High Energy Physics (Experiment)
ADoNIS: A Differentiable generatOr of Neutrino Interaction Samples
César Jesús-Valls
Neutrino interaction generators are central to precision oscillation analyses, but conventional implementations do not directly provide derivatives of their predictions with respect to physics parameters, leaving analyses to obtain this dependence through reweighting, finite differences or external response models. We present ADoNIS, a fully differentiable
neutrino interaction event generator that makes event reweighting and its gradients directly available, propagating exact derivatives through the
nuclear ground state, hard-scattering amplitudes and
stochastic intranuclear cascade. Following the physics choices of ACHILLES, we demonstrate agreement with its predictions across
neutrino, electron and
hadron probes, showing that differentiability is achieved without loss of physical fidelity. We then show how the resulting Jacobian exposes which measurements and regions of phase space constrain each parameter and how different probes break degeneracies, providing a quantitative tool for fit design, model tuning, measurement design and experiment design. The same differentiable predictions can be used directly in frequentist and
Bayesian inference and carried through detector response to reconstructed observables for unfolding, while also yielding computational gains. In sum, ADoNIS provides a practical recipe for constructing differentiable
neutrino event generators, applicable beyond the particular physics models implemented here, and this paper demonstrates their use across a wide range of tasks relevant to both theory and experiment.
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High Energy Physics (Phenomenology)
Statistical Inference of Scattering Parameters for Exotic Hadronic States in the $J/\psi\,p$ Spectrum
André Aimé Atangana Likéné, P. Pradyun Hebbar, Alexis Franck Rothen et al. (+5 more)
We present a global two-channel Flatté amplitude analysis of the hidden-charm pentaquark candidates observed by the LHCb collaboration in the J/{\psi}p invariant-mass spectrum using the Run 1+2
dataset. We simultaneously fit the three pentaquark amplitudes to the full spectrum, including a
polynomial background and complex coupling phases. The scattering length and effective range are extracted from the fitted amplitudes using the effective range expansion, with uncertainties determined through non-parametric bootstrap resampling. While real couplings yield scattering parameters compatible with a molecular interpretation, this conclusion becomes less robust when coupling phases are included. We further find that interference effects are important for the closely spaced Pc(4440)+ and Pc(4457)+ states, demonstrating the limitations of the incoherent-sum approximation.
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All authors André Aimé Atangana Likéné, P. Pradyun Hebbar, Alexis Franck Rothen, Ron Rayan Baatjes, Saralees Nadarajah, Patrice Ele Abiama, Tobias Golling, Germain Hubert Ben-Bolie
Statistical Mechanics
Convergence of the conformal Ward identity in the derivative expansion approximation
Jorge Ibañez, Matthieu Tissier and Gonzalo De Polsi
Conformal invariance is expected to be an emergent property of many systems in their critical regime. However, approximation schemes generically spoil this property. This is in particular the case of the derivative expansion, a widely used approximation scheme in the framework of the functional renormalization group. In this article, we consider Ward identities associated with conformal invariance in the 3-d Ising universality class with truncations at order 4 (next-to-next-to-leading order) in the derivative expansion, with $Z_2$ invariant composite operators. Our results confirm that the regulating functions which yield a small breaking of conformal invariance also present a small sensitivity of the universal critical exponents with the choice of this regulating function. We also show that, in the vicinity of regulator-parameter values for which the conformal constraints are best satisfied, the breaking of conformal invariance reduces as the order of the derivative expansion is increased, providing a new indication of the convergence of this approximation scheme.
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Quantum Physics
Feedback-enabled magnomechanics in lithium ferrite
Mehri Ebrahimi, Yunhu Huang, Ali Rashedi et al. (+1 more)
Lithium ferrite (LiFe) is a promising material for cavity magnonics because its large
spin density enables strong coupling between
magnons and microwave
photons. Its potential for cavity magnomechanics, however, has remained unexplored. Here, we observe magnomechanical interactions in a single-
crystal LiFe sphere using coherent microwave feedback to suppress dissipation of the cavity–
magnon polariton. In the absence of sufficient feedback, the narrow mechanical response is difficult to resolve against the much broader polariton background. Increasing the feedback gain reduces the polariton linewidth and correspondingly increases the magnomechanical cooperativity, revealing a clear magnomechanically induced transparency feature. In the measurements presented here, the effective upper-polariton linewidth is reduced from $3.53~\mathrm{MHz}$ without feedback to $5.8~\mathrm{kHz}$ in the presence of feedback, while the measured cooperativity increases from $C=1.9\times10^{-3}$ to $C=0.15$. These measurements provide, to our knowledge, the first observation of cavity magnomechanics in LiFe and demonstrate coherent feedback as a practical route for accessing weak interactions that would otherwise be obscured by dissipation.
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All authors Mehri Ebrahimi, Yunhu Huang, Ali Rashedi, John P. Davis
Mathematical Physics · Cross-listed from cs.AI
PhysElite: How Far Are LLMs from Solving Olympiad-Level Physics Problems?
Ruoran Xu, Wending Gao, Liyunfeng Chen et al. (+5 more)
Understanding how (
multimodal) large
language models perform on physics problems requires
benchmarks that reflect the difficulty and breadth of expert-level physical
reasoning. Existing physics
benchmarks remain limited in the following two important ways: (1) short of high-difficulty
datasets, and (2) lack of comprehensive coverage of visual forms, knowledge points, and step-by-step solution processes. As a result, model performance on current
datasets may not be fully representative of their ability to solve complex physics problems. To address these issues, we present PhysElite, a large-scale bilingual
multimodal benchmark for Olympiad-level physics
reasoning. PhysElite contains 11,586 Olympiad-tier problems. For each problem, we provide corresponding visual diagrams, step-by-step bilingual Chinese-English solution derivations, and the final answer. We
benchmark 18 open-source and closed-source MLLMs, and find that even the strongest model reaches only 33.7% answer accuracy. We additionally conduct step-level process evaluation to diagnose where models fail in the
reasoning chain. Our
datasets are released at https://huggingface.co/
datasets/physelite/PhysElite.
