Astrophysics of Galaxies
Too many or too bright? Status and perspectives in the study of the UV Luminosity Function at z>10
A. Fontana, H. Atek, V. Bromm et al. (+20 more)
The finding that
galaxies in the first 500Myr were much more numerous and/or brighter than expected is often cited as one of the main discoveries of the James Webb Space
Telescope in its first four years of operation. This result is now solidly based on an impressive number of surveys that have detected, spectroscopically confirmed, and characterized a relatively large sample of
galaxies up to z=14.44, the
redshift of the most distant
galaxy currently known. This finding has motivated the introduction of additional physical mechanisms into theoretical models to reproduce the observed numbers and luminosities. These results contrast with the failure, despite ongoing efforts, to confirm any
galaxy candidate beyond this
redshift. This review summarizes the status of the search for and characterization of
galaxies at z>9, focusing on the
evolution of the UV Luminosity Function (UVLF), which is the main statistical description of the
galaxy population that can be obtained at these
redshifts. We first provide a comprehensive overview of the full set of JWST data obtained so far. We perform a 'meta–analysis' on the entire data set and provide a simple yet effective description of the global
evolution of the UVLF, averaging over the various surveys. We also compare these results extensively with theoretical models that were developed to match the new JWST observations and that explore different physical mechanisms able to drive the observed
evolution. We conclude with a summary of the contrasting results regarding the search for
galaxy candidates at z>15, and outline the requirements for future surveys aimed at breaking this barrier.
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All authors A. Fontana, H. Atek, V. Bromm, A. J. Bunker, M. Castellano, P. Dayal, F. D'Eugenio, D. Elbaz, A. Ferrara, S. L. Finkelstein, S. Fujimoto, M. Giavalisco, Y. Harikane, C. Kobayashi, F. Pacucci, P. G. Pérez-González, P. Rosati, A. Trinca, R. Tripodi, P. Santini, E. Vanzella, A. Venditti, A. Weibel
Solar and Stellar Astrophysics
EWOCS-XI: Anisotropic expansion and shear in the cluster Westerlund 1. A 2D kinematic analysis with Gaia DR3
L. Prisinzano, F. Damiani, C. Ordenes-Huanca et al. (+14 more)
Westerlund 1 (Wd1) is one of the Milky Way's most massive young clusters, in which heavy extinction and field contamination have historically hampered its kinematic characterization. We aim to assess Wd1's internal kinematics, dynamical state, and formation scenario. Using a robust 5D clustering approach, we identified 559 bona fide members. We modeled their proper motions via a 2D first-order Taylor expansion to derive the velocity gradient tensor, mapping expansion, rotation, and shear. Restricting the kinematic analysis to 524
stars with proper motion uncertainties $<0.5~\mathrm{mas\,yr^{-1}}$, we find at least 103 gravitationally unbound members, including 14 walkaway
stars. The 2D analysis reveals a statistically significant divergence (>4$\sigma$) highlighting preferred expansion along the Galactic latitude (position angle $164^\circ\pm10.1^\circ$). A detected cross-gradient ($\partial v_b / \partial l = -0.41 \pm 0.08$ km s$^{-1}$ pc$^{-1}$) provides a clear signature of shear on the plane of the sky. Wd1 does not behave as a single cohesive population, but comprises two decoupled subsystems: a stable, bound core in dynamical
equilibrium and an escaping, unbound envelope. This prominent anisotropic expansion perpendicular to the Galactic plane has a kinematic timescale ($\Delta t_{\mathrm{kin}} = 2.08 \pm 0.44$ Myr) matching the independent orbital mid-plane crossing time ($\Delta t_{\mathrm{orbit}} = 2.10 \pm 0.05$ Myr). This temporal
alignment indicates the expansion onset coincided with Wd1's Galactic disk passage, triggered either by internal dynamics (e.g., early
supernova feedback) or external tidal perturbations. Finally, the robust unbound population demonstrates that active cluster dissolution is underway, driven by discrete dynamical ejection events rather than long-term stellar evaporation.
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All authors L. Prisinzano, F. Damiani, C. Ordenes-Huanca, M. Tarantino, S. Sciortino, N.J. Wright, V. Almendros-Abad, M. Andersen, A. Bayo, R. Bonito, V. Cusimano, M. Haberle, K. Mužic, I. Negueruela, E. Sabbi, A. Winter, M.G. Guarcello
Quantum Physics
The Imaginary Component of the Weak Momentum: Spectral Vanishing and Gauge Invariance
A. N. Khondker
We establish a rigorous functional-analytic framework for the imaginary component $p_I$ of the complex weak momentum $p_Q = p_R + ip_I = \frac{\hbar}{i}\nabla\ln\psi$. For every wavefunction in the Sobolev space $H^1(\Omega)$, including those with nodal sets, we prove that the expectation value of $p_I$ vanishes identically, as a consequence of the regularity of $\rho = |\psi|^2$ and without appeal to the polar form $\psi = Re^{iS/\hbar}$. We further show that \textnormal{(i)} the Bohm
quantum potential arises entirely from $p_I$ and satisfies $\langle V_{\mathrm{qu}}\rangle = \langle p_I^2\rangle/2m$, from which the known Fisher information relation follows as a corollary; \textnormal{(ii)} the group velocity of a Bloch band is the density-weighted average of $p_R/m$, with no contribution from $p_I$; \textnormal{(iii)} the decomposition is gauge-invariant under
magnetic minimal coupling, the vector potential acting only on $p_R$; and \textnormal{(iv)} the results extend to curved Riemannian
manifolds.
