High Energy Physics (Experiment)
A measurement of the Higgs boson mass in the diphoton decay channel in proton-proton collisions at $\sqrt{s}$ = 13 TeV
CMS Collaboration
A measurement of the
Higgs boson mass in the diphoton decay channel is performed using
proton-
proton collision data at a center-of-mass energy of 13 TeV. The data set recorded with the CMS detector between 2016 and 2018 is used, corresponding to an integrated luminosity of 138 fb$^{-1}$. A refined detector calibration and new analysis techniques are employed to improve the precision of the results compared to earlier measurements. The
Higgs boson mass is measured to be $m_\mathrm{H}$ = 125.13 $\pm$ 0.15 GeV = 125.13 $\pm$ 0.10 (stat) $\pm$ 0.12 (syst) GeV. In addition, a combination with the mass measurement at center-of-mass energies of 7 and 8 TeV in the diphoton final state is performed resulting in $m_\mathrm{H}$ = 125.06 $\pm$ 0.14 GeV = 125.06 $\pm$ 0.09 (stat) $\pm$ 0.11 (syst) GeV.
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Instrumentation and Methods for Astrophysics
Segment-level thermal sensitivity analysis for exo-Earth coronagraphy with segmented space telescopes
Ananya Sahoo, Laurent Pueyo, Iva Laginja et al. (+5 more)
Direct imaging and characterization of Earth-like
planets require ultra-stable wavefronts to achieve a starlight suppression level of 100 parts per trillion (ppt) in the coronagraphic dark region of the host
star. Thermal drifts in the
telescope may affect the wavefront stability. In this context, we present a segment-level thermal stability error budget for segmented space
telescopes crucial to Earth-like
planet detection and specify requirements for an ultra-stable
telescope. Our study utilizes multiple segmented primary mirror architectures, each with their respective apodizer solution developed by the Segmented Coronagraph Design & Analysis research team at the Space
Telescope Science Institute, tailored to an off-axis ~6 m-aperture space
telescope design. Using a detailed finite element model provided by L3Harris Technologies, we relate the temperature gradient at the location of the primary mirror to wavefront variations on each segment. We allocate both static and dynamic thermal tolerances for each segment using the Pair-based Analytical model for Segmented
Telescope Imaging from Space sensitivity approach, and a batch-estimation
algorithm respectively. Our analysis shows a non-uniform tolerance allocation across all segments of the primary mirror, as a result of apodization, and generally, with an increase in segment numbers, the tolerances for outer segments become less stringent. We observe trade-offs between segment size, tolerance relaxation and optimal wavefront sensing time to achieve a desired dark-hole contrast.
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All authors Ananya Sahoo, Laurent Pueyo, Iva Laginja, Bryony F. Nickson, Leonid Pogorelyuk, Laura E. Coyle, Rémi Soummer, Matthew East
Atomic Physics
Optical Dipole Trap for Hg Atoms
I. Nandi, A. Sahu, M. Veis et al. (+3 more)
We report the first realization of an optical dipole trap (ODT) for ultracold mercury atoms, overcoming the challenge posed by the exceptionally low polarizability of Hg and the resulting weak optical trapping potential. We demonstrate the transfer of six naturally abundant Hg isotopes from a magneto-optical trap (MOT) into the ODT and characterize its loading dynamics, trap depth, and lifetime. Confinement of dense samples of ultracold Hg opens new opportunities for studies of isotope-dependent collisions and photoassociation and provides a route toward
quantum degeneracy.
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All authors I. Nandi, A. Sahu, M. Veis, A. Linek, R. Ciurylo, M. Witkowski
Optics
Extreme sensitivity of nonlinear trajectories enhances optical spectral broadening
Jiachen Wang, Koorosh Sadri and Mikael C. Rechtsman
The generation of a wide spectrum of light in highly nonlinear optical fibers has broad application in spectroscopy, microscopy and medical imaging. To generate such a 'supercontinuum', an ultrashort pulse of light is injected into a highly nonlinear fiber. Then, in a process called self-phase modulation, the nonlinearity of the fiber causes the spectrum to start broadening as the pulse becomes chirped during propagation, seeding further cascaded nonlinear processes. The dynamics associated with supercontinuum generation are captured mathematically as a pulse profile evolving in time and occupying a single spatial mode. Here, we theoretically and experimentally demonstrate that a waveguide composed of multiple coupled cores - a photonic molecule' - rather than just a single core, gives rise to greater self-phase modulation for a given input power. This is perhaps counterintuitive because it may be naively expected that the strongest nonlinear effects would be achieved by concentrating all optical power in one waveguide. The increased broadening arises due to the extreme sensitivity of trajectories near a separatrix of the nonlinear dynamics. This sensitivity leads to a distortion of the temporal shape of the pulse, resulting in a broader spectrum. The effect is reminiscent of the sensitivity associated with exceptional points in coupled-resonator systems, but does not suffer in the same way from the parasitic effects of noise. This suggests that by including multiple cores, a straightforward modification of conventional nonlinear fiber design, supercontinuum sources seeded by self-phase modulation can generate a significantly wider spectrum. More broadly, this demonstrates that the sensitivity to initial conditions associated with nonlinear dynamics may be utilized to generate stronger nonlinear effects in optics.