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All authors Ruoran Xu, Wending Gao, Liyunfeng Chen, Aixin Shi, Haoyu Cheng, Zixiang Fang, Yiqiang Zou, Qiufeng Wang
Superconductivity
Probing bulk superconductivity in centrosymmetric Te-doped PtBi$_2$ single crystals
Kilian Srowik, Pablo Pedrazzini, Soumen Ash et al. (+17 more)
The Weyl semimetal $\gamma$-PtBi$_2$ has been shown to be one of the most promising novel materials, recently proposed as a topological i-wave
superconductor. A crucial requirement for observing this physics is the absence of inversion
symmetry in its trigonal $P31m$
crystal structure. Centrosymmetry has been reported to be readily restored in the $P\overline{3}m1$ structure upon electron doping, partially substituting Bi with as little as 2% Te. In this work, we synthesized Te-doped PtBi$_{2-x}$Te$_{x}$ samples and thoroughly investigated the bulk superconductivity of selected single
crystals with nominal composition PtBi$_{1.96}$Te$_{0.04}$, exhibiting the highest superconducting volume fraction of $\sim100$%. Single
crystal XRD measurements confirm the centrosymmetric $P\overline{3}m1$ structure in our samples, whereas bulk superconductivity with a critical temperature of $T_\mathrm{c} \approx 2.4\,$K was observed in magnetization and specific heat measurements. The upper critical fields for two different orientations were determined as $H^{\parallel}_{\mathrm{c2}}(0)\approx 6.3\,$kOe for in-plane and $H^{\perp}_{\mathrm{c2}}(0)\approx 4.7\,$kOe for out-of-plane
magnetic fields. Robust superconductivity was also found in resistance and point contact measurements, where the latter showed a slight enhancement of the critical temperature up to $T_\mathrm{c} \sim 3\,$K. Finally, ARPES measurements corroborate the centrosymmetric structure of our samples, showing a single surface termination and the absence of
Fermi arcs.
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All authors Kilian Srowik, Pablo Pedrazzini, Soumen Ash, Oksana Kvitnitskaya, Andrii Kuibarov, Susmita Changdar, Oleksandr Suvorov, Volodymyr Bezguba, Alexander Kordyuk, Rafał Kurleto, Dawid Wutke, Reza Firouzmandi, Robert Kluge, Swarnamayee Mishra, Alexander Mistonov, Saicharan Aswartham, Jochen Geck, Sergey Borisenko, Laura T. Corredor, Bernd Büchner
Materials Science
Intercalation of Alkali Metal into WTe2, the Crystal Structure of A0.5WTe2 and Observation of a Metal-to-Semiconductor Transition
Patrick Schmidt, Fabian Strauß, Marcus Scheele et al. (+2 more)
We explore the cationic intercalation of tungsten ditelluride (WTe2) with potassium (K), rubidium (Rb), and cesium (Cs), yielding intercalation compounds of the form A0.5WTe2 (A = K, Rb, Cs). Structural characterization was performed using powder X-ray diffraction (PXRD), while diffuse reflectance infrared
Fourier transform (DRIFT) spectroscopy and temperature-dependent conductivity measurements were employed to investigate the electronic properties. Density functional theory (DFT) calculations were carried out to support the experimental findings and to provide insight into the intercalation mechanisms and the resulting material characteristics. All synthesized compounds display semiconducting behavior with narrow band gaps, emphasizing the influence of alkali metal intercalation on the electronic structure and transport properties of WTe2. These results advance the fundamental understanding of property modulation in transition-metal dichalcogenides (TMDCs) and highlight their potential for electronic device applications.
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All authors Patrick Schmidt, Fabian Strauß, Marcus Scheele, Carl P. Romao, Hans-Jürgen Meyer
High Energy Physics (Phenomenology)
Impact of local and global event conditions in prompt charm hadron ratios
Luis Carlos Cruz Peralta and Lizardo Valencia Palomo
Fragmentation functions extracted from electron-
proton and electron-positron collisions have shown not to be able to explain
prompt charm
hadron ratios in
proton-
proton collisions at the LHC energies. New models and event generator tunes have been developed to correctly describe the data from the ALICE experiment in
proton-
proton collisions at different center of mass energies. In this work Pythia 8.312 is used to implement two of those models: the SC-CR and BLC-CR + Ropes. Both show a good performance to reproduce the data at \sqrt{s}} = 13 TeV in different event conditions for the $\Lambda_{c}^{+}/\rm{D}^0$, $\Sigma_{c}^{0,+,++}/\rm{D}^0$, $\rm{D}^{+}/\rm{D}^0$ and $\rm{D}^{*+}/\rm{D}^0$ ratios. For the particular case when the
prompt charm
hadrons are within jets, all the ratios show modifications relative to the case where the presence of jets is not required. A study in two different ranges of the relative transverse activity is also conducted. In this case only the
baryon to
meson ratios show a dependence on the underlying event activity. Results indicate that
baryon and
meson hadronisation are not affected in the same way by local effects or global event conditions
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Mathematical Physics · Cross-listed from math.FA
A Schrödinger characterization of the oscillator semigroup
Gianluca Giacchi
The oscillator (or metaplectic)
semigroup is classically defined as the two-fold cover of the
semigroup of positive complex
symplectic matrices. Although geometrically precise, this definition does not provide an intrinsic operator-theoretic characterization of the bounded operators corresponding to positive
symplectic matrices. This is in contrast with the real metaplectic group, whose relation with the
symplectic group can be expressed directly in terms of the Schrödinger representation of the Heisenberg group through its intertwining property. In the complex setting, such a relation appears in the existing literature mainly in infinitesimal form or on suitable classes of Gaussian functions. In this work we prove that the (complexified) Schrödinger intertwining relation holds for every function in $L^2(\mathbb{R}^d)$. The main point is the converse statement: if an arbitrary complex
symplectic matrix $S$ admits a nonzero bounded operator on $L^2(\mathbb{R}^d)$ satisfying this intertwining relation, then $S$ is necessarily positive and the operator coincides, up to a nonzero scalar, with the corresponding element of the oscillator
semigroup. Consequently, positive complex
symplectic matrices are exactly those admitting a nonzero bounded Schrödinger intertwiner, and the associated intertwining space is one-dimensional. This provides a Schrödinger-representation characterization of the oscillator
semigroup, parallel to the classical one for the real metaplectic group.
