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Physics Physics

physics Watch Physics

Friday 24 October

Data Analysis and Statistics · Cross-listed from astro-ph.CO

Analytic Marginalization over Binary Variables in Physics Data

Marcus Högås and Edvard Mörtsell

In many data analyses, each measurement may come with a simple yes/no correction; for example, belonging to one of two populations or being contaminated or not. Ignoring such binary effects may bias the results, while accounting for them explicitly quickly becomes infeasible as each of the $N$ data points introduces an additional parameter, resulting in an exponentially growing number of possible configurations ($2^N$). We show that, under generic conditions, an exact treatment of these binary corrections leads to a mathematical form identical to the well-known Ising model from statistical physics. This connection opens up a powerful set of tools developed for the Ising model, enabling fast and accurate likelihood calculations. We present efficient approximation schemes with minimal computational cost and demonstrate their effectiveness in applications, including Type Ia supernova calibration, where we show that the uncertainty in host-galaxy mass classification has negligible impact on the inferred value of the Hubble constant.
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Instrumentation and Detectors

Evaluation of SiC detector performances for energy and timing measurements

N.S. Martorana, G. D'Agata, A. Barbon et al. (+24 more)

The development of new detectors based on Silicon Carbide (SiC) is currently a topic of interest within the scientific community. The significant features of SiC make it highly promising for detecting charged particles, neutrons, and $\gamma$/X radiation. In this framework, within the SAMOTHRACE (Sicilian Micro and Nano Technology Research and Innovation Center) ecosystem, an array of new-generation SiC detectors is under development, specifically designed for nuclear and medical investigations using radioactive ion beams. This paper describes the results obtained in the characterization of SiC prototypes regarding energy and timing measurements. A new method, based on coincidence data analysis, is employed to evaluate the timing performances of SiC detectors. The obtained results have been compared with tests performed using a micro-channel plate as a start detector reference for timing measurements.
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All authors N.S. Martorana, G. D'Agata, A. Barbon, G. Cardella, E. De Filippo, E. Geraci, C. Guazzoni, L. Acosta, C. Altana, A. Castoldi, A. Composto, S. De Luca, P. Figuera, B. Gnoffo, F. La Via, C. Maiolino, E.V. Pagano, S. Pirrone, G. Politi, L. Quattrocchi, F. Risitano, F. Rizzo, P. Russotto, G. Sapienza, M. Trimarchi, S. Tudisco, C. Zagami

Biological Physics

Les Houches Lectures on Flow Networks in Biology

Swarnavo Basu and Karen Alim

Flows are essential to transport resources over large distances. As soon as diffusion becomes time-limiting, flows are needed. Flows are key for the function of multiple human organs, from the blood vasculature to the lungs, the digestive tract, the lymphatic system, and many more. While physics governs the flow dynamics, biology's response to flows governs the flow network architecture. We start with the fluid physics of Stokes flow, the prerequisite to describe the flows in biological flow networks. Then we explore how the network adaptation dynamics of biological flow networks reorganize network architecture to minimize flow dissipation or homogenize transport, storing memories of past flows along the way.
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Physics and Society

Butterfly: glo-cal effects of data, energy and industry, New Media and Performance Exhibition Catalogue

Rebekah Rousi, Toija Cinque, Katey O'Sullivan et al. (+3 more)

The exhibition Butterfly: Glo-cal Effects of Data, Energy, and Industry is, at its core, a meditation on entanglement-between the global and the local, the ecological and the digital, the material and the virtual. It asks how we might reframe the infrastructures that shape our lives not only as technologies of efficiency or convenience, but as ecosystems themselves: dynamic, interdependent, and in need of care. It emerges from a prior exhibition, EcoDigital Futures, presented as part of Melbourne Design Week 2024, an Australian initiative of Creative Victoria and the National Gallery of Australia. That landmark exhibition spotlighted the growing imperative to align our digital futures with ecological sensibilities. Butterfly carries forward this vision, but also intensifies it by shifting the focus from speculation to activation, from theory to lived intervention.
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All authors Rebekah Rousi, Toija Cinque, Katey O'Sullivan, Aska Mayer, Esteban Guerrero Rosero, Elina Melgin

Data Analysis and Statistics · Cross-listed from stat.ML

Bridging Prediction and Attribution: Identifying Forward and Backward Causal Influence Ranges Using Assimilative Causal Inference