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Quantum Physics
Counterdiabatic Driving under Variational Frame Dressing
Boxi Li, Franco Nori and Felix Motzoi
Counterdiabatic (CD) driving accelerates adiabatic protocols by prescribing auxiliary control fields, but often fails to map them to physically available operations. We derive a general formalism for such a mapping. We formulate CD driving in a variational dressed frame, where an unconstrained auxiliary generator reshapes the effective adiabatic problem while simultaneously forcing the applied correction to stay restricted to the native laboratory controls. This yields a laboratory-frame commutator equation that can be solved without constructing instantaneous eigenstates or the adiabatic and dressed-frame
unitaries. The additional dressed-frame freedom reveals solutions that are inaccessible in the conventional adiabatic frame. We illustrate this mechanism in three settings: suppression of spectator errors in a multi-
qubit chain driven by a single quadrature, an analytical acceleration of adiabatic Bell-state preparation with a fixed entangling interaction, and implementation of a fast adiabatic holonomic gate in a degenerate tripod
manifold with correction pulses confined to the native couplings. Our results provide a systematic nonperturbative framework for constructing implementable counterdiabatic protocols beyond the conventional adiabatic frame.
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High Energy Physics (Experiment)
Search for pair-production of vector-like $T$ quarks decaying into a top quark and a spin-0 particle in the diphoton final state in proton proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
ATLAS Collaboration
A search for pair-produced vector-like T
quarks (VLQs) is presented. Each VLQ is assumed to decay into a top
quark and an exotic (pseudo)scalar S. The search targets events with at least one resonant $S \to \gamma\gamma$ decay and large summed transverse momentum and missing transverse momentum from other final-state particles. The analysis uses data from $pp$ collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV recorded by the ATLAS detector from 2015 to 2018 and corresponding to an integrated luminosity of 140 fb$^{-1}$. This is the first VLQ search performed in this final state. No significant excess over the Standard Model background is observed. The analysis is model-independent to a large extent but targets cascade decays into final states with electroweak
bosons or $t\bar{t}$. Results are provided in the form of upper limits on the fiducial cross-section times branching ratio as a function of the masses of the VLQ and the
spin-0 particle. The fiducial volume is defined by kinematic requirements on the
photons from the
spin-0 decay.
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Mathematical Physics · Cross-listed from math.SP
New universality classes associated to fractals
Benjamin Eichinger, Alexander Kheifets, Milivoje Lukić et al. (+1 more)
The local behavior of zeros of orthogonal
polynomials is determined by the local scaling behavior of Christoffel-Darboux (CD) kernels. All previously studied behaviors are described by scaling limits, and different values of the limit kernel correspond to different universality classes. In this paper, we describe new universality classes in which instead of a single limit kernel, there is a limit cycle. These are naturally suited to Cantor spectra and to fractal behaviors of the measure. We show that these new phenomena occur for two canonical models with singular measures: the middle third Cantor measure and the balanced/
equilibrium measure on a real Julia set of an expanding
polynomial. In particular, this is the first result on the local behavior of CD kernels for an almost periodic operator with singular spectrum. As a complementary result, we describe the asymptotics of the scaling function, and the Christoffel function, at a fixed point of a quadratic iteration. This is the first such analysis for an almost periodic model with singular spectrum. It allows us to conclude that, at the fixed point, the local scaling of zeros of the
polynomial of degree $n$ is precisely of order $n^{-1/\alpha}$, where $\alpha$ is the local dimension of the measure. We also study the limit chain in this case, and prove that it can be parametrized by its asymptotics with respect to a Martin function (so-called $M$-type); this is the first result of this kind for a chain with a singular measure.
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All authors Benjamin Eichinger, Alexander Kheifets, Milivoje Lukić, Peter Yuditskii
Adaptation and Self-Organizing Systems · Cross-listed from eess.SY
Anonymous sharing is pairwise phase-blind
Brieuc Le roux tardif
Independent training jobs sharing a storage system write their checkpoints through the same finite bandwidth, and the resulting bursts of correlated I/O are commonly described as a self-reinforcing "checkpoint storm". We formalise the self-reinforcement as phase locking in a population of integrate-and-fire oscillators coupled through a shared resource, and show that within that model it fails. Call a resource anonymous if the rate it delivers to an active user depends on how many users are active and not on which. For identical jobs whose write is shorter than their compute interval, an anonymous resource produces no pairwise coupling at all: the two-job return map of the phase gap is the identity, under storage contention, under a shared power cap and under both, so the two-body interaction on which the Kuramoto and Mirollo-Strogatz frameworks are built is not weak here but absent. Anonymity also freezes the firing order, for any fleet size and any cap, so no trajectory reaches the synchronous state from outside it. What survives is a third-order effect: where all $N$ write windows overlap and the cap does not bind, the map is diagonal in the intervals between consecutive write starts, $a_j \mapsto ((N-j)/j)a_j$, with reciprocal spectrum and unit determinant, making synchrony a fixed point with $\lceil N/2\rceil-1$ expanding directions rather than an attractor. That determinant follows from anonymity and not from
fairness: for any anonymous throughput $f$ with $f(n)\le n$ the spectrum becomes $(N-j)f(j)/(j f(N-j))$, whose product is still one. Numerically, a fleet launched at random neither locks nor clusters, and absence of locking is not absence of bursts: the upper tail of the number of concurrent writers stays above its independent-phase value. Heterogeneous jobs behind a binding cap do acquire a genuine pairwise coupling, which is where the statement stops generalising.
