High Energy Physics (Theory)
Tensor Network Formulation of $\mathcal{PT}$-Symmetric Quantum Field Theory
Yasuyuki Hatsuda and Kengo Kikuchi
We develop a non-perturbative analytic tensor network formulation of $\mathcal{PT}$-symmetric scalar field theories defined on complex integration contours. Applying this formulation to the two-dimensional $\mathcal{PT}$-symmetric $\phi^4$ theory at negative quartic coupling, we derive an explicit analytic expression for the initial tensor and show that its components separate into even and odd sectors according to the parity of the sum of the tensor indices. We further formulate the theory on an alternative complex contour and analytically establish, in arbitrary dimensions, an exact finite-volume relation between the
lattice partition function defined on this contour and the real part of the analytic continuation of the Hermitian
lattice $\phi^4$ partition function to negative quartic coupling.
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Instrumentation and Methods for Astrophysics
FIRST-PL: Commissioning the first visible photonic lantern spectrograph for sub-diffraction-limit astronomy on Subaru/SCExAO
Sebastien Vievard, Elsa Huby, Sylvestre Lacour et al. (+18 more)
FIRST-PL (Fibered Imager foR a Single
Telescope - Photonic Lantern) is a newly commissioned visible-light instrument on Subaru/SCExAO achieving spectroscopy below the diffraction limit. The instrument uses a Photonic Lantern (PL)-converting multimode fiber into 19 single-mode outputs-feeding a mid-resolution spectrograph (R 3000, 630-790 nm). On-sky performance demonstrates 40% injection efficiency at 680 nm (Strehl 30%) and 12x throughput improvement over single-mode fibers. Three operational modes enable spectro-astrometry (50 microarcseconds precision demonstrated on beta-CMi), image reconstruction, and high-contrast imaging. FIRST-PL represents a significant advancement in high-throughput photonic instrumentation.
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All authors Sebastien Vievard, Elsa Huby, Sylvestre Lacour, Olivier Guyon, Manon Lallement, Mathias Nowak, Yoo Jung Kim, Aidan Walk, Jehanne Sarrazin, Sergio Leon-Saval, Chris Betters, Julien. Lozi, Miles Lucas, Vincent Deo, Nemanja Jovanovic, Michael Fitzgerald, Barnaby Norris, Thayne Currie, Garima Singh, Sandrine Juillard, Guy Perrin
Astrophysics of Galaxies
FAST Ultra-Deep Survey: the baryonic Tully-Fisher relation in FUDS0 field
Hongwei Xi, Lister Staveley-Smith, Bo Peng et al. (+4 more)
The Baryonic Tully-Fisher relation (BTFR) is one of the tightest scaling relations for disk
galaxies in the local Universe, and therefore is an important tool for studying the fomation and
evolution of
galaxies. However, the
evolution of the BTFR over
cosmic time is poorly understood due to the limited sample of HI
galaxies beyond the local Universe, limitations of optically-derived rotation curves, and selection effects. In this work, we explore the BTFR at
redshifts up to $z=0.42$ from
galaxies detected in the pilot FAST Ultra-Deep Survey (FUDS) field, FUDS0. As found in previous work, we identify two components in the plane of baryonic mass versus rotational velocity, $C_{\rm BTFR}$ (tight) and $C_{\rm Outlier}$ (dispersed). A Gaussian mixture model is employed to recover the BTFR, yielding the best fit parameters for the slope $k=3.32_{-0.11}^{+0.12}$, zero point $b=10.07_{-0.03}^{+0.03}$, and intrinsic scatter $\sigma_{\rm BTFR}=0.036_{-0.009}^{+0.010}$. A random forest classifier is used to investigate the origin of the outlier component. We find that low signal significance and inaccurate inclinations are the key factors that contribute to the outlier population, indicating that observational effects are the dominant origin. Evolutionary trends are examined in three different
redshift bins. Both the slope and zero point show consistency within 1-$\sigma$ uncertainty in the two low
redshift bins, indicating no significant
evolution. The indirectly inferred BTFR parameters from the $C_{\rm Outlier}$ component in the highest
redshift bin aligns with the conclusion. The ongoing full FUDS survey will provide a larger sample to enable more accurate constraints on BTFR
evolution.