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High Energy Astrophysical Phenomena
An updated model of neutrino emission from proto-neutron stars
Matteo Ballelli, Federica Pompa, Christoph Ternes et al. (+2 more)
We present an improved parametric model for
neutrino emission from core-collapse
supernovae that directly connects
neutrino luminosity and average energy to stellar properties during emission. Our model incorporates two critical physical processes: convection within the proto-
neutron star and the
evolution of the neutrinosphere radius during the early emission phase. Using simulated
datasets of
supernova neutrino events in the Super-Kamiokande detector, we assess the sensitivity to astrophysical properties in the event of a future detection. We show that the
neutrino mass ordering plays a crucial role in determining which parameters can be constrained by the observed
neutrino data.
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All authors Matteo Ballelli, Federica Pompa, Christoph Ternes, Marco Drago, Giulia Pagliaroli
Cosmology and Nongalactic Astrophysics
A New Era for Supernova Science with the James Webb Space Telescope
Justin Pierel, David Coulter, Christa DeCoursey et al. (+17 more)
Supernovae (SNe) are excellent probes of the physical, chemical, and cosmological context of
galaxies across the history of the Universe. The James Webb Space
Telescope (JWST ) has a truly unique combination of wavelength, sensitivity, and resolution, providing a new window into SN physics, progenitors, dust production,
redshift evolving stellar populations, and cosmology since its launch. Here we summarize the astounding observations JWST has made of SNe in its first few years of operations, as well as the corresponding advancements in our understanding of the Universe. This includes detailed views of nearby SNe, the first spectroscopic samples of high-z SNe, and a significant number of gravitationally lensed SNe valuable for both cosmological inference and high signal-to-noise (S/N) spectroscopy. While the upcoming Nancy Grace Roman Space
Telescope is expected to revolutionize space-based time-domain astronomy, JWST and its unique capabilities will continue to play a complementary role by providing high-precision spectroscopic and photometric data for a broad range of SN science cases.
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All authors Justin Pierel, David Coulter, Christa DeCoursey, James DerKacy, Ori Fox, Melissa Shahbandeh, Matthew Siebert, Michael Engesser, Conor Larison, Thomas Moore, Armin Rest, Rodrigo Angulo, Michael Dulude, Eiichi Egami, Massimo Griggio, Mitchell Karmen, Xiaolong Li, Estefania Padilla Gonzalez, Koji Shukawa, Louis-Gregory Strolger
Quantum Physics
Nearly Optimal T-Count for Symmetry-Based Quantum State Purification
Jialiang Tang, Junhong Nie, Keming He et al. (+2 more)
Protecting
quantum information from noise is essential for reliable
quantum computation and
quantum memories.
Quantum state purification addresses this challenge by processing multiple noisy copies of an unknown
quantum state to produce an output state of higher fidelity. Here we establish nearly tight upper and lower bounds on the non-Clifford resources required to implement the symmetric-projection purification protocol. For $n$ copies of a $d$-dimensional system, we construct a Clifford+T
circuit that block-encodes the symmetric projector with operator-norm error at most $\epsilon$ using $\widetilde{O}(n)$ T gates, where the tilde-$O$ notation suppresses polylogarithmic factors in $n$, $d$, and $1/\epsilon$. Conversely, using stabilizer nullity, we prove that any Clifford+T implementation of such a block encoding with error $\epsilon<\frac{1}{2}\sqrt{1-1/n}$ requires at least $2n-2$ T gates, even allowing arbitrary positive normalization and clean stabilizer ancillas. Taken together, these results establish the nearly optimal scaling of non-Clifford cost with the number of copies and uncover the fundamental resource requirements for coherent
symmetry projection in
quantum state purification.
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All authors Jialiang Tang, Junhong Nie, Keming He, Xin Wang, Xiaoming Sun
General Relativity and Quantum Cosmology
All theories of gravity with second-order traced field equations
Ángel J. Murcia
We classify all diffeomorphism-invariant theories of
gravity which possess traced field equations of motion of second order in derivatives. We also prove in the affirmative a
conjecture regarding the form of theories constructed algebraically from the Riemann tensor with second-order traced field equations and classify all
polynomial quasi-topological gravities with second-order traced field equations.
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Mathematical Physics · Cross-listed from math.GT
Character variety of the five-punctured sphere and the determinantal quintic hypersurface
Kazuhiro Hikami
Using skein-theoretic methods, we study the SL2(C) character variety of the five-punctured sphere with arbitrary conjugacy class at each of the five punctures. We show that a Fricke-Klein-Vogt-type relation is realized as a symmetric determinantal hypersurface. We also give a realization of the character variety in terms of cluster variables. We explicitly derive the Poisson structure of the simple closed curves on the surface, and prove that cluster mutations induce automorphisms of the character variety.