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Atomic Physics
High-density Optical Quantum Sensors with Pulsed Probe Read-out for Correlated Spin-Noise Reduction
Igor Savukov and Young Jin Kim
Optical
quantum sensors based on alkali-metal atoms enable highly sensitive
magnetic-field measurements at room temperature. Their ultimate performance is limited by intrinsic
spin noise once technical noise sources are sufficiently suppressed. Reducing and characterizing this noise is therefore essential for improving sensor sensitivity and for investigating
quantum-enhanced sensing protocols. Here we investigate correlated
spin fluctuations in a
radio-frequency optical
quantum sensor based on a high-density potassium vapor
cell using a pulsed probe readout scheme. The system employs orthogonal pump and probe
laser beams, while a static
magnetic field defines the sensing frequency and synchronizes the probe pulses with the
spin precession. To detect weak
spin correlations, we implement a measurement protocol that combines periodic probing, phase cycling, and window-shifted acquisition. Phase cycling suppresses reproducible probe-induced coherent transients, while subtraction of temporally correlated signals acquired within the
spin-relaxation time reduces the measured
spin-noise level. The observed noise reduction is consistent with temporal
spin correlations, including those expected in
spin-squeezing protocols, although the present measurements do not uniquely distinguish this interpretation from other correlated-noise mechanisms. The demonstrated measurement protocol provides a practical route toward operating warm-vapor optical
quantum sensors closer to their fundamental
spin-noise limit and may benefit
radio-frequency magnetometry and sensing of weak coherent signals, including emerging dark-matter detection schemes.
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Strongly Correlated Electrons
High-pressure phase transitions in the quantum spin liquid candidate Na2Co2TeO6 probed by Raman spectroscopy
Ihsan Ahmed Kolasseri, Maria Mei Ravnebæk, Subhadip Das et al. (+5 more)
The quasi-2D magnet Na2Co2TeO6 (NCTO) is a candidate for a Kitaev
Quantum Spin Liquid (KQSL) state. Pressure-tuning in such materials is of interest as a potential method to tune the Kitaev exchange interactions, which are strongly dependent on bond geometry. Here we report a Raman spectroscopic study of NCTO inside a diamond anvil
cell (DAC) with pressure applied up to 16.3 GPa. Based on the changes in the Raman modes, this pressure range is divided into three regions. The appearance and disappearance of several modes and changes in the polarization dependence of the representative modes, most prominently above 13.8 GPa, point to pressure-induced phase transitions in this material.
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All authors Ihsan Ahmed Kolasseri, Maria Mei Ravnebæk, Subhadip Das, Carl Jonas Linnemann, Haidong Zhou, Christian Frydendahl, Martin Bremholm, Yong P. Chen
Instrumentation and Methods for Astrophysics
A Singular Value Decomposition Framework for Jovian Radio Emissions from Parker Solar Probe
Evan Wille, Zack Li, Marc Pulupa et al. (+3 more)
Jovian decametric and hectometric
radio emissions provide critical insights into Jupiter's magnetospheric dynamics and its electrodynamic coupling with Io. Across 21 perihelion encounters since its first light in 2018, the Parker
Solar Probe mission has repeatedly recorded high-resolution
radio and
plasma wave data near closest approach, as a result serving as a long-term distant observer of the Jovian system. However, extracting these relatively faint planetary signals from the continuous
solar wind background presents a significant analytical challenge, as the data is routinely saturated by quasi-thermal
plasma noise, spacecraft instrumental interference, and
solar bursts. To overcome these observational barriers, we present a generalized empirical pipeline that utilizes Singular Value Decomposition coupled with a deterministic, dual-stage noise filtering process. By converting dynamic spectra into a periodic, phase-folded reference frame, this model isolates structured Jovian emissions from the
stochastic heliospheric background, demonstrating empirical Signal-to-Noise Ratio improvements of $1.54 \pm 0.11$ dB, reaching up to $3.32$ dB. Additionally, a secondary “Eigenfaces”
matrix factorization is applied to identify long-term global morphological trends and serve as a detection method for future Jovian emissions. This automated mathematical framework extracts transient planetary signals without relying on localized spatial constraints, establishing the viability of PSP as a Jovian
radio observatory.