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All authors Hongwei Xi, Lister Staveley-Smith, Bo Peng, Bi-Qing For, Bin Liu, Dejian Ding, Jianbin Li
Quantum Physics
Equilibrium Thermodynamics of Non-Hermitian Dirac Fermions: Caloric and Magnetic Responses
Francisco J. Peña, Bastian Castorene, Juan Pablo Esparza et al. (+2 more)
We establish scaling relations governing the
equilibrium thermodynamics of real-spectrum non-Hermitian Dirac
fermions in a
magnetic field. Assuming thermalization with respect to the quasi-Hermitian
Hamiltonian, a similarity transformation maps the system at the same applied field onto a Hermitian Dirac model with reduced velocity, while the Landau-level spectrum also admits a representation in terms of a reduced effective
magnetic field. This structure yields scaling relations for the chemical potential,
entropy, heat capacities, and orbital
magnetic response in different thermodynamic ensembles. At fixed projected filling factor (PFF), the self-consistent chemical potential follows the compressed ladder of Landau levels, and the canonical thermodynamic functions are rescaled Hermitian responses. At fixed chemical potential, Landau-level crossings generate oscillatory caloric and
magnetic responses governed by the same spectral compression. Quasistatic non-Hermitian deformation at fixed PFF further yields adiabatic temperature scaling. More broadly, these results establish a thermodynamic framework for real-spectrum non-Hermitian
quantum matter and provide a starting point for incorporating the effects of interactions and disorder within the same formalism.
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All authors Francisco J. Peña, Bastian Castorene, Juan Pablo Esparza, Vladimir Juričić, Patricio Vargas
Plasma Physics
Polarization-resolved attosecond gamma-ray emission from few-cycle laser interactions with cone targets
De-Sheng Zhang, Cui-Wen Zhang, Xue-Ren Hong et al. (+3 more)
Linearly polarized attosecond $\gamma$-ray pulses in the MeV range are generated from a cone target irradiated by a single few-cycle
laser pulse. Electron layers are periodically extracted from the cone walls and subsequently accelerated. Their interaction with the counter-propagating reflected attosecond field produces high-energy
photons through nonlinear Compton scattering (NCS), forming attosecond $\gamma$-ray pulses. We model this interaction using two-dimensional
quantum electrodynamics particle-in-
cell (QED-PIC) simulations that resolve electron
spin and
photon polarization during emission. The results show a shortest equivalent duration of $300\,\mathrm{as}$, with a corresponding linear polarization degree of 0.78. The
photon spectrum extends to $6\,\mathrm{MeV}$, and the linear polarization degree in the high-energy range reaches 0.88. The linear polarization degree remains high when
photons from both emission directions are collected over wide momentum-angle ranges. Scans over the cone opening angle and the coupled
laser-
plasma parameters reveal tradeoffs among
photon number, mean
photon energy, and polarization. Such highly polarized attosecond $\gamma$-ray pulses could be used to investigate ultrafast
nuclear dynamics and polarization-dependent processes in strong-field
quantum electrodynamics.
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All authors De-Sheng Zhang, Cui-Wen Zhang, Xue-Ren Hong, Feng Wan, Jian-Xing Li, Bai-Song Xie
Astrophysics of Galaxies
Cold Dark Matter and Self-Interacting Dark Matter Interpretations of Cloud-9
Morgan Ohana, Xingyu Zhang and Hai-Bo Yu
Recently, the Five-hundred-meter Aperture Spherical
Telescope discovered a gas-rich hydrogen cloud near M94 in the $21\,{\rm cm}$ band. Lacking an optical counterpart, this object, dubbed Cloud-9, has been identified as a compelling Reionization Limited Hi Cloud (RELHIC). RELHICs provide exceptionally clean laboratories for probing dark matter, free from the baryonic complexities associated with
star formation and feedback. We show that the observed hydrogen column density profile of Cloud-9 is consistent with a gas cloud embedded in either a cuspy
halo predicted by the standard cold dark matter (CDM) model or a cored
halo produced by self-interacting dark matter (SIDM). In both cases, the
halo must have an unusually diffuse central density. The best-fitting CDM
halo lies around $7\sigma$ below the cosmological concentration–mass relation, whereas SIDM core-forming
halos reduce the tension to only around $3\sigma$. We further identify Cloud-9 analogs in the Concerto suite of cosmological zoom-in simulations with velocity-dependent SIDM, demonstrating that RELHICs provide a promising new probe of dark matter self-interactions.
