Astrophysics of Galaxies
Low-Metallicity Star Formation Survey in Sh2-284 (LZ-STAR): The Core Mass Function
Yu Cheng, Jonathan C. Tan, Morten Andersen et al. (+4 more)
We present an ALMA 1.3~mm
dust continuum study of the dense core mass function (CMF) in Sh2-284, a low
metallicity outer
Galaxy star-forming complex with $Z\sim1/3$–$1/2~Z_\odot$. The observations cover six far-infrared bright subregions at $\sim$0.65" (3000~au) resolution. We identify a total of 91 candidate dense cores and define a robust catalog of 68 cores with Gaussian fitting. The high-mass CMF above 2.5 Msun is well described by a Salpeter-like slope, with a fiducial forward-modeled value of $\alpha=1.22^{+0.24}_{-0.22}$ for $dN/d\log M\propto M^{-\alpha}$. Together with existing constraints on the initial mass function (IMF) of Sh2-284, the Salpeter-like CMF is consistent with a resemblance between the CMF and IMF shapes in the outer
Galaxy environments, suggesting that moderately low
metallicity alone does not strongly reshape the high-mass CMF/IMF slope.
Read the full abstract ▾
All authors Yu Cheng, Jonathan C. Tan, Morten Andersen, Alva Kinman, Rubén Fedriani, Kei E. I. Tanaka, Yichen Zhang
Medical Physics
Unveiling neuronal microstructure in the human brain in vivo with time-dependent radial diffusivity in MRI
Ante Zhu, Jerome J. Maller, H. Douglas Morris et al. (+14 more)
Diffusion time-dependence, defined as variations in diffusivity and/or diffusional kurtosis with
diffusion time, has emerged as a valuable non-invasive imaging marker for characterizing tissue microstructural features, such as
cell size, density, packing disorder, and membrane permeability. In white matter,
diffusion time-dependent changes between the short
diffusion time and long
diffusion time in radial diffusivity (RD), defined as the diffusivity perpendicular to fiber tracts, were demonstrated to correlate strongly with mean axon diameter in ex vivo spinal cord tissues, and to reveal demyelination in mouse corpus callosum. Despite their potential to non-invasively unveil neuronal microstructures to improve the assessment and targeted therapy of neurological diseases, these novel image contrasts obtained at short
diffusion times using oscillating gradient
spin echo (OGSE) have only recently become feasible for human in vivo studies with high-performance gradient MRI systems. In this preliminary study, we characterized time-dependent RD with OGSE encoding in the human
brain in vivo. The change in radial diffusivity between short
diffusion time and long
diffusion time (delta_RD) consistently exhibited high values in the corticospinal tract, indicating high sensitivity of delta_RD to large axon diameter in human
brains. Imaging at a high OGSE frequency of 100 Hz and a moderate b-value of 800 s/mm2 produced the highest delta_RD in the corticospinal tract. This study established a baseline for future investigations of neuronal microstructural alterations in neurological disorders and diseases.
Read the full abstract ▾
All authors Ante Zhu, Jerome J. Maller, H. Douglas Morris, Jeffrey P. Guenette, Flavio Dell' Acqua, Chu-Yu Lee, Jeffrey McGovern, Stephan E. Maier, Raymond Y. Huang, Andrew L. Alexander, Maureen N. Hood, Desmond Teck Beng Yeo, Steven CR Williams, Carl-Fredrik Westin, Vincent B. Ho, Vincent A. Magnotta, Hua Li
High Energy Physics (Phenomenology)
Heavy and heavy-light mesons with arbitrary spin and parity in the Covariant Spectator Theory
Alfred Stadler and Elmar P. Biernat
This work generalizes the one-channel Covariant Spectator Theory (CST) formalism to describe
quark-antiquark
mesons of arbitrary
spin-parity $J^P$. We also improve the
quark-antiquark interaction kernel by incorporating the momentum dependence of the strong coupling. Within this framework, we perform global fits to the masses of experimentally established heavy and heavy-light
mesons with $J^P=0^\pm, 1^\pm, 2^\pm,$ and $3^\pm$. With only eight adjustable parameters, the model yields an excellent global description of the observed
quark-antiquark spectrum and predicts both unmeasured states and likely $J^P$ assignments for states with unconfirmed
quantum numbers. In particular, our results support the identifications of the recently observed $B_c(1P)^+$ candidates as $0^+$, $1^+$, and $2^+$ states, and the $B_c^{*+}$ as the lowest $1^-$ state in the bottom-charm sector, as well as the $D_{s1}(2933)^+$ as axial-vector state in the charm-strange sector.
