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Physics

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Thursday 27 August

Materials Science

Grain Boundary Phase Transitions Enable Diffusionless Climb of Disconnections

Md Sharier Nazim, Giacomo Po and Nikhil Chandra Admal

Dislocation-grain boundary (GB) interactions govern the mechanical response of polycrystalline materials by controlling dislocation absorption, transmission, and interfacial plasticity. While disconnection climb is conventionally understood to require the absorption or emission of point defects supplied through long range bulk diffusion, GBs possess intrinsic configurational degrees of freedom associated with their atomic structure, or microstate, that may provide an alternative mechanism. Here, using bicrystallography and molecular dynamics simulations, we investigate the interaction of shear dislocation loops with the [1 1 0](-5 5 14) symmetric tilt grain boundary in Al. We show that dislocation absorption generates a mobile extrinsic disconnection with a nonzero climb component that propagates conservatively along the interface without long-range bulk point-defect transport. Its motion is accompanied by a localized GB phase transformation mediated by cooperative atomic rearrangements within the GB core, producing successive metastable GB microstates. These findings establish a direct coupling between lattice dislocations and GB phase evolution and reveal a conservative mechanism for disconnection climb fundamentally distinct from conventional vacancy-mediated climb.
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High Energy Physics (Theory)

Wess-Zumino gauge for analytic prepotentials of off-shell $\mathcal{N}=2$ supergravity: bosonic sector

Nikita Zaigraev and Julia Zernina

We present a comprehensive study of the Wess-Zumino gauge for the analytic prepotentials of the off-shell $\mathcal{N}=2$ Weyl and $\mathcal{N}=2$ Einstein supergravities (the version with a non-linear tensor compensator). The field redefinitions, the full transformation laws, and the gauge superparameters that preserve the Wess-Zumino gauge are derived. As a concrete application of the obtained results, we examine the component structure of the free hypermultiplet action coupled to $\mathcal{N}=2$ supergravity. In this work, we restrict our analysis strictly to the bosonic sector.
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High Energy Physics (Experiment)

Accelerating Optical Photon Simulation in DUNE with Opticks

Ilker Parmaksiz, Aaron Higuera, Laura Paulucci et al. (+2 more)

Optical photon simulation is among the most computationally demanding tasks in complex and large detector geometries. In the Deep Underground Neutrino Experiment (DUNE), the scale of the far-detector modules makes photon-by-photon transport with GEANT4 prohibitively expensive on CPUs. We present the first implementation and performance evaluation of GPU-accelerated optical photon simulation at the 10~kt scale, based on Opticks and applied to the DUNE far-detector horizontal-drift (FD-HD) geometry. On the full FD-HD geometry, Opticks propagates the same photons as GEANT4 with a speedup of $313 \pm 3$ over single-threaded and $83 \pm 1$ over four-thread GEANT4, and is validated against the reference GEANT4 simulation across all metrics considered. We further integrate Opticks into the LArSoft-based DUNE software stack. Photons simulated on the GPU with GEANT4-equivalent physics retain full Monte Carlo fidelity at a computational cost that makes high-statistics optical studies and the generation of labeled datasets for machine learning feasible at the kiloton scale.
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All authors Ilker Parmaksiz, Aaron Higuera, Laura Paulucci, Viktor Pec, Estanislao Forino

Materials Science

3D Cloud Component Analysis of Atomic Structures

Pai Li

We present a method for decomposing atomic structures into physically meaningful components by converting discrete atomic coordinates into continuous three-dimensional density fields. Each element is represented by a Gaussian-smeared density map with values ranging from 0 to 1, computed efficiently through a bin-then-blur approach with periodic boundary conditions. The sum of all element densities, truncated at unity, defines the material region; its complement defines the vacuum. Every voxel is first assigned a chemical formula from the set of elements present above a threshold; the resulting formula map is then cleaned so that only regions with a genuine bulk interior-measured by the Euclidean distance to their own boundary-survive as components. Thin surface terminations (e.g., a Ga monolayer on GaAs) and one-to-two-voxel boundary layers between two crystals are absorbed by the neighboring stable region, so the decomposition contains exactly the bulk-like chemical-formula components and the vacuum, with no surface or interface components. For each component we determine the crystal phase with a neural prototype classifier: one phase if the trusted interior atoms vote unanimously, two phases (e.g., crystalline and amorphous Si) if they split into two confident groups, in which case the component is divided into two. Interfaces and surfaces are then derived as boundaries-material-material and material-vacuum-and every atom is labeled bulk, surface, interface, or vertex, with vertex reserved for geometric corners of a component. Inside crystalline components, inner defects are detected from coordination-number and local-density deviations. We demonstrate the approach on Si/GaAs and Si/SiO2 heterojunctions, crystalline/amorphous silicon junctions, vacancy-containing crystals, and bulk crystals.
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Quantum Physics

Optimal cloning of mixed states

Marco Fanizza, Dmitry Grinko, Thilo Scharnhorst et al. (+1 more)