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Mathematical Physics · Cross-listed from math.FA
The isoperimetric inequality for the Ky Fan norm
Luís Daniel Abreu
We show that, among all measurable sets $\Omega \subset \mathbb{C}$ with finite area $s$, the disc of area $s$ maximizes the Ky Fan norm, which is defined as the sum of the first $N$
eigenvalues of the Toeplitz operator with symbol $\mathbf{1}_{\Omega }$ on the Fock space. For $N=1$ this reduces to Nicola-Tilli's celebrated Faber–Krahn inequality and for general $N$ the result was conjectured by Nicola, Riccardi and Tilli, who proved it for radial sets. The proof combines Ky Fan's maximum principle with methods from
quantum information theory based on Fock rearrangements of density operators. As a by-product, we obtain isoperimetric inequalities for the Schatten sums in the range $0<p\leq \infty $.
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Quantum Physics
Emergence of a Macroscopic Cat State and Multi-Channel Entanglement in a Frustrated Cluster Spin Chain
Mohit Lal Bera, Andreu Anglés-Castillo, Alberto Acevedo Meléndez et al. (+8 more)
We study a one-dimensional frustrated
spin chain, which combines cluster-Ising and anisotropic next-nearest neighbor Ising models. We first offer a historical perspective that justifies the studied model. Then we study in detail the two
quantum phases and prove that they are separated by a first order
quantum phase transition. On one side, the ground state corresponds to a
ferromagnetic phase, shows the presence of macroscopic cat states, and a small gap that closes in the thermodynamic limit. On the other phase, competing interactions avoid the establishment of a topological phase, though it conserves large incommensurate
quantum correlations. We prove it is fundamentally distinct from a simple paramagnet, and we name it an incommensurate phase. This is a gapped phase, which gap does not close in the thermodynamic limit. While in the
ferromagnetic phase there are two dominant Schmidt coefficients, in the incommensurate phase there are four. This corresponds to four distinct bipartite
entanglement channels contributing substantially to the ground state. Finally, we discuss the utility of the macroscopic cat states for
quantum metrology applications and the experimental feasibility of the system.
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All authors Mohit Lal Bera, Andreu Anglés-Castillo, Alberto Acevedo Meléndez, Rafael Gómez-Lurbe, Luca Ion, Rodrigo M. Sanz, Somayeh Mehrabankar, Tanmoy Pandit, Carmen G. Almudéver, Armando Pérez, Miguel Angel Garcia-March
Accelerator Physics
Fast optics-based modeling enabling large-scale optimization of the H4 and M2 beamlines in the CERN SPS North Area
Giovanni Dal Maso, Dipanwita Banerjee and Nikolaos Charitonidis
The CERN multi-purpose secondary beamlines are invaluable facilities offering a rich and diverse physics program to the international particle physics community, providing many different particle species and beam characteristics to fixed-target experiments and test-beam users. A number of
magnetic elements are required to enable such flexibility, posing a significant challenge in the design and optimization of the beamline optics. In this work, we present the optimization of the H4 and M2 beamlines of the CERN SPS North Area using genetic
algorithms. The aim of this study is to demonstrate the effectiveness of fast optics-based tracking models (here Xsuite), to enable large-scale, multi-objective optimization on standard computing hardware. The model is benchmarked and validated with high-fidelity Monte Carlo simulations using BDSIM and cross-validation of the results with experimental measurements. The optimized optics, applied to the H4 electron configuration for NA64, achieved a 30% increase in available electron rate and a five-fold reduction in beam-related background. In the M2 line, the optimized configurations yielded a nearly two-fold increase in electron rate and a 67% improvement in
muon transmission.
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Computational Physics
Performance Benchmarking: Software for the Density Matrix Renormalization Group
Per Sehlstedt, Paolo Bientinesi and Lars Karlsson
The performance of scientific software often determines the scale of problems that can be solved in practice. As multiple implementations of the same
algorithm emerge, systematic evaluation is needed to compare their strengths and limitations. The density
matrix renormalization group (DMRG)
algorithm, widely used to study
quantum systems, has over 50 software implementations. These implementations vary in multiple aspects that can strongly affect performance. However, despite the need, performance evaluations of these implementations are scarce and lack a consistent standard; many existing evaluations are either too incomplete to enable meaningful comparisons or focus on objectives other than direct performance comparisons, thereby limiting understanding of how the implementations compare. Here, we present a performance-oriented benchmarking framework to facilitate meaningful comparisons of DMRG implementations, and we apply it to quantify the performance of eight implementations, highlighting similarities and differences among them. Furthermore, we examine multiple parameter settings, optimization strategies, and implementation-specific features to demonstrate how parameter configuration can affect performance and how systematic evaluation can reveal non-obvious trade-offs. The results show significant performance differences, up to two orders of magnitude in some cases, not only between different implementations when aligning parameters, but also within the same implementation when comparing different parameter configurations. Hence, our results demonstrate the significant value and insight that can be gained from conducting rigorous performance evaluations. Using our results and framework as a starting point, more rigorous benchmarking will ultimately help users and developers make informed decisions and support future development efforts to build better, more efficient software.