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Materials Science
Unveiling the Role of Friction in Coarse-Grained Clay: A Hybrid Framework Integrating Long-Range Interactions and Granular Contact Mechanics
Wang-Qi Xu, Yijie Wang and Zhen-Yu Yin
Given the predominant role of inter-particle physicochemical forces in governing clay behavior, researchers have increasingly utilized coarse-grained molecular dynamics (CGMD) simulations. However, inter-particle friction has been historically overlooked due to methodological limitations, and the extent to which this omission influences simulation accuracy remains an unresolved question. This study proposes a novel hybrid CGMD framework explicitly coupling long-range Buckingham potential with Hertzian granular contact mechanics. A baseline model was validated via isotropic compression, where the resulting compressibility and derived compression index (Cc) aligned with macroscopic geotechnical observations. Parametric analyses revealed that viscoelastic damping of particle contacts governs structural
evolution. Elevated damping suppresses densification, trapping platelets in disorganized, high-void-ratio configurations. Furthermore, evaluating the interplay with thermal fluctuations underscores the necessity of precise temperature control to prevent such unphysical kinetic trapping. Finally, uniaxial compression tests demonstrate the critical importance of inter-particle friction. Explicit friction locks sliding interfaces and sustains significantly higher loads compared to frictionless models; the latter rely solely on
geometric interlocking and ultimately exhibit unphysical fluid-like yielding. By bridging atomistic potentials with contact mechanics, this framework highlights the fundamental role of the inter-particle friction and offers essential guidelines for future multi-scale simulations of clay assemblies.
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High Energy Physics (Theory)
Wilson surface correlator in AdS/CFT
Andreas Gustavsson
We use the AdS/CFT correspondence to show that for two spherical Wilson surfaces, both in the fundamental representation of $SU(N)$ gauge group, in the six-dimensional $(2,0)$ theory, in the large $N$ limit there is a first order Gross-Ooguri phase transition at a certain critical separation distance that we obtain numerically.
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Quantum Physics
The Born Representation Theorem and the Unistochastic Theorem
Jacob A. Barandes
This paper presents self-contained, constructive proofs of two new
theorems about
stochastic matrices, with direct relevance to
quantum theory. The first
theorem, herein called the Born Representation
Theorem, shows that each entry of any
stochastic matrix can be expressed as the trace of a pairwise product of
matrices, where the first factor in the pairwise product belongs to a positive-operator-valued measure (POVM) and the second factor belongs to a projection-valued measure (PVM). As its name suggests, this
theorem entails that the entries of any
stochastic matrix can be expressed in terms of a generalized version of the
quantum-theoretic Born rule. It follows as a corollary that if the POVM in this first
theorem is a PVM, then the
stochastic matrix is unistochastic, meaning that its entries are each the modulus square of the corresponding entry of a
unitary matrix of the same size. The second
theorem proved in this paper, called the Unistochastic
Theorem, then shows that by dilating the underlying vector space by a bounded number of additional dimensions if necessary, each entry of any
stochastic matrix can be expressed in terms of the trace of a pairwise product for which both factors belong to PVMs, and can thus be derived via marginalization from a larger unistochastic
matrix. This second
theorem therefore establishes a kind of primacy of unistochastic
matrices over
stochastic matrices, and hints at a close connection with
unitary time
evolution in
quantum theory. The paper concludes with a brief discussion of potential applications to discrete-time deterministic processes and Markov chains.
