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Tuesday 22 September

Quantum Physics

Sustained growth of quantum circuit complexity in many-body Hamiltonian dynamics

Wonjun Lee, Saúl Pilatowsky-Cameo and Soonwon Choi

The quantum circuit complexity of an evolving many-body quantum system is believed to exhibit a sustained growth, maintained for timescales much longer than the onset of thermalization. Most previous works have focused on models which violate energy conservation, such as random unitary circuits. Here we study generic, local time-independent Hamiltonian dynamics. We unconditionally prove that for generic local Hamiltonians and typical initial product states at high effective temperature, the robust quantum circuit complexity must grow over a very long period of time, attaining an exponentially large value at late times. Our approach relies on two structural properties that we prove rigorously: (i) generic local Hamiltonians satisfy generalized spectral no-resonance conditions of arbitrary order, and (ii) typical high-temperature product states are effectively supported in exponentially many energy eigenstates. These properties have been widely assumed without proof in prior works. As corollaries of this result, we show the late-time state displays robust volume-law entanglement that is irremovable by polynomial-size circuits, and we establish a no fast-forwarding result for generic local Hamiltonians. We also lower bound the complexity of preparing sufficiently large subsystems with local quantum channels, in contrast with sufficiently small thermalizing regions which we show retain low complexity at late times.
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Astrophysics of Galaxies

DIISC-VII: Linking Radial Gas Motions to Anomalously Low Metallicity Star-forming Regions in the XUV Disk of NGC 3344

Alejandro J. Olvera, Sanchayeeta Borthakur, Enrico M. Di Teodoro et al. (+4 more)

We present evidence connecting anomalously low-metallicity regions to radial gas inflows in the extended ultraviolet (XUV) disk of the galaxy NGC 3344. Anomalously low-metallicity H II regions are hypothesized to result from the accretion of metal-poor gas, but a direct link between gas flows and low metallicity gas has not been previously established. We use high-resolution H I-21cm imaging from the Very Large Array to trace neutral gas kinematics and multi-slit optical spectroscopy from the MMT to trace the gas-phase metallicity of 76 H II regions in NGC 3344. The galaxy exhibits a negative radial metallicity gradient of $-0.378$ dex $\mathrm{R}_{25}^{-1}$, with H II regions in the XUV disk showing nearly twice the metallicity scatter of those in the inner disk and several showing an anomalously low metallicity. Modeling the H I disk as tilted rings with 3DBarolo, we find gas moving radially inwards within the XUV disk at an average radial velocity of 6 $\mathrm{km\ s^{-1}}$, likely fueling star formation and diluting the metallicity, thereby producing anomalously low metallicity regions. Chemical evolution models indicate that the gas fraction, effective yield, and mass-loading factor profiles are disrupted at the onset of the XUV disk, as expected from recent gas flows. This example is the first direct detection of how radial gas flows can support stellar disk expansion and cause inside-out galaxy growth.
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All authors Alejandro J. Olvera, Sanchayeeta Borthakur, Enrico M. Di Teodoro, Kanak Saha, Mansi Padave, Hansung B. Gim, Emmanuel Momjian

High Energy Physics (Theory)

Asymptotic limits in class-$\mathcal{S}$ theories and non-Abelian Hodge theory

Thomas W. Grimm and Amineh Mohseni

We develop a non-Abelian Hodge-theoretic refinement of asymptotic limits in type-$A$ class-$\mathcal S$ theories, enriching the geometric description of the degenerating UV curve with gauge-theoretic data encoded by the associated Hitchin system. A degeneration of the UV curve produces a long plumbing tube, which we equip with the local monodromy data of a Hitchin-Simpson flat connection admitting a regular-singular logarithmic model. The semisimple and unipotent parts of the monodromy govern, respectively, the power-law and logarithmic growth of flat sections through the tube. Combining this non-Abelian holonomy with the geometric Picard-Lefschetz monodromy yields a decorated cusp label that incorporates Higgs-bundle information and extends tube-wise to intersections of boundary divisors. We also discuss a particular class of monodromy labels for which the weak gauge algebra specified by the fixture and gluing data lies in the reductive monodromy centralizer. In type $A$, we organize the local monodromy labels into discrete types specified by the eigenspace multiplicities of the semisimple part and the Jordan type of the nilpotent logarithm of the unipotent part. Finally, we illustrate the construction for $SL(3,\mathbb C)$ on the four-punctured sphere and $SL(4,\mathbb C)$ on the two-punctured torus.
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High Energy Physics (Phenomenology)

High-Temperature Vacua of the Standard Model from One-Form Symmetry

Ling-Xiao Xu

We study the high-temperature vacua of the Standard Model from the perspective of generalized symmetries and the global structure of the gauge group. We analyze the one-loop effective potential for Polyakov loop holonomies, incorporating the gauge identifications induced by gauging discrete subgroups of the electric one-form symmetry. This provides a classification of physically inequivalent vacua for each gauge-group quotient. We further comment on the effects of additional center-charged matter on the residual one-form symmetry and the vacuum structure.
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Strongly Correlated Electrons

Fermion bag study of the two-dimensional Majorana-Hubbard model at finite hopping