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Superconductivity
B. J. Ramshaw
The confirmation of a bulk, topological
superconductor is a central goal of modern
quantum materials research. Despite decades of searching, no confirmed examples yet exist. A primary difficulty is that most experimental signatures of topological superconductivity are ambiguous and indirect. I review efforts to narrow the search for a
chiral topological
superconductor using measurements of elastic
moduli. In principle, these experiments can provide unambiguous thermodynamic evidence for multi-component superconductivity—a pre-requisite for
chiral superconductivity in 2D and quasi-2D materials. Despite the potential strength of this program, the results are still negative. I provide a pedagogical introduction to multi-component order parameters,
chiral topological superconductivity, and how superconducting order parameters couple to strain. I discuss ongoing efforts in heavy
fermion, iron pnictide, and Kagome
superconductors, and suggest routes for speeding up the search process, as well as other experimental tools that should be developed for the pursuit of this goal.
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Quantum Physics
Noise-aware emulation and cross-device validation of neutral atom analog quantum processing units
Constantin Dalyac, Sergi Julià-Farré, Lucas Leclerc et al. (+26 more)
Analog
quantum processors based on Rydberg atom arrays are a powerful platform for many-body
quantum simulation, combinatorial optimization, and graph machine learning. As these devices become increasingly accessible, establishing confidence in their outputs requires predictive models that quantitatively connect microscopic hardware imperfections to empirical results. Here, we present a noise-aware emulation framework that propagates the dominant noise mechanisms throughout the full computation cycle to predict device behavior. We validate the framework by benchmarking two representative protocols,
quantum annealing and post-quench dynamics, on three Pasqal
quantum processors where classical simulations still provide ground truth. Across all three devices, the measured observables fall within the uncertainty envelopes predicted by the emulator. Beyond reproducing the data, the framework isolates which physical mechanism dominates in each operating regime, provides quantitative guidance for
algorithm design and hardware improvements, and establishes a foundation for verifying analog processors in regimes beyond classical reach.
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All authors Constantin Dalyac, Sergi Julià-Farré, Lucas Leclerc, Vittorio Vitale, Boris Albrecht, Lucas Béguin, Kemal Bidzhiev, Petru Borta, Clémence Briosne-Frejaville, Daniel J. Campbell, Dorian Claveau, Makrem Chatti, Antoine Cornillot, Julius de Hond, Anita Devi, Thomas Eritzpokhoff, Gaétan Hercé, Fergus Hayes, Soufiane Kaghad, Arun Kumar Abhimanyu, Lucas Lassablière, Mauro Mendizabal, Anton Quelle, Julien Ripoll, Henrique Silvério, Joseph Vovrosh, Guillaume Villaret, Adrien Signoles, Alexandre Dauphin
Instrumentation and Detectors
On a Liquid Krypton TPC for double positron decay searches
S. Torelli, A. Simón Estévez and F. Monrabal Capilla
Double positron decay features the emission of four 511 keV gamma rays from positron alongside the well-known 'double blob' signature which can be tracked with a TPC. Successfully detecting these gammas creates a unique signature that cannot be replicated by any backgroun. This enables a virtually background-free search if the four gammas are efficiently tagged. In this work, we propose the concept of a
liquid Krypton Time Projection Chamber designed to search for double positron decay using this four-gamma tagging concept, and we'll show how already a small version of this prototype could set the world best limit on the search of this decay towards a sensitivity of $10^{29}-10^{30}$ y with a ton scale detector.
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Quantum Physics
No-Go Theorems for Quantum Transport Metrics from Fixed Cost Operators
Minbo Gao, Zhengfeng Ji and Tianshi Yu
Coupling-based
quantum optimal transport generalizes classical optimal transport by representing transport plans as bipartite states with prescribed marginals and evaluating their cost as the expectation of a fixed Hermitian operator. Friedland et al. [Phys. Rev. Lett. 129, 110402 (2022)] conjectured that the square root of the optimal cost associated with the SWAP projector is a metric in every dimension and that this property persists for nearby
quantum cost
matrices. Miller [arXiv:2607.07764] disproved both
conjectures by constructing explicit diagonal qutrit counterexamples. Building on his analysis, we prove a uniform no-go
theorem for standard couplings. In every dimension $d\geq3$, no fixed cost operator makes either the optimal cost or its square root a metric, with violations occurring already among commuting states. The obstruction persists under stabilization of the SWAP cost. For channel-induced couplings, global nonnegativity and vanishing self-cost force the cost operator to be zero, precluding point separation when $d\geq2$. Taken together, these no-go results show that fixed-cost coupling formulations do not lead to metrics on the full
quantum state space.