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Cosmology and Nongalactic Astrophysics
Revisiting the equation of state of dark energy from DESI BAO with SNe Ia and CMB
Jie Zheng, Da-Chun Qiang, Zhi-Qiang You et al. (+1 more)
The Dark Energy Spectroscopic Instrument (DESI) measurements of
baryon acoustic oscillations (BAO) have recently shown a mild preference for dynamical dark energy over the standard $\rm \Lambda$CDM model. In this paper, we analyze the $w_0w_a$CDM model using DESI BAO DR2, Pantheon+ SNe Ia, and Planck 2018 CMB distance prior data. To examine how different parts of the data affect the apparent deviation from $\rm \Lambda$CDM, we adopt two complementary
redshift-cut strategies, dividing the
dataset into $z<z_{\rm cut}$ and $z>z_{\rm cut}$ subsamples. We find that the most noticeable shifts occur when BAO and SNe Ia data in the
redshift range $z\sim0.4$–$0.8$ are included, reaching a significance of about $\sim2\sigma$. Within this framework, the inclusion of higher-
redshift measurements progressively weakens this deviation and brings the constraints closer to the $\rm \Lambda$CDM expectation. Moreover, the information criteria show no statistically significant preference between the $w_0w_a$CDM and $\rm \Lambda$CDM models, while the
Bayesian information criterion consistently favors the $\rm \Lambda$CDM model. In addition, a parameter-shift consistency test reveals no statistically significant tension between complementary
redshift subsamples. Within the DESI BAO DR2, Pantheon+, and CMB distance prior framework adopted here, these results do not provide statistically robust evidence favoring the $w_0w_a$CDM model over $\rm \Lambda$CDM. They instead indicate that the apparent parameter shifts under different
redshift cuts may be affected by statistical fluctuations and by the limited precision and number of datapoints in the current subsamples. Our analysis provides a complementary
redshift-dependent diagnostic for assessing how the inferred cosmological constraints vary under different
redshift selections.
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All authors Jie Zheng, Da-Chun Qiang, Zhi-Qiang You, Darshan Kumar
Strongly Correlated Electrons
Quantized topological invariant of symmetry-projected Gibbs states
Weiguang Cao and Haruki Watanabe
We study Gibbs states projected onto the symmetric sector of contractible one-form
symmetries. In a three-dimensional cluster-model interpolation, this projection stabilizes
symmetry-protected topological and projected-paramagnetic phases, both sharply distinct from thermal disorder. A flux-twisted membrane invariant distinguishes these three phases by the values $-1,+1,0$, respectively. These values are exact on the endpoint, self-dual, zero-temperature, and infinite-temperature lines; elsewhere their quantization requires positive spatial-sheet, winding-line, and interface tensions.
Quantum Monte Carlo supports the quantization through tension diagnostics and direct finite-size estimates.
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General Relativity and Quantum Cosmology
Corrections to Hawking radiation from asteroid-mass primordial black holes: analytic and numerical evaluation of the stochastic charge effect
Gabriel Vasquez, Bowen Chen, Cara Nel et al. (+3 more)
Hawking radiation sets stringent constraints on
Primordial Black Holes (PBHs) as a dark matter candidate in the $M\sim 10^{16}$ g regime based on the evaporation products produced by the black hole, motivating the need to rigorously model the
photon, electron, and positron emission spectra. This manuscript is the second in a series of two papers (see Vasquez et al. [Phys. Rev. D, 112:063002 (2025)] for the first paper in the series) with the goal of proving the
stochastic emission of electrons and positrons, known as the "
stochastic charge effect" and first predicted by Page [Phys. Rev. D, 16:2402 (1977)] using semi-classical arguments, arises from
quantum electrodynamics (QED) on a Schwarzschild spacetime. We derive the corrections to the $e^\pm$ from the relevant term in the
Hamiltonian (the long-range monopole: $H_{\rm int,0L}$) to first order in the fine structure constant ($\alpha$), and show that the semi-classical terms are also present in the QED calculation. We also highlight which terms in our analysis only appear within our
quantum mechanical approach and cannot be explained otherwise. We find that due to some cancellation of terms, over the range of $2.2\times 10^{16}$ - $1.7\times 10^{17}$ g, the net correction to the $e^\pm$ emission rate is less than 2%, versus the suppression of up to 5% previously found by semi-classical arguments.