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All authors Evan Wille, Zack Li, Marc Pulupa, Leon V.E. Koopmans, Philippe Zarka, Stuart Bale
Nuclear Experiment
Direct measurement of the in-medium $\eta^{\prime}$ mass spectrum through the $\gamma\gamma$ decay channel
Y. Matsumura, N. Muramatsu, T.A. Hashimoto et al. (+58 more)
We measured the invariant mass of the $\eta^{\prime}(958)$
meson through the $\eta^{\prime}\to\gamma\gamma$ decay channel to search for possible character change of $\eta^{\prime}$ in a
nuclear medium. The measured invariant-mass spectra were analyzed by fitting realistic spectral functions. An enhancement was observed in the lower tail of the $\eta^{\prime}$ mass peak for low-momentum ($P_{\gamma\gamma} < 1$~$\mathrm{GeV/c}$) events. Three statistical methods were applied to assess the significance of the enhancement. All methods yield a statistical significance above 3.7$\sigma$. The spectral fitting indicates a mass reduction of $57.5^{+~5.7}_{-27.8}$~$\mathrm{MeV/c}^{2}$. Our result provides the first evidence for an in-medium spectral modification of the $\eta^{\prime}$
meson obtained through a direct measurement of its invariant mass.
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All authors Y. Matsumura, N. Muramatsu, T.A. Hashimoto, M. Miyabe, H. Shimizu, A.O. Tokiyasu, J.K. Ahn, W.C. Chang, J.Y. Chen, M.L. Chu, S. Daté, T. Gogami, H. Hamano, Q.H. He, K. Hicks, T. Hiraiwa, Y. Honda, T. Hotta, Y. Inoue, T. Ishikawa, I. Jaegle, Y. Kasamatsu, H. Katsuragawa, S. Kido, R. Kobayakawa, Y. Kon, S. Masumoto, K. Mizutani, T.Z. Mo, T. Nakamura, T. Nakano, T. Nam, M. Niiyama, Y. Nozawa, Y. Ohashi, H. Ohnishi, T. Ohta, M. Okabe, K. Ozawa, C. Rangacharyulu, S.Y. Ryu, Y. Sada, T. Shibukawa, R. Shirai, K. Shiraishi, E.A. Strokovsky, Y. Sugaya, M. Sumihama, S. Suzuki, S. Tanaka, Y. Taniguchi, N. Tomida, Y. Tsuchikawa, T. Ueda, T.F. Wang, H. Yamazaki, R. Yamazaki, Y. Yanai, T. Yorita, C. Yoshida, M. Yosoi
Physics and Society
The complex relationship between anti-immigrant sentiment and exposure in the Netherlands
Benedikt Meylahn, Tommaso Giommoni, Mike Lees et al. (+1 more)
We study the relationship between exposure to immigrants and right-wing votes used as a proxy for anti-immigrant sentiment in the Netherlands. Exposure to immigrants is measured using a novel indicator, adapted from the residential segregation literature, applied to grid data available for the entire country at the aggregate level. Using the proxy of election results, we are able to study the entire voting population instead of a limited subset of panel respondents. In our cross-sectional study of the 2023 national election, we find that municipalities and neighbourhoods with greater exposure have less anti-immigrant sentiment. However, looking at the increase in right-wing vote share from the 2021 to the 2023 national elections, we find evidence of an “overexposure effect”, as this relationship reverses, and the areas that saw significant increases in migrants subsequently experienced an increase in right-wing votes. Furthermore, we see that at high levels of exposure, wealth (and inequality) plays an important role in the voting dynamics, indicating that relative deprivation theory may play a role.
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All authors Benedikt Meylahn, Tommaso Giommoni, Mike Lees, Alessandro Nai
Statistical Mechanics
Delta-Function Kicks are Optimal for Rapidly Driven Inertial Stochastic Systems
Steven Blaber
Optimal control helps guide our understanding of
stochastic thermodynamics, leading to universal properties and
geometric formulations. Among the initially surprising properties of optimal control, not only discrete jumps but delta function kicks have been shown to be necessary to minimize dissipation in specific example systems. Using a short-time approximation, I show that delta-function kicks are universally optimal for minimizing dissipation in inertial
stochastic systems, including active and
quantum dynamics under general constraints. Fundamentally stemming from basic kinematics, delta-function kicks are required to achieve linear scaling of work with short protocol durations compared to the quadratic scaling without the kicks. This implies a diverging (infinite) ratio of saved work in the short-time limit.
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High Energy Physics (Phenomenology)
Energy-independent neutrino dephasing from an ultralight axion-like background
B. A. Couto e Silva and B. L. Sánchez-Vega
We study
neutrino oscillations in an ultralight
axion-like particle (ALP) dark-matter background using a bottom-up derivative interaction for active
neutrinos. For couplings diagonal in the
neutrino mass basis, the leading relative phase is fixed by the difference of the ALP field between production and detection. More generally, an unresolved background multiplies each interference term by the characteristic function of this endpoint field difference. For a single fixed-amplitude coherent mode with uniformly sampled phase, the factor is $J_0(A_{ij})$. In the slow-flight and small-dephasing regimes, this result and a Gaussian virialized-
halo treatment agree at quadratic order and produce a leading $L^2E^0$ suppression. We identify the finite-exposure and coherence conditions under which the two statistical descriptions apply. As an application, we analytically map the energy-independent damping constraint derived from the first JUNO data onto the
flavor benchmark $g_2=g_3$. For a local ALP density of $0.4\mathrm{GeV}/\mathrm{cm}^3$, the low-mass plateau gives $|\Delta g_{21}|=|\Delta g_{31}|\lesssim0.90\mathrm{GeV}^{-1}$. This number is a baseline-matched EFT recast of the reference damping analysis. No specific ultraviolet completion is assumed.
