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Physics

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Thursday 8 October

Computational Physics

Ghost tasking for parametrized Gaussian Processes solving linear differential equations

Johanna Moser, Christopher Albert and Sascha Ranftl

Physics-informed machine learning has gained significant attention in recent years. In regimes of limited data, parametrized Gaussian processes have become popular. Existing approaches, however, often face limitations, such as requiring parametrizable (also called controllable) systems or a large number of output tasks. In this work, we introduce a systematic procedure we call "ghost tasking", using auxiliary tasks to circumvent these limitations. We prove that such ghost tasks can render any non-parametrizable system effectively parametrizable, enabling algorithmic construction of parametrized Gaussian Processes while keeping the number of required tasks (i.e. output dimensions) and latent functions low. We find that ghost tasking performs especially well in an inverse problem setting, even with very few available data. We show the usage and power of ghost tasking in three experiments, providing systematic comparisons to the only other currently available method applicable to all experiments. We provide necessary syntax and explications for two computer algebra programs that compute parametrizations for systems with polynomial or rational coefficients. Our theoretical results extend to systems with meromorphic functions.
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Quantum Physics

Exact value and rigidity of the $2\times3$ magic rectangle

Isaac Barouch Essayag and Aryeh Lev Zabokritskiy

The $2\times3$ magic rectangle is a nonlocal game in which two players match entries subject to incompatible parity constraints. We prove that its quantum value is $(1+\sqrt{2/3})/2$ and classify all optimal strategies in arbitrary finite local dimensions, allowing general measurements. Every optimal strategy contains a maximally entangled pair of four-dimensional systems, with fixed measurements on the local state supports up to local isometries and ancillary systems. The attaining construction was previously known from quantum random access codes. An exact sum-of-squares identity gives the upper bound, and its equality relations determine the measurement algebra needed for the classification. The rectangle determines the largest magic-square score compatible with perfect prediction of Alice's first row by an adversary with quantum side information. We classify all finite-dimensional strategies attaining this score with perfect prediction and show that one minus the best compatible guessing probability has linear order in the score excess above it. The same rigidity theorem classifies all optimal three-bit random access codes that hide the full input parity.
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Quantum Physics

On the separability of Bell-diagonal states with absolutely positive partial transposition

Ayan Patra and Beatrix C. Hiesmayr

Absolutely positive partial transpose (APPT) states, which remain PPT under every global unitary, provide a spectral relaxation of absolutely separable states, which remain separable under every such transformation. Despite substantial progress, whether these two notions coincide beyond qubit-qudit systems remains unresolved, motivating the study of structured state families in which the APPT spectral constraints and separability can be analyzed exactly. We study this problem for Bell-diagonal states in two settings: the standard two-qutrit Weyl-Heisenberg basis and the two-ququart lattice basis generated by two-qubit Pauli operators. In the two-qutrit case, we show that a linearized necessary condition for APPT defines a polytope of spectra in which every associated Weyl-Heisenberg Bell-diagonal state admits an exact decomposition into explicitly separable states. This yields a separability criterion that applies to a region even larger than the APPT set itself. In the two-ququart lattice Bell-diagonal setting, we show that a state remains PPT under every permutation of its Bell coefficients if and only if its six largest Bell coefficients sum to at most 1/2, and we prove that all such states are separable. Equivalently, every entangled lattice Bell-diagonal state becomes NPT after a suitable coefficient permutation and is therefore not APPT. The proofs combine convex-polytope analysis, affine and symplectic orbit reductions, and exact rational decompositions into separable states supported on affine Lagrangian subsets. Our results rule out entangled APPT states in both Bell-diagonal families, and provide simple spectral inequalities as sufficient criteria for separability in both cases. Being basis-specific, however, they do not by themselves settle whether APPT and absolute separability coincide.
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Quantum Physics

Unitary-accessible coherence-erasure distance: Exact qubit solution and a tight qutrit bound

Dong-Ping Xuan, Hua Nan, Zhi-Xi Wang et al. (+1 more)

We introduce the unitary-accessible coherence-erasure distance, which measures the minimum unitary-control cost required to transform a quantum state into an incoherent state without changing its spectrum. The target states are restricted to incoherent states on the same unitary orbit, leading to a geometry different from conventional state-space proximity. We establish inequalities relating orbit-restricted quantum transport, Bures geometry, and the unitary-control distance. These quantities coincide for pure states but can differ for mixed states. For qubits, we derive an exact expression and show that, in the nondegenerate case, the coherence-erasure cost depends on the eigenbasis orientation rather than on the eigenvalues. For nondegenerate qutrits, we reduce the problem to an optimization over the monomial unitary group. We derive the tight universal bound $\arccos[(2\sqrt2-1)/4]$ and construct an explicit eigenbasis that attains it. The resulting distance also determines the minimum coherence-erasure time under bounded unitary driving, giving it a direct operational meaning.
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All authors Dong-Ping Xuan, Hua Nan, Zhi-Xi Wang, Shao-Ming Fei

Materials Science

Multifunctional synaptic learning and neuromorphic computing using crystalline TiO$_x$/NiO$_x$ heterojunction-based memory devices

Dip Manna, Koushik Mondal, Subhajit Karmakar et al. (+5 more)

An attempt is made here to mimic different properties of biological synapses using Ag/TiO$_x$/NiO$_x$/p$^{++}$-Si memristor structure by studying its different transport properties under dc and pulsed bias. The presence of crystalline NiO$_x$ with smaller gains is found to be helpful to get TiO$_x$ deposited on its top with crystalline properties and larger grains. The heterostructure offers stable bipolar forming free non-volatile resistive switching characteristics under reverse biased condition with gradual set and reset features. These devices are also able to successfully implement the classical Pavlov's learning, study artificial nociceptor and Morse code detection. While incorporating synaptic weights derived from the measured conductance programming pulse relationship, an artificial neural network achieves nearly 95% accuracy in MNIST digit recognition. In brief, NiO$_x$/TiO$_x$ heterojunction plays the pivotal role in getting such reproducible $I-V$ characteristics for mimicking different properties of biological synapses.
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All authors Dip Manna, Koushik Mondal, Subhajit Karmakar, Pawan Kumar Ojha, Sourav Roy, Biswarup Satpati, Prasanta Karmakar, Supratic Chakraborty

Mathematical Physics · Cross-listed from math.PR

Strong RSW estimates for the FK-Ising model on s-embeddings

Dmitry Chelkak and Yanqing Wei

We adapt the 'induction over scales' scheme of Duminil-Copin, Manolescu, and Tassion to the FK-Ising model on s-embeddings. Namely, we prove the existence of crossings of rough topological quadrilaterals with unfavorable boundary conditions, known as 'strong' RSW, under the 'uniformly bounded geometry' assumption (all edge lengths are comparable to 1 and all angles are bounded from below) on the tangential quads that form an s-embedding. This result has a number of standard consequences like quasi-multiplicativity of arm events and fractal properties of the clusters. It can be applied in a variety of setups including near-critical Ising models on regular grids below the correlation length scale by considering appropriate s-embedding thereof.
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Earth and Planetary Astrophysics

Size, Shape, and Geometric Albedo of Dwarf Planet Quaoar's Largest Satellite Weywot