We consider the problem of approximate cloning of quantum states: given $n$ copies of an unknown state $\rho \in \mathbb{C}^{d \times d}$, prepare an $(n+k)$-copy state with high fidelity to $\rho^{\otimes (n+k)}$. Werner's pure state cloner is the optimal channel for the pure state case, and shows that $n = \Theta(kd/\varepsilon)$ copies are necessary and sufficient to clone $k$ additional copies of an unknown pure state to fidelity $1-\varepsilon$. The random purification channel gives a straightforward extension of Werner's cloner to mixed state inputs: given $n$ copies of a mixed state, randomly purify your input, apply Werner's channel in the larger Hilbert space, and then trace out the auxiliary registers. This gives a mixed state cloner using $n = O(krd/\varepsilon)$ copies to clone rank-$r$ states. Can one do any better? We show that the answer is no: one must use $n = \Omega(krd/\varepsilon)$ copies. We prove our lower bound by studying the special case of projector cloning, in which the input state $\rho$ is promised to be of the form $P/r$, where $P$ is a rank-$r$ orthogonal projector. As a further application of our techniques, we consider the closely related problem of approximate transposition of quantum states, where one seeks to convert $\rho^{\otimes n}$ to a $k$-copy state with high fidelity to $(\rho^T)^{\otimes k}$. Here, we again show $n = \Theta(krd/\varepsilon)$ copies are necessary and sufficient for this task.
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All authors Marco Fanizza, Dmitry Grinko, Thilo Scharnhorst, Jack Spilecki

General Relativity and Quantum Cosmology

Emergent vacua and stability constraints on black hole solutions in higher-dimensional $f(R)$ gravity

Nicolás Trullols Sandino and Andrei Galiautdinov

We investigate static spherically symmetric vacuum solutions in higher-dimensional $f(R)$ gravity, beginning with the five-dimensional Starobinsky model governed by the action $f(R) = R + \alpha R^2 - 2\Lambda$. By enforcing the ghost-free stability criterion $f'(R) > 0$ on constant scalar curvature spacetimes, we show that a stable effective cosmological constant cannot be dynamically generated from pure $R^2$ geometric corrections in five dimensions; its existence is inextricably tied to a bare cosmological constant. Generalizing this analysis to arbitrary dimensions $D$ and single-term curvature corrections $f(R) = R + \alpha R^n$ with a vanishing bare cosmological constant, we derive a universal stability bound, $n > D/2$, required for the existence of stable emergent vacua. Finally, we demonstrate that expanding the gravitational action to a multi-term polynomial hierarchy circumvents this strict limitation. By including curvature corrections up to $\mathcal{O}(R^3)$, the extended geometric degrees of freedom simultaneously satisfy the trace constraint and the stability criterion. Furthermore, we establish the exact parameter space boundaries that ensure not only asymptotic vacuum stability but strict global stability ($f'(R) > 0$ for all $R$), allowing for the dynamical generation of exact, globally ghost-free vacuum spacetimes in $D \ge 5$ purely from higher-order geometric terms. The scalaron mass requirement, $m_s^2>0$ is not imposed in full in our analysis. A detailed investigation of its implications on the models considered in this work are left for future study.
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Astrophysics of Galaxies

Exploring the survivability of higher-order multiple protostellar systems – The case of VLA1623

N. M. Murillo and A. Pérez-Villegas

Higher-order protostellar systems ($\geq$3 components) are commonly observed in the early stages of low-mass star formation. A persistent question in star formation and evolution is whether these higher-order protostellar systems survive as gravitationally bound systems or dissolve into binaries over time. We explore this question with a case study of the embedded quadruple protostellar system VLA1623 and its observational constraints, assuming that the components A1, A2, B, and W are gravitationally bound. Using $N$-body simulations, we run a grid of models considering gravity, mass accretion onto protostars, the presence of the protostellar cloud core, and its dispersal. The simulations are integrated over a period of 8 Myr to take into account the evolution from the protostellar phase (Class 0 and I, 1 Myr), through the pre-main sequence (Class II and III, 2 – 3 Myr), and into the main sequence (4 Myr). Our results show that VLA1623 has a probability of 30% to remain as a gravitationally-bound quadruple system up to 8 Myr from the current state. There is also a 25–30% probability of VLA1623 dissolving into a triple system. This suggests that the dissolution of quadruple protostellar systems contributes to the formation of stable triple (proto)stellar systems. Components A1 and A2 are the most likely to be ejected, while W has a lower probability of being ejected from the system. The stability of VLA1623 depends on a combination of component mass ratios wrt the primary, separations, and eccentricities.
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General Relativity and Quantum Cosmology

Electric and magnetic Penrose processes, charged-particle collisions and superradiance around a Lorentz-violating dyonic black hole

Fernando M. Belchior and Edilberto O. Silva

This paper is aimed at investigating electromagnetic energy extraction, charged-particle collisions, charged-field superradiance, and horizon stability in a Lorentz-violating dyonic Kalb-Ramond black hole. The geometry differs from the dyonic Reissner-Nordström solution through a modified asymptotic normalization and an effective charge combining electric and magnetic sectors. We derive the dynamics of electrically and magnetically charged probes, including monopole-induced conical motion, and formulate electric and magnetic Penrose processes as decay or collision mechanisms in which a negative-energy fragment falls into the horizon while another escapes with enhanced energy. The electric and magnetic channels are controlled by \(\Phi_H=Q/[(1-\ell)r_+]\) and \(\Psi_H=p/[(1-2\ell)r_+]\), respectively. Negative-energy states arise from electromagnetic canonical energy rather than from a geometrical ergoregion. We also obtain escape conditions for the outgoing products, test the possibility of overcharging or overmagnetizing the black hole, and analyze the center-of-mass energy of charged-particle collisions. Nonextremal same-direction collisions remain finite, whereas head-on or near-critical configurations can become large. In the extremal limit, electrically or magnetically critical particles may generate the Bañados-Silk-West divergence when the radial reachability condition is fulfilled.
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Quantum Physics

Efficient formation and identification of single emitters in 4H-SiC following maskless heavy ion implantation