Marios Andreou and Nan Chen

Causal inference identifies cause-and-effect relationships between variables. While traditional approaches rely on data to reveal causal links, a recently developed method, assimilative causal inference (ACI), integrates observations with dynamical models. It utilizes Bayesian data assimilation to trace causes back from observed effects by quantifying the reduction in uncertainty. ACI advances the detection of instantaneous causal relationships and the intermittent reversal of causal roles over time. Beyond identifying causal connections, an equally important challenge is determining the associated causal influence range (CIR), indicating when causal influences emerged and for how long they persist. In this paper, ACI is employed to develop mathematically rigorous formulations of both forward and backward CIRs at each time. The forward CIR quantifies the temporal impact of a cause, while the backward CIR traces the onset of triggers for an observed effect, thus characterizing causal predictability and attribution of outcomes at each transient phase, respectively. Objective and robust metrics for both CIRs are introduced, eliminating the need for empirical thresholds. Computationally efficient approximation algorithms to compute CIRs are developed, which facilitate the use of closed-form expressions for a broad class of nonlinear dynamical systems. Numerical simulations demonstrate how this forward and backward CIR framework provides new possibilities for probing complex dynamical systems. It advances the study of bifurcation-driven and noise-induced tipping points in Earth systems, investigates the impact from resolving the interfering variables when determining the influence ranges, and elucidates atmospheric blocking mechanisms in the equatorial region. These results have direct implications for science, policy, and decision-making.
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2510.21889 · 24 Oct · 66 pages (Main Text pp. 3–36; Appendix pp. 36–57), 11 figures (1 Graphical Abstract, 8 in Main Text, 2 in Appendix). Submitted for peer-review to Physica D: Nonlinear Phenomena. The MATLAB code used in the analyses and to generate the figures in this work can be found in https://github.com/marandmath/FBCIR_code . For further details visit https://mariosandreou.short.gy/FBCIR

Abstract PDF $ALGO ×1$BAYS ×1

Atomic Physics · Cross-listed from quant-ph

Fundamental impossibility of a superradiant neutrino laser

Yu-Kun Lu, Hanzhen Lin and Wolfgang Ketterle

Here we address the fundamental question of whether an idealized system of $N$ atoms will show collective behavior and superradiance when it emits fermions instead of photons. We show that for single-fermion emission processes, the maximum emission is $\propto N$ and not $\propto N^2$, which proves the absence of superradiance and shows that the recent proposal to realize a superradiant neutrino laser is impossible. This can be understood as either destructive interference of fermionic transition amplitudes, or Pauli blockade by collective excitations with fermionic nature. We derive the exact solution of the fermionic Dicke problem and analyze the decay dynamics in various regimes. We extend the proof to arbitrary Hamiltonians and show that the jump rate operator for neutrino emission has a maximum eigenvalue of $N$ times the single-particle rate $\Gamma_0$. States with low excitation can show collective behavior and emit at a rate of $N \Gamma_0$.
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Atomic Physics · Cross-listed from quant-ph

Can Bose-Einstein condensates enhance radioactive decay?

Hanzhen Lin, Yukun Lu and Wolfgang Ketterle

This paper lays out the principles of how Bose-Einstein condensates can modify radioactive decay. We highlight the challenges of many modes and short coherence times due to the $\approx$ MeV energies of the emitted radiation. Recent proposals for gamma ray and neutrino lasers claim that using a Bose-Einstein condensate as a source would solve these issues. We show that this is not the case, and the proposed experiments would have a gain of only $10^{-16}$ or smaller. We also analyze proposals for gamma ray lasers based on stimulated annihilation of positronium Bose-Einstein condensates.
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Computational Physics

Reduced Floating-Point Precision Implicit Monte Carlo

Simon Butson, Mathew Cleveland, Alex Long et al. (+1 more)

This work demonstrates algorithms to accurately compute solutions to thermal radiation transport problems using a reduced floating-point precision implementation of the Implicit Monte Carlo method. Several techniques falling into the categories of arithmetic manipulations and scaling methods are evaluated for their ability to improve the accuracy of reduced-precision computations. The results for half- and double-precision implementations of various thermal radiation benchmark problems are compared.
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All authors Simon Butson, Mathew Cleveland, Alex Long, Todd Palmer

Physics and Society

Mapping Responsibility Attribution in the Grenfell Tower Inquiry: A Network Analysis