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All authors Gabriel Vasquez, Bowen Chen, Cara Nel, Emily Koivu, Makana Silva, Christopher M. Hirata
Fluid Dynamics
Expansion of a hole in a viscoelastic liquid sheet
Tachin Ruangkriengsin, Rodolfo Brandão and Howard A. Stone
Experiments on highly viscous polymeric films show that punctured holes expand exponentially in time, without sustained accumulation of
liquid near the rim. This response departs from the Taylor–Culick description, in which displaced
liquid accumulates in a growing rim that moves at constant speed. Although these differences were initially attributed to viscoelasticity, they were later rationalized using a purely viscous theory, leaving the role of viscoelastic stresses unresolved. We analyze the expansion of an axisymmetric hole in a freely suspended viscoelastic
liquid sheet described by the Oldroyd-B model. Exploiting the separation of length scales between hole radius and film thickness, we derive extensional thin-film equations on the scale of the hole and an effective boundary condition from an asymptotic force balance in the tip region. Analytical solutions are obtained for weak viscoelasticity, $Wi\ll 1$, and the ultra-dilute limit, $\mu_p\ll\mu_s$, where $Wi$ is the Weissenberg number, while $\mu_s$ and $\mu_p$ are solvent and polymeric viscosities, respectively. For weak viscoelasticity, the dimensionless hole radius grows approximately as $e^{(0.5+\alpha Wi \beta_p)T}$, where $\alpha=(12 - 6\log 2-\pi)/21\approx 0.224$ and $\beta_p=\mu_p/(\mu_s+\mu_p)$. In the ultra-dilute limit, the radius grows approximately as $e^{(0.5+\alpha^{*}\beta_p )T}$, where $\alpha^{*}(Wi)>0$ is evaluated numerically. In both regimes, viscoelastic stresses increase the exponential growth rate relative to the Newtonian limit and induce film-thickness variations, with thickening near the retracting edge. This acceleration arises from azimuthal stretching and radial compression of the
polymers, which redistribute stresses in the film and modify the stress balance at the tip, leading to a stronger outward radial extensional flow.
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Instrumentation and Methods for Astrophysics
Life 2.0: A Scalable Distributed Space-Telescope Array for Biosignature Spectroscopy
Jian Ge, Zhangqi Dang, Ziru Zhang et al. (+15 more)
Answering the question "Are we alone?" requires atmospheric spectroscopy of nearby terrestrial
planets. For an Earth–Sun analog, even the strongest transmission signals are expected to be of order 1 part per million (ppm). Unlike short-period
planets, Earth 2.0
planets transit only about once per year, so single-transit sensitivity, rather than stacking repeated observations, is the fundamental design driver. Life 2.0 is a scalable space-mission concept linking Earth 2.0 candidates discovered by PLATO and the Earth 2.0 (ET) mission with atmospheric characterization and biosignature assessment. The baseline architecture comprises 900 one-meter space
telescopes, each equipped with a high-throughput Waveguide Integrated Miniature Spectrograph and an ultra-low-read-noise CMOS detector. After independent calibration, spectra acquired simultaneously during a transit are combined, providing the
photon-collecting capability of an approximately 30-m aperture at the selected spectral resolution while retaining a modular architecture. The baseline 0.2–1.05 $\mu$m range covers O$_3$, O$_2$, H$_2$O, Rayleigh scattering, and other diagnostics, with extension into the infrared as detector technologies mature. Prototype Waveguide Spectral Lens devices have demonstrated 40–66% throughput at resolving powers from $R \sim 200$ to $R \sim 20{,}000$. Lightweight silicon-carbide mirrors and sub-electron-noise CMOS detectors support replicated production. Life 2.0 must address detector systematics, instrument stability, and
stellar variability; rather than assuming these limitations disappear, it builds on calibration, detector-characterization, and data-analysis techniques advanced during the JWST era. The concept offers a scalable alternative to a monolithic 30-m-class space
telescope and a staged pathway toward biosignature spectroscopy of nearby Earth-like
planets.