Cameron Collyer, Estela Fernandez-Valenzuela, Benjamin Proudfoot et al. (+3 more)

The small satellites of dwarf-planet size worlds in trans-Neptunian space are thought to be produced through giant impacts, and are typically observed to have bright water-ice-dominated surfaces. Here we focus on Quaoar's small primary satellite, Weywot. We build on previous work by re-analyzing the June 2023 stellar occultation by Weywot using results from 11 orbits of HST imaging with the Wide Field Camera 3. Weywot's rotational lightcurve was constrained along with its independent photometric phase curve, which we used to obtain more robust measurements of Weywot's size, shape, and geometric albedo. We found Weywot's volume-equivalent radius to be req = 73+-5 km, with principal axes a = 82+5-3 , b = 73+5-3, c = 65+8-12 km, indicating a triaxial shape. This shape is consistent with a Roche-ellipsoid rubble-pile interpretation requiring only moderate internal friction at Weywot's current semimajor axis, and Weywot can retain this shape down to Quaoar's co-rotation radius. We also found Weywot's geometric albedo to be quite low, pV = 0.036+0.010-0.006, akin to that of Eris's satellite Dysnomia, but over an order of magnitude lower than Pluto's minor satellites and Haumea's satellites. We propose this may indicate that Weywot's ice-mass fraction < 100%, and that Weywot is not sourced from the water-ice mantle of a differentiated pre-impact progenitor as suggested for Pluto's minor satellites and Haumea's satellites.
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All authors Cameron Collyer, Estela Fernandez-Valenzuela, Benjamin Proudfoot, Bryan J Holler, Jose Luis Ortiz, Ishan Sharma

Chemical Physics

Gas-phase chemistry of $\mathrm{C}_3\mathrm{H}_3^+$: a key building block for carbon mass growth in space

Corentin Rossi, Jean-Christophe Loison, Anne P. Rasmussen et al. (+4 more)

The gas-phase chemistry of $\mathrm{C}_3\mathrm{H}_3^+$ plays a central role in the growth of carbonaceous species across a wide range of environments, from combustion systems to interstellar media. However, the presence of multiple isomers, primarily the linear propargyl cation and the cyclic cyclopropenyl cation, has so far prevented the determination of reliable isomer-specific reaction kinetics. In this work, we combine tunable vacuum-ultraviolet (VUV) photoionization with controlled ion–molecule reaction measurements to selectively produce and probe the reactivity of $\mathrm{C}_3\mathrm{H}_3^+$ isomers. By employing a titration approach, we extract isomer-specific reaction rate coefficients and branching ratios for reactions of $\mathrm{C}_3\mathrm{H}_3^+$ with $\mathrm{C}_2\mathrm{H}_4$, $\mathrm{C}_3\mathrm{H}_4$, and $\mathrm{C}_3\mathrm{H}_6$. Our results demonstrate a strong contrast in reactivity: the most stable cyclic isomer is found to be essentially unreactive under the investigated conditions, whereas the linear isomer exhibits efficient and diverse chemistry leading to the formation of larger hydrocarbon ions. In particular, the formation of $\mathrm{C}_6\mathrm{H}_5^+$ is observed, providing an important intermediate in pathways toward aromatic species. These findings help resolve long-standing ambiguities in previously reported rate coefficients and provide new quantitative constraints for kinetic and astrochemical models. More broadly, this work highlights the importance of isomer-specific chemistry in carbon growth processes and demonstrates the effectiveness of VUV-based photoionization methods for disentangling complex reaction networks in the gas phase.
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All authors Corentin Rossi, Jean-Christophe Loison, Anne P. Rasmussen, Roland Thissen, Nandana Pattathadathil, Christian Alcaraz, Ugo Jacovella

Solar and Stellar Astrophysics

Magnetic flux cancellation in a 3D magnetohydrodynamic simulation of an emerging flux tube with a non-uniform twist

V. Agalianou, S. Patsourakos and V. Archontis

Flux emergence is often accompanied by flux cancellation, which may drive dynamic phenomena in the solar atmosphere. We studied magnetic flux cancellation in a three-dimensional resistive magnetohydrodynamic (MHD) simulation of an emerging flux tube with a non-uniform twist profile. We solved time-dependent resistive MHD equations to model flux emergence into a magnetised background atmosphere. We identified several cancellation sites, estimated their cancellation rates, and examined the magnetic topology and associated jet activity. The non-uniform twist produced multiple opposite photospheric polarities, leading to a complex multipolar magnetic configuration rather than a simple dipolar structure. Interactions between inner secondary magnetic patches resulted in flux cancellation of the photospheric $B_z$ along their polarity inversion line (PIL). These interactions led to the formation of concave-up loops and a cancellation rate of $1.1 \times 10^{19}$ Mx hr$^{-1}$. During cancellation, magnetic reconnection between converging opposite polarities progressively created a coherent magnetic flux rope above the cancellation region. The evolution of the rope was associated with a blowout jet, as the rope expanded and released part of its stored twist into the overlying corona. We also examined two smaller secondary cancellation events at photospheric heights. Our results highlight the role of internal flux cancellation in restructuring the magnetic field and driving blowout-jet activity in emerging regions.
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Mesoscale and Nanoscale Physics

Magnon dynamics driven by the symplectic quantum metric in a chiral soliton lattice

Sidhartha Chatterjee, Andreas Haller, Peter P. Orth et al. (+1 more)

We investigate the effects of quantum geometry on the motion of magnon wave packets in one-dimensional quantum spin chains. In contrast to fermionic systems, where transport phenomena driven by the quantum metric have been extensively studied, we show that the dynamics in bosonic magnon systems are strongly affected by the symplectic structure and the pseudo-unitarity of the transformation of the magnon Bogoliubov-de Gennes Hamiltonian. A chiral soliton lattice provides a setting in which the symplectic quantum metric strongly influences the longitudinal magnon dynamics. We derive the semiclassical response of a magnon wave packet in such a system to a weak, slowly varying perturbation and demonstrate that the wave packet velocity acquires a geometric contribution proportional to the momentum derivative of the symplectic quantum metric, which dominates over the conventional group velocity for a nearly flat band. Solving the resulting equations of motion, we obtain a bounded trajectory in real time with a phase-space area determined by the symplectic quantum metric.
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All authors Sidhartha Chatterjee, Andreas Haller, Peter P. Orth, Thomas L. Schmidt

High Energy Physics (Experiment)

Observation of $\chi_{cJ}\to \Lambda K^0_S\bar \Xi^0 + c.c.$ and improved measurements of $\chi_{cJ}\to \Lambda K^-\bar \Xi^+ + c.c.$

BESIII Collaboration: M. Ablikim, M. N. Achasov, P. Adlarson et al. (+780 more)