Mariano Devoto and Pablo Ariel Cipriotti

After major disasters, formal inquiries become arenas where responsibility is publicly contested. While extensive research has examined blame attribution through qualitative and actor-centred approaches, the relational structure of blame within formal accountability processes remains poorly understood. Using evidence from the Grenfell Tower Inquiry, this study analyses the web of blame presented during the Phase 2 closing proceedings, in which Counsel to the Inquiry synthesised how core participants publicly attributed responsibility to one another. We represent this synthesis as a directed network and examine its structural properties using standard tools from network analysis. The resulting configuration is interconnected, with pronounced reciprocity and local clustering, indicating that responsibility claims were articulated within a dense institutional environment rather than as isolated, one-to-one accusations. Comparisons with neutral benchmark models show that several observed features depart from expectations based on simple structural constraints alone, revealing patterned organisation in the public articulation of blame within the Inquiry. By applying network-analytic methods to an institutionalised representation of blame attribution, this study provides a systematic structural account of responsibility relations in a major public inquiry. The findings contribute to research on crisis governance and blame avoidance by demonstrating how accountability processes generate patterned distributions of responsibility that reflect institutional arrangements and governance contexts.
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Atmospheric and Oceanic Physics · Cross-listed from astro-ph.EP

Mechanisms of Superrotation in Slowly-Rotating and Tidally-Locked Planets

Quentin Nicolas and Geoffrey K. Vallis

Superrotation is a common feature of quickly rotating gas giants, slowly rotating planetary bodies, and tidally-locked planets. In this paper we compare and contrast the mechanisms of superrotation in slow rotators and tidally-locked planets. We cover a wide range of planetary properties, varying in particular the thermal Rossby number Ro_T (controlled by planetary size, rotation rate, and instellation) and a radiative relaxation timescale T_rad (which parameterizes atmospheric optical thickness). We use a two-level model that contains the principal mechanisms for superrotation in both regimes yet remains analytically tractable. Linearizations of the model elucidate the behavior of superrotation-inducing eddies. In tidally-locked planets a Matsuno-Gill-like structure organizes the eddy effects but of itself is insufficient to produce superrotation; baroclinicity and low-level drag are additional essential ingredients. Nonlinear integrations further explore the superrotating regimes and exhibit significant time variability even in statistical equilibrium. Not all tidally-locked regimes superrotate: subrotation arises at high T_rad (optically thick atmospheres) and weak low-level drag. On axisymmetrically-forced slow rotators, superrotation is always linked to a previously identified Rossby-Kelvin instability. Perhaps surprisingly, the instability itself is also linked to the spinup of superrotation in some tidally-locked regimes. Finally, we explore the continuous transition in the mechanisms of superrotation from axisymmetrically-forced to tidally-locked planets by applying a progressively stronger asymmetric equatorial forcing. The Matsuno-Gill pattern quickly dominates over traveling planetary Rossby-Kelvin waves in forcing superrotation, although both mechanisms can coexist. These results provide a unified view of superrotation mechanisms across a wide range of planetary bodies.
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Plasma Physics

Constructing Field Aligned Coordinate Systems for Gyrokinetic Simulations of Tokamaks in X-point Geometries

Akash Shukla, Ammar Hakim, James Juno et al. (+2 more)

Structures in tokamak plasmas are elongated along the direction of the magnetic field and short in the directions perpendicular to the magnetic field. Many tokamak simulation codes take advantage of this by using a field aligned coordinate system. However, field aligned coordinate systems have a coordinate singularity at magnetic X-points where the poloidal magnetic field vanishes, which makes it difficult to use field aligned coordinate systems when simulating the core and scrape-off layer (SOL) simultaneously. Here we present an algorithm for computing geometric quantities in a standard field aligned coordinate system that avoids the singularity and allows one to conduct 2D axisymmetric simulations in X-point geometries. We demonstrate the efficacy of this algorithm with an example simulation of the Spherical Tokamak for Energy Production (STEP).
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All authors Akash Shukla, Ammar Hakim, James Juno, Gregory Hammett, Manaure Francisquez

Plasma Physics

Counter-Streaming Beams in Collisionless Pair Plasma Instability Systems III: Collisionless Heating, Acceleration, and Radiation

Michael C. Sitarz

Energetic astrophysical phenomena, such as $\gamma$-ray bursts and supernova explosion-driven shocks in collisionless plasmas, involve various plasma kinetic instabilities, such as the Weibel instability. These systems support various types of particle acceleration and radiation through a variety of mechanisms. In this paper, we explore the energy transformations and dynamical effects of violent filament mergers seen between the large current filaments formed by the Weibel instability. The radiative processes involved in the Weibel instability filament building are also discussed in relation to jitter and synchrotron radiation.
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Plasma Physics

Counter-Streaming Beams in Collisionless Pair Plasma Instability Systems II: Spectral Cone and Spectral Wave Mode Analysis

Michael C. Sitarz

Energetic astrophysical phenomena, such as $\gamma$-ray bursts, supernova explosions, and magnetar flares occur in collisionless plasmas and involve various plasma kinetic and magnetohydrodynamic instabilities. In this paper, we explore the spectral trends of the Weibel instability using spectral analysis of particle-in-cell simulations. Power dependence on viewing angle and frequency are explored and the relation to the results of the first paper in this series is discussed.
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Atomic Physics