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Optics
Single-Mode Control of High-Speed and Low-Threshold III-V/Si Quantum Dot Microring Lasers via Azimuthal Gratings
Xucheng Yang, Yingtao Hu, Eunso Shin et al. (+9 more)
Hybrid III-V/silicon
quantum-dot microring
lasers are compact, energy-efficient O-band sources, but their whispering-gallery cavities are inherently multimode and bidirectional, producing unstable mode hopping that is incompatible with dense wavelength-division multiplexing. We show that an azimuthal grating patterned into the silicon ring - a single lithographic degree of freedom - converts this multimode cavity into a wavelength-addressed, single-mode source. A coupled-mode analysis derives the angular-momentum selection rule from first principles and shows that the inner-wall corrugation replaces the degenerate counter-propagating pair with symmetric and anti-symmetric standing-wave supermodes of unequal radiative loss. At the second-order Bragg condition the anti-symmetric mode is
symmetry-protected, yielding a high-quality-factor state at exactly one azimuthal order; finite-element simulations confirm this and identify grating depth as the primary loss-engineering handle. Devices fabricated in-house on a 100 mm silicon-on-
insulator platform hold a single longitudinal order with a side-mode suppression ratio of 37.9 dB and continuous, hop-free tuning, while the emission wavelength stays fixed across a factor-of-two change in cavity loading, set lithographically rather than by the gain peak. Because the grating decouples the lasing wavelength from the
quantum-dot gain, the detuning becomes a mask-level design variable that sets the temperature of minimum threshold current, reaching 1.95 mA near 50 {\deg}C. Combined with side-mode suppression beyond 37 dB and multi-gigahertz direct modulation, these
lasers are practical building blocks for cascaded, wavelength-addressed transmitter arrays in data communication and co-packaged optics.
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All authors Xucheng Yang, Yingtao Hu, Eunso Shin, Antoine Descos, Yatiraj Ramanujam, Bassem Tossoun, Yuan Yuan, Geza Kurczveil, Jonathan Wierer, Ray Beausoleil, Di Liang, Stanley Cheung
Astrophysics of Galaxies
Tracing Galaxy Bias Through the Cosmic Web: The Role of Filaments
Constanza A. Soto-Suárez, Antonio D. Montero-Dorta, Daniela Galárraga-Espinosa et al. (+4 more)
The large-scale clustering of
galaxies depends not only on their internal properties but also on their location within the
cosmic web, which defines the anisotropic environments where
galaxies form and evolve. Filaments serve as bridges through which
galaxies and dark matter flow from low-density regions toward the highest-density nodes. In this work, we aim to map
galaxy bias, which quantifies how these tracers follow the underlying dark matter density field, through the
cosmic web, with a special emphasis on filaments. We look for dependencies on filament properties, such as length and density, and characterize the spatial variations of the large-scale bias along the filamentary spine. We applied the DisPerSE
algorithm to identify the
cosmic web in the TNG300 volume of the IllustrisTNG simulation. To measure large-scale
galaxy bias, we utilized an object-by-object
estimator, which provides advantages over standard
estimators. We find that
galaxies in node outskirts exhibit the highest large-scale bias values, reaching up to $\sim4$ times the values expected from theoretical models based on
halo mass alone. Low-mass red
galaxies in filaments and filament outskirts also display enhanced bias, which is strongly reduced after excluding
galaxies close to nodes. Together, these results suggest that proximity to massive nodes plays a central role in shaping environmental secondary bias. Furthermore,
galaxy bias decreases with filament length, from mean values of $1.4$ for short filaments to $-0.5$ for longer structures. This relation persists at fixed
halo mass and
galaxy color, and is not primarily driven by the average local
galaxy density of the filament. Finally, short filaments exhibit an approximately uniform longitudinal bias profile, whereas long filaments show an increase in normalized bias from $\sim0.85$ near the saddle point to $\sim1.06$ close to the node.
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All authors Constanza A. Soto-Suárez, Antonio D. Montero-Dorta, Daniela Galárraga-Espinosa, Ignacio G. Alfaro, Andrés Balaguera-Antolínez, Ravi K. Sheth, Pablo López
Fluid Dynamics
The Hidden Second Law of Thermodynamics behind the Boltzmann-Grad Limit
Zhaohua Wu
We show that the Boltzmann-Grad (BG) limit, $N\varepsilon^{d-1}=\alpha=\text{const}$, is not a neutral scaling condition but already encodes the Second Law of Thermodynamics, resolving Loschmidt's paradox. Newton's First Law is the bridge: applying the BG condition locally to two adjacent
cells at different temperatures, we decompose their
evolution into a free-streaming period $\delta t_f$, governed by inertia alone, during which molecules cross the interface ballistically and still carry their
cell of origin's velocity distribution; and a collisional adjustment period $\delta t_a$, governed by Newton's Second Law, during which the locally mixed, non-Gaussian population relaxes toward a new Gaussian
equilibrium. Using the one-dimensional Gaussian velocity distribution, we show that isotropy alone produces non-zero net molecular and momentum flux across the interface, directed from the warmer to the cooler
cell – the microscopic origin of the pressure gradient driving the system toward uniformity. Treating relaxation as a sum of random collisional increments, the Central Limit
Theorem fixes the collision count $n^*$ required for convergence, giving $\delta t_a \sim n^*\,\ell/\bar v$. This decomposition resolves Loschmidt's paradox: his reversal acts on a fixed, identifiable set of molecules, while the temperature field Boltzmann's equation tracks is carried by an ever-changing local population; the step relating the two – convergence under the Central Limit
Theorem – is itself a coarse-graining that discards microscopic information by construction, recoverable only at an unavoidable thermodynamic cost, by Landauer's principle. Temporal irreversibility is present from the moment the BG framework, and the coarse-graining it requires, are adopted – not generated during derivation.
