Strongly Correlated Electrons
Symmetric Mode Ansatz: Theory of Magnon Collective Modes in Chern Insulators
Miguel Gonçalves, Jonah Herzog-Arbeitman, Juan Felipe Mendez-Valderrama et al. (+3 more)
Moiré materials host integer and fractional Chern
insulators (FCIs) where time-reversal is broken spontaneously by flat band ferromagnetism. In twisted MoTe2, unlike in
quantum Hall, opposite
spins carry opposite Chern numbers and realize Ising ferromagnetism with gapped
magnon excitations. Clarifying the nature of these collective modes and the origin of the
magnon gap is key to understanding the stability of the Chern magnets in these materials. To do so, we develop a generalized single-mode approximation, which we call the symmetric mode ansatz (SyMA), to describe the low-energy
magnon spectrum. We find it to be in exceptional agreement with numerical calculations at integer filling, and qualitatively accurate across fractional fillings including FCIs. To explain the accuracy of the SyMA, we present two families of Hubbard models (including the Haldane model and continuum ideal bands) whose collective modes are analytically solvable and for which the SyMA is either exact or an accurate approximation. For a class of these models where SyMA is exact, we prove two-sided bounds on the zero-momentum
magnon gap in terms of the Chern number, Berry
curvature, and
quantum metric, revealing that uniform
quantum geometry is sufficient for stabilizing magnetism in Chern bands.
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All authors Miguel Gonçalves, Jonah Herzog-Arbeitman, Juan Felipe Mendez-Valderrama, Andreas Feuerpfeil, B. Andrei Bernevig, Nicolas Regnault
Quantum Physics
Quantum Networking at the Speed of Quantum Computation: Kilohertz Entanglement in a Heterogeneous Quantum System
Lukas Hartung, Pierre Barral, Noah Glachman et al. (+35 more)
Distributed
quantum computing requires rapid, high-fidelity
entanglement between
qubits in separate processor modules. Photonic links between single-atom
qubits provide switchable, long-range connections, but
photon loss limits their
entanglement rate. Here we entangle a trapped $^{138}$Ba$^{+}$ ion with a silicon-vacancy (SiV$^{-}$) center in a diamond nanophotonic cavity. A
photon emitted by the ion is converted in wavelength and encoding, reflected from the SiV$^{-}$–cavity system and detected, so that a single detected
photon heralds
entanglement. Including all conversion losses, we generate ion–SiV$^{-}$ Bell pairs at an average rate of 1.03(1) kHz with a fidelity of 87.9(7)%. This is four times the rate of the fastest photonic link between two trapped ions and corresponds to one Bell pair per millisecond, matching the cycle time of planned trapped-ion processors.
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All authors Lukas Hartung, Pierre Barral, Noah Glachman, George Toh, Jacob H. Davidson, Sagnik Saha, Alexander Chuang, Matthew C. Cambria, Madison Sutula, Alexander Abulnaga, Julia Brevoord, John Chiaverini, Ian Counts, Aos Dabbagh, Christian Dangel, Skylar Deckoff-Jones, Chawina De-Eknamkul, Jonathan Dietz, Riley Forst, Prithvi Gundlapalli, Jeonghoon Ha, Michael Haas, Ezekiel Meulbroek, Andrea Mucchietto, Daniel Riedel, Jonah Sachs, Jeremy Sage, Mikhail Shalaev, Harriet Shi, Denis Sukachev, Yichao Yu, Christopher Monroe, Nicholas Mondrik, Mihir Bhaskar, Bart Machielse, Matteo Pompili, Carsten Robens, David Levonian
High Energy Physics (Theory)
Scattering entanglement entropy between one particle species and the others
Yuan-Hao Zheng and Jiayin Gu
We construct the
entanglement entropy of a general scattering process between one particle species (denoted as $A$) and the rest of the final state. Assuming a pure initial momentum eigenstate, we show that the reduced density
matrix in particle $A$'s Fock space is block-diagonal in zero-, one- and multi-particle states, and is diagonal in the momentum basis for the one-particle state. As a result, we could write down the Von Neumann
entropy of particle $A$, $S_A$, in terms of scattering probabilities and differential cross sections, assuming no more than one particle $A$ is produced in the final state. $S_A$ contains the information of both the total scattering probabilities (or cross sections) and the differential distributions — the latter depends on a phase-space resolution factor as a result of the infinite-dimensional momentum
Hilbert space. Our result is general and model-independent since we consider the full final state from time
evolution ($S|i\rangle$) rather than a specific outcome, and is applicable as long as the probability for producing multiple particle $A$ is subleading. We also obtain the $n\geq2$ Tsallis and Rényi
entropies in our framework and find out that, at the leading order, they are proportional to the total scattering probability and carry no differential information.
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Computer Vision
Seeing Through the Glare: A Multi-Source Benchmark and Ocular-Adaptive Pixel MeanFlow for Eyeglass Reflection Removal
Tao Liu, Youwei Pang, Kailai Zhou et al. (+7 more)
Eyeglass reflection removal is important across smartphone imaging,
video conferencing, and other face-centric visual applications. The task is challenging because reflections range from mild photometric contamination to severe ocular occlusion, requiring selective correction and plausible reconstruction without altering identity or natural appearance. Existing
datasets cover limited reflection conditions, constraining generalization to complex real-world scenes and systematic evaluation. We introduce OcuBench, a multi-source
benchmark comprising 10,280 controllable synthetic pairs, 732 real-input pseudo-pairs, and 458 independent real-world test images, supporting both paired evaluation and assessment beyond generated supervision. We further propose OcuFlow, an ocular-adaptive pixel MeanFlow (pMF) framework for efficient, detail-preserving restoration. It combines geometry-adaptive representation with one-step pMF to focus reconstruction on reflection-obscured ocular regions, together with native-resolution frequency-preserving synthesis to retain reliable observed details. Experiments across diverse reflection conditions demonstrate that OcuFlow achieves consistent advantages in reflection removal quality, ocular fidelity, and efficiency. In a blind user study, it receives $67.32\%$ of selections, $6.2\times$ the next-best share. Both the code and
dataset will be released.