RydIQule Version 2: Enhancing graph-based modeling of Rydberg atoms

Benjamin N. Miller, David H. Meyer, Carter A. Montag et al. (+4 more)

Rydberg atomic radio-frequency (rf) sensors are an emerging technology platform that relies on vaporous atoms, interrogated with laser beams and nearly ionized, to receive rf signals. Rydberg rf sensors have a number of interesting fundamental distinctions from traditional receiver technologies, such as those based on metallic antennas, since they are governed by the quantum physics of atom-light interactions. As Rydberg sensors quickly advance from laboratory experiments into fieldable devices, there is a need for a general software modeling tool that fully encompasses the internal physics of the sensor. The Rydberg Interactive Quantum Module (RydIQule) is a Python package designed to fill this need. The initial public release of RydIQule in late 2023 built the core functionality described above. Here we outline RydIQule's version 2 release which expands on its capabilities to more accurately model real-world atoms.
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All authors Benjamin N. Miller, David H. Meyer, Carter A. Montag, Omar Nagib, Teemu Virtanen, Peter K. Elgee, Kevin C. Cox

Atomic Physics

Observation of spin singlet butterfly Rydberg molecules in an ultracold atomic Rb gas

Markus Exner, Rohan Srikumar, Richard Blättner et al. (+4 more)

We report the observation of spin-singlet ultra-long range Rydberg butterfly molecules consisting of a ground-state atom bound to a Rydberg atom by $P$-wave scattering of $^{87}$Rb Rydberg electrons from $^{87}$Rb(5s) atoms. A three-photon excitation scheme enables the photoassociation of these molecules by weakly admixing Rb($18f_{7/2}$) states. The measured binding energies, kilo-Debye permanent electric dipole moments, and lifetimes are in excellent agreement with theory. Two long-lived vibrational levels, red detuned from the Rb($18f_{7/2}$) threshold, are observed. This experiment is a foundational step in the production of ultra-cold anions and heavy Rydberg ion-pair systems.
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All authors Markus Exner, Rohan Srikumar, Richard Blättner, Peter Schmelcher, H. R. Sadeghpour, Matthew T. Eiles, Herwig Ott

Optics

Wide-field stroboscopic imaging of topologically protected phononic modes

Ilia Chernobrovkin, Maurice Debray, Frederik Holst Knudsen et al. (+5 more)

Imaging spatial mode profiles is important for understanding the behavior of mechanical resonators. The recent development of phononic circuits has increased the demand for a fast imaging method based on principles of coherent detection. However, it becomes complicated to perform measurements on a large surface area. Here, we present a frequency-detuned collimated-beam interferometry measurement scheme with in-plane spatial resolution of about 6 um, which can provide information about the phase dynamics of the entire mechanical oscillation cycle on a time scale of a few seconds. We employ a stroboscopic pulse probing method to resolve high-frequency vibrational motion with a standard CMOS camera. We use this setup to image megahertz frequency resonant mode profiles present in a Valley-Hall topological triangular cavity, over an area of more than 20 mm2. We relate the obtained data to numerical simulations of the topological edge modes to reveal the relation between backscattering and the mode profile distribution. The presented protocol can become a staple for characterizing mesoscopic mechanical resonators.
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All authors Ilia Chernobrovkin, Maurice Debray, Frederik Holst Knudsen, Thibault Capelle, Mads Bjerregaard Kristensen, Michael Pitts, Xiang Xi, Albert Schliesser

Applied Physics

Dose Constraints for High-Resolution Imaging of Biological Specimens with Extreme Ultraviolet and Soft X-ray radiation

Chang Liu, Leona Licht and Jan Rothhardt

We present a theoretical evaluation of radiation dose constraints for extreme ultraviolet (EUV) and soft X-ray microscopy. Our work particularly addresses the long-standing concern regarding strong absorption of EUV radiation in biological specimens. Using an established dose-resolution model, we compare hydrated and dehydrated cellular states and quantify the fluence required for nanoscale imaging. Our analysis identifies a protein window spanning photon energies from 70 eV up to the carbon K-edge (284 eV), where EUV microscopy could in principle achieve sub-10 nm half-pitch resolution in dehydrated samples at doses well below the Henderson limit, thereby eliminating the need for cryogenic conditions. In this situation, the radiation dose required for EUV imaging is also substantially lower than what is required for comparable resolution in water window soft X-ray microscopy. Furthermore, EUV photons with sufficiently high energy exhibit penetration depths of um-level in dehydrated biomatter, enabling exceptional amplitude and phase contrast through thin cellular regions and small cells. These findings provide quantitative guidelines for photon energy selection and establish the EUV protein window as a dose-efficient and physically viable modality for high-resolution, label-free, material-specific imaging of dehydrated biological matter.
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Optics

