$) deformation of the compressed column, matching the square cross-section recorded by the experiment's end-on framing camera, a feature beyond the reach of the two-dimensional models previously applied to this device. Running on modest GPU hardware, this work brings integrated, first-principles kinetic modeling of fusion-relevant FRCs within reach.

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General Physics

Induced Couplings and Causal Bounds from Nondegenerate Dirac Lagrangians

Marcelo Netz-Marzola, David Vasak, Vladimir Denk et al. (+2 more)

The standard Dirac Lagrangian is linear in the field derivatives and therefore has a vanishing Hessian. We identify the minimal null deformations of this Lagrangian that make the covariant Legendre map locally invertible. Imposing global phase invariance, reality, proper Poincaré covariance, and absence of external background tensors leaves the two-parameter spinorial bivector $\mathcal E^{\mu\nu}=\ell\sigma^{\mu\nu} +\ell_5{}^\star\sigma^{\mu\nu}$, where the star denotes the Hodge dual and $\ell^2+\ell_5^2\neq0$. This extends the analysis of \cite{struckmeier2024pauli} by a parity-odd term. After minimal $U(1)$ gauging, this free null term is no longer variationally trivial and induces magnetic- and electric-dipole Pauli operators, together with an identically conserved dipole current. These dipole terms make the species-dependent regularization lengths directly constrainable by precision moment measurements. Metric-affine gauging in a Lorentz-spinor prescription then produces spin-curvature, torsion, and nonmetricity corrections to the Dirac operator. Applying the Velo-Zwanziger criterion, we exclude all nonzero pure axial, pure trace, and mixed axial-trace torsion backgrounds, as well as nonzero pure Weyl and second-trace nonmetricity backgrounds. The combined trace-vector nonmetricity sector is not excluded only when the effective trace vector vanishes. Tensor torsion and general tracefree nonmetricity remain unclassified without further algebraic assumptions, while the Levi-Civita limit preserves the metric light cone and leaves only lower-order curvature-dependent mass terms. Thus, gauging a Legendre-regular Dirac representative turns a free variational ambiguity into observable couplings, while non-Riemannian sectors are sharply constrained by causality bounds.

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All authors Marcelo Netz-Marzola, David Vasak, Vladimir Denk, Jürgen Struckmeier, Horst Stoecker

Chemical Physics

Q-Score: A Quantum-Native Scoring Function for Molecular Docking

Kangyu Zheng, Yidong Zhou, Ruihao Li et al. (+3 more)

Molecular docking predicts how a small molecule binds to a protein and is a key bottleneck in drug discovery. Classical scoring functions sum empirical pairwise contacts, blind to quantum-mechanical effects like orbital charge transfer that govern binding specificity. We introduce Q-Score, encoding GNN-predicted orbital donor-acceptor energies into a weighted graph and scoring binding by solving a maximum-weight vertex clique problem via Digitized-Counterdiabatic QAOA. Each interaction anchor maps to one qubit and compatibility constraints become edges. Across 11 protein targets, DC-QAOA recovers the exact optimum on 8 at 10 qubits. On 1000 AI-generated molecules, Q-Score is orthogonal to classical scoring with Spearman rho of 0.05, driven by orbital quality with rho of 0.90, and free of molecular-weight bias, enriching for strong orbital interactions at twice the random rate. DC-QAOA achieves a mean approximation ratio of 0.94 with 52 percent exact. Execution of 1000 circuits on IBM Eagle confirms 6-qubit solvability on NISQ hardware.

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All authors Kangyu Zheng, Yidong Zhou, Ruihao Li, Zixin Ding, Zhiding Liang, Shaohua Li

Applied Physics · Cross-listed from cs.RO

Saturation-Aware Robust Trajectory Optimization for Reusable Launch Vehicles via Differentiable Physics

Liwei Chen and Tong Qin

The high-angle-of-attack flip maneuver of reusable launch vehicles presents significant challenges for robust trajectory optimization due to the combined effects of highly nonlinear dynamics, aerodynamic uncertainties, and actuator saturation. This paper presents a differentiable physics framework for saturation-aware robust trajectory optimization. At its core, a Differentiable Particle Tube Control (DPTC) scheme is developed to optimize uncertainty evolution through an ensemble-based distribution shaping strategy. State uncertainty is represented by a Lagrangian particle ensemble, while hard actuator projection operators are embedded directly into the computational graph, enabling the joint optimization of the nominal feedforward trajectory and a time-varying feedback policy via end-to-end backpropagation. The proposed framework is evaluated against an automatic differentiation-based Successive Convexification (AD-SCvx) baseline combined with a conventional covariance steering feedback strategy. Six-degree-of-freedom Monte Carlo simulations demonstrate that, although the baseline achieves nominal fuel-optimal solutions, its unconstrained feedback formulation becomes susceptible to actuator saturation under aerodynamic disturbances, leading to degraded closed-loop robustness. In contrast, the proposed DPTC framework proactively performs a constraint-aware performance trade-off by relaxing spatial tracking to preserve critical control authority. These results demonstrate that integrating differentiable physics with ensemble-based optimization provides an effective and practical framework for robust guidance in highly constrained aerospace flight systems.