By analyzing $(2712.4\pm14.3)\times10^6$ $\psi(3686)$ events collected with the BESIII detector operating at the BEPCII collider, we report the first observation of $\chi_{cJ}\to \Lambda K^0_S\bar \Xi^0 + c.c.$ ($J=0,1,2$) with significances greater than $10\sigma$, including systematic uncertainties, and improved measurements of $\chi_{cJ}\to \Lambda K^-\bar \Xi^+ + c.c.$ The branching fractions of these decays are determined to be $\mathcal{B}(\chi_{c0}\to \Lambda K^0_S\bar \Xi^0+c.c.)=(1.13\pm0.13\pm0.13)\times10^{-4}$, $\mathcal{B}(\chi_{c1}\to \Lambda K^0_S\bar \Xi^0+c.c.)=(0.74\pm0.08\pm0.07)\times10^{-4}$, $\mathcal{B}(\chi_{c2}\to \Lambda K^0_S\bar \Xi^0+c.c.)=(1.16\pm0.11\pm0.14)\times10^{-4}$, $\mathcal{B}(\chi_{c0}\to \Lambda K^-\bar \Xi^++c.c.)=(1.90\pm0.08\pm0.16)\times10^{-4}$, $\mathcal{B}(\chi_{c1}\to \Lambda K^-\bar \Xi^++c.c.)=(1.40\pm0.05\pm0.11)\times10^{-4}$, and $\mathcal{B}(\chi_{c2}\to \Lambda K^-\bar \Xi^++c.c.)=(1.95\pm0.07\pm0.15)\times10^{-4}$. The first uncertainties are statistical, and the second are systematic.
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All authors BESIII Collaboration: M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, C. S. Akondi, R. Aliberti, A. Amoroso, Q. An, Y. H. An, M. S. Anderson, Y. Bai, O. Bakina, H. R. Bao, X. L. Bao, M. Barbagiovanni, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, D. Cabiati, H. Cai, M. H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, T. T. Chang, G. R. Che, Y. Z. Che, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, W. Chen, X. R. Chen, X. T. Chen, X. Y. Chen, Y. B. Chen, Y. Q. Chen, Z. K. Chen, J. Cheng, L. N. Cheng, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. Cottee-Meldrum, H. L. Dai, J. P. Dai, X. C. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denisenko, M. Destefanis, F. De Mori, E. Di Fiore, X. X. Ding, Y. Ding, Y. X. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, Z. J. Dong, M. C. Du, S. X. Du, Shaoxu Du, X. L. Du, Y. Q. Du, Y. Y. Duan, Z. H. Duan, P. Egorov, G. F. Fan, J. J. Fan, K. X. Fan, Y. H. Fan, J. Fang, Jin Fang, S. S. Fang, W. X. Fang, Y. Q. Fang, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, Q. X. Feng, Y. T. Feng, M. Fritsch, C. D. Fu, J. L. Fu, Y. W. Fu, H. Gao, Xu Gao, Y. Gao, Y. N. Gao, Y. Y. Gao, Yunong Gao, Z. Gao, S. Garbolino, I. Garzia, L. Ge, P. T. Ge, Z. W. Ge, C. Geng, A. Gilman, K. Goetzen, J. Gollub, J. B. Gong, J. D. Gong, L. Gong, W. X. Gong, W. Gradl, M. Greco, M. D. Gu, M. H. Gu, C. Y. Guan, A. Q. Guo, H. Guo, J. N. Guo, L. B. Guo, M. J. Guo, R. P. Guo, X. Guo, Y. P. Guo, Z. Guo, A. Guskov, J. Gutierrez, J. Y. Han, T. T. Han, X. Han, F. Hanisch, K. D. Hao, X. Q. Hao, F. A. Harris, C. Z. He, K. K. He, K. L. He, F. H. Heinsius, C. H. Heinz, Y. K. Heng, C. Herold, P. C. Hong, G. Y. Hou, X. T. Hou, Y. R. Hou, Z. L. Hou, H. M. Hu, J. F. Hu, Q. P. Hu, S. L. Hu, T. Hu, Y. Hu, Y. X. Hu, Z. M. Hu, G. S. Huang, K. X. Huang, L. Q. Huang, P. Huang, X. T. Huang, Y. P. Huang, Y. S. Huang, T. Hussain, N. Hüsken, N. in der Wiesche, J. Jackson, Q. Ji, Q. P. Ji, W. Ji, X. B. Ji, X. L. Ji, Y. Y. Ji, L. K. Jia, X. Q. Jia, D. Jiang, S. J. Jiang, X. S. Jiang, Y. Jiang, J. B. Jiao, J. K. Jiao, Z. Jiao, L. C. L. Jin, S. Jin, Y. Jin, M. Q. Jing, X. M. Jing, T. Johansson, S. Kabana, X. L. Kang, X. S. Kang, B. C. Ke, V. Khachatryan, A. Khoukaz, O. B. Kolcu, B. Kopf, L. Kröger, L. Krümmel, Y. Y. Kuang, M. Kuessner, X. Kui, N. Kumar, A. Kupsc, W. Kühn, Q. Lan, W. N. Lan, T. T. Lei, M. Lellmann, T. Lenz, C. Li, C. H. Li, C. K. Li, Chunkai Li, Cong Li, D. M. Li, F. Li, G. Li, H. B. Li, H. J. Li, H. L. Li, H. N. Li, H. P. Li, Hui Li, J. N. Li, J. S. Li, J. W. Li, K. Li, K. L. Li, L. J. Li, L. K. Li, Lei Li, M. H. Li, M. R. Li, M. T. Li, P. L. Li, P. R. Li, Q. M. Li, Q. X. Li, R. Li, S. Li, S. X. Li, S. Y. Li, Shanshan Li, T. Li, T. Y. Li, W. D. Li, W. G. Li, X. Li, X. H. Li, X. K. Li, X. L. Li, X. Y. Li, X. Z. Li, Y. Li, Y. H. Li, Y. B. Li, Y. C. Li, Y. G. Li, Y. P. Li, Z. H. Li, Z. J. Li, Z. L. Li, Z. X. Li, Z. Y. Li, Zaiyi Li, C. Liang, H. Liang, Y. F. Liang, Y. T. Liang, Z. Z. Liang, G. R. Liao, L. B. Liao, M. H. Liao, Y. P. Liao, J. Libby, A. Limphirat, C. C. Lin, C. X. Lin, D. X. Lin, T. Lin, B. J. Liu, B. X. Liu, C. Liu, C. X. Liu, F. Liu, F. H. Liu, Feng Liu, G. M. Liu, H. Liu, H. B. Liu, H. M. Liu, Huihui Liu, J. B. Liu, J. J. Liu, K. Liu, K. Y. Liu, Ke Liu, Kun Liu, L. Liu, L. C. Liu, Lu Liu, M. H. Liu, P. L. Liu, Q. Liu, S. B. Liu, T. Liu, W. M. Liu, W. T. Liu, X. Liu, X. K. Liu, X. L. Liu, X. P. Liu, X. T. Liu, X. Y. Liu, Y. Liu, Y. B. Liu, Yi Liu, Z. A. Liu, Z. D. Liu, Z. Q. Liu, Z. X. Liu, Z. Y. Liu, Ziqiang Liu, X. C. Lou, H. J. Lu, J. G. Lu, X. L. Lu, Y. Lu, Y. H. Lu, Y. P. Lu, Z. H. Lu, C. L. Luo, J. R. Luo, J. S. Luo, M. X. Luo, T. Luo, X. L. Luo, Z. Y. Lv, X. R. Lyu, Y. F. Lyu, Y. H. Lyu, C. L. Ma, F. C. Ma, H. L. Ma, Heng