Mark Johnston and Emilie Huffman

The two-dimensional Majorana-Hubbard model on the $\pi$-flux lattice involves the most local interaction possible for a lattice with one relativistic Majorana fermion per site. It is predicted to host a Majorana semimetal, dimerized phases, and quantum-critical points with an emergent $U(1)$ symmetry. Nonperturbative lattice calculations for this model remain a major open challenge, thus far limited to zero hopping. We present quantum Monte Carlo simulations of the model at finite hopping using Hamiltonian fermion bags, which are based on a continuous-time expansion with Boltzmann weights that are Pfaffians of a matrix with dimension set by the expansion order, and which give the sign of the weight. Sign problem severity is related to the location of zero modes in the free hopping matrix, and for couplings $g\lesssim 0.7$ and $\beta=L/4$ it is fully removed for lattices up to at least $256$ sites. The interaction strength $g>0$ enhances the $U(1)$-charged dimerization doublet and suppresses the neutral channel, as the renormalization group predicts. Increasing the interactions also restores $U(1)$ symmetry in the component of the dimerization correlator that is even under bond orientation exchange, but not its odd component. There is a persistent anisotropy in the odd component with the symmetry of a lattice nematic. The data is consistent with a gapless semimetal throughout the sign-problem-minimal window.
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Quantum Physics

Bosonic Error Correction with Fluxonium

Shantanu R. Jha, Shoumik D. Chowdhury, Gabriele Rolleri et al. (+22 more)

Bosonic quantum error correction (QEC) offers a hardware-efficient route to fault-tolerant quantum computing. To date, however, superconducting circuit implementations of bosonic codes have utilized centimeter-scale 3D microwave cavities controlled by fixed-frequency transmon qubits, with logical lifetimes limited by transmon bit-flip errors. Here, we realize bosonic QEC in a fully planar architecture by pairing a heavy fluxonium, whose $451 \pm 70~\mu\mathrm{s}$ bit-flip lifetime exceeds that of any control qubit in previous demonstrations, with an on-chip Archimedean spiral resonator several orders of magnitude smaller in mode volume than prior 3D cavities. We prepare finite-energy Gottesman-Kitaev-Preskill (GKP) states and stabilize them using measurement-free error correction with rapid fluxonium reset, extending the logical lifetime by a factor of $1.59 \pm 0.05$. These results provide the first demonstration of resonator control using a weakly coupled fluxonium and, with it, the first realization of standalone bosonic QEC in a fully planar superconducting circuit architecture.
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All authors Shantanu R. Jha, Shoumik D. Chowdhury, Gabriele Rolleri, Anaida Ali, Lev-Arcady Sellem, Réouven Assouly, David Pahl, Lukas Pahl, Junyoung An, Farid Hassani, Hung-Yu Tsao, Chia-Chin Tsai, Aranya Goswami, Gabriel D. Cutter, Jeremie Boudreault, Jeffrey M. Gertler, Michael A. Gingras, Bethany M. Niedzielski, Jeffrey M. Knecht, Mollie E. Schwartz, Kyle Serniak, Jeffrey A. Grover, Baptiste Royer, Max Hays, William D. Oliver

Instrumentation and Methods for Astrophysics

EPIMETHEUS: Effective PSF inferred from mosaics

Pietro Benotto, Benedetta Vulcani and Vittoria Altomonte

Accurate knowledge of the point spread function (PSF) is essential for a wide range of astronomical applications, from astrometry to precision photometry. However, deriving a robust average effective PSF (ePSF) from astronomical mosaics is particularly challenging due to the superposition of exposures taken at different epochs, under different observing conditions, and with varying position angles (PAs). To address this issue, we present EPIMETHEUS, an open-source Python library designed to manage the entire ePSF construction workflow, from initial star selection to final model generation. Built with a modular architecture, EPIMETHEUS avoids black-box methodologies, ensuring full transparency and giving the user complete control over the stellar sample to use for the ePSF building to meet specific scientific requirements. The software can process multiple images or mosaics simultaneously to retrieve the ePSF, a crucial feature when individual fields lack a sufficient number of bright, unsaturated stars. Candidate stars can be automatically filtered based on orientation and light concentration, with options for manually excluding stars through a semi-automatic visual inspection. Although EPIMETHEUS is specifically optimised to handle the roto-translation complexities inherent to multi-epoch mosaics, it is versatile and can be equally applied to derive ePSFs from simpler, single-orientation images where rotational corrections are not required. Finally, to demonstrate the software's capabilities and provide an immediate resource, we release empirical ePSFs for standard HST and JWST filters across the COSMOS, UDS, Abell 2744, and GOODS-S fields.
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High Energy Astrophysical Phenomena

Compact Object Mergers and Micro-Tidal Disruption Events: A Multi-Messenger Probe of Dense Stellar Environments

Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna et al. (+1 more)

Dense stellar environments such as globular clusters and young massive clusters produce both compact-object mergers detectable in gravitational waves and tidal disruption events observable electromagnetically. We investigate compact-object mergers, tidal disruption events, and micro-tidal disruption events ($\mu$TDEs) in these environments using rapid Monte Carlo star-cluster simulations with the Rapster code, extended with a unified treatment of neutron-star (NS) and black-hole (BH) spin evolution under disk accretion across the NS-to-BH transition, as well as new dynamical channels for disruptions by single compact objects and by BH-BH binaries. Simulating $10^5$ clusters across ten model variations and two formation histories, we find a BH-BH merger-rate density peaking at $z\approx2$-$3$ at several tens ${\rm Gpc}^{-3}\,{\rm yr}^{-1}$, consistent with the local LVK rate, while the cumulative number of $\mu$TDEs exceeds that of mergers by a factor of a few. Since we include only dynamically formed binaries, $\approx90\%$ of $\mu$TDEs proceed through single compact-object-star encounters, and our rates are conservative lower limits. Prograde accretion during $\mu$TDEs spins up compact objects, providing a purely dynamical, randomly oriented pathway for producing high-spin BHs, and can drive accretion-induced collapse of NSs to BHs that populate the lower mass gap.
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All authors Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna, Emanuele Berti

Astrophysics of Galaxies

Euclid Quick Data Release (Q1): Disc breaks highlight the structural evolution of galaxies through time

Euclid Collaboration: P. M. Sanchez-Alarcon, J. Román, S. Comeron et al. (+301 more)