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Instrumentation and Detectors
First demonstration of $50\,\mathrm{ps}$ four-dimensional vertex reconstruction with the Timepix4 beam telescope
David Bacher, Kazu Akiba, Martin van Beuzekom et al. (+10 more)
The first demonstration of 4D vertex reconstruction at the $50\,\mathrm{ps}$ scale using a silicon pixel detector is reported. Hadronic interactions are produced by directing a $180\,\mathrm{GeV}/c$ mixed-
hadron beam onto a fixed target upstream of the Timepix4 beam
telescope at the CERN SPS. The resulting particles are reconstructed using 4D track and vertex fits that include time directly alongside the spatial parameters. The vertex time resolution follows the expected statistical scaling with the number of timing measurements, reaching $54\pm5\,\mathrm{ps}$ for vertices reconstructed from 16 timing-plane clusters. An irreducible component of $29.2\pm0.6\,\mathrm{ps}$ remains in the fitted resolution model, including sizeable contributions from the clock distribution and the time reference system rather than from the combination of the timing measurements. The observed scaling down to $54\,\mathrm{ps}$ without an unforeseen resolution floor above represents a significant experimental step towards precision-timing in future high-pile-up detectors.
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All authors David Bacher, Kazu Akiba, Martin van Beuzekom, Victor Coco, Raphael Dumps, Tim Evans, Kevin Heijhoff, Malcolm John, Edgar Lemos Cid, Loris Martinazzoli, Tommaso Pajero, Yutaro Takahashi, Espen de Wit
General Relativity and Quantum Cosmology
Gravitational radiation from a photon on the light ring: multipole fluxes and the logarithmic divergence
Enrico Barausse
A massless particle on the circular null geodesic of a Schwarzschild or Kerr black hole radiates gravitational waves at all multipoles $\ell$ with a power that falls off only as $1/\ell$, so that the total instantaneous power is logarithmically divergent. We derive this result analytically from the Zerilli–Regge–Wheeler and Teukolsky equations with a null stress-energy tensor as source, and find that both the power radiated to infinity and the power absorbed by the horizon approach $\dot{E}_\ell\to g(a) \kappa E^2/(M^2\ell)$, where $E$ is the energy of the particle, $M$ the mass of the black hole and $a$ its
spin, with $\kappa=0.063653$ and a
spin factor $g(a)$, for which we obtain, for any
spin, the closed form $g=27M^2(r_0-M)/[r_0^2(r_0+3M)]$ in terms of the radius $r_0$ of the Kerr light ring. The $1/\ell$ behavior has two causes: the near-resonance of the
photon with the quasinormal modes, which prevents any exponential suppression at large $\ell$, and a cancellation in the source that is specific to massless particles, which reduces the power per multipole by a factor $\ell^2$ with respect to a generic source. At leading order half of the radiation falls into the black hole, and we compute the first correction to this equal split in the non-spinning case. The same analysis describes massive particles on orbits close to the light ring, where the mass turns the $1/\ell$ law into an exponential cut-off. We recover the dominant, even-parity term of the geodesic synchrotron radiation formulae for massive particles of Breuer, Ruffini, Tiomno and Vishveshwara (1973), but we find that their odd-parity term is too small by a factor of four. All results are checked against numerical solutions, up to $\ell=12800$ in Schwarzschild and $\ell=800$ in Kerr.
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Mathematical Physics · Cross-listed from math.CT
Fiber product of condensable algebras and critical points of boundary phase transitions
Hanlin Lin and Hao Zheng
In this work, we propose a mathematical description of the critical point of boundary phase transitions in 2+1D topological orders. Given two boundary phases, $\mathcal{C}_A$ and $\mathcal{C}_B$, with corresponding Lagrangian
algebras $A$ and $B$ in a 2+1D topological order $\mathcal{C}$, respectively, we propose that the critical point of the phase transition between these two phases, if it exists, corresponds to $D = A \times_{M} B$, which is the fiber product of $A$ and $B$ over $A$-$B$-
algebra $M$. We prove that $D$ is also a condensable
algebra. Additionally, we present an alternative classification of condensable
algebras in $Z(Vec_G^\omega)$ and reveal splitting phenomenon that arises during the condensation of certain
algebras. We also perform explicit computations for the condensable
algebras within several examples of $Z(Vec_G^\omega)$, covering both Abelian and non-Abelian groups $G$.
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Atomic and Molecular Clusters
Multiple photoelectron inelastic scattering in large He nanodroplets
Niklas Scheel, Narcis Silviu Blaj, Rajni Rajni et al. (+7 more)
Helium nanodroplets are ideal testbeds for elucidating secondary processes induced by ionizing radiation in condensed matter. Here we study photoionization electron spectra of large He nanodroplets in the extreme ultraviolet region, where photoelectrons undergo multiple inelastic collisions with He atoms in the nanodroplets. The resulting characteristic electron energy-loss features are identified by their dependence on
photon energy and nanodroplet size and by comparison with a simple numerical simulation. Conditions for minimizing electron scattering with the He nanodroplets are discussed.