Ma, J. L. Ma, L. L. Ma, L. R. Ma, Q. M. Ma, R. Q. Ma, R. Y. Ma, T. Ma, X. T. Ma, X. Y. Ma, F. E. Maas, I. MacKay, M. Maggiora, S. Maity, S. Malde, Q. A. Malik, L. M. Mansur, Y. J. Mao, Z. P. Mao, S. Marcello, A. Marshall, F. M. Melendi, Y. H. Meng, Z. X. Meng, G. Mezzadri, H. Miao, T. J. Min, R. E. Mitchell, X. H. Mo, A. F. Mohammad, B. Moses, N. Yu. Muchnoi, J. Muskalla, Y. Nefedov, F. Nerling, H. Neuwirth, Z. Ning, S. Nisar, Q. L. Niu, W. D. Niu, Y. Niu, C. Normand, S. L. Olsen, Q. Ouyang, I. V. Ovtin, S. Pacetti, Y. Pan, C. Y. Pang, A. Pathak, Y. P. Pei, M. Pelizaeus, G. L. Peng, H. P. Peng, X. J. Peng, Y. Y. Peng, K. Peters, K. Petridis, J. L. Ping, R. G. Ping, S. Plura, V. Prasad, L. Pöpping, F. Z. Qi, H. R. Qi, L. Y. Qian, S. Qian, W. B. Qian, C. F. Qiao, J. H. Qiao, J. J. Qin, J. L. Qin, L. Q. Qin, L. Y. Qin, P. B. Qin, X. P. Qin, X. S. Qin, Z. H. Qin, J. F. Qiu, Z. H. Qu, J. Rademacker, K. Ravindran, C. F. Redmer, A. Rivetti, M. Rolo, G. Rong, S. S. Rong, F. Rosini, Ch. Rosner, M. Q. Ruan, W. R. Ruangyoo, N. Salone, A. Sarantsev, Y. Schelhaas, M. Schernau, K. Schoenning, M. Scodeggio, W. Shan, X. Y. Shan, Z. J. Shang, J. F. Shangguan, L. G. Shao, M. Shao, C. P. Shen, H. F. Shen, W. H. Shen, X. Y. Shen, B. A. Shi, Ch. Y. Shi, H. Shi, J. L. Shi, J. Y. Shi, M. H. Shi, S. Shi, S. Y. Shi, X. Shi, H. L. Song, J. J. Song, M. H. Song, T. Z. Song, W. M. Song, Y. X. Song, Zirong Song, S. Sosio, S. Spataro, S. Stansilaus, F. Stieler, M. Stolte, S. S Su, G. B. Sun, G. X. Sun, H. Sun, H. K. Sun, J. F. Sun, K. Sun, L. Sun, R. Sun, S. S. Sun, T. Sun, W. Y. Sun, Y. C. Sun, Y. H. Sun, Y. J. Sun, Y. Z. Sun, Z. Q. Sun, Z. T. Sun, H. Tabaharizato, N. T. Tagsinsit, C. J. Tang, G. Y. Tang, J. Tang, J. J. Tang, L. F. Tang, Y. A. Tang, Z. H. Tang, L. Y. Tao, M. Tat, J. X. Teng, J. Y. Tian, W. H. Tian, Y. Tian, Z. F. Tian, K. Yu. Todyshev, I. Uman, E. van der Smagt, B. Wang, Bin Wang, Bo Wang, C. Wang, Chao Wang, Cong Wang, D. Y. Wang, F. K. Wang, H. J. Wang, H. R. Wang, J. Wang, J. H. Wang, J. J. Wang, J. P. Wang, K. Wang, L. L. Wang, L. W. Wang, M. Wang, Mi Wang, N. Y. Wang, P. Wang, S. Wang, Shun Wang, T. Wang, W. Wang, W. P. Wang, X. F. Wang, X. L. Wang, X. N. Wang, Xin Wang, Y. Wang, Y. D. Wang, Y. F. Wang, Y. H. Wang, Y. J. Wang, Y. L. Wang, Y. N. Wang, Yanning Wang, Yaqian Wang, Yi Wang, Yuan Wang, Z. Wang, Z. L. Wang, Z. Q. Wang, Z. Y. Wang, Zhi Wang, Ziyi Wang, D. Wei, D. H. Wei, D. J. Wei, H. R. Wei, F. Weidner, H. R. Wen, S. P. Wen, U. Wiedner, G. Wilkinson, J. F. Wu, L. H. Wu, L. J. Wu, Lianjie Wu, S. G. Wu, S. M. Wu, X. W. Wu, Z. Wu, H. L. Xia, L. Xia, B. H. Xiang, D. Xiao, G. Y. Xiao, H. Xiao, Y. L. Xiao, Z. J. Xiao, C. Xie, K. J. Xie, Y. Xie, Y. G. Xie, Y. H. Xie, Z. P. Xie, T. Y. Xing, D. B. Xiong, G. F. Xu, H. Y. Xu, Q. J. Xu, Q. N. Xu, T. D. Xu, X. P. Xu, Y. Xu, Y. C. Xu, Z. S. Xu, F. Yan, L. Yan, W. B. Yan, W. C. Yan, W. H. Yan, W. P. Yan, X. Q. Yan, Y. Y. Yan, H. J. Yang, H. L. Yang, H. X. Yang, J. H. Yang, L. Y. Yang, R. J. Yang, X. Y. Yang, Y. Yang, Y. G. Yang, Y. H. Yang, Y. M. Yang, Y. Q. Yang, Y. Z. Yang, Youhua Yang, Z. Y. Yang, W. J. Yao, Z. P. Yao, M. Ye, M. H. Ye, Z. J. Ye, K. Yi, Junhao Yin, Qiqin Yin, Z. Y. You, B. X. Yu, C. X. Yu, G. Yu, J. S. Yu, L. W. Yu, T. Yu, X. D. Yu, Y. C. Yu, Yongchao Yu, C. Z. Yuan, H. Yuan, J. Yuan, Jie Yuan, L. Yuan, M. K. Yuan, S. H. Yuan, Y. Yuan, C. X. Yue, Ying Yue, A. A. Zafar, F. R. Zeng, S. H. Zeng, X. Zeng, Y. J. Zeng, Yujie Zeng, Y. C. Zhai, Y. H. Zhan, B. L. Zhang, B. X. Zhang, D. H. Zhang, G. Y. Zhang, Gengyuan Zhang, H. Zhang, H. C. Zhang, H. H. Zhang, H. L. Zhang, H. Q. Zhang, H. R. Zhang, H. Y. Zhang, Han Zhang, J. Zhang, J. J. Zhang, J. L. Zhang, J. Q. Zhang, J. S. Zhang, J. W. Zhang, J. X. Zhang, J. Y. Zhang, J. Z. Zhang, Jianyu Zhang, Jin Zhang, Jiyuan Zhang, L. M. Zhang, Lei Zhang, N. Zhang, P. Zhang, Q. Zhang, Q. Y. Zhang, Q. Z. Zhang, R. Y. Zhang, S. H. Zhang, S. N. Zhang, Shulei Zhang, X. M. Zhang, X. Y. Zhang, Y. T. Zhang, Y. H. Zhang, Y. P. Zhang, Yao Zhang, Yu Zhang, Yu Zhang, Z. Zhang, Z. D. Zhang, Z. H. Zhang, Z. L. Zhang, Z. X. Zhang, Z. Y. Zhang, Z. Z. Zhang, Zh. Zh. Zhang, Zhaoke Zhang, Zhilong Zhang, Ziyang Zhang, Ziyu Zhang, G. Zhao, J.-P. Zhao, J. Y. Zhao, J. Z. Zhao, L. Zhao, Lei Zhao, M. G. Zhao, R. P. Zhao, S. J. Zhao, Y. B. Zhao, Y. L. Zhao, Y. P. Zhao, Y. X. Zhao, Z. G. Zhao, A. Zhemchugov, B. Zheng, B. M. Zheng, J. P. Zheng, W. J. Zheng, W. Q. Zheng, X. R. Zheng, Y. H. Zheng, B. Zhong, C. Zhong, X. Zhong, H. Zhou, J. Q. Zhou, S. Zhou, X. Zhou, X. K. Zhou, X. R. Zhou, X. Y. Zhou, Y. X. Zhou, Y. Z. Zhou, A. N. Zhu, J. Zhu, K. Zhu, K. J. Zhu, K. S. Zhu, L. X. Zhu, Lin Zhu, S. H. Zhu, T. J. Zhu, W. D. Zhu, W. J. Zhu, W. Z. Zhu, Y. C. Zhu, Z. A. Zhu, X. Y. Zhuang, M. Zhuge, J. H. Zou, J. Zu