Chip-scale modulation-free laser stabilization using vacuum-gap micro-Fabry-Pérot cavity

Mohamad Hossein Idjadi, Haotian Cheng, Farshid Ashtiani et al. (+5 more)

Narrow-linewidth lasers are vital for a broad range of scientific and technological applications, including atomic clocks and precision sensing. Achieving high frequency stability is often as critical as ensuring scalability, portability, and cost-effectiveness in the development of low noise laser systems. Conventional electro-optic stabilization techniques, such as Pound-Drever-Hall locking to ultra-high-finesse resonators held in a vacuum chamber, provide excellent performance but remain challenging to scale. Here, we propose and experimentally demonstrate a cavity-coupled interferometric laser stabilization technique implemented on a silicon photonic chip and integrated with a compact, scalable micro-Fabry-Pérot cavity. The vacuum-gap optical cavity operates in air, achieving a quality factor of approximately $2.0\times 10^9$ and a fractional frequency instability of $1.45\times 10^{-12}$ at one-second averaging time. Integration of the proposed technique with the compact cavity yields more than 38-fold reduction in the laser's integrated linewidth and nearly three orders of magnitude suppression of frequency noise at 10 Hz offset frequency. The hybrid-integration of the proposed photonic chip with the micro-Fabry-Pérot cavity establishes a scalable and portable route toward chip-integrated ultra-stable lasers, paving the way for precision optical systems deployable beyond laboratory environments.
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All authors Mohamad Hossein Idjadi, Haotian Cheng, Farshid Ashtiani, Benjia Li, Kwangwoong Kim, Naijun Jin, Franklyn Quinlan, Peter T. Rakich

Biological Physics · Cross-listed from cond-mat.soft

Kinetic theory of emulsions with matter supply

Jacqueline Janssen, Frank Jülicher and Christoph A. Weber

In this work, we propose a theory for the kinetics of emulsions in which a continuous supply of matter feeds droplet growth. We consider cases where growth is either limited by bulk diffusion or the transport through the droplets' interfaces. Our theory extends the Lifshitz-Slyozov-Wagner (LSW) theory by two types of matter supply, where either the supersaturation is maintained or the supply rate is constant. In emulsions with maintained supersaturation, we find a decoupling of droplets at all times, with the droplet size distribution narrowing in the diffusion-limited regime and a drifting distribution of a fixed shape in the interface-resistance-limited case. In emulsions with a constant matter supply, there is a transition between narrowing and broadening in the diffusion-limited regime, and the distribution is non-universal. For the interface-resistance-limited regime, there is no transition to narrowing, and we find a universal law governing coarsening kinetics that is valid for any constant matter supply. The average radius evolves according to a power law that is independent of the matter supply, and we find a closed-form expression for the droplet size distribution function. Our theory is relevant to biological systems, such as biomolecular condensates in living cells, since droplet material is not conserved and the growth of small droplets is proposed to be interface-resistance-limited.
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Biological Physics · Cross-listed from cond-mat.soft

Swimming patterns of a multi-mode bacterial swimmer in fluid shear flow

Valeriia Muraveva, Agniva Datta, Jeungeun Park et al. (+5 more)

Bacterial swimming is well characterized in uniform liquids at rest. The natural habitat of bacterial swimmers, however, is often dominated by moving fluids and interfaces, resulting in shear flows that may strongly alter bacterial navigation strategies. Here, we study how fluid shear flow affects the swimming motility of the soil bacterium Pseudomonas putida, a bacterial swimmer that moves in a versatile pattern composed of three different swimming modes, where the flagella may push, pull, or wrap around the cell body (multi-mode swimmer). We introduce a computer automated cell tracking and swimming mode detection tool to show that shear induced alignment depends on the swimming mode, while motility and proximity to surfaces counteract the alignment effect. Moreover, filament wrapping becomes less efficient with increasing shear stress. Numerical simulations of realistic swimmer geometries complement our experimental results, providing more detailed mechanistic insights into movement patterns of bacterial swimmers in a shear flow.
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All authors Valeriia Muraveva, Agniva Datta, Jeungeun Park, Veronika Pfeifer, Yongsam Kim, Wanho Lee, Sookkyung Lim, Carsten Beta

Atmospheric and Oceanic Physics

Direct test for critical slowing down before Dansgaard-Oeschger events via the volcanic climate response