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All authors Niklas Scheel, Narcis Silviu Blaj, Rajni Rajni, Asbjørn Ørnemark Lægdsmand, Jayesh Sadasivan, Subhendu De, Sivarama Krishnan, John Bozek, Aleksandar R. Milosavljevic, Marcel Mudrich
Strongly Correlated Electrons
Field-resolved hierarchy of superconducting energy gaps in PdTe
Sangyun Lee, A. M. Donald, D. Duong et al. (+4 more)
Resolving how multiple superconducting energy scales evolve under
magnetic field is important for distinguishing multiband, anisotropic, and surface-sensitive superconducting responses. Here, we investigate the superconducting state of PdTe using low-temperature soft point-contact spectroscopy in a sealed $^3$He immersion environment. The resulting Andreev-reflection spectra reveal two characteristic superconducting energy scales near 0.5 and 1.1 meV that are not adequately described by a single-gap BTK model. Both energy scales are progressively suppressed upon warming toward the same superconducting transition temperature $T_c$. In contrast, their
magnetic-field
evolution reveals two distinct characteristic fields near 4.5 and 7.5 kG. The lower scale is associated with the loss of the zero-resistance superconducting state, whereas the higher-energy spectroscopic response persists to substantially larger fields. Independent field-dependent gap analysis yields suppression scales consistent with those identified from the zero-bias conductance. These results reveal a field-resolved hierarchy of superconducting energy scales in PdTe and indicate superconducting responses with distinct
magnetic-field robustness.
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All authors Sangyun Lee, A. M. Donald, D. Duong, S. Huang, R. Gazizulin, C. Huan, Rongying Jin
Quantum Physics
A deterministic polynomial chaos Galerkin method for non-Markovian quantum state diffusion
Quanhui Zhu and Zhenning Cai
Developing general-purpose numerical methods for non-Markovian
quantum state
diffusion has long been a challenge in the simulation of open
quantum systems. This paper proposes a deterministic
polynomial chaos Galerkin method, which is easy to implement, accurate, and efficient. By combining a low-rank decomposition of bath correlations with Galerkin projection onto a
polynomial chaos basis, the method yields a deterministic formulation compatible with standard numerical solvers for partial differential equations. The reduced density
matrix is obtained from a single deterministic solve at a cost comparable to that of computing one
stochastic hierarchy trajectory. Replacing an ensemble of $N_{\mathrm{traj}}$ trajectories therefore reduces the computational cost by approximately a factor of $N_{\mathrm{traj}}$ and eliminates statistical sampling error.
Benchmark comparisons show that the proposed method achieves smaller errors at lower computational cost than the tested
stochastic hierarchy methods. Applications involving nonquadratic potentials, diffraction and interference, and coupled three-dimensional dynamics demonstrate its ability to handle challenging problems.
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Chemical Physics
MAST: Motif-Augmented Diffusion with Search Tree for Spectroscopic Molecular Structure Elucidation
Chenghao Jia, Mengdi Liu, Hong Chang et al. (+2 more)
Elucidating molecular structures from spectra is a foundational problem in chemical and materials characterization, yet remains challenging due to spectral ambiguity and the vast molecular space. Although recent
diffusion-based generators show strong promise for spectra-conditioned elucidation, existing methods struggle to learn robust spectra-structure relationships from limited paired data when relying solely on global spectral representation. Moreover, the repeated full sampling inference strategy incurs substantial computation overhead. To address these limitations, we propose MAST, a Motif-Augmented
diffusion framework with Search Tree, for joint 2D-3D spectroscopic molecular structure elucidation. MAST introduces explicit, interpretable motif priors as intermediate evidences throughout denoising, reducing conditional ambiguity and facilitating spectra-conditioned optimization. We further cast
diffusion sampling as reward-guided tree search to prioritize high-reward denoising trajectories, yielding a compact set of spectra-consistent candidates under limited budgets. On the QM9S multi-spectra
benchmark, MAST achieves 94.89% exact recovery and improves 3D fidelity, while preserving high chemical validity and stability. Code is available at https://github.com/Jia040223/MAST.
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All authors Chenghao Jia, Mengdi Liu, Hong Chang, Shiguang Shan, Xilin Chen
Optics
Minimizing round-trip loss for near-unity quantum efficiency in organic light-emitting diodes
Junho Kim, Seonjeong Lee, Seunghyup Yoo et al. (+1 more)
Modern organic light-emitting diodes (OLEDs) reach internal
quantum efficiencies close to 100%, yet in a planar device only 20-30% of
photons escape. External outcoupling structures on high-index substrates recover some of the trapped light, but external
quantum efficiencies (EQEs) have stalled at 55-60% across different optical designs, and the origin of this ceiling is not fully understood. Here we identify light extraction in such OLEDs as a multi-pass process: light that the outcoupling structure fails to extract returns to the OLED, is reflected back and may escape over multiple passes, with the efficiency governed by the absorption per round trip. Absorption loss is minor in conventional planar OLEDs, but it becomes dominant and accounts for the observed efficiency ceiling when an outcoupling structure is attached. Consistent with this picture, adding a low-loss auxiliary reflector raised the EQE of an OLED on a high-index microlens substrate from 51% to 77% without any change to the OLED stack or the outcoupling structure, the highest value reported for a single-junction OLED without a macroscopic extraction lens; for an OLED on a conventional glass substrate an estimated 92% of the light delivered to the substrate was extracted. We derive four design rules that keep round-trip losses to a few percent and predict that EQEs around 90% are feasible with established materials. Under these rules, microcavity tuning and emitter orientation largely cease to matter, and high efficiency is retained across a wide range of microlens designs and scattering layers.