S. Eserin, L. K. S. Zimmermann, E. Schneider et al. (+12 more)

Single photon emitters in silicon carbide (SiC) are a leading platform for scalable quantum technologies. Recent interest has focused on oxygen-vacancy-related emitters, which show exceptionally high optical brightness and strong spin readout contrast. One barrier to scalable quantum devices based on these emitters is the challenge of maskless formation and rapid identification. Here, we demonstrate the formation of isolated bright single emitters in 4H-SiC, using low-energy maskless implantation of heavy ions bismuth and tin. Following annealing, up to 18% of implanted sites host a single emitter, with optimal yields achieved at annealing temperatures of 900-1000 degrees C. Occupancy statistics are modelled to estimate the implantation dose that maximises single-emitter yield. We introduce a tiered characterisation scheme, where a simple intensity threshold isolates single-emitter candidates, confirmed through photon correlation measurements, after which correlations between polarisation, saturation count rate and magnetic resonance frequency assign emitter type. It is shown that time-consuming low-temperature spectroscopy is not necessary to distinguish emitter types. Together, maskless heavy-ion implantation and selective screening offer an efficient route to forming and rapidly identifying near-surface single emitters for room-temperature quantum technologies such as quantum sensing.
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All authors S. Eserin, L. K. S. Zimmermann, E. Schneider, M. Ludlow, J. Heiler, O. G. Lloyd-Willard, K. Stockbridge, G. Aresta, L. Antwis, S. K. Clowes, M. Hofmann, S. Kucera, P. Berwian, F. Kaiser, B. N. Murdin

High Energy Physics (Phenomenology)

From the November Revolution toward the Millennium

Chris Quigg

The 4th International Symposium on the History of Particle Physics spanned two decades, from approximately 1980 to 2000. In this opening keynote lecture, I survey developments in particle physics from the prehistory of the $J/\psi$ discovery to the early nineteen-eighties. I offer context for the contributions that follow in the symposium program.
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Materials Science

Benchmarking of Fast and Interpretable UF Machine Learning Potentials

Pawan Prakash, Sam Dong and Richard G. Hennig

Machine learning interatomic potentials (MLIPs) have emerged as a powerful alternative to density functional theory (DFT) for molecular dynamics simulations, offering near-DFT accuracy at a fraction of the computational cost. However, many state-of-the-art MLIPs remain computationally demanding and act as black boxes, limiting physical interpretability. In this work, we evaluate the ultra-fast force field (UF$^3$) potential, which employs linear regression with cubic B-spline basis to represent effective two- and three-body interactions. We show that UF$^3$ displays accuracy comparable to established models such as GAP, MTP, NNP (Behler Parrinello), and qSNAP MLIPs. We further investigate the transferability of UF$^3$ by computing melting points for six elemental systems with potentials fitted without any solid-liquid interface configurations or explicit thermodynamic information about melting. The model reproduces experimental melting points within $\sim$6% for simple metals (Ni, Cu, Li), but substantially underestimates them for Mo and Si and fails to yield a stable potential for Ge, reflecting the limitations of a fixed expansion truncated at the three-body term for systems with strong angular or covalent bonding. We further illustrate how UF$^3$'s spline-based formulation allows direct visualization of the learned interactions, enabling identification of unphysical behavior that black-box approaches often obscure.
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Materials Science

Grain-Boundary Premelting in High-Entropy Transition Metal Carbides

Marium M. Mou, Caleb Schenck, Samuel E. Daigle et al. (+4 more)

Grain-boundary segregation and thermally induced interfacial disordering were investigated in four high-entropy transition metal carbides using Monte Carlo (MC) sampling and molecular dynamics (MD) with the universal MACE-OMAT-0 machine-learning interatomic potential. MC sampling segregated the group-VI element (Cr, Mo, or W) and Zr to grain boundaries, where the group-VI content reached approximately 45 at.%, consistent with STEM-EDS observations. During MD heating, the grain-boundary Lindemann index, a normalized measure of interatomic distance fluctuations, reached the liquid-like threshold of $\delta=0.15$ near $1390^{\circ}\mathrm{C}$ for the Cr-containing carbides, $1660^{\circ}\mathrm{C}$ for Mo, and $1890^{\circ}\mathrm{C}$ for W, while the grain interiors remained below the threshold. A chemically random (Cr,Hf,Ta,Ti,Zr)C reference crossed about $60^{\circ}\mathrm{C}$ later and showed less boundary-localized disorder, highlighting the role of interfacial chemistry in premelting. Species-resolved displacements showed enhanced grain-boundary mobility, particularly for carbon. Overall, Cr-rich interfaces showed the earliest and most extensive premelting-like response, followed by Mo- and W-containing boundaries.
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All authors Marium M. Mou, Caleb Schenck, Samuel E. Daigle, William G. Fahrenholtz, Bharat Gwalani, Stefano Curtarolo, Donald W. Brenner

Fluid Dynamics

Energy transfer and scale organisation in dense canopy turbulence

Riccardo Bertoncello, Alessandro Chiarini, Giulio Foggi Rota et al. (+2 more)

This study identifies the scale-dependent processes that sustain turbulence in dense submerged canopy flows. Using a scale-resolved energy budget, we determine where in space and at which scales production, pressure-strain redistribution, and inter-scale transfer predominantly occur, and how they link the canopy layer to the overlying shear flow. We show that energy production is localised at the interfacial shear layer, over a narrow range of streamwise and spanwise scales, while fluctuations within the canopy are primarily maintained through inter-scale transfer and pressure-strain redistribution. The dynamically active scales in the canopy are largely imposed by outer-layer structures, with their organisation and coherence mediated by these inherited motions. Energy exchange across the canopy interface is asymmetric but not unidirectional: although the dominant transfer is from the outer layer towards the canopy, intermittent reverse interactions occur at all scales. The most intense cross-interface exchanges are associated with finer-scale motions rather than large-scale structures, indicating that extreme interfacial energy fluxes are governed predominantly by small-scale dynamics. The flexibility of the canopy weakens the coherence of outer-layer structures and reduces the efficiency of inter-layer energy transfer, thereby altering both the organisation and scale of the fluctuations within the canopy. These results clarify how turbulence in dense canopies is organised and sustained, providing a unified energetic interpretation that links coherent structures to scale-dependent mechanisms.
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All authors Riccardo Bertoncello, Alessandro Chiarini, Giulio Foggi Rota, Maurizio Quadrio, Marco Edoardo Rosti