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All authors Tao Liu, Youwei Pang, Kailai Zhou, Jiaming Zuo, Hanqi Liu, Wei Ji, Peng-Tao Jiang, Xiaofeng Liu, Weisi Lin, Xiaoqi Zhao
Quantum Physics
Combining Error Verification and Privacy Amplification in Quantum Key Distribution
Devashish Tupkary, Zhiyao Wang and Ernest Y.-Z. Tan
Quantum Key Distribution (QKD) protocols typically involve two separate steps of error-verification and
privacy amplification. Both steps involve the application of a hash function sampled from a suitable hash family to classical data. A potentially simpler alternative is to implement a single-step hashing procedure, announce and compare a fixed number of bits of its output for error-verification, and retain the remaining bits as the final output key. This reduces the complexity of classical postprocessing, the amount of classical communication, and the amount of randomness needed in the protocol. While this construction has appeared in the literature, a suitable mathematical justification is lacking. In this work, we show that the security of such protocols, under certain simple conditions, follows from a slightly modified notion of secrecy of the protocol without the final error-verification step. In particular, we show that for most
entropy-based proofs, the combined protocol can be implemented with no change to the key rate, and a minor change to the security parameter.
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Earth and Planetary Astrophysics
EK Cha b: multi-tracer detection of a protoplanet candidate in a gas-rich environment
Felipe Alarcón, C. Swastik, Stefano Facchini et al. (+2 more)
Despite sustained community efforts and advances in instrumentation and high-contrast imaging, the search for protoplanets remains difficult, with only two widely accepted systems to date in Class II systems (PDS 70 and WISPIT 2). Here we present the detection of EK Cha b, a new protoplanet candidate, identified through CO emission, millimeter continuum and 0.82 micron broadband photometry, linked to EK Cha, a young late-type M
star. The detection of a new protoplanet candidate offers an additional opportunity to advance our understanding of
planet formation. By exploiting the wealth of archival data available for nearby
star-forming regions, we aim to place EK Cha b in context, characterize its properties, and motivate future campaigns targeting similar systems. We analyzed high-spatial-resolution archival observations of EK Cha from HST, VLT/NACO, VLT/MUSE, and ALMA. We searched for EK Cha b in broadband continuum and gas tracers, reporting the measured flux with uncertainties, and upper limits for non-detections. EK Cha b shows a spectrally-resolved footprint that matches the CO J=2–1 emission, together with 0.82 micron and millimeter continuum emission. EK Cha b is spectrally resolved in CO J=2–1 emission, kinematically consistent with a circumplanetary disk. Best fits from evolutionary models place EK Cha b as a planetary mass companion, although deeper observations are required to fully confirm its nature. Although
giant planets are uncommon around M
dwarfs, these
stars host the highest
planet occurrence rate while remaining severely underrepresented in protoplanet searches. EK Cha b demonstrates that such systems are now within reach, and the advent of extremely large
telescopes and improved high-contrast imaging – where the lower host luminosity relaxes the required contras– will open this overlooked regime to systematic exploration.
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All authors Felipe Alarcón, C. Swastik, Stefano Facchini, Edwin A. Bergin, Gabriele Cugno
Mesoscale and Nanoscale Physics
Millisecond phonon lifetimes in piezoelectric nanomechanical resonators
Oliver A. Hitchcock, Matthew P. Maksymowych, Kaveh Pezeshki et al. (+5 more)
Piezoelectric nanomechanical resonators operating at gigahertz frequencies are a promising platform for
quantum information processing and precision sensing, but
phonon lifetimes have been limited to the microsecond range, widely attributed to the higher intrinsic loss of piezoelectric materials. Here we show that this limitation is not fundamental. Using a fabrication process informed by recent studies of defect-mediated loss in lithium niobate, we combine chemical restoration of ion-milled surfaces with a shadow-mask metallization process to produce lithium niobate phononic
crystal resonators with inferred internal
phonon lifetimes of up to 21 milliseconds at 3.6 gigahertz, corresponding to quality factors exceeding $4\times10^8$ ($f\cdot Q_i > 10^{18}$) at millikelvin temperatures. By systematically varying the electrode-to-resonator spacing, we demonstrate that the measured lifetime is set by external coupling between the device and the measurement
circuit rather than material loss. This establishes that lithium niobate, once fabrication-induced surface damage is removed, achieves an intrinsic quality comparable to the best mechanical materials while remaining an intrinsically piezoelectric platform with strong electromechanical coupling.
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All authors Oliver A. Hitchcock, Matthew P. Maksymowych, Kaveh Pezeshki, Takuma Makihara, Erik Szakiel, Chou-Wei Kiang, Daniel Rugar, Amir H. Safavi-Naeini
Solar and Stellar Astrophysics
Atypical White Dwarfs in Open Clusters
David R. Miller, Ilaria Caiazzo, Jeremy Heyl et al. (+1 more)
Open clusters are powerful laboratories for investigating the formation and
evolution of white
dwarfs (WDs), as their well-constrained ages link WDs to their progenitor
stars. This is particularly valuable for atypical WDs, including
magnetic WDs and those with non-hydrogen-dominated spectra, whose origins can be difficult to disentangle in the field. We assemble the largest sample to date of atypical WDs in open clusters: eight non-
magnetic WDs with helium-dominated spectra, five with featureless spectra, and five
magnetic WDs showing hydrogen or helium lines. We find no significant difference between the initial–final mass relations of hydrogen- and helium-atmosphere WDs, nor robust spatial or kinematic differences. The strongest difference from the field is a deficit of non-DAs between $0.8$ and $1.0\,\mathrm{M}_\odot$, where the field predicts $6.0^{+0.8}_{-0.7}$ WDs, yet none are observed, with a probability of only $0.37\%$. Massive
magnetic WDs show a similar deficit: only one of 20 cluster WDs with $M_{\mathrm{WD}}\geq1.0\,\mathrm{M}_\odot$ and $T_{\mathrm{eff}}\geq20{,}000\,{\rm K}$ is
magnetic, compared with 10 of 16 in the field. Together, these deficits are consistent with an additional field population of massive merger remnants, particularly high-mass
magnetic WDs and warm/hot DQs. Such objects may be underrepresented in clusters because young systems provide limited time for certain classes of delayed mergers, while older clusters lose members or dissolve; the field accumulates binary
evolution products over
Galactic timescales.