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All authors Junho Kim, Seonjeong Lee, Seunghyup Yoo, Malte C. Gather
Optics
Observation of robust corner states in photonic crystals without global symmetries
Zitao Ji, Jianfeng Chen, Yidong Zheng et al. (+2 more)
Robust corner states have attracted considerable
attention in recent years, particularly in photonic systems. They are typically realized in second-order topological
insulators, including shrunken-expanded
lattices and breathing Kagome
lattices, where global
symmetries are essential in their formation. This reliance on
symmetry, however, can make these states highly sensitive to structural disorder. Here, we propose and experimentally demonstrate a class of robust corner states in photonic
crystals that require neither global
symmetry nor nontrivial
topology. By locally tailoring the corner geometry of an otherwise topologically trivial structure, we create strongly localized modes that remain stable under both position and radius disorder. These states are not accidental; rather they originate from a pair of Dirac points in the bulk band structure.
Geometric tuning shifts the flatband edge states connecting the Dirac points into an otherwise trivial bandgap, thereby inducing strongly localized corner states. Our findings uncover a previously overlooked class of
symmetry-independent, disorder-resilient corner states, extend robust localization beyond conventional topological protection, and provide a route toward light localization in all-dielectric photonic systems.
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All authors Zitao Ji, Jianfeng Chen, Yidong Zheng, Zhaogang Dong, Zhi-Yuan Li
High Energy Physics (Experiment)
Optimising Geometric Deep Learning for Varied Reconstruction Tasks in High Granularity Calorimeters
Matthieu Melennec and Frédéric Magniette
In the recent years, high energy physics discoveries have been driven by the increasing of luminosity and/or detector granularity. This
evolution gives access to bigger statistics and data samples, but can make it hard to process the detector outputs with current methods and
algorithms. Graph Neural Networks (GNNs), have been shown to be powerful tools to address these challenges. While GNNs can deal with the non-euclidean nature of the data extracted from these detectors, their deployment presents significant difficulties, mainly from the computational complexity of the
algorithms they are based on. We propose to use the known geometries of the detectors to optimise the
algorithms used for GNN pipelines, which usually have quadratic algorithmic complexities. We validate the validity of our optimised approach on various tasks, such as particle identification, energy regression and instance segmentation. Finally, we present HIBOU, a generic modular architecture that provides a blueprint for how these GNN blocks are to be implemented within experiment-specific reconstruction frameworks.
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Astrophysics of Galaxies
Binding Energies of Astrophysically Relevant Molecules on CO$_2$ Clusters: Benchmarking and the Donor-Acceptor Origin of Surface-Dependent Binding
Aneesa Ahmad, Catherine Walsh and Stefan Vogt-Geisse
Carbon dioxide (CO$_2$) is among the most abundant interstellar ices and has been observed by JWST in water-rich mixtures and pure CO$_2$ environments. Astrochemical models adopt binding energies (BEs) measured on water ice because few BEs are available for CO$_2$ ice. We calculate BE distributions for twelve adsorbates (N$_2$, CH$_4$, HCl, C$_2$H$_2$, H$_2$S, HF, HCN, H$_2$CO, HCOOH, HNC, CH$_3$OH, H$_2$O) on CO$_2$ clusters containing two to five molecules using DFT calibrated against CCSD(T)/CBS, a coupled-cluster treatment extrapolated to the complete-basis-set limit. Binding strength depends on whether the adsorbate requires the surface to donate a hydrogen bond (H-bond). CO$_2$ can accept an H-bond but cannot donate one, and all six species compared with water ice from Ahmad et al. (2026) bind more weakly on CO$_2$. The ratio of the BE on CO$_2$ to water ice ranges from 0.66 for H$_2$CO and 0.75 for H$_2$O to 0.87 for CH$_3$OH, 0.89 for HCOOH and 0.92 for C$_2$H$_2$. Formaldehyde is predicted to desorb near 57 K from CO$_2$-rich ice, compared with 85 K from water-rich ice, and could contribute to cold gas-phase H$_2$CO. Although the mean binding energies are changing with cluster size for several species, the differences can be traced to local binding interactions likely to remain important in larger ice models. The BEs vary by more than 500 K between sites, while the desorption peaks range from 11 K for CH$_4$ to 132 K for HCOOH. The limited H-bonding capacity of CO$_2$ may favour separation of mixed H$_2$O:CO$_2$ ice into CO$_2$-rich domains.
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Instrumentation and Methods for Astrophysics
On-chip filled array hyperspectral kinetic inductance detectors (FHYKID) for line intensity mapping
Emile Prêle, Martino Calvo, Usasi Chowdhury et al. (+3 more)
The next generation Line Intensity Mapping (LIM) experiments will require very high throughput instrumentation, and as a consequence high pixel counts focal planes. For the study of the [CII] line in the
redshift range z=7-8, we develop a hyperspectral filled focal plane (FHYKID) operating in the range 210-235 GHz and with a spectral resolution reaching 120. The spectral filtering is achieved thanks to planar Slot Split Ring Resonators (SSRR) coupled to Lumped Element Kinetic Inductance Detectors (LEKID). This robust concept achieves, thanks to its simplicity, large
quantum efficiency and is scalable, even with current readout electronics systems, to several tens of thousands beams on Sky. Our FHYKID will be one of the four channels of the NIKONA instrument, currently seeking funding and to be installed at the IRAM 30-meter
telescope at Pico Veleta. Among the science goals, simultaneously mapping the local (galactic and nearby-
galaxies) CO line and the cosmological [CII].