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Earth and Planetary Astrophysics
Kilometre-scale Jovian moon characterized for a potential JUICE flyby
Juan Luis Rizos, Jose Maria Gomez-Limon, Yucel Kilic et al. (+51 more)
Jupiter's irregular satellites are thought to be relics of early
Solar System planetesimals. However, their small sizes, large distances from Earth and close angular proximity to Jupiter make them difficult to characterize remotely. Here we report multi-instrument observations of kilometre-sized Kallichore, the only irregular moon of Jupiter amenable to a close flyby by ESA's Jupiter Icy Moons Explorer (JUICE), whose astrometric and physical properties were still poorly constrained. We used Hubble photometry and astrometry, followed by a ground-based, multi-site
stellar occultation campaign and astrometric and photometric observations with the 10.4-m Gran Telescopio Canarias. We reduced Kallichore's orbital uncertainty by up to approximately 80% and determined its shape: an elongated object with a minimum semi-axis ratio of a/b = 1.53 +/- 0.10, an area-equivalent diameter of 3.8 (+2.3/-0.3) km and a dark surface with a
geometric albedo of 3.7% (+0.7/-2.2). No close companions were detected. These new constraints provide a viable pathway towards a JUICE flyby once the spacecraft arrives in the Jupiter system in 2031.
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All authors Juan Luis Rizos, Jose Maria Gomez-Limon, Yucel Kilic, Altair R. Gomes-Junior, Jose Luis Ortiz, Nicolas Morales, Alvaro Alvarez-Candal, Pasquale Palumbo, Luisa M. Lara, Simon Porter, Benjamin Proudfoot, Evelyn Christiny M. Prais, Jean Marc Christille, Stefano Sartor, Antonio Cabrera, Stefan Geier, Alessia Spolon, Alice Lucchetti, Andrea Soffiantini, Anne Verbiscer, Armin Behrend, Elena Mazzotta Epifani, Jean-Louis Dumont, Luca Zampieri, Mike Skrutskie, Maurizio Pajola, Michel Boutet, Michele Fiori, Raoul Behrend, Stefano Sposetti, Vadim Nikitin, Fabien Cavaille, Jocelyn Serot, Laurent Miralabe, Marc Buie, Mehmed Naim Bagiran, Metin Altan, Mohammad Niaei, Noel Robichon, Orhan Erece, Pierre-Louis Phan, Raphael Lallemand, Suleyman Fisek, Valentin Etienne, Valery Lainey, Yavuz Guney, Yusuf Avcioglu, Francois Poulet, Paul Hartogh, Oliver Witasse, Pablo Santos-Sanz, Julia de Leon, Flavia L. Rommel, Fernando Tinaut-Ruano
Atmospheric and Oceanic Physics
An unstructured-grid, nonhydrostatic, GVC ocean model Part I: Model description and application of vertical hybrid coordinates to internal solitary waves
B. J. Pauken, L. Yue, Y. Zhang et al. (+2 more)
We present a nonhydrostatic ocean model with a horizontally unstructured, C-grid and a moving, generalized vertical coordinate (GVC) designed for the simulation of nonhydrostatic processes in realistic ocean domains. The GVC system can represent any of the well-known z-level, terrain-following, or isopycnal coordinates while also being able to employ hybrid vertical coordinates. In this paper we outline the specific steps needed to incorporate the GVC system into the unstructured, C-grid, nonhydrostatic, z-coordinate SUNTANS model of Fringer et al. (2006). The approach is adapted from the nonhydrostatic, isopycnal-coordinate method of Vitousek and Fringer (2014), yet our model differs from that implementation through the development of a conservative momentum advection scheme and a positivity-preserving layer height scheme for horizontally unstructured grids. We validate the momentum advection implementation with simulations of a turbulent channel flow and demonstrate the advantages of the hybrid vertical coordinate approach over z- or terrain-following coordinates through simulations of internal solitary waves and the associated bottom boundary layer instability.
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All authors B. J. Pauken, L. Yue, Y. Zhang, S. Vitousek, O. B. Fringer
Physics Education
Uniform and Accelerated Circular Motion with a Smartphone: A No-Code, AI-Generated Browser Laboratory
Josep Ll. Suñer, Francisco M. Muñoz-Pérez, Juan C. Castro-Palacio et al. (+4 more)
Smartphones have become a standard measurement instrument in the physics laboratory. Their built-in accelerometers, gyroscopes, magnetometers, and cameras have been used to investigate a wide range of phenomena in mechanics, and rotational motion in particular has proven especially well-suited to smartphone-based experiments. A recurring limitation, however, is that most experiments rely on precompiled sensor apps whose interfaces cannot be tailored to a specific activity, and until recently creating customized smartphone laboratories required programming knowledge beyond what most physics teachers possess. This paper makes two connected contributions. First, we present a validated smartphone experiment for uniform circular motion (UCM) and uniformly accelerated circular motion (UACM), in which the angular velocity and the angular acceleration are obtained from two independent smartphone channels and checked against independent
video analysis with Tracker.10,14 Second, we show that generative AI can serve as a no-code development tool for the physics laboratory: the browser-based application used here was produced entirely through natural-
language prompting, with no manual coding, extending to rotational motion the approach we recently introduced for acoustic experiments. The emphasis is therefore not only on what is measured, but also on how the measuring instrument itself was built.