Fluid Dynamics

On the relationships between pressure geometrization and vortex identification

Han Tu, Hang Zhao and Qi Gao

The profound mathematical and conceptual analogy between pressure in fluid mechanics and gravity in general relativity motivates a novel geometric reinterpretation of flows. This article proposes a theoretical framework for geometrizing pressure by establishing a Newton-Cartan geometry and applying a conformal transformation to the spatial metric. The pressure field is reinterpreted as a geometric potential that induces an effective spatial curvature, encoded in the Ricci tensor Rij and the associated Einstein-like tensor Gij. Within this curved effective space, fluid particles under the exclusive influence of pressure follow geodesics, and the classical Euler equation is recovered in the weak-field limit. The pressure Poisson equation emerges naturally as a consequence of the geodesic equation and the Bianchi identity, revealing pressure as an instantaneous geometric constraint rather than an external force. This framework provides a unified geometric interpretation of widely used vortex identification criteria, demonstrating that the prevailing Eulerian and Lagrangian schemes correspond to different geometric invariants or projections of the effective curvature. In the degenerate two-dimensional (2D) limit, the effective spatial tensor vanishes identically, and the global integral of the total curvature vanishes as well. This topological constraint offers a novel interpretation of the dual-cascade scenario in 2D turbulence: the inverse energy cascade arises from geometric condensation of positive-curvature structures toward larger scales, while the forward enstrophy cascade results from geometric dispersion of negative-curvature structures toward smaller scales.
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Materials Science

Homogeneous Charge Relaxation in Organic Mixed Ionic-Electronic Conductors

Silan Zhang, Scott T. Keene, Junfu Tian et al. (+11 more)

Organic mixed ionic-electronic conductors (OMIECs) couple ionic and electronic signals, enabling energy storage, neuromorphic computing, and bioelectronics. However, how charge relaxes in water once the bias is removed, which determines how long stored states persist, remains unclear. Using operando charge photometry, we tracked charge in OMIEC films during biasing and open-circuit relaxation. Under bias, charges moved as redox fronts. After bias removal, charge instead relaxed uniformly across the channel. Modeling and cryo-electron microscopy indicate that swelling creates connected water-rich pathways through the bulk. These pathways speed ion motion but also let stored charge leak away. Tuning the terminal side chain of a polythiophene controls water uptake and ion trapping. Bulky hydrophobic side chains enable stable programmable states, whereas hydrophilic side chains support fast electrophysiology sensing.
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All authors Silan Zhang, Scott T. Keene, Junfu Tian, Georgina E. Lindop, Simon M. Fairclough, Zhengkang Qu, Xian Wei Chua, Christopher Slaughter, Christina J. Kousseff, Caterina Ducati, Iain McCulloch, Henning Sirringhaus, Akshay Rao, George G. Malliaras

Statistical Mechanics

Mutual Linearity of Complexes in Chemical Reaction Networks

Pedro E. Harunari, Guilherme Fiusa and Matteo Polettini

Exact statements about how a system far from equilibrium responds to changes in its rate constants are scarce beyond linear response, yet they are central to the control of biochemical networks. A notable exception is mutual linearity: in a jump process, controlling the rates of a single transition makes any two stationary probabilities obey an exact affine relation, arbitrarily far from equilibrium. With nonlinear mass-action kinetics, and conservation laws in place of a normalization, chemical reaction networks seem to defy mutual linearity since species concentrations obey no such relation. We show that it was there all along, in the complexes' activities (mass-action monomials) rather than in the concentrations of species. For zero-deficiency networks with a single linkage class, controlling one reaction makes any three stationary activities obey a linear relation whose coefficients are independent of the controlled rate constants, the conserved quantities (hence the initial state), and even of the stoichiometry of complexes. This predicts hidden activities and bounds the activity ratios the control can reach, while a violation signals nonzero deficiency or multiple linkage classes.
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Geophysics

Escaping Geological Generative Prior Distributions in Bayesian Travel Time Tomography

Pratyay Roy, Xuebin Zhao and Andrew Curtis

Solutions to geophysical inverse problems are generally non-unique, and greatly benefit from additional geological prior information. Generative Neural Networks (GNNs) are commonly used to parametrise such information, typically restricting solutions to a lower-dimensional latent space. The final inversion result is obtained by mapping the latent space parameters to the original higher-dimensional model space using the GNNs. However, solutions then remain confined to a low-dimensional geological generative manifold; if the true Earth model lies outside of this manifold, standard latent space inversion fails. We propose a Bayesian model space inversion method that uses the generative manifold as a guide to find the solutions that lie outside this manifold. We validate our approach in non-linear travel-time tomography experiments on both simple and more geological structures. By comparing our method with model space inversion using uniform prior probabilities and standard latent-space inversion, we demonstrate that the less informative uniform prior fails to constrain the solution, while the latent space approach fails when the true Earth model lies outside of the generative manifold. Conversely, our new model-space inversion method successfully recovers complex off-manifold geological features while maintaining low solution uncertainty.
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General Relativity and Quantum Cosmology

Testing General Relativity with Binary Lens Microlensing Events

Xinyang Jin, Shuo Cao, Xuanni Chen et al. (+3 more)