Magnetic cluster WDs consistent with single-
star evolution further suggest mass-dependent
magnetic-field emergence, with fields appearing early in some massive WDs while young lower-mass WDs remain consistent with delayed emergence.
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All authors David R. Miller, Ilaria Caiazzo, Jeremy Heyl, Pier-Emmanuel Tremblay
Astrophysics of Galaxies
Lauri Sassali, Cecilia Bacchini, Aku Venhola et al. (+2 more)
The origin of cold gas
turbulence in
galaxies has long been debated.
Supernovae (SNe), the dominant form of
stellar feedback, were thought insufficient to sustain it against dissipation, especially in
galactic environments with low
star formation rates (SFRs). We investigate the origin of the neutral atomic gas (HI)
turbulence in
dwarf irregular
galaxies, a challenging regime of low masses and SFRs. We build on a recent study of spirals showing that disc flaring prolongs the dissipation timescale, reducing the energy needed to sustain
turbulence and making SN feedback viable. We measure the SN efficiency, that is the fraction of SN energy required to sustain HI
turbulence, in 14
dwarfs, and test whether a "universal" efficiency holds across a sample representative of the
star-forming main sequence. From the observed HI distributions and kinematics, we derive the radial profiles of the HI kinetic energy per unit area and model them as the sum of thermal energy and turbulent energy from SNe, constrained by the observed SFR surface density. We consider pure cold and warm neutral medium (WNM) phases as limiting cases, as well as a mixed two-phase scenario, obtaining the SN efficiency and WNM fraction via hierarchical
Bayesian inference. We find that the observed HI kinetic energy in
dwarfs requires only $\lesssim 3\%$ of the SN energy, and that a "universal" efficiency of $\approx 2\%$ explains the HI
turbulence across our main-sequence sample. Our findings suggest that the SN efficiency remains similar across
galaxies with different properties, offering valuable constraint for feedback recipes in
galaxy evolution models.
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All authors Lauri Sassali, Cecilia Bacchini, Aku Venhola, Giuliano Iorio, Antonino Marasco
Quantum Physics
The surprising simplicity of forecasting quantum chaotic many-body dynamics
Francesco Perciavalle, Agostino Gallo, Francesco Plastina et al. (+3 more)
Accurately simulating chaotic
quantum many-body dynamics remains a major computational challenge for classical methods, due to the rapid buildup and spatial spreading of
entanglement during the
evolution. This raises the question of whether machine learning can provide an effective alternative for predicting
quantum dynamics. We address this question by formulating
quantum dynamics as a time-series
forecasting problem, using a few-
qubit PXP chain, realizable with Rydberg-atom arrays, as a
benchmark. By varying the initial state, the system spans dynamical regimes ranging from ergodic behavior to
quantum many-body scarring, providing a controlled setting for testing
forecasting models across qualitatively different dynamics. We compare two contrasting architectures: an expressive nonlinear
Transformer and DLinear, a simple linear
forecasting model. The
Transformer accurately predicts dynamics in the more ergodic regime, but its performance progressively deteriorates as the initial state approaches the scarred limit. In contrast, DLinear remains accurate across the entire family of initial states, with its main deviations consisting of small high-frequency oscillations that have little effect on the overall prediction error. Remarkably, these results show that observables generated by complex
quantum many-body dynamics can be forecast with high accuracy through a simple linear mapping from past to future observations. This reveals that the complexity of the underlying
quantum evolution need not translate into an equally complex
forecasting problem.
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All authors Francesco Perciavalle, Agostino Gallo, Francesco Plastina, Gianluigi Greco, Nicola Lo Gullo, Carlo Adornetto
High Energy Physics (Phenomenology)
A Texture of Leptons for the Koide and Alikhanov relations
Alessandro Strumia
Koide and Alikhanov proposed intriguing empirical relations among charged-
lepton masses and
neutrino mass splittings, respectively. We present mass-
matrix textures that realise these relations and can jointly account for the observed
lepton mixing angles, while yielding predictive correlations among them and the
neutrino CP phases.
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High Energy Astrophysical Phenomena
The Origin of the Fermi Halo-like Emission: A New Model of the Fermi Bubbles
Ilias Cholis, Leo Qiyuan Hu and Yi-Ming Zhong
We study the gamma-ray sky at high latitudes for energies between 0.3 and 900 GeV. We search for a contribution in the high-latitude sky and in the region of the
Galactic Stellar Halo that would be beyond known astrophysical emissions, i.e., the
galactic diffuse emission, the isotropic mostly extragalactic gamma-ray background, the
Fermi Bubbles, Loop I, the contribution from the
Galactic Center Excess, and the known point and extended gamma-ray sources detected by the
Fermi-LAT Collaboration. We perform a sequence of template fits to the
Fermi gamma-ray data, testing different regions of interest of the
galactic sky, utilizing a large set of alternative
galactic diffuse emission models, and implementing alternative fitting schemes to assess the impact of increased modeling complexity of the gamma-ray sky. We find that the
halo-like emission recently reported by Totani (2025) is real, but it is likely due to emission from the
Fermi Bubbles rather than dark matter annihilation in the
Galactic halo. We provide new templates for the
Fermi Bubbles, including an updated model for the Flat Bubbles and a detailed model of their substructures, the Cocoons and the Inner Bubbles. In combination, these components account for the previously reported
halo-like emission. We also estimate the associated fluxes and spectral properties of the Flat Bubbles, the Inner Bubbles, and the Cocoons. This updated model for the
Fermi Bubbles provides new input toward understanding their origin.