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All authors Josep Ll. Suñer, Francisco M. Muñoz-Pérez, Juan C. Castro-Palacio, Juan A. Monsoriu, Martín Monteiro, Cecilia Stari, Arturo C. Martí
Cosmology and Nongalactic Astrophysics
Multi-branch classification of diffuse cluster radio emission from the LOFAR two-metre sky survey
Markus Bredberg and Emma Tolley
Context.
Galaxy clusters sometimes host synchrotron radiation on scales of approximately 100 kpc to approximately 1 Mpc, with a surface brightness only a few times the image noise. This diffuse cluster
radio emission is a sensitive probe of
magnetic fields and intracluster medium dynamics, but disentangling the underlying physical processes requires statistically large samples spanning a wide range of cluster masses, dynamical states, and
redshifts, together with a sufficient sensitivity to low-surface-brightness emission. Aims. We explore two techniques for improving the detection of diffuse emission in
galaxy cluster images, relative to a baseline classifier: the scattering transform (ST) and squeeze-excitation (SE)
attention. Methods. We integrated an ST encoder into a dual-branch classifier (DualSSN) and a scattering network (ScatterNet). We incorporated SE
attention into the DualSSN and dual-branch convolutional neural network (DualCSN). These classifiers were then benchmarked against a simple convolutional neural network (CNN), across ten image pre-processing configurations and three cropping strategies. Performance was evaluated on small labelled
datasets from the second data release of the LOFAR Two-metre Sky Survey overlapping with the Second Planck catalogue of Sunyaev-Zel'dovich sources (LoTSS-DR2/PSZ2). Results. Alongside the multi-branch approach with SE and ST, cropping the image to a fixed number of
telescope beams and uv tapering (smoothing to a coarser angular resolution) improve classification performance, while tacking multiple pre-processed versions of an image does not. Conclusions. Scattering-transform-based multi-branch architectures with beam-normalised cropping are a promising direction for diffuse emission classification in the SKA era.
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High Energy Physics (Phenomenology)
Tengyu Ai, Qi Bi, Yuxin He et al. (+3 more)
Missing
neutrinos need not destroy
collider spin tomography. We formulate the visible measurement under kinematic ambiguities arising from invisible particles as a coarse-grained positive-operator-valued measure on the production
spin density
matrix. We show that information loss is governed by the null space of the resulting visible-data map, not by the number of kinematic solutions. In $e^+e^-\to\tau^+\tau^-\to\pi^+\pi^-+\nu\bar\nu$, the twofold ambiguity leaves only the antisymmetric
spin-correlation combination $C_{nr}-C_{rn}$ unidentifiable, while the differential production rate and the remaining fourteen
spin coefficients are identifiable. For practical reconstruction under kinematic ambiguities, we develop a self-consistent fixed-point unfolding method using only visible data, without assuming a theoretical production template. Closure tests in Standard Model and anomalous tau-dipole
benchmarks show that the method reproduces the truth-level differential production rate and all identifiable
spin coefficients, whereas the usual flat average over kinematic folds gives significantly biased reconstructions. When a nontrivial null space is present, the reconstructed identifiable subspace together with positivity yields controlled ranges for concurrence and the CHSH parameter.
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All authors Tengyu Ai, Qi Bi, Yuxin He, Zekun Li, Jia Liu, Xiao-Ping Wang
Quantum Physics · Cross-listed from math.CO
The cycle C9 does not admit uniform mixing
Alison Gray, Pransu Patel and Isaiah Young
We study continuous-time
quantum walks (CTQWs) on cycles. In particular, we prove that the cycle $C_9$ does not admit uniform mixing at any time via algebraic geometry and Gröbner basis techniques to rule out all cyclic 9-roots.
Soft Condensed Matter
Thermodynamics and Kinetics of a Three-Arm Star Polymer Translocating through a Nanopore
Bhavesh R. Sarode and Harshwardhan H. Katkar
In this work, voltage-driven translocation of uniformly charged long linear and three-arm
star polymers through narrow nanopores is investigated. Langevin dynamics simulation is performed using a coarse-grained model of the
polymer and a semi-implicit representation of the nanopore. The mean translocation time of a linear
polymer is found to be inversely proportional to the applied voltage over a wide range of voltages. In contrast, the mean translocation time of a three-arm
star polymer of the same molecular weight exhibits a pronounced deviation from this scaling relation below a threshold voltage. The threshold voltage is found to be nearly independent of the molecular weight of the
polymer, but depends on the size of the nanopore and salt concentration. Metadynamics simulation is used to estimate the free-energy landscape for the translocation of the three-arm
star polymer. Below the threshold voltage, the free energy exhibits a pronounced second barrier resulting from an entropic contribution and electrostatic interactions between segments of the trailing arm inside the nanopore. A Fokker-Planck model developed using the estimated free-energy accurately predicts the deviation from the scaling relation below the threshold voltage and shows a remarkable agreement with the Langevin dynamics simulation results using a voltage-independent fitting parameter. The agreement between the theory and the Langevin dynamics simulation results is seen for different nanopore radii, molecular weights of the
polymer and salt concentrations studied. A simple extension of the free energy landscape is suggested to predict translocation kinetics for higher molecular weights of the
polymer without performing additional computationally expensive simulations.