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All authors Emile Prêle, Martino Calvo, Usasi Chowdhury, Gregory Garde, Florence Levy-Bertrand, Alessandro Monfardini
High Energy Physics (Theory)
Mass quench in interacting finite-size quantum field system
Grachik A Simonian, Alexey G. Mikhaylenko and Andrew G. Semenov
In this work, we theoretically investigate the non-
equilibrium evolution of the correlation functions of a
quantum scalar field following a mass
quantum quench in a finite-size system. The self-consistent equation for the Keldysh (statistical) correlation function is solved numerically in the one-loop approximation. A specific spatio-temporal effect is observed: at a point in time approximately equal to half the system size, the effective mass experiences a strong disturbance. It is shown that this effect is driven by the interference of counter-propagating wave fronts of fluctuations that propagate within the light cone and is induced by periodic boundary conditions.
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Strongly Correlated Electrons
Strange-metal behavior in correlated molecular conductors
Savita Priya, Maxim Wenzel, Christian Prange et al. (+10 more)
The $\kappa$-BEDT-TTF salts are prototypical Mott systems, realizing a correlation-driven electronic transition from a Fermi-
liquid state to a Mott
insulator. The metallic compounds with spatially modulated Hg-containing anions, $\kappa$-(BEDT-TTF)$_4$Hg$_{3-\delta}X_8$ ($X$ = Br, and Cl), however, fall outside this classification. Our temperature-dependent transport and broad-range optical investigations reveal a $\rho(T)\propto T$ dependence of the resistivity up to elevated temperatures and a power-law behavior of the frequency-dependent conductivity $\vert\hat{\sigma} (\omega)\vert \propto \omega^{-0.7}$; well-known hallmarks of “strange metals”. The linear-in-frequency scattering rate of these strange metals scales to the Planckian dissipation. We demonstrate that this response only occurs in systems with incommensurate anion layers and establish a direct link to large-scale spatial modulations. Our conclusions can be extended to other strongly correlated strange-metal compounds
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All authors Savita Priya, Maxim Wenzel, Christian Prange, Bertold Rasche, Christian Sindlinger, Takuya Kobayashi, Hiromi Taniguchi, Dita Puspita Sari, Yasuyuki Ishii, Kazuya Miyagawa, Kazushi Kanoda, Simone Fratini, Martin Dressel
Solar and Stellar Astrophysics
Volume Dependence of Helicity-based Eruption Diagnostics in Recurrent Coronal Jets
Chang Zhou, Jinhan Guo, Yang Guo et al. (+3 more)
Recurrent solar coronal jets originate from the same source region, providing a useful setting for studying the buildup, redistribution, and release of
magnetic energy and helicity. However, how these quantities can characterize
magnetic evolution and the onset conditions of the eruptions remains unclear. We perform a full three-dimensional (3D) thermodynamic magnetohydrodynamic simulation of recurrent jets driven by converging motions imposed at the bottom boundary. The simulation naturally produces two successive eruptions. The current-carrying helicity $H_J$ decreases during the first jet and gradually recovers between the two jets. In contrast, the free
magnetic energy $E_{\mathrm{free}}$ shows no clear accumulation after its first release. This difference indicates that $H_J$ provides information on
magnetic evolution beyond that provided by $E_{\mathrm{free}}$. Furthermore, the commonly used helicity ratio $H_J/H_V$ reaches different peaks near the onset of the two jets and is sensitive to the integration volume. By comparison, the locally normalized quantity $H_J/\Phi_{\mathrm{closed}}^2$ reaches similar peaks near the onset of both jets and is relatively insensitive to the choice among the tested integration volumes, where $\Phi_{\mathrm{closed}}$ is the single-polarity
magnetic flux of the closed-field domain. These results reveal the local nature of the eruptions and suggest that $H_J$ normalized by the square of the closed
magnetic flux may be a useful diagnostic of eruptive conditions.
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All authors Chang Zhou, Jinhan Guo, Yang Guo, Jiajia Liu, Zekun Lu, Yuhang Gao
High Energy Physics (Experiment)
Using Geometric Deep Learning for the Detection of the Diffuse Supernova Neutrino Background in Water-Cherenkov Detectors
Matthieu Melennec, Andrew D. Santos, Thomas Mueller et al. (+1 more)
The study of the Diffuse
Supernova Neutrino Background (DSNB) is an essential approach to improve our understanding of the formation of Core-Collapse
Supernovae, as well as investigating fundamental
neutrino properties. The detection of the DSNB flux however is a difficult task, as it requires the disentanglement of its signal with many competitive backgrounds in the low energy range. The main DSNB detection channel is the Inverse Beta Decay (IBD), which is characterised by a distinct, time-separated two-signal signature. This work introduces the use of Graph Neural Networks (GNNs) to handle critical detection and reconstruction tasks for the DSNB through the IBD channel. In particular, we present a model to recover the energy of the first signal from a low energy positron. Additionally, we develop a signal-to-background classifier optimised for the secondary signal, which corresponds to the characteristic
photon emission following a
neutron capture event. We test our models on two simulations in a Hyper-Kamiokande-like water Cherenkov detector geometry, and show that we obtain performances that are comparable to the state of the art.