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Strongly Correlated Electrons
Anthony Rey, Ömer M. Aksoy, Claudio Chamon et al. (+2 more)
We investigate how spontaneous
symmetry breaking and
symmetry-protected
topology compete and cooperate in one-dimensional
quantum spin-1/2 systems. We introduce two families of local
Hamiltonians with $\mathbb{Z}^{\,}_{2}\times\mathbb{Z}^{\,}_{2}\times\mathbb{Z}^{T}_{2}$
symmetry which host a zoo of broken-
symmetry phases with and without gapless boundary
spins, namely, six long-range-ordered gapped phases that differ by their $\mathbb{Z}^{\,}_{2}$-
symmetry-breaking patterns (FM$^{\,}_{x,y,z}$ and Neel$^{\,}_{x,y,z}$), their partner
symmetry-protected topological phases (FM$^{\mathrm{SPT}}_{x,y}$ and Neel$^{\mathrm{SPT}}_{x,y}$), and two gapless phases (gFM$^{\,}_{z}$ and gNeel$^{\,}_{z}$) with incommensurate $\mathbb{Z}^{T}_{2}$-breaking
magnetic long-range order and central charge $\mathsf{c}=1$. Direct transitions between competing gapped phases can be continuous or weakly first order. We demonstrate that continuous phase transition lines have exotic critical properties. For example, a line of deconfined
quantum critical points (between the Neel$^{\,}_{x}$ and Neel$^{\,}_{y}$ phases) described by Tomonaga-Luttinger
liquid theory is terminated by the gFM$^{\,}_{z}$ phase at a Lifshitz tricritical point which exhibits spontaneous breaking of the continuous U(1)
symmetry despite the locality and one-dimensionality of the
Hamiltonian, contrary to a naive expectation from the Hohenberg-Mermin-Wagner-Coleman
theorem. Furthermore, critical lines between
symmetry-protected topological phases with different $\mathbb{Z}^{\,}_{2}$-
symmetry breaking (e.g., Neel$^{\mathrm{SPT}}_{x}$ and Neel$^{\mathrm{SPT}}_{y}$) additionally retain low-energy boundary degrees of freedom, realizing
symmetry-enriched criticality (or a gapless SPT phase). Our results reveal unconventional mechanisms by which competing
symmetry breaking and
topology generate ordered critical phases and multicriticality.
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All authors Anthony Rey, Ömer M. Aksoy, Claudio Chamon, Akira Furusaki, Christopher Mudry
High Energy Physics (Theory)
General Spin-1 Dynamics During Inflation: Microcausality Constraints and Cosmological Collider Signals
Trevor Cheung, Carlos Duaso-Pueyo, David Stefanyszyn et al. (+1 more)
We construct the general theory of a
spin-1 field propagating on an inflationary background consistent with scale invariance, rotations, Bunch-Davies conditions and microcausality. Our Boostless Proca theory generalises the usual massive Proca theory to a Lagrangian with 5 free parameters: 4 corresponding to parity-even terms and a single parity-odd term. We impose three degrees of freedom from the outset and find that microcausality, the statement that field operators vanish outside the lightcone, requires the kinetic terms to be gauge invariant. We couple this
spin-1 state to the inflaton and study the signatures it imprints on cosmological correlators. We find no new signals for the bispectrum meaning that the known signals are the most general thereby providing a very clean model-independent probe of new physics in this leading form of non-Gaussianity. For the trispectrum and higher-point functions, the boostless Proca theory produces new shapes with all 5 parameters in principle measurable.
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All authors Trevor Cheung, Carlos Duaso-Pueyo, David Stefanyszyn, Dong-Gang Wang
High Energy Physics (Phenomenology)
Effective field theory for strong phase transitions
Oliver Gould, Farbod-Sayyed Rassouli and Paul M. Saffin
We show how to construct perturbative effective field theories for strong phase transitions, where the standard tools of high-temperature dimensional reduction fail. By identifying the relevant power counting relations for the couplings, masses and background fields, we construct a controlled perturbative expansion adapted to this regime. We find that the order parameter field remains light at the transition, so that there is a controlled derivative expansion, even though large external fields need to be resummed. The resulting effective field theories for strong phase transitions live in three dimensions and have nonpolynomial field dependence. Applying our framework to a two-scalar model, we verify renormalisation scale cancellation through next-to-next-to-leading order and find decreasing corrections to the latent heat as the perturbative order is increased. Extending to include
fermions and gauge fields, we identify a broad class of models in which strong-transition thermodynamics are systematically improvable.
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High Energy Astrophysical Phenomena
Accreting Neutron Stars in Low-Mass X-ray Binaries
M. C. Baglio, S. E. Motta, A. P. Nitindala et al. (+1 more)
Neutron star low-mass X-ray binaries (NS LMXBs) are systems in which a
neutron star accretes matter from a Roche-lobe-filling companion via an
accretion disc, releasing gravitational energy with an efficiency of order 10-20% of the rest-mass energy. Unlike black holes,
neutron stars possess a solid surface and a
magnetic field, making NS LMXBs uniquely rich laboratories for high-energy astrophysics and dense-matter physics. In this chapter we review the current understanding of
accretion onto
neutron stars in LMXBs, tracing matter from the outer disc radii to the
stellar surface across five decades of observational discovery. We survey the principal classes of accreting
neutron star systems - canonical atoll and Z-sources, ultracompact X-ray binaries, accreting millisecond
pulsars, and transitional millisecond
pulsars - and discuss how their spectral states, timing properties, and multiwavelength behaviour encode the physics of the inner
accretion flow. We examine thermonuclear Type-I X-ray bursts as probes of
nuclear burning and
neutron star structure, and review the boundary and spreading layers where accreted matter decelerates onto the
stellar surface. We discuss relativistic jets and ionised disc winds as regulators of the
accretion-ejection cycle. Finally, we present X-ray polarimetric results from the Imaging X-ray Polarimetry Explorer (IXPE), which for the first time provide new, though model-dependent, constraints on the geometry of the emission regions - disc, corona, spreading layer, and jets - that spectroscopy alone cannot resolve, alongside complementary optical and infrared polarimetric observations.