Astrophysics of Galaxies

Revisiting the enigmatic sixth star cluster in the Fornax dwarf spheroidal galaxy

Chiara Crociati, Annette M. N. Ferguson, Raffaele Pascale et al. (+7 more)

The Fornax dwarf spheroidal (dSph) galaxy is one of only two Local Group dSphs that host a population of globular star clusters (GCs), the present-day properties of which have often been used to investigate the nature of the dark matter. An additional overdensity of stars called Fornax 6, lying at a projected distance of $\sim$0.3 kpc from the galaxy centre, was recently identified as a sixth GC residing in Fornax. However, this conclusion was based on shallow, low-resolution photometric observations and a limited number of spectra. Here, we reinvestigate the nature of Fornax 6 by analysing MUSE/Wide-Field-Mode observations alongside deep GMOS-S imagery. Using a sample of 132 spectra of red giant and horizontal branch stars, we confirm the Fornax 6 overdensity as a distinct chemo-dynamical component with respect to the surrounding field population. Specifically, we identify 43 likely members associated with the cluster, from which we measure $\rm [Fe/H] =-0.61\pm0.03\,$dex, $v_{\rm los} = 50.9^{+0.8}_{-0.7}\,\rm km \,s^{-1}$, $\sigma_v = 3.2^{+1.4}_{-1.5}\,\rm km \,s^{-1}$. The main-sequence turn-off, observed here for the first time, strongly suggests that these stars are coeval and well described by a $\sim$3 Gyr old isochrone. The cluster is characterised by an irregular morphology, a large half-light radius ($R_{h}=8.8^{+1.1}_{-1.3}\,$pc), a small flattening ($e=0.14^{+0.12}_{-0.10}$), and low luminosity ($M_{V} = -5.0 \pm 0.4$). Our improved characterisation of Fornax 6 supports its classification as a genuine low-mass cluster likely undergoing tidal disruption, making it the youngest and most metal-rich member of Fornax's unique GC system.
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All authors Chiara Crociati, Annette M. N. Ferguson, Raffaele Pascale, Sebastian Kamann, Silvia Martocchia, Jess M. Howell, Pete B. Kuzma, Dougal Mackey, Sakurako Okamoto, Masato Onodera

Lattice Field Theory

Efficient Quantum Simulations of Yang-Mills theory with Maximal-tree Gauge

Tianyin Li, Ying-Ying Li, Xiaoyang Wang et al. (+1 more)

We develop a quantum algorithmic framework for the efficient simulation of Yang–Mills theories, including the $\mathrm{SU}(3)$ gauge theory in Quantum Chromodynamics (QCD). The framework uses maximal-tree gauge in terms of gauge field variables that removes all local gauge redundancies. In the resulting gauge-fixed formulation and digitization in the field-amplitude basis, we show that Hamiltonian time evolution admits an efficient implementation based on quantum singular value transformation (QSVT). We derive upper bounds on the total number of qubits and gate complexity, finding polynomial scaling with the inverse simulation precision $1/\varepsilon_s$, lattice volume $\mathcal{V}$, gauge coupling $g$, and target energy scale $E$. Our results provide a rigorous complexity-theoretic demonstration that non-Abelian Yang–Mills theories can be simulated efficiently on quantum computers, paving the way toward first-principles quantum simulations of non-perturbative QCD dynamics.
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All authors Tianyin Li, Ying-Ying Li, Xiaoyang Wang, Hongxi Xing

Instrumentation and Detectors

Design and performance of the Fast Beam Condition Monitor for luminosity and background measurement at the CMS Experiment in LHC Run 3

The CMS BRIL Collaboration: Eliana Acurio, Ying An, Iakov Andreev et al. (+110 more)