Changes in the slope of the radial surface brightness profiles of disc galaxies, or disc breaks, encode valuable information about the processes driving disc formation and growth. Until now, due to the resolution and depth required, statistical studies of break types have been limited mostly to the local Universe. We aim to study the structural properties and redshift evolution of disc breaks in a large and statistically representative sample of galaxies out to redshift z=1 using the superb depth and resolution of Euclid. We develop an automatic pipeline to extract and analyse surface brightness profiles of 8748 disc galaxies selected from the Euclid Q1 dataset. The pipeline includes advanced masking, surface brightness profile extraction, integrated photometry and structural parameter measurements, and piecewise modelling to classify galaxies into Types I (pure exponential), Type II (down-bending), Type III (up-bending), and composite break (e.g., Type~II+III, Type~II+II, etc) profiles. We quantify structural parameters such as scale lengths, break radii, and surface brightness levels, and analyse their distributions and redshift dependence. Our automatic method produces reliable masks and deep surface brightness profiles, and classifies galaxy profiles with an estimated accuracy of 70%. Using a subsample of 4385 galaxies with reliable classifications, we find that the most common profiles are Types II, II+III, I, and III. We find substantial evolution in the fraction of disc breaks with time. Type II profiles dominate at low redshift (50%), while Types III and II+III profiles increase in frequency with lookback time, reaching 30% each at z~1. Our study provides the first statistically robust measurement of the evolution of disc break types over 5 Gyr. The observed trends support a scenario in which secular processes replace environmental influences as galaxies mature.
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All authors Euclid Collaboration: P. M. Sanchez-Alarcon, J. Román, S. Comeron, J. H. Knapen, M. Huertas-Company, F. Buitrago, M. Montes, A. S. Borlaff, P. M. Marcum, J. Junais, E. Duran-Camacho, M. N. Le, M. Dunn, H. Dannerbauer, B. Altieri, A. Amara, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, M. Bolzonella, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, A. Costille, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, C. Dolding, H. Dole, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. Gwyn, W. G. Hartley, S. V. H. Haugan, J. Hoar, H. Hoekstra, W. Holmes, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, M. Magliocchetti, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, N. Mauri, E. Medinaceli, S. Mei, M. Melchior, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, P. Monaco, A. Mora, M. Moresco, C. Moretti, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, C. Padilla, K. Paech, S. Paltani, F. Pasian, W. J. Percival, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, C. Porciani, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, I. Risso, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, J. Skottfelt, L. Stanco, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, E. Zucca, V. Allevato, M. Ballardini, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, J. A. Escartin Vigo, J. Martín-Fleitas, S. Matthew, R. B. Metcalf, A. A. Nucita, M. Pöntinen, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, P. Bergamini, D. Bertacca, M. Bethermin, A. Blanchard, L. Blot, M. Bonici, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, T. Contini, A. R. Cooray, O. Cucciati, G. Desprez, A. Díaz-Sánchez, S. Di Domizio, J. M. Diego, P. Dimauro, P.-A. Duc, M. Y. Elkhashab, A. Enia, Y. Fang, A. Finoguenov, F. Fontanot, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, V. Gautard, R. Gavazzi, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, M. Guidi, C. M. Gutierrez, A. Hall, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, J. Kim, C. C. Kirkpatrick, S. Kruk, L. Legrand, M. Lembo, F. Lepori, G. Leroy, G. F. Lesci, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, A. Loureiro, J. Macias-Perez, E. A. Magnier, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, G. Morgante, K. Naidoo, P. Natoli, A. Navarro-Alsina, S. Nesseris, D. Paoletti, F. Passalacqua, K. Paterson, A. Pisani, D. Potter, S. Quai, M. Radovich, G. Rodighiero, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, A. Schneider, M. Schultheis, D. Sciotti, E. Sellentin, F. Shankar, L. C. Smith, J. G. Sorce, K. Tanidis, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, G. Verza, P. Vielzeuf, N. A. Walton, D. Scott

High Energy Physics (Phenomenology)

Precise QCD Predictions for the Scotogenic Model at Colliders

Mohammed Boukidi, Camila Ramos and Richard Ruiz

Motivated by the anticipated data rates of the high-luminosity phase of the Large Hadron Collider, we report the first predictions up to next-to-leading order in quantum chromodynamics with parton-shower matching for the production and decay of scalars and heavy neutrinos from the Scotogenic model for neutrino masses and dark matter at $\sqrt{s}=14$ TeV and $\sqrt{s}=100$ TeV. We carry out our simulations using the FeynRules+MadGraph5\_aMC@NLO+Pythia8 pipeline. As a byproduct, we report the public release of the SM\_Scoto Universal FeynRules Object libraries for modeling the Scotogenic model in high-energy processes. We comment on prospects of observing new rare $Z$ decays at future $e^+e^-$ collider facilities as well as on the production of new particles at a multi-TeV $\mu^+\mu^-$ collider.
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High Energy Physics (Theory)

Collapse to extremality: The third law of black hole thermodynamics in quantum gravity

Gustavo J. Turiaci and Chih-Hung Wu

We present a two-step construction to violate the classical third law of black hole thermodynamics for charged black holes in four dimensions. A near-extremal black hole with an $\mathrm{AdS}_2\times X$ throat is first prepared and then driven to extremality in finite time by a charged shell. This construction suggests that the second step is universal for near-extremal black holes, and can be used to construct violations of the third law for Kerr black holes. The same description allows us to study the process in quantum gravity. The classical collapse condition selects a BF-violating matter sector, for which we construct a holographic dictionary and derive the quantum transition amplitude. Quantum effects replace the classical extremal endpoint by a probability distribution that vanishes at extremality and peaks at positive energy. This obstruction is consistent with the absence of non-supersymmetric extremal black hole states in quantum gravity. We show that driving the peak close enough to extremality for quantum gravity to become important requires a preparation time that scales with the black hole entropy.
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Earth and Planetary Astrophysics