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All authors M. C. Baglio, S. E. Motta, A. P. Nitindala, J. Poutanen
Machine Learning
Learning infinite context windows in recurrent architectures via spatial neural computing
Aleix Salvador-Pomarol, Arthur N. Montanari, Earl K. Miller et al. (+2 more)
Recurrent neural networks (RNNs) offer linear-time scaling with sequence length while requiring only constant
memory, yet they struggle to capture long-range dependencies due to vanishing gradients and limited receptive fields. To address these limitations, we introduce a second-order recurrent model in which the standard
neuron-to-
neuron communication is replaced by a spatially evolving field governed by (discretized) partial differential equations. Drawing inspiration from the role of cortical waves in
brain computation, this mechanism allows structured spatiotemporal patterns to serve as an implicit, high-capacity
memory. We show that the resulting model is equivalent to a structured infinite-order RNN in which the current state depends explicitly on its entire history of past states, yielding an effectively unbounded receptive field with a fixed number of parameters. We further derive constructive conditions to ensure marginal stability, constraining the gradient spectrum on the unit circle and thereby eliminating vanishing and exploding gradients. Empirically, the proposed architecture outperforms other recurrent models on long-horizon
benchmarks while using substantially fewer parameters, demonstrating that spatial dynamics can effectively bridge the gap between efficient inference and long-term
memory.
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All authors Aleix Salvador-Pomarol, Arthur N. Montanari, Earl K. Miller, Adilson E. Motter, Jorge Cortés
High Energy Astrophysical Phenomena
Discovery of a Nearby Ultra-fast Magnetic White Dwarf Propeller: Common Pathways to Magnetic Cataclysmic Variables
Antonio C. Rodriguez, Kareem El-Badry, R. Michael Rich et al. (+11 more)
The fastest spinning white
dwarfs (WDs), which approach break-up speeds, are found in close binary systems. In the two known
magnetic WD “propellers”, AE~Aqr and LAMOST J0240+1952, the
magnetic WD
spins so rapidly that it ejects the material transferred by its Roche-lobe-filling companion rather than accreting it. We report the discovery of the third such system, 1eRASS J042633.5$-$250226 (1eRASS J0426/Valeria), at only 265 pc, identified by combining SRG/eROSITA and
Gaia data via the “X-ray Main Sequence”. TESS photometry shows AE~Aqr-like flaring and orbital modulation with $P_{\mathrm{orb}} \approx 6.62$ hr, and ZTF shows month-long high/low state changes. Phase-resolved Palomar/DBSP spectroscopy confirms the orbital period and yields a donor radial velocity of $K_2 = 202\pm7$ km s$^{-1}$. High-speed Palomar/CHIMERA photometry detects optical pulsations on three nights with the strongest detection at $P_\textrm{spin} = 26.8$ sec, though further observations are needed to confirm this as the WD
spin. Spectral fitting of the donor in the low state reveals a late K-type
star with $T_{\mathrm{donor}} = 4100\pm150$ K. Zeeman splitting in the optical spectrum yields a candidate field strength of $B_{\mathrm{WD}} = 26 \pm 3$ MG, meaning the system will evolve into a polar. Like other WD propellers, the system is X-ray faint ($L_X \approx 7\times 10^{30}$ erg s$^{-1}$), but is not detected in the
radio, and a
spin period is not detected in X-rays by SRG/eROSITA. The proximity of this system and evolutionary model constraints on the timeframe of the propeller phase yield a birth rate density of $\sim8\times10^{-16} \textrm{pc}^{-3} \textrm{yr}^{-1}$, which agrees with that of
magnetic CVs, suggesting that a substantial fraction of
magnetic CVs pass through a propeller phase.
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All authors Antonio C. Rodriguez, Kareem El-Badry, R. Michael Rich, Kevin N. Ortiz Ceballos, Ingrid Pelisoli, Casey J. Law, Kaya Mori, Boris Gaensicke, Edo Berger, Liam Connor, Ilkham Galiullin, Ilaria Caiazzo, Matthew Graham, Samuel Whitebook
High Energy Physics (Phenomenology)
Matter-Antimatter Asymmetry from Dirac-Majorana Flip-Flop
Debasish Borah, Arnab Dasgupta, Debalina Nandy et al. (+2 more)
The observed matter-antimatter asymmetry can be generated dynamically via leptogenesis, where a non-zero
lepton asymmetry is generated first and then gets converted into
baryon asymmetry via sphalerons. Creation of non-zero
lepton asymmetry typically requires
lepton number violation (LNV) which, within the seesaw framework, results in the Majorana nature of light
neutrinos. With no signs of LNV at terrestrial experiments, we propose a novel leptogenesis scenario where LNV occurs at high temperatures while zero-temperature physics is consistent with the pure Dirac nature of
neutrinos. In a concrete model of this "Dirac-Majorana flip-flop", the right
chiral parts of Dirac
neutrinos initially acquire a large Majorana mass in the early Universe when a singlet scalar field with two units of
lepton number acquires a non-zero
vacuum expectation value (VEV), thereby facilitating leptogenesis from out-of-
equilibrium decay of heavy Majorana
fermions. At lower temperatures, the VEV of the scalar singlet gets restored to zero to be consistent with
lepton number conservation. A first-order VEV-restoring phase transition can lead to observable gravitational waves, while light Dirac
neutrinos can generate detectable dark radiation at
cosmic microwave background experiments.