Einstein's General Relativity (GR), which has been precisely tested on galaxy and solar system scales, is still poorly constrained in extremely weak gravitational fields (with dimensionless Newtonian potentials of $\Phi \sim 10^{-8}$). In this Letter, we propose a new method to probe such a weak-field regime of gravity and measure the spatial curvature generated per unit mass. Specifically, binary microlensing events provide a laboratory to measure the parameterized post-Newtonian (PPN) parameter ($\gamma$), by combining the lensing mass ($M_{\rm lens}^{\rm GR}$) inferred from microlensing with the dynamical mass ($M_{\rm dyn}$) determined from interferometric astrometry. Astrometric tracking of binary lenses was previously hindered by their faintness and minuscule angular separations (typically a few milliarcseconds). This limitation has been alleviated by the deployment of GRAVITY+, which pushes the instrument's sensitivity and astrometric precision to unprecedented heights. Based on astrometric simulations of the binary microlensing event ASASSN-22av, we directly estimate $\gamma$ at the precision of ~23%. Such test of GR in the extremely weak-field regime can be further improved to much higher precision (~3%), based on more binary microlensing events with precise determination of the dynamical/lens mass.
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All authors Xinyang Jin, Shuo Cao, Xuanni Chen, Yalong Nan, Xuchen Tai, Shuxun Tian

Optics

Temporal chirality in Floquet photonic media

Rui-Chuan Zhang, Yixin Sha and Yi Yang

We reveal temporal chirality in time-modulated photonic media: reversing the orientation of a closed loop traced by the complex permittivity can leave the Floquet spectrum unchanged while strongly modifying the directional scattering response under the same excitation. This behavior is linked to two symmetry constraints on the evolution operator, namely pseudo-Hermiticity and pseudo-unitarity. We prove the general occurrence of temporal chirality based on a complex Bogoliubov parametrization of the scattering amplitudes. We illustrate these findings in a single-harmonic temporal-$\mathcal{PT}$-symmetric system: both modulation-loop orientations support the same vacuum-like Floquet photonic bands at the phase transition, but one suppresses backward photon generation whereas the other induces strong growth, as confirmed by full-wave simulations. Our results establish temporal chirality as a distinct notion in time-varying photonics and identify modulation-loop orientation as a control knob for Floquet wave dynamics.
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High Energy Physics (Phenomenology)

Reassessing the $X(2370)$ in $J/\psi\to\gamma K_S^0K_S^0\pi^0$ beyond the one-dimensional mass projections

Xiang-Kun Dong, Teng Ji, Meike Küßner et al. (+1 more)

The BESIII Collaboration recently extracted the properties of the $X(2370)$ from a fit to the one-dimensional $K_S^0K_S^0\pi^0$ invariant-mass spectrum in $J/\psi\to\gamma K_S^0K_S^0\pi^0$. The intermediate two-body structures visible in the mass correlations, including the $K_0^*(1430)$ bands, require a coherent treatment of cross-channel interference when interpreting the enhancement near 2.3 GeV. We reassess the need for an additional $X(2370)$ contribution by fitting the published data using an effective coupled-channel framework with an approximate detection efficiency depending on the three-body invariant mass. The three-body parent amplitude is parameterized using a $K$-matrix that describes scattering among several quasi-two-body channels. The seven- and eight-bare-state models give similar mass distributions. Adding the eighth bare state lowers the Poisson deviance by 1.22% and produces an additional pole at $E=(2419-i152)$ MeV, substantially broader than the $X(2370)$ mass-width reference. This pole is model-dependent, and its identification with the $X(2370)$ is not clear. The present analysis does not establish the need for an additional $X(2370)$ contribution in $J/\psi\to\gamma K_S^0K_S^0\pi^0$, thereby weakening the flavor-singlet argument based on the suppression of $K^*\bar K$ relative to the total $K\bar K\pi$ contribution. A more comprehensive experimental amplitude analysis, incorporating coherent interference, mass and angular correlations, and detector effects across related decay channels, is needed to establish the role and decay properties of the $X(2370)$.
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All authors Xiang-Kun Dong, Teng Ji, Meike Küßner, Ulf-G. Meißner

Nuclear Theory

Active-learning construction of hyperspherical-harmonics spaces for A = 3

Elena Filandri, Andrea Di Luca, Laura Elisa Marcucci et al. (+1 more)

The hyperspherical-harmonics (HH) expansion does not require uniform resolution: different components of the wave function converge at very different hyperangular and hyperradial scales. We use active learning to exploit this structure, allowing the calculation to distribute resolution instead of prescribing it. The HH space is decomposed into physically identifiable classes whose hyperangular and hyperradial cutoffs evolve independently; a Gaussian-process surrogate learns the marginal variational gain of each admissible extension, and a cost-aware acquisition selects the next one. The surrogate never replaces the many-body solver: every accepted extension is followed by an explicit solution in the enlarged space, so each reported energy is variational in an explicitly constructed basis. We test the construction on $^3$H and $^3$He with the Argonne $v_{18}$ two-nucleon interaction, without and with the Urbana IX three-nucleon interaction, against uniform HH ladders extended to $K=60$ that reproduce established benchmarks within $1$~keV. Asked for $5$~keV, the adaptive runs reproduce the energy of the uniform $K=60$ space within $4$~keV in every case and certify it, leaving more than $60$% of that space unbuilt. The reduction grows as the requested accuracy is relaxed, to about $88$% at $20$~keV and $95$% at $100$~keV. The selected spaces reproduce the known class hierarchy of the trinucleon, and the one-body radii and magnetic moments are converged at about the $2\times10^{-3}$ level (relative error) in the energy-selected space. A run started from the resolution reached by the mirror nucleus, or by the same nucleus with the two-nucleon interaction alone, certifies a smaller space with a third of the exact solves.
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All authors Elena Filandri, Andrea Di Luca, Laura Elisa Marcucci, Michele Viviani

Physics and Society

A Gauge-Invariant Clustering Coefficient for Complex-Weighted Bipartite Networks

Anjali Waghmare, Yu Tian and Renaud Lambiotte

Structural measures such as the clustering coefficient and the average shortest-path length characterise how a network is organised. These measures are typically formulated for real, non-negative edge weights. A class of quantum and photonic architectures has complex edge weights instead, whose phases determine whether alternative routes interfere constructively or destructively. These architectures are also bipartite, so triangles are absent and the smallest closed cycle is a four-node square. Existing measures address complex weights and bipartite structure separately: bipartite clustering coefficients quantify clustering through four-node squares but do not contain phase information, while interferometric coefficients retain phase but are defined on triangles. In this work, we define a clustering coefficient for complex-weighted bipartite networks which reduces to the classical bipartite coefficient when the phases vanish, becomes negative when alternative routes cancel, and can be obtained for all nodes from a single sparse matrix product. We show that the phase accumulated around a square is the smallest gauge-invariant carrier of structural phase information in a bipartite network. The clustering coefficient factorises into a topological contribution and a phase contribution, making a bipartite Watts–Strogatz ensemble analytically tractable. For phases uniformly distributed on $[-\Delta,\Delta]$, the mean phase contribution is $(\sin\Delta/\Delta)^4$, independent of node, degree, and topology. We also derive closed-form expressions for the clustering coefficient, open-path visibility, and phase variance. We numerically verify these predictions and further show that phase disorder increases coherent distance.
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High Energy Physics (Theory)