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All authors Jian Ge, Zhangqi Dang, Ziru Zhang, Chenxu Gao, Shijie Ke, Ziyang Zhang, Rong Shu, Wen Chen, Jie Yin, Yunzhou Zhu, Leiming Lei, Zhongming Chen, Jiancheng Ji, Xiangsen Tian, Jun Yang, Xinyi Song, Rafael Luque, Enric Palle
Optics
Xi Liu and Wenxi Fang
We analyze the integration of
quantum optical phenomena, such as cavity
quantum electrodynamics (CQED), Fabry Perot resonances, and strong light-matter coupling, into the design and engineering of next generation photovoltaic systems. We examine how these phenomena can be harnessed through photonic structures including optical cavities, plasmonic materials, and metasurfaces to improve light trapping, absorption, and carrier dynamics in future
solar cell devices. Specific focus is given to
semiconductor materials such as perovskites, organics, transition metal dichalcogenides (TMD), cadmium telluride (CdTe), and silicon. For perovskite
solar cells, we analyze device architectures, interfacial engineering with hyperbranched
polymers, and additive optimization using molecular dopants and nanosheets to enhance film morphology and stability. We further examine
laser-based metrology for thin-film characterization and coherent spectroscopy techniques involving frequency combs and high-harmonic generation. The paper also shows how machine learning (ML), combined with density functional theory (DFT), accelerates material screening and performance prediction for next-generation
solar cell absorbers. These developments demonstrate how
quantum optoelectronic design principles are transforming photovoltaic research and enabling higher efficiency, stability, and functionality in
solar energy devices.
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Fluid Dynamics
Beyond the Mean-flow: A Spectral-Dynamic Approach to Unraveling the Physics of Droplet Capture in Fog Harvesting Meshes
Pradyumna Das, Ranjan Ganguly and Ashoke De
Fog harvesting efficiency with mesh collectors is governed by complex interactions between droplet inertia and geometry-induced flow structures. Although previous studies have primarily relied on mean-flow metrics, the present work introduces a spectral-dynamic framework to examine an important but often overlooked control on droplet capture. A two-way coupled Eulerian-Lagrangian model is used to simulate droplet-laden flow (2-40 microm) across five representative mesh geometries. The results show that capture efficiency correlates not only with the magnitude of velocity fluctuations, but also with their spectral distribution and persistence. Frequency-domain analysis indicates that mesh geometry redistributes fluctuation energy across pore and obstruction regions, thereby defining a characteristic flow timescale. By comparing this flow timescale with the droplet response time, a dynamic matching parameter, {\Pi}= droplet response time/flow time scale, is introduced. The highest capture efficiency occurs when {\Pi} is order unity, corresponding to sustained droplet-flow interaction in the near-mesh region. Geometries that generate broadband, moderately amplified spectral content (e.g., triangular mesh) increase droplet residence time and interception probability, whereas geometries with either weak or highly localized fluctuations reduce performance through insufficient forcing or premature bypass. A physics-inspired correlation for capture efficiency is proposed based on this condition. The study therefore provides mechanistic design guidance, rather than a definitive optimum, for geometry optimization in fog-harvesting meshes.
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Instrumentation and Methods for Astrophysics
He'e-Lab: A modular testbed for astrophotonics and wavefront sensing development
Sebastien Vievard, Christopher Hamner, Nour Skaf et al. (+14 more)
Advanced astronomical instrumentation requires accessible, reconfigurable platforms to validate novel technologies and
algorithms before on-sky deployment. We present the design, architecture, and
alignment validation of the Hawaii Experimental Engineering Lab (He'e-Lab), a state-of-the-art modular testbed dedicated to two complementary research tracks: (A) the integration and characterization of astrophotonics components within a real-time computing loop, and (B) the development of advanced wavefront sensing and control (WFS&C)
algorithms. The testbed features a broadband supercontinuum source (500 nm to 2 microns), a high-order 1k-actuator Boston Micromachines deformable mirror, and a 37-segment hexagonal mirror assembly providing piston-tip-tilt control to emulate segmented apertures like Keck and JWST. Downstream capabilities include a HASO 126 Shack-Hartmann sensor, a real-time computing environment driven by the CACAO package, and a modular injection platform coupled to a visible-wavelength spectrograph (R3, 000). We report on the successful system
alignment and outline the roadmap for upcoming adaptive optics and photonic device validation frameworks.