Revealing the Shiny Nature of Lava Worlds: Small Planet Phase Curves with TESS

Brandon Park Coy, Michael Zhang, Fei Dai et al. (+1 more)

Recent thermal emission observations suggest that `lava worlds'–Earth-sized exoplanets hot enough to melt their silicate surfaces–have atmospheres on a population-level. This evidence comes from measured dayside brightness temperatures much lower than expected for a dark, maximally hot bare rock. However, these results are degenerate between a thick atmosphere advecting heat to the planet's nightside or a high albedo reflecting incoming radiation. This degeneracy can be resolved through visible light phase curve observations, which can constrain how much light is reflected by the planet. Here, we present a population-level analysis of the visible-light TESS phase curves of $R\lesssim5\,R_{\oplus}$ exoplanets. We select the population by defining a `Reflection Spectroscopy Metric' meant to quantify the relative signal-to-noise of reflected light observations. We report new $>3\,\sigma$ detections of the TESS phase curve signals of LTT 9779 b and the lava worlds TOI-2431 b, TOI-561 b, 55 Cancri e, K2-141 b, and TOI-1444 b. We use these results and previous results from Kepler and CHEOPS to homogeneously derive geometric albedos for these planets, revealing that lava worlds generally show high albedos compared to the low geometric albedos measured for hot Jupiters at similar temperatures. These results support an emerging picture of reflective silicate clouds on these worlds cooling their daysides. The upcoming PLATO mission is expected to tightly constrain the reflected light phase curves of lava worlds.
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All authors Brandon Park Coy, Michael Zhang, Fei Dai, Qiao Xue

Soft Condensed Matter

Experimental Characterization of the Passive Mechanical Behavior of Rat Pelvic Floor Muscles: Effects of Test Conditions and Pregnancy

Jose L. Monclova, Matthew Shankel, Ava M. English et al. (+2 more)

Purpose: Pelvic floor muscles undergo large deformations during vaginal delivery, yet the passive tensile behavior of pregnant and non-pregnant pelvic floor muscle and the influence of testing protocols remain incompletely characterized. This study evaluated how pregnancy, loading rate, preconditioning, and storage affect passive tensile mechanics of rat pelvic floor muscle. Methods: Levator ani samples from pregnant and non-pregnant rats were tested in uniaxial tension to failure across multiple preconditioning amplitudes, two loading rates, and fresh or frozen storage conditions. Peak and transition metrics, strain energy density, toe-region stiffness, and high-strain stiffness were extracted using automated region-detection methods. Rat properties were also compared with digitized human cadaver levator ani data. Results: Pregnant rat samples reached greater peak strains than controls, although the difference was not significant. Preconditioning affected peak strain in a loading-rate-dependent manner: responses tapered near 2% preconditioning strain at 0.5% strain/s, whereas no comparable tapering occurred through 15% at 1% strain/s. Compared with human cadaver data, rat samples reached substantially larger peak strains and lower high-strain stiffness. Conclusion: This study provides one of the first direct experimental comparisons of passive pelvic floor muscle mechanics between pregnant and non-pregnant tissue, while systematically evaluating how multiple testing-protocol variables influence the measured response. Distinguishing protocol-dependent variability from biological differences provides a more reproducible basis for cross-study comparison and constitutive model calibration. Rat pelvic floor muscle is a useful model for pregnancy-associated adaptation, but absolute mechanical values should be translated to human tissue cautiously.
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All authors Jose L. Monclova, Matthew Shankel, Ava M. English, Mona Eskandari, Heidi P. Feigenbaum

High Energy Physics (Phenomenology)

The LHC is not enough: the LZ High-Recoil Event at FCC-hh and a Muon Collider

Benedikt Maier and Michael Spannowsky

The high-energy nuclear-recoil candidate reported by LUX-ZEPLIN could point to dark matter beyond the reach of the LHC. We examine how future colliders could test this interpretation, starting with the thermal Higgsino and extending to a broad class of electroweak multiplets containing neutral and charged particles. We assume an approximately pure multiplet protected by an exact stabilizing symmetry, with dominant inelastic Z exchange and the full dark-matter abundance set by gauge-dominated thermal freeze-out, where mixing and additional interactions affecting production or freeze-out are negligible. In this setting, heavy thermal masses, rare production and invisible neutral transitions make the Higgsino's main collider obstacles generic across the class, independently of supersymmetry. Charged lifetimes vary, but the benchmark spectra studied, including radiative doublet splittings, remain beyond the projected HL-LHC reach. We show how FCC-hh and a high-energy muon collider can overcome these obstacles. Our FCC-hh estimates show sensitivity to the doublets and several larger multiplets through disappearing charged tracks and complementary channels that do not depend on the charged lifetime. Muon-collider projections cover the fermionic doublet and triplet at 10 TeV and the full fermionic family considered here at 30 TeV, subject to the stated spectrum and systematic assumptions. This connects a possible underground signal to a concrete program for testing thermal electroweak dark matter at future colliders.
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Strongly Correlated Electrons

Easy-plane anisotropy of magnetic fluctuations in UTe2

Zehao Wang, Ewan Scott, David W. Tam et al. (+9 more)