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Chemical Physics
Visualizing and Quantifying Atomic Contributions to Raman Intensities governed by Spatially-Resolved Atomic Interferences
Marc Bröckel, Johannes Gierschner, Alfred J Meixner et al. (+1 more)
Raman spectroscopy is commonly reduced to molecular fingerprint sensing, neglecting Raman intensities. Atomic Raman intensity contributions trace Raman intensities back to their microscopic origin and act as local electronic structure descriptors; however, a both physical but intuitive framework is missing by now. Therefore, in this work, we combine the two main lines of decomposing Raman intensities: atomic Raman tensors and atomic Raman Intensity Densities (RIDs). The former are used to define atomic Raman intensities which quantify both the magnitude and the phase of each atom's contribution to the global Raman signal, demonstrating that weak Raman bands may arise from destructive interference of individually strong atomic contributions. The latter build on redefined atomic Raman Polarizability Densities, RPDs, and are defined in analogy to our atomic Raman intensities. They show how the motion of an individual atom modulates the polarizability of the entire molecule. Atomic RIDs thus show local interferences of different atomic contributions. They integrate to the atomic Raman intensities bridging the two main lines. Additional (atomic) Charge Density Differences (CDDs) extend the RIDs to electronic structure effects. Finally, we apply the methodology to experimental surface-enhanced Raman spectra of substituted 2-mercaptobenzothiazole derivatives and discuss substituent-induced Raman intensity changes. We show that such changes do not necessarily stem from globally altered polarizabilities but from changes in the relative phase of atomic contributions. However, this method is not limited to SERS but widely applicable to all kinds of Raman, SERS or picocavity TERS experiments offering a basis for atomically resolved investigations of molecular processes such as adsorption, catalysis, and chemical reactions
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All authors Marc Bröckel, Johannes Gierschner, Alfred J Meixner, Kai Braun
High Energy Physics (Phenomenology)
NuGlass: A Fast and Interactive 3D Visualization of Neutrino Oscillations
Chao Zhang
Neutrino oscillation phenomenology is usually communicated through two-dimensional projections (probability curves, oscillograms, and bi-probability plots), each of which flattens a function of many parameters (baseline, energy, matter density, mass ordering, and the CP-violating phase) onto a single static figure. We present NuGlass, an open-source, web-based application that renders six complementary, fully interactive 3D views of the same underlying three-
flavor evolution: an oscillogram surface, a bi-probability trajectory extruded along energy, a Bloch-sphere projection of the
quantum flavor state, a matter-eigenstate phasor decomposition of the oscillation amplitude, a
flavor-composition tube along the propagation baseline, and a worldline view that plots the probabilities against L/E and makes the matter-induced breaking of the
vacuum degeneracy visible. An oscillation channel switcher, experiment presets, and customizable animation controls are provided. NuGlass can be used both as a research exploration tool and as a public-engagement exhibit. The application runs entirely client-side and is deployed at https://czczc.github.io/nuglass/ .
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Soft Condensed Matter
Persistence length of short homopolymeric single-stranded DNA sequences in polyvalent cations
Balaka Mondal and D. Thirumalai
We used simulations of short single stranded DNA (ssDNA) homopolymers, based on the sequence dependent Three Interaction Site (TIS) model, to calculate the persistence length ($l_p$) in polyvalent cations. The TIS model accounts for stacking interactions and electrostatic interactions are treated using the Coulomb potential. We find that $l_p$ for $\mathrm{dT_{30}}$ (T is thymine) and $\mathrm{dA_{30}}$ (A is adenine) is quantitatively fit using $l_p = l_p^0 + \lambda \kappa^{-1}$ ($l_p^0$ is the bare persistence length, $\lambda$ is a dimensionless constant, and $\kappa$ is the inverse Debye length) in the divalent cations $\mathrm{Mg^{2+}}$ and $\mathrm{Ca^{2+}}$. The dependence of $l_p$ on $\kappa$ is surprising because it was derived for long flexible polyelectrolytes in which the charges interact via the Debye-Hückel potential. The $l_p^0$ values are 0.4 nm and 1.1 nm for polyT and polyA, respectively. Strikingly, $l_p$ is almost independent of the tetravalent spermine concentration. There is no clear theoretical explanation although simulations suggest that the number of spermine molecules that bind to the ssDNA saturates at a small value. A qualitative picture, based on the restrictions of access to the phosphate groups due to volume exclusion of the anisotropic structure of $\mathrm{Spm^{4+}}$, rationalizes the simulation results. The predicted dependence of $l_p$ in spermine awaits experimental test.
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Instrumentation and Methods for Astrophysics
Study of Vibrations at SOAR
Andrei Tokovinin
The 4.1-m Southern Astrophysics Research (SOAR)
telescope in Chile resembles larger optical
telescopes by its thin actively controlled primary mirror, built-in tip-tilt correction, lightweight structure, and adaptive optics (AO)
turbulence correction. The non-stationary vibration of the SOAR optical axis with a frequency of 50 Hz and an amplitude reaching 20-30 mas has been detected by the AO system, degrading the quality of optical speckle interferometric data. Accelerometers revealed that the 50 Hz tremor, driven by an external source, propagates within
telescope structure and is strongly amplified by the response of the fast tip-tilt mirror servo system, producing characteristic elliptical beam path. The AO system also evidenced periodic components at 47 Hz in the defocus (matching the frequency of fans in electronic racks and computers) and at ~65 Hz in the astigmatism. The latter is associated with structural resonances of the SOAR primary mirror support, apparently excited by the wind. Periodic tracking errors with typical frequencies of 0.5-2.5 Hz are mostly caused by periodic errors of the encoders, depending on their
alignment, and can be amplified by the mount servo at fast tracking rates. Vibration characterization at SOAR informs similar studies at other
telescopes.