Read the full abstract ▾
Quantum Physics
Classically Augmented Zero-Noise Extrapolation
Timon Scheiber
We investigate a hybrid
quantum-classical approach to
quantum error mitigation. We propose Classically Augmented Zero-Noise Extrapolation, a hybrid error-mitigation method in which high-noise Richardson extrapolation nodes are replaced by classically simulated estimates. These classical nodes have negligible sampling variance but introduce deterministic simulation bias. We derive the resulting variance reduction under optimal shot allocation and show that, for linear node spacings and fixed index cutoff, the coefficient-level reduction can be exponential. We validate the prediction numerically using Pauli-propagation simulations and demonstrate a reduction in mean-squared error when the truncation bias is sufficiently small.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Late-Time Cosmological Tests of a Minisuperspace Generalized-Uncertainty-Principle Deformation
G.G.L. Nashed
The investigation of possible
quantum-
gravity effects in cosmology is of considerable interest, especially when such effects can be tested against observations of the late-time expansion. In the present work we study a quadratic generalized-uncertainty-principle (GUP) deformation of the FLRW minisuperspace Poisson
algebra. At first order in the deformation parameter, the construction modifies the Friedmann equation and hence the homogeneous expansion history. Since it does not determine a unique perturbation sector, we restrict the analysis to background observables, using 31
cosmic-chronometer measurements, the uncalibrated 1580-object Pantheon$+$ Hubble-flow sample, and the 13-component DESI DR2
baryon-acoustic-oscillation likelihood, while treating the sound horizon as a nuisance parameter. We compare the resulting cosmology with flat \LCDM{} and with the Chevallier–Polarski–Linder parametrization. For the baseline normalization we obtain $\betastar=-0.086^{+0.040}_{-0.032}$ at $68\%$ credibility and $-0.142<\betastar<0.005$ at $95\%$ credibility.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Compositeness relations for near-threshold p-wave bound states
Guo-Ying Chen
We generalize Weinberg's compositeness relations to near-threshold p-wave bound states and derive the relations among the p-wave effective range expansion parameters, binding energy B, and the field renormalization constant Z. Unlike the s-wave case, the field renormalization constant Z for p-wave states depends on the renormalization scale. We obtain the renormalization equation for Z and provide its solution. We find that the negative-norm state reported more than a decade ago in p-wave sector can be avoided by an appropriate choice of the renormalization scale. We also present the general propagator for p-wave near-threshold states. Our results are expected to have broad applications in studying exotic states, as well as the structure of
halo nuclei and Fashbach molecules.
Read the full abstract ▾
Soft Condensed Matter
Physical Mechanism of Vacuole Formation in Liquid Droplets
Pranay Jaiswal, Ivar S. Haugerud, William Verstraeten et al. (+3 more)
Vacuoles have been observed in
liquid droplets across variety of experimental systems, ranging from biomolecular condensates composed of
proteins and RNA, to synthetic coacervates formed by charged
polymers or synthetic nanostars. These vacuoles are long-lived domains depleted of droplet material, and their formation is puzzling because the associated increase in interfacial area is thermodynamically unfavorable. Using theory, we show that vacuoles form through a generic mechanism: a local spinodal instability within the droplet. We demonstrate this mechanism in several experimentally relevant scenarios, including temperature quenches and droplets coupled to chemical processes occurring either inside or outside the droplet. Using non-
equilibrium thermodynamics, we develop a theoretical framework that identifies the physicochemical conditions controlling whether vacuoles form and how big vacuoles can become. Our results suggest molecular designs and chemical pathways that promote vacuolation, enabling multi-compartment formation with engineered functions such as enhanced surface catalysis and compartment fission.
Read the full abstract ▾
All authors Pranay Jaiswal, Ivar S. Haugerud, William Verstraeten, Kerstin Göpfrich, Job Boekhoven, Christoph A. Weber
Solar and Stellar Astrophysics
Toward 3D orbits of wide sdO/B binaries I. Six composite systems spatially resolved with VLTI/GRAVITY
K. Deshmukh, S. Geier, H. Sana et al. (+7 more)
Hot subdwarf
stars (sdO/Bs) are widely considered to be products of binary
evolution. A significant fraction of them are found in long-period or wide binaries ($P>500$ d) with main sequence (MS) companions, likely resulting from a stable mass transfer episode where the MS companion stripped the hydrogen envelope of the sdO/B progenitor. Consequently, wide sdO/B binaries represent a key population in our pursuit of understanding stable mass transfer. They exhibit a modest range of orbital periods and eccentricities as revealed by long-term spectroscopic campaigns, though the component masses are not well constrained. In this Letter, we present the first long-baseline interferometry campaign to observe wide sdO/B + MS binaries and take the first step toward determining their 3-dimensional (3D) orbits and model-independent component masses. We target six composite sdO/B + MS systems with VLTI/
GRAVITY and spatially resolve all of them. The projected physical separations range between $1-3$ au, with uncertainties between $1-8$%. When combined with complementary information from spectroscopic or astrometric observations, our precise measurements will be crucial to constrain 3D orbits for these systems. Additionally, we also identify a potential third component in BD+10 2357, although additional data will be necessary for confirmation. In light of continued spectroscopic monitoring and the imminent
Gaia Data Release 4, we strongly encourage expanding the interferometric sample presented here to establish new, precise orbital and mass constraints for this key population of binary interaction products.