Johannes Lohmann

It is tested whether past abrupt climate changes support the validity of statistical early-warning signals (EWS) as predictor of future climate tipping points. EWS are expected increases in amplitude and correlation of fluctuations driven by noise. This is a symptom of critical slowing down (CSD), where a system's recovery from an external perturbation becomes slower as a tipping point (represented by a bifurcation) is approached. EWS are a simple, indirect measure of CSD, but subject to assumptions on the noise process and measurement stationarity that are hard to verify. In this work the existence of CSD before the Dansgaard-Oeschger (DO) events of the last glacial period is directly tested by inferring the climate's recovery from large volcanic eruptions. By averaging over hundreds of eruptions, a well-defined, stationary perturbation is constructed and the average climate response is measured by eight ice core proxies. As the abrupt DO warming transitions are approached, the climate response to eruptions remains the same, indicating no CSD. For the abrupt DO cooling transitions, however, some key proxies show evidence of larger climate response and slower recovery as the transitions are approached. By comparison, almost all proxies show statistical EWS before cooling and warming transitions, but with only weak confidence for the warming transitions. There is thus qualitative agreement of CSD and EWS, in that the evidence for bifurcation precursors is larger for the cooling transitions. However, the discrepancy that many proxies show EWS but no direct CSD (and vice versa) highlights that statistical EWS in individual observables need to be interpreted with care.
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Instrumentation and Detectors

TES Proton Irradiation Result Analysis for Future Space Applications

A. Besnard, V. Sauvage, S. L. Stever et al. (+8 more)

As observed on the signal of the Planck-HFI highly sensitive bolometers, the effect of cosmic rays on detectors is a major concern for future similar space missions. Their instruments will have a larger detection surface, increased sensitivity, and more stringent requirements on the suppression of systematic effects. To study the impact of cosmic rays on detector prototypes in operational conditions, IAS has designed a state-of-the-art cryogenic system to irradiate particles by coupling this facility to particle accelerators. An irradiation campaign has been carried out on LiteBIRD-HFT TES prototypes to study their response to particle hits. In this article, we present the results and the analysis of this first test campaign.
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All authors A. Besnard, V. Sauvage, S. L. Stever, B. Maffei, P. dal Bo, T. Lari, M. de Lucia, A. Tartari, G. Signorelli, J. Hubmayr, G. Jaehnig

Atmospheric and Oceanic Physics

Characterizing global tropical cyclone events of 2024

Lingke Jiang, G. Brooke Anderson, Yanran Li et al. (+3 more)

Full impact assessment of tropical cyclones each year requires a comprehensive sociodemographic analysis. We evaluated sociodemographic characteristics of tropical cyclone-impacted regions during the 2024 calendar year in recent historical context of 1980-2024. In 2024, tropical cyclone-force wind affected an estimated 429,902,820 people (5.5% of global population), and hurricane-force wind an estimated 59,672,600 people (0.8%). Our findings provide a global context for tropical cyclones to better guide resilience and recovery efforts.
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All authors Lingke Jiang, G. Brooke Anderson, Yanran Li, Xiao Wu, Victoria D. Lynch, Robbie M. Parks

Physics Education

Subatomic Heroes

Anshika Bansal, Guido Bell, Aritra Biswas et al. (+44 more)

Sharing the amazing achievements of the (particle) physics world with the general public is at the heart of the mission of the Subatomic Heroes, based at the University of Siegen, Germany. Originally this started out as an endeavor of theoretical particle physics, now we are steadily spreading out to cover and include more branches of physics and science. Our activities range from merging art with public physics lectures via marvelous artistic performances at the local theater, over dedicated events for high-school students, to our Subatomic Heroes channel on Instagram and TikTok where you may also find out when and where our famous "hadronic ice-cream" will be served next! So follow us on https://www.instagram.com/subatomic_heroes and https://www.tiktok.com/@subatomic_heroes.
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All authors Anshika Bansal, Guido Bell, Aritra Biswas, Diptaparna Biswas, Anastasia Boushmelev, Carsten Busse, Markus Cristinziani, Carmen Diez Pardos, Qader Dorosti, Sebastian Edelmann, Thorsten Feldmann, Ivor Fleck, Jan Hahn, Dennis Horstmann, Tobias Huber, Jack Jenkins, Wolfgang Kilian, Danny Koschwitz, Nils Krengel, Martin Lang, Björn Lange, Alexander Lenz, Eleftheria Malami, Thomas Mannel, Ilija Milutin, Ali Mohamed, Denise Müller, Jakob Müller, Marcus Niechciol, Jaime del Palacio Lirola, Chiara Papior, Arwen Pieck, Thomas Reppel, Markus Risse, Elisabeth Schopf, Noah Siegemund, Tobias Striegl, Gilberto Tetlalmatzi-Xolocotzi, Tom Tong, Jette Vedder, Katharina Voß, Daniel Vladimirov, Wolfgang Walkowiak, Oliver Witzel, Zachary Wüthrich, Christof Wunderlich, Michael Ziolkowski