The large directional anisotropy of superconducting UTe2 along the lattice a, b, c directions in magnetic susceptibility, upper critical fields, and Knight shift suggests spin-triplet Cooper pairing. If spin fluctuations bind the Cooper pair, one needs to determine their anisotropy in spin space to characterize the superconducting state. Here we use polarised and unpolarised inelastic neutron scattering (INS) experiments to show that antiferromagnetic (AFM) spin fluctuations at the Y point are highly isotropic within the ac-plane but have no observable magnitude along the b-axis. Our results rule out the assumed Ising anisotropy and constrain the possible pairing channels. AFM exchange is no longer pair forming in the triplet channel and the d vector along b is strongly favoured. We capture the experimental observations within a microscopic framework that encompasses the dual nature of 5f electrons. We include itinerant and localized 5f-moments in a tight-binding model fitted to quantum oscillations data. In congruence with INS, the exchange between localized moments generically consists of a strong FM intra-dimer interaction, maxima close to the Y and T points, mediated by 5p_y and 6d_{3z^2-r^2} orbitals respectively, and magnetically decoupled ab-planes. We find that anisotropy and dimerization of the moments can lead to gapped excitations that, in combination with Landau damping, can produce the observed overdamped response at the Y point. We suggest that enhancement of the response and its observed near-O(2)-symmetry could both be driven by proximity to a quantum critical point where the dimer excitation gap closes and gives place to incommensurate helical order. Analysis of the linearized gap equation for a nearest-neighbour pairing interaction favours the B1u triplet with a dominant d-vector component along b, although the possibility of spin singlet pairing cannot be ruled out.
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All authors Zehao Wang, Ewan Scott, David W. Tam, Philippe Bourges, Keke Feng, Tyler W. Wannamaker, Paul Steffens, Arno Hiess, Ryan E. Baumbach, M. Brian Maple, Michal P. Kwasigroch, Pengcheng Dai

Physics and Society

Network-based modeling of cocaine trafficking flows and displacement effects

H.A. Peters, Frederike Oetker, Robby Roks et al. (+3 more)

The worldwide cocaine market is undergoing an extraordinary surge. Insights on how cocaine is trafficked from production countries to consumer markets are limited, and often based on observed trafficking routes (e.g., seizures) alone. In this paper, we introduce a network-based model of actual transnational cocaine flows, beyond flows seized. In this model, cocaine is routed through an international transportation network of land and sea connections, where each link is assigned an interception risk metric for containerized transport. This interception risk metric combines features related to law enforcement inspections, containerized trade, and transport connectivity into three key driving components of interception risk using Principal Component Analysis (PCA). The interception risk metric on each link is then constructed from these driving components, where the importance of each component is characterized by a strength parameter. Given a set of strength parameters, cocaine is assumed to be routed from production countries to consumption countries via routes that minimize the total risk of interception, subject to country-specific supply and demand constraints. In the end, the strength parameters are calibrated by comparing the corresponding flow outcomes with known trafficking activity. From these final trafficking flows associated with the calibrated parameters, we are able to identify `blind spots' (e.g., nonzero flows on links with small or none observed trafficking activity) and provide more evidence of the waterbed effect (e.g., changing routes as a result of increased interdiction efforts by law enforcement).
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All authors H.A. Peters, Frederike Oetker, Robby Roks, Roy Lindelauf, Robbert Fokkink, Huijuan Wang

Atomic Physics

Quantum Chemistry in a Novel Hybrid Dipolar Atom-Ion Mixture

Claudia Galantini, Mateo Londoño, Luc Verwaal et al. (+3 more)

Merging trapped ions with cold atomic clouds offers intriguing prospects for quantum chemistry and many-body quantum simulations. Especially when going beyond the standard alkali atomic baths by using lanthanide atoms, opportunities arise to study the interplay between the intermediate-range atom-ion interaction and the tunable long-range dipolar atom-atom interactions. However, the high total angular momentum of the ground-state of open-shell lanthanides, e.g. $^{5}I_{8}$ for dysprosium, affects the atom-ion potential. Here, we discuss the implications for long- and short-range atom-ion interactions and present a novel apparatus which combines an ytterbium ion (Yb$^{+}$) with dipolar dysprosium (Dy) atoms. We highlight the consequences of this novel Dy-Yb$^{+}$ mixture for observing buffer gas cooling, (non-) radiative charge transfer, and three-body recombination. While the energy-averaged rates are dominated by radiative charge transfer, particularly radiative association, we find that three-body recombination can compete with molecular-ion formation at Dy densities $n\gtrsim 10^{12}$ cm$^{-3}$. This competition is further enhanced by the expected non-thermal distribution of ion energies. These processes could be experimentally characterised through controlled variation of the atom-ion interaction parameters, providing a direct test of our theoretical predictions.
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All authors Claudia Galantini, Mateo Londoño, Luc Verwaal, Edgar J. D. Vredenbregt, Jesús Pérez-Ríos, Rianne S. Lous

Atomic Physics

A Cryogenic Penning Trap Based on Permanent Magnets

F. Völksen, K. K. Anjum, R. P. Czampiel et al. (+30 more)

We report on a Penning trap based on NdFeB permanent magnets operated at 4\,K with a magnetic field strength of 280\,mT. Reliable loading and confinement of protons, H$_2^+$ ions, and electrons was demonstrated with non-destructive single-particle detection sensitivity of protons and H$_2^+$ ions using superconducting image-current circuits. The axial frequency of individual particles reaches a shot-to-shot stability of 47 parts-per-billion comparable to that of state-of-the-art precision Penning-trap experiments. Measurements of the proton modified-cyclotron frequency show a shot-to-shot scatter of $0.14$ parts per million (p.p.m.), presently limited by millikelvin-level temperature fluctuations of the permanent-magnet assembly. We outline a route towards improving this performance by more than an order of magnitude. This development offers broad potential for axial-mode-related precision measurements and cost-efficient Penning-trap experiments, and represents an important step towards compact, scalable, and transportable antiproton-trap systems.
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All authors F. Völksen, K. K. Anjum, R. P. Czampiel, N. Daehnhardt, S. Gavranovic, J. Hoentges, L. Kürschner, J. D. Regier, D. Schweitzer, 1, 2, P. Schöps, A. M. Thomas, S. Wienhues, B. Arndt, T. Imamura, S. Endoh, B. M. Latacz, M. Leonhardt, P. Micke, J. Morgner, D. Natakala, S. Stahl, H. Yildiz, K. Blaum, J. A. Devlin, Y. Matsuda, C. Ospelkaus, W. Quint, A. Soter, J. Walz, C. Smorra, S. Ulmer