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All authors Debasish Borah, Arnab Dasgupta, Debalina Nandy, Indrajit Saha, Harman Singh
Astrophysics of Galaxies
Cosmic Duets II. Growth and accretion in Gaia Multi-Peak dual AGN at Cosmic Noon
M. Scialpi, F. Mannucci, D. Izquierdo-Villalba et al. (+36 more)
We present the first statistical characterization of the physical properties of
Cosmic Duets: dual AGN in the
redshift range 0.5 $\leq$ z $\leq$ 3.0 with projected separations of 1-7 kpc, corresponding to systems in which both AGN are expected to reside within the same merger remnant. We analyze the largest homogeneous sample currently available, consisting of 30 spectroscopically confirmed
Cosmic Duets selected via the
Gaia Multi-Peak technique. Using rest-frame UV-to-optical integral-field spectroscopy for all targets, primarily with VLT/MUSE, VLT/ERIS, and Keck/OSIRIS, we spatially resolve the two AGN components and extract separate spectra for each system. We decompose the continuum, emission lines, and Fe II complexes through spectral fitting. We derive black hole masses of log($M_{BH}/M_{sun}$) ~ 7.4-10.1 and bolometric luminosities of log($L_{bol}/erg s^{-1}$) ~ 44.8-47.2, consistent with those of single AGN at similar
redshifts. We finally carry out the first comparison of dual AGN properties with semi-analytical models and hydrodynamical simulations, including L-GalaxiesBH and Astrid. Astrid provides a closer match to the observed black-hole mass-ratio distribution, but its selected systems are predominantly at lower
redshifts, resulting in lower bolometric luminosities at fixed G-band magnitude. L-GalaxiesBH perfectly reproduce the observed parameter space, but it predicts more heterogeneous pairs, with higher primary-bolometric luminosity, lower-mass secondary SMBHs, and higher Eddington ratios, resulting in an excess of near-Eddington accreting AGN due to its adopted
accretion prescription. Our results suggest that, in GMP-selected systems, secondary SMBH growth is more efficient than predicted by current models, leading to more comparable black-hole masses and
accretion power between the two components.
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All authors M. Scialpi, F. Mannucci, D. Izquierdo-Villalba, A. Marconi, J. Singh, M. Volonteri, C. Marconcini, Q. D'Amato, B. Moreschini, M.V. Zanchettin, G. Tozzi, M. Ceci, L. Ulivi, E. Bertola, S. Bonoli, C. Bracci, E. Cataldi, C. Cicone, A. Ciurlo, M. Colpi, G. Cresci, A. De Rosa, M. Dotti, M. Fumagalli, M. Ginolfi, I. Lamperti, E. Nardini, M. Parvatikar, M. Perna, F. Rigamonti, K. Rubinur, B. Sala, A. Sesana, P. Severgnini, C. Spingola, D. Spinoso, G. Venturi, C. Vignali, S. Yeh
High Energy Physics (Theory)
Covariant BCFW for All Masses
Jacob L. Bourjaily and Michael Plesser
We use the massive spinor-helicity formalism to describe a novel construction for massive spinors which allows one to connect the many choices of bases useful in the representation of amplitudes involving massive particles, and we use this to derive a new formulation for the general BCFW shift that is valid regardless whether or which of the particles involved are massive or massless. This formalism should help facilitate a more coherent implementation of on-shell recursion for computing amplitudes involving massive particles in four dimensions.
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High Energy Astrophysical Phenomena
Neutrino flavor conversion alters the lepton-emission self-sustained asymmetry in core-collapse supernovae
Noah Roux, Irene Tamborra and Maryna Mesiura
We solve the
neutrino equations of motion in a half annulus, accounting for two spatial dimensions. At any location in the annulus, the
neutrino momentum is characterized by a polar-angle distribution, two effective azimuthal angles, and an energy distribution. We explore how
neutrinos change their
flavor while decoupling from matter in the presence of the
neutrino-driven hydrodynamical instability LESA (i.e., the
Lepton-number Emission Self-sustained Asymmetry) during the stalled-shock phase of a core-collapse
supernova. In our setup, LESA is responsible for an excess of $\nu_e$'s ($\bar\nu_e$'s) in the Northern (Southern) region of the annulus. Crossings in the $\nu_e$-$\bar\nu_e$ angular distributions appear in the ELN-depleted Southern region of the annulus, while crossings in the energy distributions of $\nu_e$-$\nu_x$ and $\bar\nu_e$-$\bar\nu_x$ are present throughout the annulus. We find that collisional instabilities drive
flavor conversion just before
neutrino decoupling, fast instabilities are prominent in the Southern region of the annulus, and slow instabilities dominate otherwise.
Flavor conversion is most efficient in the Southern region and is responsible for a $5$-$10\%$ enhancement of the LESA dipole, independent of the
neutrino-mass ordering. Our findings suggest that direction-dependent
flavor conversion can have implications for the development of global
neutrino asymmetries and hydrodynamical instabilities in core-collapse
supernovae.
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Quantum Physics
Quantum non-Markovian response spectra
Aaron Sander, John F. Kam, Gauthameshwar S. et al. (+2 more)
Quantum systems are rarely isolated from their surroundings. These hidden environments can retain information and return it later, producing correlated errors in
quantum computers and complicating the interpretation of experiments. On a
quantum processor, for example, one job can therefore leave an environmental trace that affects the next, even after the
qubits themselves have been reset. Learning how this hidden influence persists and affects later behavior is therefore important, but the environment is often impossible to measure directly, and fully reconstructing its effects through
tomography rapidly becomes impractical. Here, we introduce a response
matrix that uses controlled interventions and observations of the system alone to reveal the temporal structure of environmental
memory. The
matrix records how future observations change across different controlled histories. Its spectrum characterizes how
memory is structured and how it persists under specified system resets, while suitable linear combinations of its entries can rule out specified classical models of that
memory. Because its history-future queries can be evaluated independently, numerical response
matrices can be assembled in parallel. We establish the framework theoretically, characterize response spectra in an interacting
spin process, and certify
quantum memory in a two-
qubit benchmark. This approach turns system observations into a probe of inaccessible environments and could support the diagnosis of correlated noise, tests of open system models, and
memory-aware control design.