Physics and Society

The dynamics of discovery and the Heaps-Zipf relationship

Célestin Zimmerlin, Thomas Louail, Manuel Moussallam et al. (+1 more)

When following a sequence - such as reading a text or tracking a user's activity - one can measure how the "dictionary" of distinct elements (types) grows with the number of observations (tokens). When this growth follows a power law, it is referred to as Heaps' law, a regularity often associated with Zipf's law and frequently used to characterize human discovery processes. While random sampling from a Zipf-like distribution can reproduce Heaps' law, this connection relies on the assumption of temporal independence - an assumption often violated in real-world systems although frequently found in the literature. Here, we investigate how temporal correlations in token sequences affect the type-token curve. In human behaviors like music listening and web browsing, domain-specific correlations in token ordering lead to systematic deviations from the Zipf-Heaps framework, effectively decoupling the type-token plot from the rank-frequency distribution. Using a minimal one-parameter model, we reproduce a wide variety of type-token trajectories, including the extremal cases that bound all possible behaviors compatible with a given frequency distribution. Our results demonstrate that type-token growth reflects not only the empirical distribution of type frequencies, but also the domain-specific, temporal structure of the sequence - a factor often overlooked in empirical applications of scaling laws to characterize human behavior.
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All authors Célestin Zimmerlin, Thomas Louail, Manuel Moussallam, Marc Barthelemy

Biological Physics · Cross-listed from cond-mat.soft

Probing and modeling cell-cell communication in 2D biomimetic tissues

Cécile Marie Vincent, Sapna Ravindran, Alexis Michel Prevost et al. (+3 more)

In tissues, cells in direct physical contact with each other can exchange ions or molecules via protein clusters called gap junctions that form channels across the membranes of adjacent cells. Here, we use a simplified biomimetic approach, coupled with theoretical modeling, to unravel the physical mechanisms controlling such transport. Tissues are mimicked with 2D hexagonal networks of monodisperse aqueous droplets connected by lipid membranes called Droplet Interface Bilayers (DIBs), decorated with $\alpha$-Hemolysin ($\alpha$HL) transmembrane proteins forming nanopores through heptamerization in the membrane. The diffusion of calcein across 2D DIB networks is thoroughly studied using epifluorescence microscopy at various $\alpha$HL concentrations. The results are successfully confronted with a Continuous Time Random Walk model in hexagonal networks, with an average waiting time increasing nonlinearly with the concentration of pore monomers.
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All authors Cécile Marie Vincent, Sapna Ravindran, Alexis Michel Prevost, Léa-Laetitia Pontani, Olivier Bénichou, Elie Wandersman

Fluid Dynamics

Statistics of near-inertial waves over a background flow via quantum and statistical mechanics

Alexandre Tlili and Basile Gallet

We revisit the interaction of an initially uniform near-inertial wave (NIW) field with a steady background flow, with the goal of predicting the subsequent organization of the wave field. To wit, we introduce an exact analogy between the Young Ben Jelloul (YBJ) equation and the quantum dynamics of a charged particle in a steady electromagnetic field, whose potentials are expressed in terms of the background flow. We derive the time-averaged spatial distributions of wave kinetic energy, potential energy and Stokes drift in two asymptotic limits. In the `strongly quantum' limit where the background flow is weak compared to wave dispersion, we compute the wave statistics by extending a strong-dispersion expansion initially introduced by YBJ. In the `quasi-classical' limit where the background flow is strong compared to wave dispersion, we compute the wave statistics by leveraging the equilibrium statistical mechanics of classical systems. We compare our predictions to numerical simulations of the YBJ equation, using an instantaneous snapshot from a two-dimensional turbulent flow as the steady background flow. The agreement is very good in both limits. In particular, we quantitatively describe the preferential concentration of NIW energy in anticyclones. We predict weak NIW concentration in both asymptotic limits of weak and strong background flow, and maximal anticyclonic concentration for background flows of intermediate strength, providing theoretical underpinning to observations reported by Danioux, Vanneste and Bühler (Journal of Fluid Mechanics, 773, 2015).
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Instrumentation and Detectors · Cross-listed from hep-ex

Constraints on ultraheavy dark matter from the CDEX-10 experiment at the China Jinping Underground Laboratory