Solar and Stellar Astrophysics

Spectroscopic Study of the Circularly Polarised Radio Source TYC 2834-1385-1: An Active Binary

Tamara A. S. Bleeker, Alexander Hoogerbrug, Elise Koo et al. (+2 more)

Close binaries with active chromospheres have recently been shown to emit circularly polarised radio emission at low frequencies, motivating detailed studies of their orbital properties. We present high-resolution ($R=85,000$) optical spectroscopy of TYC 2834-1385-1, a previously unclassified radio source, obtained with the HERMES spectrograph on the Mercator Telescope. We identify the source as a double-lined spectroscopic binary and measure radial velocities from both metallic absorption and Ca II emission lines. We find an orbital period of $P=3.601\pm0.002$ days and nearly equal radial-velocity semi-amplitudes for the two components. The system exhibits strong Ca II H and K emission, which is consistent with a BY Dra-type binary containing two similar late-G/early-K main-sequence stars, with a preliminary classification of K0V. This represents one of the first spectroscopic confirmations of a chromospherically active binary following its identification in a low-frequency radio survey.
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All authors Tamara A. S. Bleeker, Alexander Hoogerbrug, Elise Koo, Rudy Wijnands, Joseph R. Callingham

Statistical Mechanics

Analytical Solution of the Nonlinear Boltzmann Equation For Multicomponent Systems

Linyuan Wei, Yi Wang, Jin Hu et al. (+1 more)

We present exact analytical solutions to the nonlinear relativistic Boltzmann equation for homogeneous, isotropic massless multi-component systems with non-isotropic scattering cross sections. For a two-component system, we identify three distinct classes of exact solutions, each corresponding to specific constraints among initial energy densities, particle number densities, and scattering cross sections. These solutions comprise the equilibrium state and two novel classes: a hybrid structure featuring a non-equilibrium Maxwell-Juttner distribution coupled with a nontrivial distribution; the former is unprecedented in kinetic theory, while the latter refers to nontrivial dynamics shared by both species, which is novel in the relativistic context.
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All authors Linyuan Wei, Yi Wang, Jin Hu, Baoyi Chen

Materials Science

Suppressed Defect Emission and Enhanced Blue Luminescence of Zn-Doped CuBr Quantum Dots synthesized in Room-Temperature Synthesis

Aryamol Stephen, Ruchi Kumari, Saparja Roy et al. (+3 more)

Deep-blue-emitting CuBr quantum dots (QDs) hold promise as nontoxic and heavy-metal-free optoelectronic materials, yet their efficiency is limited by intrinsic defects. We report Zn doping as an effective strategy to mitigate defect-mediated recombination in CuBr QDs synthesized via an eco-friendly supersaturated recrystallization method under ambient conditions. XRD shows lattice contraction, Rietveld refinement confirms substitutional doping, and XPS verifies Cu$^+$/ Zn$^{2+}$ states without secondary phases. HR-TEM analysis reveals uniform 3.46 $\pm$ 0.12 nm Zn:CuBr QDs with reduced bandgap, after doping, indicating weaker quantum confinement. The dominant emission peaks appear at 406 nm ($Z_f$) and 431 nm ($Z_{1,2}$) under 365 nm excitation. Narrows defect FWHM, elevated band-edge emission, and extends carrier lifetimes, achieving 96.4 % color purity with CIE coordinates (0.1520, 0.0395). These findings demonstrate that Zn doping is a simple, scalable, and environmentally benign strategy for engineering efficient blue-emitting CuBr QDs.
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All authors Aryamol Stephen, Ruchi Kumari, Saparja Roy, P. Jayaram, A. Biju, P. M. Sarun

Astrophysics of Galaxies

The First Blind Survey of Intervening NaI Absorbers: Incidence and Cosmic Evolution with DESI

Abhijeet Anand and Sowgat Muzahid

We present the first blind statistical survey of intervening NaI absorbers over the last $\simeq3$~Gyr using quasar spectra from the Dark Energy Spectroscopic Instrument Data Release~1. We identify 3636 NaI D doublets at $0.01\lesssim z_{\rm abs}\lesssim0.27$ along 214,035 quasar sightlines. We quantify the survey selection function through end-to-end injection–recovery tests and estimate the residual contamination from visual inspection. The completeness reaches 50% at a rest-equivalent width of the NaI $\lambda5891$ line, $W_{5891}\simeq0.95$ Angstrom, and the catalog-weighted purity is $\simeq77\%$. For the fiducial sample with $0.95<W_{5891}<3.5$ Angstrom, we measure the equivalent-width distribution ($f(W_r)$), absorber incidence ($dN/dX$), and cosmic NaI mass density ($\Omega_{\rm Na\,I}$). From $z\simeq0.25$ to $z\simeq0.03$, $dN/dX$ rises by a factor of $\simeq3.4$ in both rest-equivalent-width subsamples, split at the median $W_{5891}=1.41$ Angstrom, while $\Omega_{\rm Na\,I}$ increases by a similar factor. This corresponds to a smooth increase in the product of the comoving number density of NaI-absorbing hosts ($n_{\rm com}$) and the cross-section of the NaI-bearing gas ($\sigma_{\rm eff}$) with cosmic time. The similar evolution of $\Omega_{\rm Na\,I}$ and $dN/dX$ indicates little change in the mean measured NaI column density per absorber. We also find preliminary evidence that NaI absorbers are associated with foreground galaxies at relatively small projected separations and that their quasar sightlines are redder than matched controls. These results support a picture in which NaI traces dense neutral gas in and around galaxies. Dedicated galaxy surveys and CGM/ISM simulations can test the inferred incidence and cross-section, while spectral stacking can probe the associated gas and dust.
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Quantum Physics