Multipartite Entanglement Geometry in AdS/BCFT

Debarshi Basu, Qiang Wen and Mingshuai Xu

Multipartite entanglement measures probe how quantum correlations are organized beyond what can be inferred from pairwise entropies. We study how this structure is reshaped by a physical boundary in a holographic BCFT. The end-of-the-world brane opens new relative-homology channels for multipartite entanglement, allowing connected bulk webs to reorganize and factorize at scales that need not coincide with any ordinary Ryu–Takayanagi transition. In static AdS$_3$/BCFT$_2$, this produces a characteristic hierarchy of multipartite phases and a nontrivial dependence of genuine multi-entropy on the boundary. In the thermofield-double state, genuinely connected webs can instead be supported through the Einstein–Rosen bridge, leading to growth, reconnection and saturation scales distinct from the usual Hartman–Maldacena transitions. These results show that multipartite entanglement is sensitive not only to extremal-surface areas but also to how bulk entanglement structures are allowed to join, split and terminate in the presence of a boundary.
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General Relativity and Quantum Cosmology · Cross-listed from math.DG

The Hawking and Penrose singularity theorems for low regularity Finsler spacetimes

Darius Erös, Ettore Minguzzi, Argam Ohanyan et al. (+1 more)

We prove the Hawking and Penrose singularity theorems for Lorentz–Finsler structures of mixed horizontal/vertical regularity $C^{(1,2)}$ in the $C^1$ weighted case and $C^{(1,3)}$ in the unweighted case. At this regularity, geodesics need not be uniquely determined by their initial conditions, and the (weighted) Ricci curvature must be interpreted distributionally. Our approach relies on a two-stage approximation procedure: first, a homogeneity-preserving convolution, which is of independent interest in the broader semi-Riemann–Finsler setting, and second, a causality-adapted approximation à la Chruściel–Grant. In the special case of $C^1$ Lorentzian metrics, our results extend the $C^1$ singularity theorems of Graf to the $C^1$ weighted case.
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All authors Darius Erös, Ettore Minguzzi, Argam Ohanyan, Shin-ichi Ohta

Materials Science

Comprehensive study of massively overlapping cascades in common elemental metals

Aslak Fellman, Jesper Byggmästar and Fredric Granberg

Massively overlapping cascades simulations were carried out in 21 elemental metals: Be, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Rh, Pd, Ag, Hf, Ta, W, Pt, Au and Pb. These elements have simple FCC, BCC and HCP lattice structures. For each element, 2000 cumulative 5 keV cascades were simulated using molecular dynamics. The overlapping cascades were simulated using various classical analytical interatomic potentials as well as with machine-learning interatomic potentials for many of the elements. The general conclusion is that results from massively overlapping cascades simulations are very sensitive to the choice of interatomic potential across the periodic table. Furthermore, we see that FCC metals all form stacking fault tetrahedra due to irradiation, and also typically include interstitial type Shockley partial and Frank type dislocations. In BCC materials typically form interstitial 1/2$\langle$1 1 1$\rangle$ dislocations, but vacancy type 1/2$\langle$1 1 1$\rangle$ dislocations were also observed in V and Nb. HCP materials tend to form complex dislocation structures mainly consisting of a-type dislocations that can be of both vacancy or interstitial type. Correlations between saturated defect concentrations and fundamental underlying material properties are explored.
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Statistical Mechanics

The Fiedler dimension of networks of networks: from fractal to small-world architectures

Lorenzo Grimaldi, Andrea Gabrielli and Pablo Villegas

Is the relaxation of a modular network dictated by its modules or by the network that connects them? The answer fixes the time scales of diffusion, consensus, and synchronization, all set by the Fiedler eigenvalue. We show that, for bundled networks, the two levels act one after the other: a random walker must first escape from its module and then spread over the network that connects them. The equilibration time is the sum of these two times, the time needed to reach the base from inside a fiber and the relaxation time of the base, slowed down by the mass of the fibers. The consequences are unexpected. However large the modules are, a small-world core always imposes its own Fiedler dimension; the modules survive only as a logarithmic correction, which slows down equilibration and hides the true exponent up to sizes far beyond any real network. Effective dimensions measured on finite modular systems can therefore be systematically biased. We analytically work out all combinations of finite-dimensional and small-world bases and fibers, and compare them with numerically exact spectra of representatives of each category.
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Soft Condensed Matter

Fluid deformable surfaces with variable thickness - a Surface Shallow-Water-Helfrich model

Jan Magnus Sischka and Axel Voigt

Epithelial tissues play a fundamental role in morphogenesis. Mechanically they can be viewed as thin soft materials exhibiting a solid-fluid duality. The Surface Navier-Stokes-Helfrich model accounts for these properties by combining bending and surface hydrodynamics. In order to account for varying cell thickness we incorporate a thickness field in the spirit of a shallow-water equation, but defined on the (self-)evolving surface. This replaces the inextensibility constraint of the two-dimensional fluid and with it the conservation of surface area by an incompressibility constraint of the thin film fluid allowing for changes in surface area. We develop a numerical scheme based on surface finite elements, perform convergence tests, demonstrate the impact on shape evolution of closed surfaces with a constant enclosed volume and discuss implications on modeling morphogenesis.
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Quantum Physics

Emergent SSH physics and localization in a cavity–atom system beyond the rotating-wave approximation

H. Shen, J. Cao, R. Wang et al. (+1 more)

We investigate a cavity–atom system beyond the rotating-wave approximation and recast its dynamics as an effective tight-binding problem in the excitation-number basis. The same experimentally relevant light–matter platform exhibits two distinct regimes controlled by the photon number. In the large-photon-number regime, the hopping amplitudes become nearly uniform and the effective lattice reduces to a dimerized SSH-type chain subject to a linear energy gradient. The spectrum then organizes into one or two Wannier–Stark ladders, giving rise to controllable Bloch and Bloch–Zener oscillations and quantitatively explaining the observed revival patterns. In the small-photon-number regime, the intrinsic $\sqrt{\bar n+(\cdots)}$ dependence produces a pronounced hopping deformation, namely dimerized couplings that increase along the excitation-number lattice. This deformation reshapes the density of states, enhances collective localization, and generates an energy-resolved spatial bias of the eigenstates. The corresponding real-time dynamics displays direction-dependent anomalous diffusion together with Bloch-like revivals and beat phenomena in selected parameter windows. Our results show that the same cavity–atom platform can realize both emergent ladder spectra and hopping-induced localization in excitation-number space.
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All authors H. Shen, J. Cao, R. Wang, X. Z. Zhang

Biological Physics

Femtosecond Three-Dimensional Imaging of Single-Protein with Hard X-ray Laser

Paul Lourdu Xavier, Andrew J. Morgan, Johan Bielecki et al. (+66 more)