The Fast Beam Condition Monitor (BCM1F) has been used at the CMS Experiment since the first LHC circulating beams in 2008. Originally meant as a beam-induced background monitor for fast beam losses detection, it showed a potential also for luminosity measurements in 2012 running, and has been used for luminosity measurements since the beginning of Run 2 data taking in 2015 as a part of the Beam Radiation, Instrumentation and Luminosity (BRIL) system. Over the years, the system has undergone various upgrades to the sensors, the front-end and back-end electronics, providing improvements in the precision of the measurements, that remain valid in the higher pileup conditions of LHC Run 3 (2022-2026). Based on the experience of all BCM1F Run 2 upgrades, the detector was completely rebuilt prior to LHC Run 3 using AC-coupled silicon-pad diodes and active cooling. This latest detector version exhibits excellent linearity with instantaneous luminosity and achieves nanosecond-level timing precision, enabling improved systematic corrections for luminosity and background measurements. This paper presents a detailed overview of the detector system for LHC Run 3, including the selection and qualification of sensors as well as a summary of the readout system. It also outlines the processing and calibration strategy for luminosity data, discussing operational hurdles and comparing BCM1F measurements to other CMS luminosity measurements to assess the system's performance as a luminometer. Lastly, the implications for the design of a future luminosity detector to be used in the envisioned HL-LHC upgrade are discussed.
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All authors The CMS BRIL Collaboration: Eliana Acurio, Ying An, Iakov Andreev, Tomas Atehortua, Georg Auzinger, Hamed Bakhshiansohi, Gergely Balint, Luis Ignacio Banos, Juan Pedro Barajas Ibarria, Hugo Alberto Becerril, Jose Feliciano Benitez, Philip H. Butler, Alan Campbell, Edgar Fernando Carrera Jarr{\i}n, Alfredo Castaneda Hernandez, Marco Costa, Antonio Cota Rodriguez, Luis Enrique Cuevas Picos, Anne Dabrowski, Vladyslav Danilov, Andres Guillermo Delannoy Sotomayor, Hedwin Aaron Encinas Acosta, Krisztian Farkas, Anna Feherkuti, Mahmoud Moussa Abdelkhalek Gadallah, Luis Gabriel Gallegos Marinez, Angela Giraldi, Alfredo Gurrola, Moritz Guthoff, Mykyta Haranko, Maria Hempel, Hans Henschel, Shilpi Jain, Armin Kadlecsik, Jan Kaplon, Adam Kardos, Olena Karacheban, Nimmitha Karunarathna, Joscha Ahauser, Georgios Krintiras, Leen Lambers, Jessica Leonard, Moises David Leon Coello, Maksim Jenihhin, Willard Johns, Markus Klute, Wolfgang Lange, Kuan-Yu Lin, Wei Heng Liu, Wolfgang Lohnmann, Arkady Lokhovitskiy, Robert Loos, Peter Major, Sophie Mallows, Jeremiah Mans, Daniel Marlow, Badder Marzocchi, John-Erik Meißner, Philip Jason Meltzer, Stefano Mersi, Andreas Bernhard Meyer, Dmitri Mihhailov, Valeria Monti, Michele Mormile, Javier Alberto Murillo Quijada, Vlodymyr Myronenko, Cristina Oropeza Barrera, Younes Otarid, Christopher Palmer, Jose David Ochoa Flores, Michelangelo Pari, Gabriella Pasztor, Marek Penno, Fabio Lucas Pereira Carneiro, Elena Popova, Attila Jozsef Radl, Evan Altair Ranken, Beatriz Ribeiro-Lopes, Francesco Romeo, Carlos Romero, Jonas Rubenach, Alexander Ruede, Vladimir Ryjov, Santeri Saariokari, Alessia Saggio, Valerie Scheurer, Vahid Sedighzadeh Dalavi, Mohammad Sedghi, Tatiana Selezneva, Konstantin Sharko, Alexey Shevelev, Konstantin Shibin, Sunil Somalwar, Rafael Sosa, Stefan Spanier, David Stickland, Robert Stone, Andromachi Tsirou, Oleksii Turkot, Lizardo Valencia Palomo, Cristina Vazquez Velez, Roger Rusack, Paola Tropea, Balazs Ujvari, Mayda Velasco, Piero Giorgio Verdini, David Walter, Joanna Wanczyk, Jesus Alberto Velazquez Corral, Daniel John Wilbern, Zhen Xie, Maryam Zeinali, Wolfram Zeuner

Materials Science

Crystal Structure Prototype Identification via Element-Mapped Rotation-Invariant Descriptors

Pai Li

We present a method for identifying crystal structure prototypes from local atomic environments. A center atom and its neighbors within a distance-normalized cutoff are mapped to anonymous element types (A/B/C/D) by proximity, and a NEP-style descriptor-radial Chebyshev moments plus contracted spherical-harmonic (S-vector) invariants-is computed per type block. The descriptor is rotation-invariant by construction (MLFF-style contraction with analytic normalization constants), so no rotation augmentation is needed. A trainable block-diagonal projection compresses the 316-dimensional raw basis into a 168-dimensional learned descriptor fed to a three-layer MLP. The model classifies each atom into one of 271 AFLOW crystal structure prototypes or the amorphous class (272 classes), reaching 99.38% accuracy on 538,190 per-atom samples. The full pipeline (descriptor extraction + inference) runs on a single CPU core at 3.9 s per 10,000 atoms, making it suitable for website deployment.
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High Energy Physics (Phenomenology)

An Axial $U_A(1)_{L_\mu-L_\tau}$: UV Completion and Experimental Searches

Rundong Fang, Jinhui Guo, Ming Li et al. (+3 more)

We propose an anomaly-free and renormalizable axial $U_A(1)_{L_\mu-L_\tau}$ model and study its experimental signatures for $A'$ masses from the MeV scale to the TeV scale. The opposite charges of the left- and right-handed charged leptons forbid the usual muon and tau Yukawa interactions. Their masses are instead generated by a singlet scalar and heavy vector-like leptons through a universal-seesaw mechanism. We focus on heavy vector-like leptons, small light–heavy mixing, and $m_s\gtrsim10~\mathrm{GeV}$. In this limit, the observables considered here depend mainly on $(m_{A'},g_X)$, while the other model parameters are restricted by mixing and perturbativity. We confront this benchmark with current experimental searches. For neutrino trident production, our finite-$m_\mu$ calculation shows that $A'$ modifies the axial weak coefficient, rather than the vector coefficient relevant to the usual $L_\mu-L_\tau$ model. The longitudinal mode enhances muon bremsstrahlung and gives a negative contribution to $(g-2)_\mu$; the latter dominates over the scalar contribution in our benchmark. Combining these results with invisible meson decays and four-muon resonance searches, we summarize the phenomenological constraints in the $(m_{A'},g_X)$ plane. For $m_{A'}\gg m_\mu$, vector and axial final-state-radiation rates become nearly identical, so the corresponding collider limits can be obtained by rate matching. At a future muon collider, the total rate alone does not fully resolve the interaction structure, whereas angular distributions, especially the forward–backward asymmetry in $\mu^+\mu^-\to\tau^+\tau^-$, retain direct sensitivity to chirality.
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All authors Rundong Fang, Jinhui Guo, Ming Li, Jia Liu, Xiao-Ping Wang, Yiheng Xiong