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All authors Aaron Sander, John F. Kam, Gauthameshwar S., Robert Wille, Kavan Modi
Astrophysics of Galaxies
A Multi-dimensional Analysis of the Open Clusters NGC 2423 and NGC 2482 with Gaia DR3
W. H. Elsanhoury, Deniz Cennet Ç{\i}nar and A. Ahmed
We present a homogeneous photometric, astrometric, and kinematic study of the Hyades-like open clusters NGC 2423 and NGC 2482 based on
Gaia DR3 data. Cluster memberships are determined using the UPMASK
algorithm in the multi-dimensional parameter space of (alpha, delta, parallax, mu_alpha cos(delta), mu_delta), with radial velocities incorporated when available. Gaussian modelling of the astrometric distributions yields mean trigonometric parallaxes of 1.060 +/- 0.035 mas and 0.735 +/- 0.061 mas, corresponding to astrometric distances of 944 +/- 31 pc and 1361 +/- 113 pc for NGC 2423 and NGC 2482, respectively. Fundamental parameters are derived through PARSEC isochrone fitting, resulting in ages of 1250 +/- 100 Myr and 445 +/- 50 Myr, observed distance
moduli (m-M)_obs = 9.90 +/- 0.10 and 10.80 +/- 0.20 mag, and reddening values E(G_BP-G_RP) = 0.07 +/- 0.01 and 0.10 +/- 0.02 mag, equivalent to E(B-V) = 0.054 and 0.078. The corresponding photometric distances are 892 +/- 50 pc and 1311 +/- 146 pc. We further investigate the internal and global kinematics of both clusters using velocity-ellipsoid parameters, the convergent-point method, and action-angular-momentum diagnostics. The derived kinematic properties show that NGC 2482 closely matches the velocity-space characteristics of the Hyades stream, while NGC 2423 shares the characteristic rotational velocity and angular momentum of the Hyades-like population but is offset in its U component. Both clusters occupy the angular-momentum range associated in the literature with Hyades-like clusters and bar-related resonances, although this association is based on their present-day kinematics and action-space locations rather than a direct dynamical demonstration of resonance trapping.
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Strongly Correlated Electrons
Spin Chain with Continuous Exponential Symmetry: Topological Phase and Beyond
Biao Lian and Zhen Bi
We study symmetric gapped ground states of one-dimensional
spin $S$ chains with a continuous exponential
symmetry $U(1)\rtimes\mathbb Z_2$ with integer base $q$, where the U(1) charge has a modulated unit of charge $q^{L-j}$ decaying exponentially with site $j$. The simplest model is a
quantum breakdown model that can be viewed as a $q$-deformation of the XXZ Haldane
spin chain. We show that the
topology of their symmetric ground states crucially depends on $S$ and $q$. For integer $S$, odd $q$ allows a nontrivial $\mathbb Z_2$ Haldane-type
symmetry-protected topological (SPT) phase with protected edge modes, while even $q$ allows no nontrivial SPT phase. For half-odd integer $S$, odd $q$ prohibits any unique symmetric gapped ground state due to a Lieb-Schultz-Mattis obstruction, whereas even $q$ enforces a novel symmetric gapped phase which we name as the “half-SPT" phase. Unconventionally, the half-SPT phase only has a
symmetry protected edge mode on one edge, and has half of the string orders of an SPT phase. Our results uncover a new type of
symmetry-protected gapped phases beyond existing classification schemes.
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High Energy Astrophysical Phenomena
Wind-Fed Magnetic Flux and the Emergence of X-ray Coronae in Active Galactic Nuclei
Rostom Mbarek
We propose a scenario for the onset of radiatively efficient Active
Galactic Nuclei (AGN) in which circumnuclear
stellar and
supernova-driven winds supply mass and partially ordered
magnetic flux to a compact disk reservoir around a supermassive black hole. A coherent poloidal component surviving advection to small radii strengthens inward, lowering the gas
plasma beta until mean Maxwell stresses overtake MRI
turbulence, compress the disk vertically, and open a magnetically dominated wedge above it. Within a quasi-force-free description of this wedge, the field self-organizes toward a critical twist at which the net radial transport changes sign, defining a
magnetic saturation radius $r_c\sim10\,r_g$. The
magnetic squeezing of the disk fixes the pressure balance at the interface between the disk and wedge, confining the accumulated flux at $r_c$: flux advected toward this boundary is preferentially shed, fixing $B_r\propto r^{-2}$ in the interior. From the field
topology alone we then derive a normalized saturation flux $\phi \sim 50$, consistent with the MAD plateau of GRMHD simulations. The resulting compact, time-dependent saturation region is a natural candidate for the AGN X-ray corona, being collisionless, magnetized, and, at high compactness, plausibly pair-rich, with hadronic pair injection providing a conditional additional channel. Its size, variability, and spectral hardness are controlled by $r_c$, the compactness, and the magnetization. We connect these scalings to observed coronal sizes, variability, and the power partition between the corona and jet. We further propose that Little Red and Blue Dots could represent a disk-reservoir phase preceding luminous AGN activity.