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All authors Matthieu Melennec, Andrew D. Santos, Thomas Mueller, Frédéric Magniette
Materials Science
Emergent gold-induced interfacial magnetism in monolayer FePS$_3$
Giuseppe Buccoliero, Anita Polli, Marli dos Reis Cantarino et al. (+10 more)
Owing to their atomically clean interfaces and extreme thinness, two-dimensional (2D) materials are ideal hosts for strong proximity effects, whereby contact with an adjacent material reshapes their ground state. Here, we demonstrate such an effect within a hybrid
heterostructure, between the 2D antiferromagnet FePS$_3$ and an ultrathin gold film. Rather than a passive support, the latter profoundly changes the nature of the magnetism in the 2D magnet, inducing a sizeable interfacial moment. Large-area flakes from Au-assisted exfoliation, combined with element-selective X-ray absorption mapping, enable a layer-by-layer study from monolayer to bulk, benchmarked against an inert SiO$_2$ substrate reference. At 9 T and 5 K, the monolayer on gold shows a three-fold enhanced X-ray
magnetic circular dichroism relative to SiO$_2$, with a $\sim$40% reduction of the orbital-to-
spin moment ratio. Resonant inelastic X-ray scattering reveals a collapse of the
crystal-field (d-d) excitations and a massive spectral-weight transfer to the charge-transfer region, unveiling the microscopic mechanism behind this change. Supported by atomic multiplet calculations, we identify interfacial charge transfer and Fe 3d-Au hybridization as the origin of these effects, which decay over the first three layers and vanish at the pentalayer, establishing layer number combined with substrate engineering as an atomically precise handle.
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All authors Giuseppe Buccoliero, Anita Polli, Marli dos Reis Cantarino, Rachel Nickel, Aloïs Arrighi, Roberto Sant, Tristan Riccardi, Valérie Reita, Nedjma Bendiab, Laëtitia Marty, Kurt Kummer, Johann Coraux, Nicholas B. Brookes
High Energy Physics (Phenomenology)
Constructing $SU(N)$ strongly coupled dark sectors by extending the Standard Model: mixed representations, flavor structure, global symmetries and various portals
Yi Chung
Motivated by the potential existence of a dark QCD sector, we construct a $SU(N)$ strongly coupled dark sector by extending the Standard Model (SM) gauge group to an enlarged $SU(N+5)\times SU(N+1)\times U(1)$, under which the dark
quark candidates naturally arises from the same multiplets as the SM
fermions. The dark QCD sector from the extension inherits the rich structure of the SM, featuring three distinct properties: (1) Mixed representations: There are dark
quarks of three different representations, including fundamental ($\chi_f$), antisymmetric ($\chi_a$), and symmetric ($\chi_s$), which can be traced back to the chiral structure of the SM. (2) Flavor: Each representation features three generations, with their flavor structures and Yukawa interactions directly related to those of the SM. (3) Global
symmetries: Alongside the conventional dark baryon number $D$, we identify an exotic dark baryon number $\widetilde{D}$ from a conserved $(B-L)-\widetilde{D}$
symmetry. These features provide novel perspectives on the structure of dark QCD sectors. Furthermore, the extension of the scalar and gauge sectors introduces various portals between the dark QCD sector and the SM sector. We systematically study these portals, including
quark portal, lepton portal,
Higgs and $Z$ portal, heavy $Z'$ portal, kinetic mixing portal, dipole portal, and dark pion/
axion portals. With a concrete UV model, their origin become robust, providing additional guidance for experimental searches of the dark sector.
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Mesoscale and Nanoscale Physics
Symmetry-Dependent Polarity Reversal of Bulk Spin-Orbit Torque in Single-Layer MnCoGa
Rongkun Han, Mingsong Zhang, Dahai Wei et al. (+3 more)
Controlling the magnitude and polarity of
spin-orbit torque (SOT) is essential for manipulating magnetization in spintronic devices. Here, we realize bulk
spin-orbit torque (SOT) in a single-layer Mn1.6Co1.4Ga (MCG) Heusler
alloy and achieve
lattice strain-controlled reversal of SOT polarity. SOT-driven magnetization switching is achieved over a thickness range of 3-20 nm, with the switching polarity reversed between the strongly strained ultrathin regime and thicker films. First-principles calculations reveal a sizable intrinsic
spin Hall conductivity (SHC) in MCG originating from its topological band structure, which is enhanced by the tetragonal distortion without changing sign. Together with the thickness-dependent structural
evolution, we demonstrate that the reversal of SOT polarity does not originate from a sign change of the SHC, but rather from
lattice distortion induced
symmetry breaking that modifies the conversion of
spin current into a net bulk SOT, thereby controlling its polarity. These results establish strain-controlled structural
symmetry as an additional degree of freedom for tuning bulk SOT in
magnetic single layers.