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All authors Sebastien Vievard, Christopher Hamner, Nour Skaf, Dylan Hively, Michael Bottom, Mark Chun, Christoph Baranec, Olivier Guyon, Julien Lozi, Aidan Walk, Josh Corn, Branden Allen, Elsa Huby, Sylvestre Lacour, Guillermo Martin, Manon Lallement, Vincent Deo
Solar and Stellar Astrophysics
Doppler-shifted Signatures in the Chromospheric Line Profiles of II Pegasi
Cao Dongtao and Gu shenghong
Stellar flares are frequently accompanied by prominence eruptions, coronal mass ejections (CMEs), and other forms of
plasma motion. Based on the long-term high-resolution spectroscopic monitoring data set of the RS CVn-type
star II Pegasi (II Peg), we search for
stellar prominence eruptions and potential CMEs by investigating asymmetric signatures in the H$_{\alpha}$ and H$_{\beta}$ line profiles during the
flare events. We observed seven optical
flares with asymmetric spectral profiles, releasing low limit energies of $10^{33}$–$10^{34}$ erg in the H$_{\alpha}$ line. Five of these
flares were associated with six potential CMEs, identified through the Doppler-shifted emission signatures in the chromospheric line profiles, particularly the H$_{\alpha}$ line. The mass estimates for the CME candidates range from $10^{19}$ to $10^{20}$ g, while the kinetic energies are calculated to be around $10^{33}$–$10^{34}$ erg. The most massive CME candidate was simultaneously recorded in the H$_{\alpha}$, H$_{\beta}$, and He I D$_{3}$ lines. For II Peg, the possible
flare-CME association rate is about 30%. There were also some redshifted excess absorption signatures in the H$_{\alpha}$ line profiles. These signatures could not only be observed in the flaring spectra but also in the spectra without
flare, which could be interpreted as features resulting from
flare-driven coronal rain and quiescent rain, respectively.
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Statistical Mechanics · Cross-listed from math.PR
The rank and layer distributions in random recursive trees
Huck Stepanyants, P. L. Krapivsky, Harrison Hartle et al. (+1 more)
The distribution of node depths in a network is crucial for analyzing network structure. Two measures, rank and layer, quantify how deep inside a network a node is. The rank is the node's distance to the closest leaf, a node of degree 1. The layer is the number of times all leaves must be stripped off for the node to become a leaf. We derive exact recursive expressions for the rank and layer distributions in random recursive trees. We show that the rank and layer distributions decay factorially and geometrically, respectively, and prove the self-averaging of the numbers of nodes with fixed rank or layer. Unlike previous studies, our approach does not depend on labels or a root node, providing a more versatile framework for analyzing rank and layer distributions in complex networks.
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All authors Huck Stepanyants, P. L. Krapivsky, Harrison Hartle, Dmitri Krioukov
Geophysics
Regional Chaos Synchronization towards controlling high-dimensional open environmental systems
Yohei Sawada
Although controlling chaos can be regarded as a form of chaos synchronization, conventional chaos synchronization does not provide a practical framework for controlling high-dimensional open chaotic systems, such as weather. In high-dimensional open environmental systems, it is simply impossible to make the difference between drive and response systems asymptotically approach zero over the entire domain. Instead of conventional global chaos synchronization, here I define regional chaos synchronization, in which state variables within only a small target region are synchronized with a target trajectory using actuators located in the target region. Theoretical considerations and numerical experiments show that the performance of regional chaos synchronization is substantially degraded by the injection of errors from exterior regions that the controller is not intended to modify. Even under the same actuator specifications, the performances of regional chaos synchronization differ among trajectories, which is not the case of conventional global chaos synchronization. An appropriate target trajectory differs substantially from the natural trajectory only in the target region. This choice of target trajectories can minimize the injection of errors from exterior regions and thereby enable successful regional chaos synchronization. The implications of this new framework for realistic control problems such as weather control are discussed.