High Energy Physics (Phenomenology)

Hunting long-lived doubly charged scalars at the HL-LHC

Biplob Bhattacherjee, Rituparna Ghosh, Swagata Mukherjee et al. (+1 more)

This work studies the collider phenomenology of long-lived doubly charged scalars. After reviewing the existing searches for the doubly charged scalar in both the prompt and the long-lived regimes, we identify an intermediate range of proper decay length, namely, $\mathcal{O}(0.1~\mathrm{mm}) \lesssim c\tau \lesssim \mathcal{O}(100~\mathrm{mm})$, where conventional searches lose sensitivity. We investigate the prospects for probing the doubly charged scalar both in the presence and in the absence of the $\Delta L=2$ Yukawa coupling of the $SU(2)_{L}$ complex triplet. In the presence of this coupling, $H^{\pm\pm}$ can be long-lived only for masses in the range $100$-$150~\mathrm{GeV}$, whereas in the fermiophobic scenario (i.e., in the absence of the $\Delta L=2$ coupling), the range extends to $\mathrm{TeV}$ scale. We propose a displaced-vertex search at the HL-LHC for doubly charged scalars with masses up to $\approx 1~\mathrm{TeV}$ and $c\tau=10$-$100~\mathrm{mm}$ in the fermiophobic scenario, while a benchmark point with a doubly charged scalar of mass $120~\mathrm{GeV}$ and $c\tau = 5~\mathrm{mm}$ is considered when the complex triplet scalar couples to leptons. We show that a cut on the invariant mass of the displaced vertex as reconstructed from the associated tracks can strongly suppress Standard Model backgrounds. We present projected limits on the Drell-Yan pair-production cross section for the doubly charged scalar at $\sqrt{s}=14~\mathrm{TeV}$ with an integrated luminosity of $3000~\mathrm{fb}^{-1}$, considering two illustrative assumptions for the residual background. Displaced-vertex searches thus probe a region complementary to those covered by prompt and heavy stable charged-particle searches.
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All authors Biplob Bhattacherjee, Rituparna Ghosh, Swagata Mukherjee, Nabin Kumar Pidikaka

Atomic Physics

Influence of Many-Body Dipole-Dipole Interactions on Excitation Transfer in a Dense Gas

A. A. Bobrov, S. A. Saakyan, B. B. Zelener et al. (+1 more)

We study non-radiative dipole-dipole induced excitation transfer in dense Rb vapour. We show that density dependence of characteristic time of the excitation diffusion changes from linear to non-linear for high Rb density. It is attributed to the breakdown of binary collisions approach to the dipole-dipole excitation transfer. It is shown that the observed result can be qualitatively described if the mean free path is replaced by mean interatomic distance for the chracteristic diffusion length.
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All authors A. A. Bobrov, S. A. Saakyan, B. B. Zelener, V. A. Sautenkov

Soft Condensed Matter

Asymmetric Ions in Solution are Similar to Active Brownian Particles

Setare Mostajabi Sarhangi and Dmitry V. Matyushov

Molecular dynamics simulations of electrolyte ions with charge shifted by the distance $d$ from the ion geometrical center have shown that mechanical equilibrium in the ion's body frame is not established beyond a critical shift distance $d^*$. A sharp crossover to a non-zero body-frame force occurs due to frustration of water molecules failing to compensate the electrostatic pull with a local density augmentation. A solution ion with asymmetric charge experiences a net body-frame force similar to self-propelled motion of active-matter Brownian particles. Thermal equilibrium and zero laboratory-frame force are still maintained, but the diffusion constant drops significantly ($\sim 400$ times) when the charge displacement crosses the threshold value $d^*$. Alternative routes to the diffusion constant become inequivalent and the diffusion constant from the mean-squared displacement is much higher than those from velocity and force correlation functions.
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Statistical Mechanics

Long-time Dynamics of Many-body Open Quantum Systems using Quantum Generating Functions

Katha Ganguly, Dario Poletti and Bijay Kumar Agarwalla

The interplay between coherent unitary evolution and environment-induced dissipation can give rise to a wide range of non-equilibrium dynamics in open quantum systems, ranging from interesting transport phenomena to dynamical phase transitions. However, accessing such long-time dynamics remains challenging for the existing methods developed for the simulation of many-body open quantum systems. We address this problem by developing a quantum generating function (QGF) formalism for open many-body systems for both ensemble-averaged dynamics governed by a Markovian quantum master equation and trajectory-resolved dynamics described by the quantum trajectory formalism, including quantum jumps, and quantum state diffusion. Our approach computes the dynamics of higher-order moments and fluctuation statistics without explicitly evolving the quantum state, thereby providing an efficient and scalable approach for investigating many-body open quantum systems. We demonstrate the versatility of the formalism by applying it to both the integrable open XXZ chain and the nonintegrable open next-nearest-neighbor XXZ spin chain, where it uncovers distinct initial state dependent long-time transport regimes. Our work establishes quantum generating functions as an efficient and scalable framework for investigating long-time dynamics in open quantum many-body systems.
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High Energy Physics (Phenomenology)

Enigmatic properties of $\Xi(1620)$ and $\Xi(1690)$

Taísa Veloso, K. P. Khemchandani, A. Martinez Torres et al. (+2 more)