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All authors Rongkun Han, Mingsong Zhang, Dahai Wei, Yuan Lu, Wenxu Zhang, Jianhua Zhao
Plasma Physics
FHiVI$^{2}$: A Fast High-Voltage approach for Ionisation Improvement in the context of plasma-assisted magnetron sputtering
R. Jean-Marie-Desiree, L. De Poucques and S. Cuynet
Ionisation control remains a key challenge in
plasma-assisted processes and more particularly in magnetron sputtering. In this context, the former directly governs species transport and thin-film properties. Although HiPIMS substantially enhances the ionisation rate of sputtered species, its performance remains constrained by the coupling between sputtering and ionisation, which limits discharge tunability. Here, we introduce Fast High Voltage for Ionisation Improvement (FHiVI$^{2}$), a new transient electrical regime designed to improve the ionisation rate without requiring additional elements. By applying an ad hoc very short, high-voltage pulse during
plasma sputtering processes, FHiVI$^{2}$ regime is expected to induce a strongly anisotropic electric-field burst intended to enhance sputtered metallic species ionisation while limiting back-attraction losses and sputtering. To assess the ionising potential of this regime, optical emission spectroscopy together with mass spectrometry were carried out. More particularly, mass spectrometry measurements show an improvement of the ionisation rate by a factor of 2.7 compared with the HiPIMS regime, for an applied voltage of 2 kV which correspond to an additional mean power of only 1.2 W, using a 2-inch tungsten target. These findings suggest that FHiVI$^{2}$ provides a flexible route towards improved ionisation control in magnetron sputtering and opens new perspectives for
plasma-assisted processes.
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Mesoscale and Nanoscale Physics
Field-Free Reconfigurable Spin Logic in Compositionally Graded MnxCoAl Layer
Haohang Cheng, Pengju Wang, Hongrui Qin et al. (+4 more)
Spintronic logic-in-
memory provides a route to reducing data-transfer energy consumption and accelerating computation by integrating nonvolatile storage and logic functions within a single physical unit. Here, we investigate field-free
spin-orbit-torque (SOT) switching and reconfigurable
spin logic in a vertically composition-graded MnxCoAl/Pt
heterostructure. In contrast to the uniform-composition Mn1.8CoAl/Pt and Mn2.5CoAl/Pt control devices, the Mn1.8-2.5CoAl gradient device exhibits deterministic SOT switching under zero external
magnetic field. Dzyaloshinskii-Moriya interaction (DMI)-related measurements reveal a finite characteristic effective-field scale, indicating the involvement of chiral magnetization-reversal processes. Meanwhile, the vertical composition gradient introduces
magnetic inhomogeneity that can modify domain nucleation and propagation, and the combined effects are consistent with the observed field-free switching behavior. The composition-gradient device further exhibits accumulative multistate switching with stable intermediate Hall-resistance states under zero
magnetic field, whereas the uniform-composition controls do not show comparable stable multistate behavior. By tailoring the amplitude, polarity, and sequence of current pulses, the device can be tuned between binary and multilevel switching modes, enabling the experimental realization of AND, OR, NAND, and NOR Boolean operations within the same Hall-bar device without any external
magnetic field. These results extend Mn-Co-Al Heusler
heterostructures from field-assisted SOT switching toward field-free magnetization control, multistate operation, and reconfigurable
spin logic through vertical composition engineering.
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All authors Haohang Cheng, Pengju Wang, Hongrui Qin, Rongkun Han, Dong Pan, Dahai Wei, Jianhua Zhao
Quantum Physics
Who can sample forever? Shot noise effects in quantum linear regression
Gabriele Lo Monaco, Salvatore Lorenzo, Alessandro Ferraro et al. (+3 more)
Quantum fidelity kernels and
quantum extreme learning machines share the same basic architecture: a fixed
quantum device generates features that are combined through a classically trained linear model. We refer to this broad non-variational setting as
quantum linear regression. A defining aspect of these models is that the
quantum features are not directly available, but must be estimated from a finite number of shots. We show that finite statistics makes
quantum linear regression unavoidably ill-conditioned. Ideal feature vectors are confined to a subspace determined by the dimension of the
Hilbert space, whereas finite-shot estimates generically acquire components outside this subspace. Training then attempts to fit directions that disappear in the infinite-statistics limit, making the learned model increasingly sensitive to sampling noise. We analyze this mechanism for
quantum extreme learning machines trained on $n_{\rm tr}$ states with $N$ shots per state. Despite the ill-conditioning, predictions remain controlled when the training targets are exact. Finite sampling produces a systematic prediction error that decreases quadratically with $N$, while fluctuations induced by the random training measurements decrease inversely with the total training budget. Thus, unlike in standard linear regression with exactly known features, increasing the
dataset size alone cannot remove the error caused by sampling noise. If the training targets are also noisy, due for instance to state-preparation errors, the otherwise hidden directions become active. The test error can then increase with $N$, a behavior that we ascribe to a form of
quantum overfitting. Our results expose a fundamental tradeoff between
dataset size and per-state statistics in non-variational
quantum learning and provide a baseline for resource-aware training and regularization strategies.
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All authors Gabriele Lo Monaco, Salvatore Lorenzo, Alessandro Ferraro, Mauro Paternostro, G. Massimo Palma, Luca Innocenti