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High Energy Astrophysical Phenomena
Exemplary Merging Clusters II: XMM-Newton and Chandra X-ray Observations of MACS J1752.0+4440 and ZwCl 1856.8+6616
K. HyeongHan, K. Finner, W. Lee et al. (+10 more)
Using deep XMM-Newton and Chandra observations, we compare the double-
radio-relic
galaxy cluster mergers MACS J1752.0+4440 and ZwCl 1856.8+6616. Both are 1:1 mass-ratio mergers with similar relic separations but differing nearly an order of magnitude in total mass. In MACS J1752.0+4440, the surface-brightness discontinuity at the northeastern relic yields Mach $M_{\rho}=1.4\pm0.2$, while the temperature jump provides a weaker constraint, corresponding to $M_{kT}\lesssim2.3$ at the $2\sigma$ level, lower than the
radio-derived $M_{\rm radio}=3.1\pm0.1$. No discontinuity is detected at the southwestern relic. Thermodynamic maps and axial profiles reveal surviving relatively low-
entropy cores embedded in Mpc-scale stripped-gas structures. The nearly uniform X-ray tail brightness and a southwestern plateau coincident with a third
lensing mass peak favor a non-zero impact parameter and complex assembly history. In ZwCl 1856.8+6616, we do not detect a clear surface brightness discontinuity at either relic. The northern X-ray peak leads its brightest cluster
galaxy (BCG) and
lensing peak, while the hotter southern X-ray peak is laterally offset from its BCG and
lensing peak. The asymmetric intracluster emission favors a phase near or after first apocenter, when displaced gas can develop a slingshot-like morphology. We present two TNG-Cluster analogs in which a minor merger followed by an off-axis major collision produces extended X-ray tails resembling MACS J1752.0+4440 and later leads to gas structures resembling ZwCl 1856.8+6616. X-ray morphology independently confirms the merger phases inferred from relic-based chronometry, placing MACS J1752.0+4440 before and ZwCl 1856.8+6616 after first apocenter, and demonstrating that similar relic and
lensing configurations can correspond to distinct dynamical states.
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All authors K. HyeongHan, K. Finner, W. Lee, E. Silich, W. Forman, C. Jones, A. Tümer, S. Randall, J. ZuHone, M. James Jee, D. Wittman, R. J. van Weeren, M. Troxel
Strongly Correlated Electrons
SC$^\sharp$: superconductivity intertwined with topological order
Zhi-Qiang Gao, Yan-Qi Wang, Hui Yang et al. (+2 more)
Superconductivity and intrinsic topological order can intertwine in ways that go beyond simple coexistence. Here we develop a classification framework for (2+1)D gapped
superconductors with condensate charge $2ne$. By focusing on the topological properties of superconducting
vortices, we precisely characterize this interplay. We obtain a classification with increasing levels of intertwinement, from the well known invertible
superconductors without topological order, to untwisted and twisted SC$^\ast$, and finally to SC$^{\sharp}$. Our main finding is the family SC$^{\sharp}$, in which the elementary
vortex carrying $h/(2ne)$ flux cannot be factorized into an invertible
superconductor vortex dressed by bulk anyons, and every elementary
vortex is necessarily non-Abelian. For such phases, we also obtain no-go results: the elementary
vortex sector has
quantum dimension at least $\sqrt{6}$ and cannot satisfy Fibonacci fusion rules. We develop a systematic algebraic framework to obtain all these superconducting phases through anyon condensation, allowing us to construct several infinite families of examples and make connections to anyon superconductivity. Finally, we introduce primitive SC$^\sharp$ phases for which factorization of every nontrivial
vortex sector is obstructed, and argue that they cannot arise by disordering the relative phases of lower-charge superconducting condensates. Our classification scheme based on
vortex properties allows us to uncover new distinctions between topologically ordered
superconductors and constrain how they can be realized.
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All authors Zhi-Qiang Gao, Yan-Qi Wang, Hui Yang, Zhaoyu Han, Ashvin Vishwanath
High Energy Physics (Theory)
Hawking Amplitudes: Subtle Points About Saddle Points
Owen Lear, Daniel McLoughlin, Sebastian Mizera et al. (+1 more)
Hawking amplitudes provide a new way of determining the Hawking spectrum of black holes, using on-shell techniques borrowed from the literature on scattering amplitudes. In this paper, we investigate the interplay between the semi-classical and weak-field approximations previously used to compute Hawking amplitudes. We find that these limits do not necessarily commute, highlighting subtleties with the saddle point analyses governing the semi-classical limit. Resolving these issues allows us to compute semi-classical Hawking amplitudes in a range of black-hole backgrounds, including Tangherlini, Reissner-Nordström, and Hernquist metrics. Moreover, we describe the saddle-point contributions dominating Hawking amplitudes for different energies and propose a new method for determining the temperature of the resulting thermal spectrum based on Stokes lines of Hawking amplitudes.
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All authors Owen Lear, Daniel McLoughlin, Sebastian Mizera, John Staunton
Cosmology and Nongalactic Astrophysics
Primordial black holes as a natural consequence of scale-invariance
TaeHun Kim and Wan-Il Park
We show that a scale-invariant $U(1)$ gauge theory can naturally realize large
curvature perturbations around the end of thermal inflation, seeding the formation of
primordial black holes (PBHs). The allowed nonminimal gravitational interaction $\xi$ of the
Higgs field induces a Hubble-scale negative mass-squared term for positive $\xi \sim \mathcal{O}(1)$, and triggers a second order phase transition that ends thermal inflation while keeping the extra $e$-folds small. This sharp contrast to the minimally coupled case allows the gauge coupling to be much smaller than unity. It turns out that field fluctuations are dominated by thermal fluctuations around the onset of the phase transition, and sufficiently amplified to produce an appreciable amount of PBHs with a wide range of possible masses. The associated scalar-induced gravitational waves (GWs) are accompanied by
cosmic-string induced GWs coming from the breaking of the $U(1)$
symmetry. As a result, the generated PBH population can have a correlated GW signature relevant to
pulsar timing arrays, space-based interferometers, or ground-based detectors.
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