Y. F. Wang, L. T. Yang, Q. Yue et al. (+85 more)

We report a search for ultraheavy dark matter (UHDM) with the CDEX-10 experiment at the China Jinping Underground Laboratory. Using a Monte Carlo framework that incorporates Earth shielding effects, we simulated UHDM propagation and energy deposition in p-type point-contact germanium detectors. Analysis of 205.4 kg$\cdot$day exposure in the 0.16–4.16 keVee range showed no excess above background. Our results exclude the spin-independent UHDM-nucleon scattering with two cross section scales, with the UHDM mass from $10^6$ to $10^{11}$ GeV, and provide the most stringent constraints with solid-state detectors below $10^8$ GeV.
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All authors Y. F. Wang, L. T. Yang, Q. Yue, K. J. Kang, Y. J. Li, H. P. An, Greeshma C., J. P. Chang, H. Chen, Y. H. Chen, J. P. Cheng, J. Y. Cui, W. H. Dai, Z. Deng, Y. X. Dong, C. H. Fang, H. Gong, Q. J. Guo, T. Guo, X. Y. Guo, L. He, J. R. He, H. X. Huang, T. C. Huang, S. Karmakar, Y. S. Lan, H. B. Li, H. Y. Li, J. M. Li, J. Li, M. C. Li, Q. Y. Li, R. M. J. Li, X. Q. Li, Y. L. Li, Y. F. Liang, B. Liao, F. K. Lin, S. T. Lin, J. X. Liu, R. Z. Liu, S. K. Liu, Y. D. Liu, Y. Liu, Y. Y. Liu, H. Ma, Y. C. Mao, A. Mureed, H. Pan, N. C. Qi, J. Ren, X. C. Ruan, M. B. Shen, H. Y. Shi, M. K. Singh, T. X. Sun, W. L. Sun, C. J. Tang, Y. Tian, H. F. Wan, G. F. Wang, J. Z. Wang, L. Wang, Q. Wang, Q. Wang, Y. X. Wang, H. T. Wong, Y. C. Wu, H. Y. Xing, K. Z. Xiong, R. Xu, Y. Xu, T. Xue, Y. L. Yan, N. Yi, C. X. Yu, H. J. Yu, X. Yu, M. Zeng, Z. Zeng, F. S. Zhang, P. Zhang, P. Zhang, Z. Y. Zhang, M. G. Zhao, J. F. Zhou, Z. Y. Zhou, J. J. Zhu

Optics · Cross-listed from quant-ph

3D micro-printing: An enabling technique for arbitrary potential landscapes for photonic quantum-gases

Julian Schulz, Kirankumar Karkihalli Umesh, Sven Enns et al. (+2 more)

Photonic quantum gases explore the physics of open driven-dissipative quantum systems under ambient conditions and thus open access to thermodynamics and transport phenomena in quantum gases in the weakly interacting regime. Here we introduce the technology of 3D micro-printing to create potential landscapes for photonic quantum gases in dye-filled micro cavities, which surpass the current state of the art in terms of potential size and definition, potential depth, coupling strength, and number of coupled potentials by at least an order of magnitude. We realize as demonstration of the capabilities box potentials with rectangular side walls, anisotropic harmonic potentials, double-well potentials with dimensions on the scale of the wavelength of light as well as potential lattices with topological non-trivial properties. This approach paves the way for experimentally studying the physics of open quantum systems on lattices and might find applications in solving complex ground-state problems like the XY-model.
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All authors Julian Schulz, Kirankumar Karkihalli Umesh, Sven Enns, Frank Vewinger, Georg von Freymann

Biological Physics

Spatial self-organization of enzymes in complex reaction networks

Vincent Ouazan-Reboul, Ramin Golestanian and Jaime Agudo-Canalejo

Living systems contain intricate biochemical networks whose structure is closely related to their function and allows them to exhibit robust behavior in the presence of external stimuli. Such networks typically involve catalytic enzymes, which can have non-trivial transport properties, in particular chemotaxis-like directed motion along gradients of substrates and products. Here, we find that taking into account enzyme chemotaxis in models of catalyzed reaction networks can lead to their spatial self-organization in a process similar to biomolecular condensate formation. We develop a general theory for arbitrary reaction networks, and systematically study all closed unimolecular reaction networks involving up to six chemicals. Importantly, we find that network-wide propagation of concentration perturbations can be key to enabling self-organization. The ability to self-organize is highly dependent on the relative signs of the chemotactic mobilities of the enzymes to their substrate and product and on the global network structure. We find that spontaneous self-organization through chemotaxis can provide an avenue for the self-regulation of metabolic activity in complex catalyzed reaction networks. The network-induced interaction mechanism we uncover operates in the regime where the substrate molecules are diffusion-limited, suggesting that signaling molecules could take advantage of this scenario towards their functionality.
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