Quantum Advantage for Distributed Symmetry Breaking

Maxime Flin, Longcheng Li and Jukka Suomela

We present a distributed quantum algorithm that $3$-colors cycles in $O(1)$ rounds, with high probability. It follows that all locally checkable labeling problems (LCLs) that have round complexity $O(\log^* n)$ in the classical LOCAL model can be solved in $O(1)$ rounds in the quantum-LOCAL model, with high probability; this includes problems such as maximal independent set and maximal matching in bounded-degree graphs. This presents the first natural examples of graph problems with an asymptotic distributed quantum advantage for the LOCAL model; all prior examples that separate LOCAL and quantum-LOCAL are artificial problems constructed merely for the sake of demonstrating quantum advantage.
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Astrophysics of Galaxies

The BRIDGE Survey. I. Metallicities and Physical Properties of Gas Probing the Circumgalactic Medium at Cosmic Noon

Saloni Deepak, Nicolas Lehner, J. Christopher Howk et al. (+3 more)

We present BRIDGE-I, a metallicity survey of \HI-selected absorbers probing “CGM-like” gas ($16.4\leq \log N_{\rm HI}<20.3$) at Cosmic Noon ($1\leq z \leq2.2$), the epoch of peak star formation and AGN activity. Combining archival HST UV spectra with Keck/HIRES and VLT/UVES optical spectra, we estimate metallicities and physical conditions for 105 absorbers. The Cosmic Noon metallicity distribution (median $[\rm{X/H}]=-1.19$) is statistically indistinguishable from that at $z<1$ ($-1.18$) but differs significantly from $z>2.2$ ($-2.02$). This plateau is driven by the most diffuse absorbers ($16.4\leq \log N_{\rm HI}<17.2$), which reach their $z<1$ enrichment level by Cosmic Noon, whereas denser absorbers remain more metal-poor than their $z<1$ counterparts and continue to be enriched at later times. Unlike at $z>2.2$, no absorber falls below $[\rm{X/H}]=-3.5$, indicating no pristine CGM-like gas at Cosmic Noon. Absorbers in BRIDGE-I trace overdensities of $400\lesssim \delta_b\lesssim2200$, higher than at $z>2.2$. Mean $N_{\rm HI}$ differs by a factor of 400 across absorber types, but mean total hydrogen column by only 2.5, as higher $N_{\rm HI}$ is offset by a higher neutral fraction. The absorber classes thus differ in ionization state and metallicity rather than the total gas content. A metallicity floor of $[\rm{X/H}]\sim-2.0$ emerges for $\log N_{\rm HI}>19.0$ absorbers, indicating that denser, more ISM-like gas is well mixed as a population, while more diffuse gas retains a metal-poor population that is not yet fully mixed.
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All authors Saloni Deepak, Nicolas Lehner, J. Christopher Howk, John O'Meara, Celine Peroux, J. Xavier Prochaska

Quantum Physics

Error Suppression in Distributed Quantum Computing with Heterogeneous-Distance Lattice Surgery

Daniel Dilley, Anastashia Jebraeilli, Rayat Roy et al. (+3 more)

Distributed quantum computing requires fault-tolerant operations across inter-QPU links that can be substantially noisier than local gates. Uniformly increasing code distance provides additional protection but also enlarges data patches used for local storage and computation. Here, we introduce distributed heterogeneous-distance lattice surgery using an eight-data-patch ancilla-mediated (8-DAM) architecture, which will be useful for near-term quantum devices with less qubit overhead. In this architecture, the central ancilla spanning the inter-QPU boundary is enlarged while the data patches retain distance $d$. The protocol uses traveling stabilizers to suppress hook errors during merge and split operations between these unequal-distance patches. Circuit-level simulations of rotated surface codes at fixed local depolarizing noise show that logical-readout error rates depend only weakly on link noise. The resulting advantage over conventional lattice surgery grows as link errors increase. Comparisons with uniform distance implementations demonstrate comparable logical error suppression with reduced physical-qubit overhead. We also demonstrate how 8-DAM layouts support two simultaneous distributed logical CNOT operations between four logical data qubits using a single enlarged ancilla. At higher link noise, this construction yields lower logical error rates and more stability than two independent distributed logical CNOTs. These results support selective ancilla enlargement as a resource-efficient approach to fault-tolerant distributed quantum computing.
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All authors Daniel Dilley, Anastashia Jebraeilli, Rayat Roy, Shobhit Gupta, Alvin Gonzales, Zain Saleem

Astrophysics of Galaxies

Comparing phylogenetic trees of stars with spectral graph distances

Theosamuele Signor, Matias Neto, Paula Jofré et al. (+9 more)