Motivated by a considerable release of data on first two excited states of the doubly strange baryon, $\Xi(1620)$ and $\Xi(1690)$, from different experimental collaborations in recent years, we investigate meson-baryon interactions in a coupled-channel approach. The systems are composed of pseudoscalar and vector mesons and the calculations are done for the total spin 1/2 and isospin 1/2 configuration. The tree-level interactions are deduced from Lagrangians based on chiral and hidden local symmetries. Specifically, we make an attempt to describe (1) data on the $K^-\Lambda$ femtoscopic correlation function coming from $p\,p$ and $Pb\,Pb$ collisions, and (2) the available data on invariant mass distributions for different systems: $\pi\Xi$, $\bar K \Sigma$ and $\bar K \Lambda$. We find that the amplitude which yields the correlation function close to the data results in mass distributions of different meson-baryon systems that are in discordance with the experimental data and vice-versa.
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All authors Taísa Veloso, K. P. Khemchandani, A. Martinez Torres, Luciano M. Abreu, Li-Sheng Geng

Accelerator Physics

Large Magnet Structures for Fusion Technology: Lessons from ITER

Neil Mitchell

Over a period of 40 years, the ITER project has provided many examples in large magnet structures, from pre-concept to design to manufacture to delivery and assembly, from which lessons can be learned for the future. This presentation is divided into three parts. The first, 'Making and Assembling Large (steel) Cryogenic Structures for Magnets' is based on ITER Coil Structure experience, particularly the Central Solenoid (CS) and Toroidal Field (TF) structures and particularly on large 316LN forgings weighing about 50t individually, requiring then high accuracy machining and deep (up to 0.3m) welds with controlled distortion. New materials development is often proposed. This is easy on a laboratory scale, but often not transferable to an industrial large scale. Examples are provided. The issues to be considered (and solved) are large scale quality (and repair of defects), joining, tolerances and assembly. The second 'Designing Large Steel Support Structures for Magnets' is concerned with structural design codes & criteria, and modern analysis, especially of imperfect, but manufacturable structures. Points that are considered are typical critical issues with cyclically loaded thick components, analysis of partial penetration welds and other welds not permitted under normal American Society of Mechanical Engineers (ASME) welding procedures (including fillet welds and/or those volumetrically not inspectable by Non-Destructive Examinations (NDE)) and allowing for tolerance compensation (i.e. designing with overmetal or designing for shimming). The third 'Avoiding or Reducing Large Steel Support Structures for Magnets' shows how it is possible to choose other routes to include structural materials in magnets, for example (as in ITER TF coils) by using plates to contain the conductor, or by using a thick conductor jacket to at least share the loads with massive steel cases.
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Mathematical Physics

2-Morita Theory of $E_2$-Algebras and Module Categories

Rongge Xu and Holiverse Yang

Building on our previous work on 2-Morita equivalence for $E_2$-algebras using topological pictures, we develop a systematic framework for Morita equivalence of topological orders in different dimensions in terms of $n$-Morita categories $\mathrm{Mrt}_{E_n}(\mathcal{C})$. In this framework, various notions of $n$-Morita equivalence are unified as equivalences of objects in $\mathrm{Mrt}_{E_n}(\mathcal{C})$. We also compare the constructions of higher Morita categories due to Haugseng and to Gwilliam–Scheimbauer. For $n=1,2$, we prove that the functor $\mathrm{Mod}_n:\mathrm{Mrt}_{E_n}(\mathcal{C})\to \mathrm{Mrt}_{E_{n-1}}(\mathrm{LMod}^{\mathrm{rep}}(\mathcal{C}))$ is an equivalence, relating the algebraic description of higher Morita theory to its realization in terms of module categories. In this formulation, the notion of a bi-bimodule arises naturally and provides a common framework for local and confined modules. Its explicit orientation data, together with the corresponding fusion rules, clarifies the relations among defects arising from condensation in topological orders.
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Chaotic Dynamics

Exploring continuous beta-ensembles: A Python implementation for random matrix spectral statistics

Dorin Weissman

We present an open-source Python package for sampling the Gaussian, Laguerre, Jacobi, and Circular $\beta$-ensembles of random matrix theory. The package implements the Dumitriu–Edelman and Killip–Nenciu constructions, allowing efficient generation of random spectra for general $\beta > 0$. In addition to spectrum generation, it includes tools for the analysis of spectral statistics, from standard nearest-neighbor spacings and spacing ratios to non-adjacent $k$-spacings and the spectral form factor. These tools can be applied to generic spectral data, allowing users to compare them with and fit them to $\beta$-ensemble predictions. In this note, we review the $\beta$-ensembles, describe the package interface, and illustrate its use through several numerical experiments motivated by applications to quantum chaos. Our numerical results include an analysis of $\beta$ as a continuous fitting parameter in spacing ratio statistics, an examination of the numerical evidence for the conjectured $k$-spacing ratio distributions, and a study of the spectral form factor for general values of $\beta$.
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Instrumentation and Methods for Astrophysics

Towards the exploration of astrophysical datacubes through volumetric rendering within CARTA

Ixaka Labadie-García, Adrianna Pińska, Angus Comrie et al. (+5 more)

Data products from astrophysical observations may contain three or more dimensions: most commonly two spatial dimensions and a third spectral dimension, and possibly additional axes such as polarisation or time. Visualising three-dimensional image data is particularly useful for analysing the kinematics and evolution of various objects; however, the large scale of data produced by next-generation observatories and the complexity of displaying 3D data on a 2D screen make visualisation challenging. In this article, we present a scalable and interactive 3D visualisation approach within the astronomy software CARTA. We implemented a prototype 3D rendering widget with ThreeJS and known techniques to improve efficiency (e.g. compression, downsampling) and found that large datacubes up to 128 GB can be visualised locally with a loading time of a few minutes. We analysed the performance in the frontend and in the backend, finding that the bottleneck of our implementation lies in the frontend. This is due to storing the data in a single array in the frontend, unlike in the backend, where it is accessed and sent in blocks. This study paves the way for making 3D visualisation of large datacubes available to the community by implementing a 3D rendering widget in a future release of CARTA.
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All authors Ixaka Labadie-García, Adrianna Pińska, Angus Comrie, Michaela van Zyl, Manuel Parra-Royón, Susana Sánchez-Expósito, Lourdes Verdes-Montenegro, Julián Garrido