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Astrophysics of Galaxies
To be lensed or not to be lensed: on the nature of the alleged high-z lensed quasars J0109-5424 and P170+20
Aurora Mata-Sanchez, Emanuele P. Farina, Anniek J. Gloudemans et al. (+17 more)
We present a detailed multi-wavelength analysis of two gravitationally lensed z>6
quasar candidates: J0109-5424 and P170+20. Using JWST/NIRSpec near-infrared data from the Aether survey, we demonstrate that J0109-5424 is in fact a FeLoBAL
quasar at z=2.07, exhibiting strong iron broad absorption lines that mimic the Lyman break. From the Pabeta emission line, we estimate a black hole mass of 3.9 x 10^8 Msun and a bolometric luminosity of Lbol = 7.7 x 10^45 erg/s for this
quasar. Follow-up HST/ACS WFC imaging of P170+20 with the F555W filter, probing emission below the Lyman limit of the
quasar, reveals a compact source located 0.09+/-0.04 arcsec from the
quasar position. PSF modelling and subtraction yield no evidence for extended emission. This is inconsistent with a foreground
galaxy acting as a lens. Furthermore, we obtain Gemini-South/Flamingos 2 near-infrared observations to complement the existing optical Gemini-North/GMOS spectrum of P170+20. Our spectral analysis shows that the observed spectral shape of P170+20 is consistent with a composite
quasar and M-
dwarf spectrum. However, this interpretation remains uncertain, as a chance
alignment between an ultracool
dwarf and a
quasar within 0.1 arcsec would be unlikely. Overall, our findings establish J0109-5424 as an intermediate
redshift source and do not favor the lensed nature of P170+20, although this possibility cannot be conclusively ruled out, highlighting the challenges of selecting lensed
quasars at high
redshift.
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All authors Aurora Mata-Sanchez, Emanuele P. Farina, Anniek J. Gloudemans, Debora Pelliccia, Roberto Decarli, Eduardo Banados, Silvia Belladitta, Manuela Bischetti, Sarah E. Bosman, Xander Byrne, Thomas Connor, Frederick B. Davies, Thales A. Gutcke, Weizhe Liu, Chiara Mazzucchelli, Romain A. Meyer, Silvia Onorato, Fabian Walter, Feige Wang, Jinyi Yang
Quantum Physics
A Unified Framework for Operator Backpropagation and Observable Measurement in Quantum Computing
Kevin Dougherty and Ji Liu
Decoherence imposes severe limits on
quantum circuit depth, motivating methods to reduce
circuit depth. Operator backpropagation has recently been proposed as a way to lower
circuit depth by classically backpropagating observables through subcircuits. While it lowers the
circuit depth, it also significantly increases the number of backpropagated observables that must be measured. This calls for an efficient measurement protocol tailored to these backpropagated observables. Moreover, errors arise both during the backpropagation procedure and during measurement, and they accumulate in the final computation. No prior work has examined how to integrate operator backpropagation with advanced measurement protocols, and how to jointly optimize the combined process. In this paper, we introduce a comprehensive framework to determine the appropriate measurement protocol to achieve a desired level of accuracy with the fewest number of measurements based on the number of
qubit-wise commuting (QWC) groups formed from operator backpropagation. We analyze and categorize the primary sources of error that arise through our workflow, including error incurred from the backpropagation
algorithm, truncation error, and shot noise variation. We also examine truncation strategies to reduce the number of backpropagated observables by characterizing the structure of the set of backpropagated observables.
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Computational Physics
Rapidly Convergent Finite-Element Domain Decomposition Method With Two-Channel Transmission Conditions
Furkan Ş{\i}k, Fernando L. Teixeira and Balasubramaniam Shanker
A novel dual-primal finite element tearing and interconnecting (FETI-DP) domain decomposition method (DDM) is introduced for solving Maxwell's equations. The proposed method is built upon a two-channel transmission condition (TC) enforcing both tangential-field and normal-flux continuity across subdomain interfaces. Two interface channels are separately constructed from the Faraday and Ampere-Maxwell equations. Simultaneously enforcing tangential-field and normal-flux continuity reduces interface jumps by several orders of magnitude relative to the widely used Robin TC. The resulting global interface equation exhibits markedly improved iterative convergence. Numerical experiments across different partitioning strategies, subdomain counts and volumes, mesh resolutions, and geometries demonstrate drastic reductions in iteration counts, while accuracy, massive parallelism, and scalability are preserved.
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Other Condensed Matter
Raman magnon spectroscopy of local interactions and ground state selection in $\mathrm{Sr_2IrO_4}$
Xiang Li, Scott E. Cooper, Ahmed E. Fahmy et al. (+7 more)
Competing and coupled
spin and charge interactions in
quantum materials lead to a variety of ordered states where local configurations preferentially influence the long-range order. When these interactions are finely balanced in energy, disorder and fluctuations play an outsized role. Raman scattering is particularly well-suited to revealing the underlying physics in such situations because of its sensitivity to local environments and ability to reveal overall
symmetries. We perform angle-resolved Raman polarization measurements on single
crystals of the correlated, layered magnet, \ce{Sr2IrO4}, where the Mott insulating ground state arises from strong
spin-orbit coupling. We characterize the
symmetries of both the
phonon and
magnon modes through comprehensive measurements in both the $ab$-plane and out-of-plane geometries from 10 to 700 cm$^{-1}$, and trace the
evolution of these modes in both configurations to 12 GPa in a diamond anvil
cell with perforated diamonds. Pressure does not significantly alter the
lattice as the
phonon modes shift linearly under compression, but at the same time the
magnon modes become position dependent and spread over a range of wavenumbers. We attribute this
magnetic heterogeneity to pressure-enhanced variations in the weak interlayer interactions, which may locally favor competing
magnetic stacking configurations, and compare our experimental results to the predictions of linear
spin wave calculations. Our results demonstrate that Raman-active
magnons amplify $\mu$eV-scale interactions responsible for ground-state selection into easily measurable spectral changes.