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General Physics

On the Classical Limit of Quantum Mechanics

Marcello Baldo

One of the main unsolved question in Quantum Mechanics (QM) is its compatibility with classical mechanics. The laws of QM, which describe the microscopic world, must merge into the classical ones for large enough physical systems, but it is still unknown at which point, if any, the transition occurs and if the transition is smooth or sudden as the size increases. Furthermore, a strict extension of QM to the macroscopic world leads to well known 'paradoxes', which is not straightforward to solve. This question is tightly connected with the measurement problem, since any measurement apparatus must give a response which can be described at classical level. Many experiments have been performed to answer to this question. They mainly try to find to which extent the number of particles can be increased in order to observe clear evidence of violation of standard QM. In this paper we argue that the macroscopicity parameter is not the number of particles but the number of independent degrees of freedom, as proposed in a recent model for the completion of QM. This introduces a sort of change of paradigm. To support this claim a representative set of well known experiments are analyzed from this point of view. This brings to a new interpretation of the experiments. A general scheme for the quantum-classical transition is discussed in some details.

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General Physics

Why Do Light Nuclei Survive at the Large Hadron Collider?

Sushanta Tripathy and Raghunath Sahoo

Light nuclei and antinuclei, such as deuterons, are produced abundantly at the Large Hadron Collider (LHC) in hadronic and nuclear collisions. Even though their binding energies are only a few MeV, they survive in the extremely high temperatures of the order of a few hundred MeV. This contradiction, often referred to as “Snowballs in Hell”, has become a sharp test of how quantum chromodynamics (QCD) turns quarks and gluons into composite matter. Strikingly, two very different frameworks can reproduce the same inclusive yields, i.e., late-stage nucleon coalescence, where nuclei form from nearby nucleons as the system dilutes, and statistical thermal models, where nuclei emerge as part of an equilibrated hadronization chemistry at a temperature close to 155 MeV. Here, we review how recent LHC measurements and model developments are shifting the question–from whether light nuclei are produced, to when and how they form, with broader implications for QCD matter and cosmic-ray antinuclei searches.

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General Physics

Late-time cosmological constraints on three holographic dark energy models with DESI DR2 BAO and Type Ia supernovae

Jiayuan Huang, Tonghua Liu and Chenggang Shao

We constrain three holographic-inspired dark energy models, namely holographic dark energy (HDE), agegraphic dark energy (ADE), and Ricci dark energy (RDE), using late-time observations from cosmic chronometers, Type Ia supernovae (SNe Ia), DESI DR2 baryon acoustic oscillations (BAO), and {redshift-space distortion (RSD) growth measurements}. Five data combinations are considered: $H(z)+$Pantheon+, $H(z)+$DESI DR2+Pantheon+, $H(z)+$DESI DR2+DES-Dovekie, $H(z)+$DESI DR2+DESY5, and {$H(z)+$DESI DR2+DES-Dovekie+RSD}. We perform Bayesian Markov chain Monte Carlo parameter estimation and compare the models with AIC and BIC. In the BAO-included combinations, HDE gives $H_0\simeq67.3$–$68.0~\mathrm{~km~s^{-1}~Mpc^{-1}}$, $\Omega_{m0}\simeq0.270$–$0.272$, and $c\simeq1$, indicating an expansion history close to the de Sitter boundary rather than a robust phantom regime. ADE yields a stable agegraphic parameter $n\simeq2.78$–$2.81$, while RDE gives $\gamma\simeq0.53$–$0.55$ and persistently favors a low matter density, $\Omega_{m0}\simeq0.215$–$0.219$. {Treating $r_d$ as a free parameter reveals a strong negative correlation between $H_0$ and $r_d$, and the RSD-included combination provides a growth-level consistency check through $f\sigma_8(z)$ without constituting a full perturbative stability analysis.} None of the three models significantly alleviates the Hubble tension. Overall, HDE shows the most balanced phenomenological behavior among the three models, although current late-time data do not decisively prefer it over $\Lambda\text{CDM}$.

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Mesoscale and Nanoscale Physics

Universality and Dynamical Inequivalence in Isospectral Non-Hermitian Anderson Transitions

Aziz Hasan, Anant Vijay Varma, Namit Anand et al. (+1 more)

The Hatano Nelson paradigm establishes that extensive bulk nonreciprocity can destabilize Anderson localization via an imaginary gauge flux. Here, we demonstrate that extensive nonreciprocity is not a necessary ingredient: a single non-Hermitian boundary bond in a disordered one-dimensional ring suffices to drive the localization-delocalization transition. More generally, we construct an exactly isospectral family of non-Hermitian Hamiltonians that continuously interpolates between the uniform Hatano Nelson model and the single-bond limit. We show that the universal critical behavior encompassing spectral, eigenstate, and topological diagnostics is gauge invariant and governed solely by the total imaginary gauge flux, regardless of its spatial distribution. Remarkably, despite sharing identical spectra and critical exponents, different configurations within this isospectral family exhibit qualitatively distinct quantum dynamics, establishing a fundamental separation between static and dynamical universality in non-Hermitian systems. Specifically, the single boundary realization features rapid operator scrambling, oscillatory wavepacket acceleration, and a double re-entrant steady state entanglement transition. Finally, we propose an experimentally feasible realization based on multi-terminal topological transport, providing a realistic route toward observing boundary induced non Hermitian criticality and its unconventional dynamical signatures.

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All authors Aziz Hasan, Anant Vijay Varma, Namit Anand, Sourin Das