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High Energy Astrophysical Phenomena
A Real-Time Jet Laboratory in Swift J1727.8-1613
Callan M. Wood, James C. A. Miller-Jones, Arash Bahramian et al. (+16 more)
We present the results of our intensive VLBI campaign on the black-hole low-mass X-ray binary (LMXB) Swift J1727.8-1613 during its 2023-2024 outburst. We observed the repeated quenching and re establishment of the highly-extended continuous jet during several transitions between hard-intermediate and soft-intermediate states, and the repeated ejection of transient jets. Using time-dependent visibility model fitting, we tracked the motion of nine discrete jet
knots, obtaining some of the most precise measurements of transient jet proper motions and ejection dates in an LMXB. These ejecta were only detectable for a short time with VLBI, and some showed rapid intra-observation flux density variability that was not captured in image reconstructions. For the first time, we use time-dependent visibility modelling to fit a piecewise model for the jet
knot flux densities, allowing us to create complex, non-parametric light curves of their intra-observation variability. We observed the launching of multiple ejecta across several state transitions, however, we could not identify a consistent signature of jet ejection in the available X-ray intensity or hardness data. We constrained the intrinsic speeds and bulk Lorentz factors of the jet
knots, finding that Swift J1727.8-1613 launched both mildly relativistic and highly relativistic ejecta throughout its outburst. We used their proper motions to constrain a posterior distribution for the maximum inclination angle of the jet axis, which had 50th, 84th, and 99th percentiles of 40{\deg}, 50{\deg}, and 66{\deg}, respectively. These unique observations of the repeated ejection of transient jets by a single LMXB reveal that fixed parameters such as black-hole mass, black-hole
spin, and
spin-orbit misalignment do not uniquely determine the varying properties of transient jets, particularly their speeds and Lorentz factors.
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All authors Callan M. Wood, James C. A. Miller-Jones, Arash Bahramian, Steven J. Tingay, Sara E. Motta, Hongmin Cao, Thomas D. Russell, Francesco Carotenuto, Pikky Atri, Diego Altamirano, Alexandra J. Tetarenko, Rob Fender, Elmar Körding, Dipankar Maitra, Sera Markoff, David M. Russell, Gregory R. Sivakoff, Roberto Soria, Valeriu Tudose
Solar and Stellar Astrophysics
Further Investigation on Chromospheric Activity Patterns of the RS Canum Venaticorum Star V711 Tauri
Cao Dongtao and Gu Shenghong
We present new long-term spectroscopic observations of the very active RS Canum Venaticorum (RS CVn)
star V711 Tauri (V711 Tau), obtained during several observing runs from 2005 to 2021. By means of spectral subtraction technique, several optical chromospheric activity indicators $\mbox{Ca {\sc ii}}$ infrared triplet, H$_{\alpha}$, $\mbox{Na {\sc i}}$ D$_{1}$, D$_{2}$ doublet, $\mbox{He {\sc i}}$ D$_{3}$, and H$_{\beta}$ lines, are analyzed. V711 Tau shows strong excess emission in the chromospheric activity lines, and the emission is mainly associated with the K1 IV primary component. The G5 V secondary component also shows weak emission features. There are four optical
flare events during our observations, characterized by the $\mbox{He {\sc i}}$ D$_{3}$ line emission features and stronger emission in other activity lines, which have similar order of magnitude as the strong
flares of other active RS CVn-type
stars. We separate our long-term observations to twelve observing groups, and find that V711 Tau has two active longitudes around phases 0.25 and 0.75 to dominate the activity in most of time. The chromospheric activity level shows a long-term variation, indicating possible chromospheric activity cycle. Moreover, a close spatial connection between photospheric spots and chromospheric active regions in short and long timescale is found for V711 Tau.
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