The extremely intense pulses of X-ray free-electron lasers (XFELs) have enabled imaging of radiation-sensitive samples, such as macromolecular microcrystals, beyond radiation damage limits. These sources have the potential to deliver biomolecular single-particle imaging, similar to cryo-electron microscopy but without the need for cryo-fixation and with temporal resolution from femtoseconds to milliseconds. While this possibility was recognized before XFELs were built, the biological single-particle imaging work-flow has previously only been demonstrated on large virus particles. Based on decades of improvements in X-ray beam focusing, particle delivery, diffraction detection, and advanced analysis, here we demonstrate imaging of a single molecular complex, the giant-hemoglobin erythrocruorin (Ery) with X-ray laser pulses. Two-dimensional classes of diffraction patterns could be reconstructed to 15 Angstrom resolution, and 3D images to approximately 20 Angstrom, while the 3D merged intensity in reciprocal space extended beyond 20 Angstrom. The resolution discrepancy is likely due to heterogeneity caused by gas-phase compaction of the complexes. With increased throughput, this approach could be used to reveal in-situ structural details during mass spectrometry studies of biomolecules, while improvements in sample delivery may provide ultrafast snapshot imaging of biological single-particles in their native-state beyond the limitations of radiation damage.
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All authors Paul Lourdu Xavier, Andrew J. Morgan, Johan Bielecki, Amit K. Samanta, Simon Dold, Chufeng Li, Xinyue Gao, Spencer K. Passmore, Ruslan P. Kurta, Tim B. Berberich, Emiliano De Santis, Wenhui Zhang, Juncheng E, Faisal H. M. Koua, Romain Letrun, Luca Gelisio, Oleksii Turkot, Egor Sobolev, Lukas V. Haas, Jannik Lübke, Jingxuan He, Madeline B. F. Memovich, Kevin Janson, Stefanie Lenzen, Safi Rafie-Zinedine, Mansi Butola, Oleksandr Yefanov, Fabian Trost, Chan Kim, Tomas Popelar, Tokushi Sato, Yevheniy Ovcharenko, Rebecca Boll, Sergey Usenko, Thomas M. Baumann, Alberto De Fanis, Björn Senftleben, Matteo Porro, Andrea Castoldi, Ibrahym Dourki, Cyril Danilevski, Ekaterina Round, Christina Schmidt, Huijong Han, Roberto Alvarez, Ervin Chia, Cornelia Cazey, Carolin Seuring, Ruojie Sha, Maia Azubel, David A. Bushnell, Sébastien Boutet, Sergey Ovchinnikov, Adrian P. Mancuso, Michael Meyer, Richard Bean, Anton Barty, Filipe R. N. C. Maia, Richard A. Kirian, Thomas D. Grant, N. Duane Loh, Carl Caleman, Erik G. Marklund, Nadia Zatsepin, Andrew V. Martin, Saša Bajt, Roger D. Kornberg, Jochen Küpper, Henry N. Chapman

Physics and Society

Tracking High-Impact Researchers Through Highly Cited Tails

Hirushan Sajindra and Eoin Ó Colgáin

It is well recognised that field weighted citations are approximately lognormally distributed. This skewness reflects competition for attention, whereby most publications are gradually forgotten and only a minority continue to be recalled years later. Exploiting this observation, we construct a researcher-level indicator based on authorship of top 10% cited papers in All Science Journal Code (ASJC) bins and apply it to publications affiliated with Irish institutions over a typical funding cycle. Restricting attention largely to original research papers, we find that researchers authoring strictly more than one ASJC top-decile paper in a given year exhibit persistent participation in the highly cited tail of the literature in subsequent years, thus the simple track record indicator possesses predictive value. In contrast, the median researcher in cohorts of Research Ireland and European Research Council awardees selected through qualitative peer review either authors no top-decile paper or less than the median researcher in our ranking. These results demonstrate that research excellence as judged by qualitative peer review and influence on the research literature identify substantially different cohorts of researchers. In the absence of evidence, funding bodies and universities may conflate these two. While research reputation may be enhanced through many channels, highly cited papers constitute the most widely observable manifestation of international scholarly influence. Our analysis indicates that literature influence may be improved through greater use of data in track record pre-screening prior to qualitative peer review.
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Plasma Physics

Compressional heating above 1 keV on the LM26 magnetized target fusion machine

S. J. Howard, D. Krotez, P. Carle et al. (+43 more)

The LM26 device has achieved a peak electron temperature of $T_e = 1180 \pm 65$ eV as measured by filtered X-ray diodes, supported by adjacent Thomson scattering measurements of $T_e = 1090 \pm 40$ eV, with a deuterium ion temperature of $T_i = 459 \pm 33$ eV as inferred from neutron yield. LM26 compresses a spherical tokamak plasma inside an initially 1.76 m diameter solid lithium liner imploded by theta-pinch coils. Radial compression by a factor of 2.75 increases $T_e$ over fivefold, while $T_i$ increases as much as twofold. The integrated observation of magnetic flux compression, electron heating, ion heating, and neutron production in a magnetized plasma compressed by a large lithium liner is an important milestone for magnetized target fusion
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All authors S. J. Howard, D. Krotez, P. Carle, J. Sanchez Rojo, R. Underwood, A. Froese, M. Reynolds, N. Sirmas, K. Conquergood, K. Epp, P. Forysinski, D. Plant, R. Zindler, E. Love, D. P. Brennan, N. Kumar, C. MacDonald, A. Wong, W. Zawalski, B. Rablah, W. Kozicki, C. Preston, A. Lee, X. Feng, M. Schellenberg-Beaver, R. Tingley, J. Gorenstein, V. Suponitsky, Z. Seifollahi Moghadam, D. Froese, E. Cessford, J. Pratt, J. Crofts, J. Sardari, G. Faust, D. Ross, J. Wilkie, S. Bernard, C. Connor, S. Bolanos, C. Gutjahr, E. Chan, C. Eyrich, A. Mahoney, M. Davidson, M. Laberge

Atmospheric and Oceanic Physics

legoESM: a modular, differentiable, multiscale, AI-ready Earth system model built with AI agents

Pierre Gentine, Dhruv Balwada, Aytaç Paçal et al. (+12 more)

Earth system models (ESMs) have grown tremendously in realism, yet key uncertainties persist in the climate response to greenhouse-gas forcing, particularly due to cloud radiative feedbacks. In addition, their software architecture was not designed for accelerator hardware or modern artificial intelligence (AI). Here we present legoESM, a composable, differentiable, multiscale ESM written in JAX. It builds on decades of community-developed parameterizations and numerical methods, recast in a unified framework by AI coding agents under a human-specified scientific contract and verified through benchmarking. Dynamical cores, physics schemes, grids, complexity levels and components are swappable like building blocks, and can use conventional physics or machine-learned emulators. A single code base spans metre-scale large-eddy simulation to global simulations and weather to climate. End-to-end differentiability enables gradient-based calibration, variational data assimilation and online training. legoESM modular architecture enables systematic evaluation of diverse model variants to explore structural uncertainty and test hypotheses. legoESM produces realistic simulations across scales, reduces land-surface temperature bias through gradient-based calibration, and scales efficiently on GPUs to kilometer-scale simulations. It offers an open, community infrastructure for hypothesis testing, research and teaching in Earth sciences and a template for multiscale physical systems.
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All authors Pierre Gentine, Dhruv Balwada, Aytaç Paçal, Linnia Hawkins, Alistair Adcroft, Hang Fan, Jianing Fang, Aya Lahlou, Kara D. Lamb, David M. Lawrence, Julien Le Sommer, Joseph Mouallem, Juan Nathaniel, Duncan Watson-Parris, Veronika Eyring