Read the full abstract ▾
All authors K. Deshmukh, S. Geier, H. Sana, H. Dawson, M. Dorsch, A. J. Frost, U. Heber, T. Kupfer, A. Picco, M. Vučković
General Relativity and Quantum Cosmology
Echoes and quasinormal modes for static loop quantum black bounces
Huajie Gong, Guoyang Fu, Shulan Li et al. (+3 more)
We investigate scalar perturbations of the static loop
quantum black bounce (LQBB) spacetime with multipole index $l=1$, focusing on time-domain signals and fundamental quasinormal frequencies (QNFs). The LQBB model provides a unified description of regular black holes (RBHs) and traversable wormholes, governed by the
quantum parameter $\alpha$ and the bounce parameter $r_b$. Using the finite difference method, we find no echoes for the displayed RBH configurations with a single-barrier effective potential, whereas clear echoes are produced by the potential well structure in selected traversable wormhole configurations. The QNFs obtained from the Prony method and the direct integration method are in good agreement. In the RBH case, increasing $r_b$ or $\alpha$ leads to a slower decay. In the wormhole case, the QNFs depend non-monotonically on the model parameters, and the emergence of echoes is closely tied to the effective potential profile. These results show that the LQBB spacetime provides a useful framework for studying wave dynamics in RBHs and traversable wormholes, and for clarifying how horizon and throat structures affect ringdown and echoes.
Read the full abstract ▾
All authors Huajie Gong, Guoyang Fu, Shulan Li, Jian-Pin Wu, Qin Tan, Qiyuan Pan
High Energy Physics (Theory)
Balanced Metrics Know About SYZ
Per Berglund, Tristan Hübsch, Vishnu Jejjala et al. (+2 more)
Numerical
Ricci-flat metrics on Calabi-Yau
manifolds are becoming increasingly accurate. However, they often lack the interpretability required to extract theoretical insights. In this paper, we introduce a novel variant of Donaldson's
algorithm based on the Moore-Penrose pseudo-inverse that operates on the global sections of the ambient space rather than the
manifold itself. This approach allows us to use the canonical monomial basis to compute interpretable balanced metrics even at large degrees $k$. Applying our ambient
algorithm to multiple families, including the Dwork family and complete intersection Calabi-Yau
manifolds, we discover that the metric parameters obey novel power laws near the Large Complex Structure Limit (LCSL). We connect these to the Gromov-Hausdorff metric collapse predicted by the SYZ
conjecture.
Read the full abstract ▾
All authors Per Berglund, Tristan Hübsch, Vishnu Jejjala, Viktor Mirjanić, Challenger Mishra
Medical Physics · Cross-listed from cs.CV
A systematic evaluation of machine learning classifiers for event-by-event background rejection in LAFOV PET scanners
Konrad Klimaszewski, Michał Obara, Mateusz Bala et al. (+5 more)
The introduction of LAFOV PET scanners brings significant sensitivity gains but also a substantial increase in the background rate from accidental coincidences, phantom-scattered and detector-scattered
photons. While machine learning methods have been applied to background reduction in PET imaging, they target specific background components in post-processing rather than event-by-event classification on the raw data. In this work, we formulate coincidence classification as a supervised multi-class problem and evaluate XGBoost, AdaBoost and Neural Network classifiers as pre-reconstruction filters, using Monte Carlo simulations of the Siemens Biograph
Vision Quadra scanner with NEMA IEC and anthropomorphic XCAT phantoms. We investigate two feature sets: a 4-feature representation based on the Attenuation Factor,
photon time difference, energy sum, and energy difference, and an extended 6-feature set that incorporates
topology-based variables. A systematic robustness study via cross-phantom inference reveals that the 4-feature models generalise significantly better across different phantom geometries, with XGBoost suffering an accuracy loss of only 0.04 compared to 0.13 for the 6-feature variant. Our best models achieve accuracies of up to 0.74 and 0.69 for the NEMA IEC and XCAT phantoms, respectively, outperforming traditional geometry-based cuts. However, we show that this compact feature set not only provides limited suppression of in-phantom scattered coincidences, but it also can lead to non-trivial spatial patterns. With scattered coincidences being the dominant background component in clinical conditions, this suggests that while the method serves as an effective and geometry-agnostic replacement for traditional cut-based selection, meaningful further gains in image quality will require either larger input representations or dedicated treatment of the phantom-scattered component.