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Chemical Physics
Wavelength-Resolved Photoinduced Spin Polarization in a Broad Optical Range for a Porphyrin-Quinone System
Liubov Chuchkova, Oleg Tretiak, Kirill F. Sheberstov et al. (+3 more)
Photochemically induced dynamic
nuclear polarization (photo-CIDNP) in
liquid-state donor-acceptor systems is typically studied at a limited number of excitation wavelengths, leaving its spectral dependence incompletely characterized. Understanding the wavelength dependence of photo-CIDNP is important both for elucidating the underlying
spin-chemical mechanisms and for optimizing hyperpolarization strategies in chemically and biologically relevant molecular systems. Here, we investigate wavelength-resolved photo-CIDNP in a tetraphenylporphyrin-1,4-benzoquinone donor-acceptor system over the 350-800 nm spectral range.
Photon-flux-normalized CIDNP amplitudes were measured using both a tunable
laser system and a broadband xenon lamp equipped with interchangeable 10 nm interference filters. The CIDNP response exhibits a non-monotonic dependence on excitation wavelength. Pronounced hyperpolarization is observed near 350 nm and in the 500-550 nm region, whereas excitation within the strongly absorbing 400-450 nm range results in a substantially reduced CIDNP response. Comparison with the UV-Vis absorption spectrum demonstrates that photo-CIDNP efficiency is not governed solely by optical absorption and reflects wavelength-dependent photophysical processes. After normalization to the excitation
photon flux, lamp- and
laser-based measurements yield consistent CIDNP results, validating broadband filtered excitation as a reliable and experimentally accessible approach for wavelength-resolved photo-CIDNP studies. These results establish excitation wavelength as an independent control parameter for
liquid-state photo-CIDNP and provide a framework for systematic investigations of wavelength-dependent
spin hyperpolarization.
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All authors Liubov Chuchkova, Oleg Tretiak, Kirill F. Sheberstov, Danila A. Barskiy, Raphael Kircher, Dmitry Budker
High Energy Physics (Theory) · Cross-listed from math.DG
SU(3)-structures on quotients of 3-Sasakian orbifolds
Quentin Peres and Dimitrios Tsimpis
We show that if $(S,g,\xi_i,\eta_i,\Phi_i)$ is a quasi-regular $3$-Sasakian orbifold of dimension $7$, then its quotient $Z$ by one of the Reeb vector fields inherits an $SU(3)$-structure parametrized by two real parameters. We compute its torsion and show that it is an LT-structure. Moreover, for certain values of the parameters, we can provide a nearly Kähler structure on $Z$ appearing as a special case of our construction. We give several examples in the regular, quasi-regular and orbifold cases.
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Quantum Gases
Fulde-Ferrell-Larkin-Ovchinnikov transition and quantum criticality in polarized Fermi gases
Francesco Pirolo, Leonardo Pisani and Pierbiagio Pieri
We investigate the zero-temperature transition from the polarized normal phase to the FFLO state in a two-dimensional
Fermi gas by means of a diagrammatic t-
matrix approach. We first show that the standard non-self-consistent theory produces an unphysical critical polarization because of a severe violation of the Luttinger
theorem. Motivated by this observation, we introduce a minimal self-consistent extension that largely restores compliance with the Luttinger
theorem while preserving the analytical simplicity of the original formalism. This leads to a physically consistent critical polarization over the whole interaction range. Building on this improved description, we characterize the
quantum critical behavior of the FFLO transition through the quasiparticle decay rates, quasiparticle weights, momentum distributions, and the critical dynamics of both fermionic and bosonic degrees of freedom. We further compare the two- and three-dimensional systems, showing that their critical properties can be understood within a unified geometrical picture based on the nesting of the majority and minority
Fermi surfaces. Finally, for a three-dimensional
lattice, we demonstrate within the Hertz-Millis framework that vertex corrections are irrelevant, thereby placing the FFLO
quantum phase transition in the mean-field universality class, in close analogy with the itinerant antiferromagnet transition.
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High Energy Physics (Experiment)
Search for high-mass dilepton resonances in $pp$ collisions at $\sqrt{s}=13.6$ TeV combined with 13 TeV results using the ATLAS detector
ATLAS Collaboration
A search for
spin-1 $ee$ and $\mu\mu$ resonances in the high-mass range is presented. Two
proton-
proton ($pp$) collision
datasets recorded by the ATLAS detector at CERN's Large
Hadron Collider are utilised. A search is first performed using a
dataset recorded at a center-of-mass energy of 13.6 TeV between 2022 and 2024, corresponding to an integrated luminosity of 165 fb$^{-1}$. The results of this search are subsequently statistically combined with results using 140 fb$^{-1}$ of data recorded between 2015 and 2018 at 13 TeV. The dilepton invariant mass spectrum is fitted with a functional form to model the contribution from Standard Model background processes. A generic
spin-1 signal shape is used to determine the significance of observed deviations from the background expectation. No significant deviation is observed, therefore upper limits are placed at the 95% confidence level on the fiducial cross-section times branching ratio for a
spin-1 resonance with various width hypotheses, individually for $ee$, $\mu\mu$ final states and for their combination. From the combined 13 TeV and 13.6 TeV results, mass limits are extracted for various
benchmark model
bosons, including a $Z^{\prime}_{\text{SSM}}$ (5.5 TeV), $Z^{\prime}_{\chi}$ (5.1 TeV) and $Z^{\prime}_{\psi}$ (4.8 TeV). These results represent the most stringent limits to date on high-mass dilepton resonances on the considered $Z'$ models.