Phylogenetic trees offer a hierarchical representation of chemical similarities among stars, from which their evolutionary histories can, in principle, be reconstructed. Simulation-based work suggests that phylogenetic trees built under different chemical evolution scenarios carry distinguishable structural imprints, but whether existing methods can detect this signal in practice is unclear. We evaluate distance measures, both classical tree-based and graph-theoretical, for comparing phylogenetic trees, seeking measures robust to observational noise that separate trees built from populations with distinct chemical enrichment histories. We construct Neighbor-Joining trees from chemical abundance vectors of solar twins and of stars associated with the Milky Way (MW) disk, Gaia-Sausage-Enceladus (GSE), and the Sagittarius dwarf spheroidal galaxy (Sgr). Two benchmark tests assess stability under input perturbations within the same evolutionary history and discriminative power between distinct stellar populations used as proxies for different evolutionary histories. Tree metrics rapidly saturate under perturbations of order the typical uncertainty ($\approx2\sigma$, or $\approx0.05$ dex per element) and fail to distinguish trees when leaf sets differ. In contrast, spectral distances vary smoothly with perturbation amplitude and provide a label-invariant method for comparing trees built from disjoint sets of stars. Among the spectral measures evaluated, the Laplacian spectral distance shows the most consistent separation across population pairs, while the normalized variant is weakest. Applied to MW, GSE, and Sgr stars, spectral measures recover a distance ordering consistent with their known chemical enrichment histories. This framework also provides a route to comparing observed enrichment histories against simulations to identify those that best reproduce the observed tree structure.
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All authors Theosamuele Signor, Matias Neto, Paula Jofré, Sara Vitali, Xia Hua, Patricia B. Tissera, Claudia Aguilera-Gómez, Payel Das, Brian Tapia-Contreras, Robert M. Yates, Luis Martí, Nayat Sánchez-Pi

Atomic Physics

Optical Ion Clock with Engineered Immunity to Motion-Induced Frequency Shifts

Mark Lide, Wesley Hardin and Christian Sanner

Spectroscopic frequency shifts due to residual motion of the probed atoms significantly contribute to the uncertainty budgets of state-of-the-art optical ion clocks. For clock transitions with second-order Doppler and quadratic Stark shifts of opposite signs, it is possible to configure electrodynamic ion confinement such that these two shift effects become anticorrelated causing zero net shift. Here, we introduce a spectroscopic interrogation protocol which leads, for systems with unknown and varying motional energy gain rates, to first-order auto-suppression of corresponding frequency shifts without requiring the opposite-sign configuration. We experimentally demonstrate the proposed method on a new ytterbium ion optical clock probing the 467 nm electric octupole (E3) transition, where the combined fractional uncertainty contribution from motion-induced frequency shifts is reduced from $1.3\times10^{-18}$ to $0.3\times10^{-18}$. An interleaved optical frequency ratio measurement against ytterbium's electric quadrupole transition (E2) at 435 nm delivers an E3/E2 frequency ratio of $0.932 \,829 \,404 \,530 \,965 \, 340 (39)$. Combined with previously published ratio data this leads to a limit for a potential fractional temporal variation of the fine-structure constant of $2.4 (2.7) \times 10^{-19}/$yr, in agreement with existing bounds.
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High Energy Physics (Phenomenology)

Resonant neutrino flavor conversion within dark matter spikes

P. S. Bhupal Dev, Elisa Gaido, Alejandro Ibarra et al. (+1 more)

We investigate how neutrino–dark matter (DM) interactions modify the flavor composition of high-energy neutrinos from active galactic nuclei (AGNs). Coherent forward scattering in a DM spike around the central supermassive black hole can generate a flavor-dependent potential, inducing flavor conversion as the neutrinos escape. We calculate the flavor composition at Earth for pion-decay and muon-damped sources and find substantial departures from vacuum-oscillation expectations. At neutrino energies around $100\,\mathrm{TeV}$, the matter potential begins to compete with vacuum oscillations when the coupling-weighted net DM number density reaches $|\epsilon_\alpha(n_\chi-n_{\bar\chi})|\sim10^{18}\,\mathrm{cm}^{-3}$. We compare our predictions with IceCube flavor triangle measurements under the illustrative assumption that the diffuse flux originates from AGNs with common neutrino-production and DM-spike properties. Under this assumption, when the DM-induced potential acts on the muon flavor and dominates the vacuum terms at production, the $p\gamma$ muon-damped predictions lie outside the 95% MESE contour. High-energy neutrino flavor measurements can therefore provide a novel probe of neutrino-DM interactions in astrophysical environments.
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All authors P. S. Bhupal Dev, Elisa Gaido, Alejandro Ibarra, Yago Porto

Quantum Physics

On the Complexity of Finding Decoherence Free Subspaces

Evan Borras

Decoherence free subspaces are a steady-state structure of the open quantum system which preserves quantum coherence between the states lying with in it and thus has found a variety of applications throughout quantum information science and technology. In this paper we study the computational complexity of deciding whether an open quantum system admits a decoherence free subspace or not. More specifically we study this problem with in the context of Markovian open quantum systems, governed by the time-independent Lindblad master equation. Along the way we introduce the $k$-Local Lindbladian problem, which captures the difficulty of computing purity decay rates under Lindbladian dynamics. We show that both problems are hard for the complexity class Quantum Merlin Arthur (QMA) when the locality $k \geq 5$, with the first under perfect completeness and the second being complete for QMA. Our hardness construction generalizes Kitaev's clock Hamiltonian construction to the open quantum system setting by encoding the execution of a quantum circuit into the steady subspace of a Lindbladian containing both pure and mixed history states. This subspace is then mixed depending on the output of the encoded circuit. Our results suggest that deciding whether a generic Markovian open quantum system admits a decoherence free subspace is intractable even for quantum computation.
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High Energy Physics (Phenomenology)

Tachyonic particle production in strongly supercooled phase transitions

Mateusz Kulejewski, Bogumila Swiezewska and Jorinde van de Vis

In strongly supercooled cosmological phase transitions, which generically lead to strong, observable gravitational-wave backgrounds, the scalar field typically transitions to a value well below the minimum of its potential. We study particle production caused by the subsequent evolution of the field. Because some modes feature temporarily tachyonic masses, they can be efficiently produced, and a significant fraction of the energy density released in the phase transition can get converted to particles rather than gradient energy. This has consequences for the shape and amplitude of the gravitational-wave spectrum caused by the interactions in bubbles and sources a new, high-frequency signal. Moreover, it affects the bubble expansion velocity and equation of state, which can facilitate the formation of primordial black holes.
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