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All authors Xiang Li, Scott E. Cooper, Ahmed E. Fahmy, Yuan-Ming Lu, A. de la Torre, R.S. Perry, D. Hsieh, T.F. Rosenbaum, Yejun Feng, D. M. Silevitch
Earth and Planetary Astrophysics
Tidal Demise: The Evolution and Fate of a Hypothetical Venus Moon
Stephen R. Kane, Franck Selsis, Jeremy Leconte et al. (+1 more)
Venus possesses no natural satellite, raising the question whether a formed moon could have survived. We explore the
tidal evolution of a Venus-moon system, coupling Venus's
spin to the satellite's orbit under tides from the moon and Sun. We survey
spin period ($P_0 = 5$–100~hr), moon mass ($M_m = 0.01$–$10~M_{\rm Moon}$), eccentricity, quality factor, and initial semi-major axis under both constant-$Q$ and constant time lag models. Survival depends on competition between outward migration ($\propto M_m$) and synchronous radius expansion ($\propto M_m^2$): for circular orbits around rapidly spinning Venus ($P_0 \lesssim 12$~hr), a lunar-mass satellite survives the age of the
Solar System in both models. For $P_0 \lesssim 10$~hr, eccentricity pumping can destabilize low-mass satellites, while for $P_0 \gtrsim 15$~hr or $M_m \gtrsim 2~M_{\rm Moon}$ the synchronous radius overtakes the orbit and drives Roche destruction within $\sim$0.03–1.7~Gyr in the constant-$Q$ model. The constant time lag model instead permits quasi-synchronous survival for massive moons at fast
spin. Explaining Venus's present state requires satisfying two constraints simultaneously: loss of the satellite and despinning of an initially rapid rotator. Both are met only within a restricted region of parameter space, favoring moderate post-impact
spin periods and lunar-to-super-lunar masses.
Giant impact simulations predict
spin periods $\gtrsim$12~hr for Venus's present rotation, placing a lunar-mass satellite at the survival boundary. For last-impact conditions within this region, the present absence of a Venusian satellite arises through
tidal evolution alone; a subsequent catastrophic stripping event, while capable of removing a moon, is not required.
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All authors Stephen R. Kane, Franck Selsis, Jeremy Leconte, Sean N. Raymond
Earth and Planetary Astrophysics
Kepler-50: Two Planets in Close Resonance Perturbed by a Non-transiting Planet
Daniel Jontof-Hutter, Jason F. Rowe, Jack J. Lissauer et al. (+1 more)
Kepler-50 has two transiting
planets close to the 6:5 commensurability. We analyze transit times measured from Kepler data with dynamical fits. We attribute the residual signal to a near-resonance non-transiting third
planet in the system. The parameters of the third
planet are degenerate. We identified 55 (15) regions of interest for an exterior (interior) perturber, and characterize system parameters in each region of interest with posterior sampling. We find that removing samples that are not long-term stable provides few additional constraints on posteriors, and that the transit times do not confirm the likely 2-body resonant state of the transiting
planets as $\approx$ 68% of posterior samples that are likely stable are also likely in libration. We identify a small fraction of samples that are in 3-body libration. Despite the degeneracies, we recover robust, tightly constrained masses for Kepler-50 b and c ($2.35^{+0.48}_{-0.43}$ $M_{\oplus}$ and $4.43^{+0.45}_{-0.49}$ $M_{\oplus}$, respectively) and strongly detected non-zero relative eccentricity for Kepler-50 b and c with ($e_c\cos\varpi_c$ - $e_b\cos\varpi_b$) = -0.045 $\pm 0.003$, and ($e_c\sin\varpi_c$ - $e_b\sin\varpi_b$) = -0.030 $\pm 0.004$. These close neighbors are in the radius valley and sub-Neptune by size, respectively ($1.750 \pm 0.038$ $R_{\oplus}$ and $2.079 \pm 0.060$ $R_{\oplus}$). With one of the closest
planet pairs known and one of the closest to first-order commensurability, the Kepler-50 system is an especially valuable
benchmark for
planet formation theory.
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All authors Daniel Jontof-Hutter, Jason F. Rowe, Jack J. Lissauer, Daniel C. Fabrycky
Cosmology and Nongalactic Astrophysics
Cosmic topology. Part Va. Information content of the observable Universe
Deyan P. Mihaylov, Mikel Martin Barandiaran, Stefano Anselmi et al. (+14 more)
If the Universe possesses a compact spatial
topology with characteristic scale not much larger than the diameter of the observable Universe, then the associated
symmetry transformations imprint specific statistical correlations on density perturbations. We derive the covariance between perturbation modes in the full
topology volume and compute the induced covariance between modes in the observable subvolume. We then use this covariance to estimate the available information about
topology contained in the full set of observable linear perturbations. For two sample Euclidean examples - the cubic three-
torus ($E_1$) and a three-
torus with a quarter turn ($E_3$) - the three-dimensional density field carries enough information to detect
topology on scales up to 25 percent larger than those accessible from the two-dimensional
cosmic microwave background anisotropies alone. Future probes of the
cosmic density field using deep
galaxy surveys or neutral-hydrogen 21-cm intensity mapping, combined with computationally intensive searches over the large parameter space of admissible
topologies, thus offer a plausible avenue to extending the range of detectable
cosmic topologies.
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All authors Deyan P. Mihaylov, Mikel Martin Barandiaran, Stefano Anselmi, Javier Carron Duque, Glenn D. Starkman, Yashar Akrami, Craig J. Copi, Andrew H. Jaffe, Arthur Kosowsky, James B. Mertens, Anna Negro, George Alestas, Ricardo G. Rodrigues, Thiago S. Pereira, Amirhossein Samandar, Andrius Tamosiunas, Cynthia Trendafilova