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Fluid Dynamics
Compressible solved-volatility stochastic fluid thermodynamics: source-consistent energy, finite-correlation reservoirs, entropy admissibility and boundary conditions
Hsieh-Chen Tsai
A variable-density thermodynamic extension is developed for the solved-
volatility stochastic-fluid formulation of arXiv:2607.25536. Source-inclusive
stochastic transport separates mass, momentum and total-energy conservation into time-
evolution partial differential equations and martingale compatibility constraints. Density and temperature are the primitive thermodynamic fields: mass conservation determines density, internal energy determines temperature, and the equation of state determines pressure
evolution along
stochastic particle paths. The resolved kinetic-energy identity is combined with a finite-correlation reservoir, Green–Kubo calibration, an
equilibrium counterterm and adjoint resolved-unresolved exchange. A
stochastic Gibbs identity and Gaussian relative
entropy yield a conditional
entropy-admissibility result for a Hencky-reservoir formulation. Equation-of-state pressure fluctuations are distinguished from mechanical stress impulses; regular finite-Mach fluctuations produce no independent white-noise bulk pressure impulse, while fast mechanical pressure is represented by a causal finite-correlation carrier. Conservative boundary conditions and a calorically perfect ideal-gas specialization are given. In the zero-
volatility limit, the classical compressible Navier–Stokes–
Fourier equations are recovered. A frozen descriptor analysis identifies a mixed
hyperbolic–
parabolic drift subsystem coupled to algebraic martingale constraints, with closure-dependent
elliptic blocks and a singular low-Mach pressure limit. Canonical calculations verify the pressure carrier, acoustic dispersion, viscous-thermal energy balance and low-Mach scaling. Nonlinear well-posedness, shock admissibility and developed
turbulence are not claimed.
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Strongly Correlated Electrons
Coupled Spin-Density-Wave and Bond-Order Driven Metal-Insulator Transition in Altermagnetic CsCr$_2$S$_2$O
Chenchao Xu, Wansheng Bai, Guo-Xiang Zhi et al. (+4 more)
A metal-
insulator transition (MIT) driven by bond order (BO) coupled with a secondary
spin-density wave (SDW) is identified in CsCr$_2$S$_2$O. Such coupling is enabled as a result of the broken time-reversal
symmetry due to the pre-existing C-type
antiferromagnetic (C-AFM) order. First-principles calculations reveal an orbital-selective physics that Cr-$d_{yz}$ orbitals form local moments and establish the altermagnetic order, while the Cr-$d_{xz}$ orbitals remain metallic and hybridize with S-$p_z$. Thus the low-energy physics is governed by the Cr-$d_{xz}$ and S-$p_z$ orbitals. On-site interactions then enhance a secondary SDW ($s$SDW) instability of the itinerant $d_{xz}$ electrons, which couples to the Cr-$d_{xz}$-S-$p_z$ bonding order. The resulting coupled $s$SDW-BO simultaneously produces experimentally observed structural distortion, charge disproportionation, local Cr-moment modulation, and gap opening. Our results establish an orbital-selective mechanism upon which pre-existing altermagnetism and electronic correlations cooperate to drive a structural MIT.
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All authors Chenchao Xu, Wansheng Bai, Guo-Xiang Zhi, Yi Liu, Xiaoqun Wang, Jianhui Dai, Chao Cao
Cosmology and Nongalactic Astrophysics
Growth, geometry, and early-universe split of the matter density parameter $\Omega_{\rm m}$
Felicitas Keil, Isaac Tutusaus and Alain Blanchard
While the $\Lambda$ cold dark matter ($\Lambda$CDM) model can successfully reproduce the measurements of many cosmological probes, some discrepancies have recently emerged. It is therefore necessary to test the standard cosmological model for consistency. An important stress test is to separate the effect of different cosmological regimes on the parameter inference. We treat three regimes separately here: geometry, growth, and the early Universe. The
geometric regime concerns the expansion and
curvature history, the growth regime governs structure formation, and the early-universe regime affects physics prior to recombination. Previous analyses have performed the split between geometry and growth, whereas we also consider the influence of the early Universe separately. We performed this split for the present-day matter density parameter $\Omega_{\rm m}$ using multiple cosmological observables. The data we used are
galaxy clustering and weak-
lensing statistics (3x2pt) from the Dark Energy Survey,
cosmic microwave background data from Planck,
baryon acoustic oscillations from the Dark Energy Spectroscopic Instrument, type Ia
supernovae samples from Pantheon+, and
redshift-space distortions from a collection of
galaxy surveys. For each of these probes, we introduced a phenomenological split into these three regimes. The correlation between the
geometric and the early regime for the matter density is strong, but that between the growth regime and the others is not. All regimes are compatible in the posterior distribution, but the difference between the geometry and the early regimes, $\Delta\Omega_{\rm m}^{\rm geo,early}$, has a 2$\sigma$ discrepancy with 0.
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