Solar and Stellar Astrophysics

Bright Metal-Poor Star Survey - I. Tomo-e Gozen narrow-band photometric survey and medium-resolution spectroscopic follow-up

Hiroko Okada, Takumi Iwasaki, Nozomu Tominaga et al. (+21 more)

We present the Tomo-e Gozen Bright Metal-Poor Star Survey (TeMPS), a wide-area narrow-band photometric survey for bright metal-poor stars in the northern sky. The survey uses the Tomo-e Gozen camera on the 1.05 m Kiso Schmidt telescope with four narrow-band filters centered on the \ion{Ca}{2} H and K lines, the CH $G$ band, H$\alpha$, and a reference wavelength region. We review the survey strategy, photometric processing, and calibration of metallicity and carbon abundance estimates derived from narrow-band colors. We further present medium-resolution spectroscopic follow-up with Nayuta/MALLS to validate the photometric selection and identify new metal-poor stars. The current data set covers $\gtrsim 22,000$d̃eg$^{2}$ in all four bands with a total integration time of $\sim 100$ hr. The median limiting magnitudes at S/N = 20 correspond to $G\sim12.5$. By combining narrow-band photometry with archival broad-band photometry and Gaia distances, we estimate $T\_{\rm eff}$, $\log (g)$, metallicity, and carbon abundance. Calibration against literature abundances derived from high-resolution spectra shows typical scatters of $< 0.3$ dex in metallicity and $< 0.4$ dex in carbon abundance. We estimate metallicities for $\sim 1.7$ million stars and identify $\sim 16,000$ very metal-poor candidates with [M/H]$_{\rm NB,fin}<-2$. We show that Nayuta/MALLS medium-resolution spectra provide metallicities consistent with high-resolution measurements, with a scatter of $\sim 0.27$ dex. Among 32 photometrically selected candidates followed up with MALLS, 24 are confirmed to have [M/H]$_{\rm MALLS}< -2$, including one newly identified star with [M/H]$_{\rm MALLS}\simeq -3.4$. These results demonstrate that Tomo-e Gozen narrow-band photometry and MALLS medium-resolution spectroscopic follow-up efficiently select bright metal-poor stars for future high-resolution abundance studies. (abbreviated)
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All authors Hiroko Okada, Takumi Iwasaki, Nozomu Tominaga, Wako Aoki, Satoshi Honda, Kurumi Furutsuka, Tadafumi Matsuno, Tomoki Morokuma, Takuma Suda, Miho N. Ishigaki, Naoto Kobayashi, Hidenori Takahashi, Yuu Niino, Satoshi Takita, Sohei Kondo, Yuki Mori, Kenzo Kinugasa, Shigeyuki Sako, Tomio Kanzawa, Hikaru Iwashita, Kenji Mitsui, Takeo Fukuda, Keiko Kaneko, Mitsuhiro Fukushima

Quantum Physics

Tight Bounds for Purity and Product Testing from Partial Transposition

Oren Akresh and Jacob Beckey

Coherent measurements across multiple copies of an unknown quantum state can substantially reduce the number of samples required to learn its properties, but remain experimentally challenging. Current experiments typically prepare and measure one copy at a time, potentially adapting later measurements to earlier outcomes. A central challenge is adaptivity, which makes the space of possible measurement strategies difficult to characterize. The positive-partial-transpose (PPT) relaxation bypasses this complexity by considering a larger, mathematically tractable class of measurements, at the risk of weakening the resulting bounds. Here we show, surprisingly, that the relaxation loses nothing at the level of asymptotic sample complexity for two fundamental tasks: purity testing and product testing. In both cases, lower bounds against the full class of PPT measurements are matched by nonadaptive single-copy protocols. Moreover, our proof requires only basic symmetric subspace identities, providing a simple route to sharp lower bounds for adaptive single-copy measurements.
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Mathematical Physics · Cross-listed from math.NA

QH-GEM: Quantum-Hydrodynamic Generative Modeling

Harbir Antil, Alex Kaltenbach and Sarswati Shah

In this paper, we develop a deterministic, physically constrained generative framework based on the Madelung formulation of the free-particle Schrödinger equation. A reference Born probability density and a controllable initial phase function serve as initial data for the free Madelung system, which couples the Born probability density and phase function through the Bohm quantum potential, while the phase function determines the hydrodynamic velocity field. Provided that the Born probability density remains positive and the hydrodynamic velocity field generates a unique global characteristic flow, samples drawn from the reference density and transported along the characteristic flow are distributed according to the evolving Born probability density at every time. As a consequence, randomness enters only through the initial sampling; the subsequent generation is deterministic and involves neither stochastic dynamics nor an independently parameterized time-dependent velocity field. We formulate terminal-time distribution matching as a PDE-constrained phase-identification problem and derive the underlying Hamiltonian and Fisher-information structure. For isotropic Gaussian wave packets, we obtain explicit dynamics and a necessary and sufficient condition for exact reachability of isotropic Gaussian targets by quadratic initial phase functions, together with the corresponding sampling map. For a smooth prescribed potential initial velocity field, we further establish that the characteristic flow approximates the associated first-order transport map with an O(T^2) error, both uniformly and in the 1- and 2-Wasserstein distances. A numerical Gaussian benchmark validates the fully discrete forward solver, while full-grid PDE-constrained phase identification is demonstrated for asymmetric bimodal targets.
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