Read the full abstract ▾
All authors Konrad Klimaszewski, Michał Obara, Mateusz Bala, Beatrix C. Hiesmayr, Lech Raczyński, Roman Y. Shopa, Wojciech Zdeb, Wojciech Krzemien
Nuclear Theory
Path-length dependence of parton energy loss across collision systems: a Bayesian analysis of charged-particle RAA, consistent with a universal exponent from O+O to Pb+Pb
Fouad A. Majeed, Hussein Ali Hussein Al Naffakh, Sarah M. Obaid et al. (+1 more)
How parton energy loss in the
quark-
gluon plasma (QGP) scales with the in-medium path length $L$ encodes the mechanism: collisional ($\Delta E \propto L$), radiative ($\Delta E \propto L^2$), or strong-coupling ($\Delta E \propto L^3$). Exploiting the new CERN LHC light-ion data, we extract this scaling from the system size itself, jointly analysing CMS charged-particle
nuclear modification factors $R_{AA}$ in four systems - O+O, Ne+Ne, Xe+Xe and Pb+Pb - spanning mass number $A = 16$ to $208$. A
Bayesian analysis with a data-driven spectral baseline and a Monte-Carlo Glauber geometry yields an effective system-size exponent $n = 1.78 \pm 0.15\,\mathrm{(stat)} \pm 0.05\,\mathrm{(syst)}$. Nested-sampling model selection decisively favours an effective exponent near the radiative value ($n = 2$) over the collisional ($n = 1$) and strong-coupling ($n = 3$) values, a conclusion stable across all 160 analysis variants. Because fluctuations can only lower the effective exponent below its microscopic counterpart, the measurement bounds the latter from below at fixed geometry, excluding purely collisional energy loss. The medium density and the path length are degenerate across system size, so we quote the effective exponent as our primary result. A Bayes-factor test finds no change of regime between small and large systems, consistent with a universal exponent; the same framework gives decisive evidence for non-zero energy loss in O+O alone, quantifying the onset of suppression in the smallest system. The energy-loss magnitude corresponds to $\hat{q}/T^3 \approx 2$–$5$, consistent with the JETSCAPE determination.
Read the full abstract ▾
All authors Fouad A. Majeed, Hussein Ali Hussein Al Naffakh, Sarah M. Obaid, Muntaha Abdullah Reishaan
Mesoscale and Nanoscale Physics
Quantum metric quadrupoles in elemental bismuth thin films
Rhonald Burgos Atencia, Pavlo Makushko, Gabriele Naselli et al. (+11 more)
The nonlinear transport properties of solids are deeply rooted in the
quantum geometry of their electronic wavefunctions, which is encoded in the
quantum geometric tensor. Its real part, known as the
quantum metric, has been recently identified as a primary origin of nonlinear transport in
quantum materials where time-reversal and inversion
symmetries are not simultaneously present. Consequently, the influence of the
quantum metric on the largest class of materials – non-
magnetic and centrosymmetric systems – has remained entirely elusive. Here, we demonstrate that third-order transport in centrosymmetric materials hosting relativistic
fermions is governed by
quantum metric quadrupoles (QMQs). We show that these QMQs can originate from both the non-Abelian
quantum geometry of bulk three-dimensional Dirac
fermions and the Abelian
quantum geometry of
spin-orbit-coupled surface states. In stark contrast to all zero-field nonlinear transport signatures known to date, the current driven by these QMQs persists as a robust, non-vanishing observable even in highly scalable polycrystalline thin films. We experimentally validate this
quantum metric footprint by measuring nonlinear transport in thin films of elemental bismuth, observing a robust, surface-dominated, and broadband third-harmonic generation that persists up to room temperature. Our findings uncover a hidden role of the
quantum metric in polycrystalline systems, establishing third-order nonlinear transport as a high-precision diagnostic tool of wavefunction geometry under ambient conditions.
Read the full abstract ▾
All authors Rhonald Burgos Atencia, Pavlo Makushko, Gabriele Naselli, Debottam Mandal, Paul Chekhonin, Sergey Kovalev, Steffen Kober, Zhe Wang, Igor Veremchuk, Oleksiy Pashkin, Fabian Ganss, Maria Teresa Mercaldo, Denys Makarov, Carmine Ortix
Solar and Stellar Astrophysics
Herbig AeBe Star AS442A as a UXOR-type system
Nariman Ismailov, Faida Surkhai Huseynova, Volkan Bak{\i}ş et al. (+3 more)
Detailed studies of the physical characteristics of young intermediate-mass Herbig Ae/Be (HAeBe)
stars require extensive sets of homogeneous observational data collected over long periods. In this paper, we present the results of a multi-year study focusing on the faint Herbig Ae/Be
star AS 442A. The goal of this study was to investigate the spectral and photometric variability of the
star, utilizing long-term archival photometry alongside our own spectroscopic observations. The long-term photometric variability was statistically investigated using approximately 3,500 archival measurements spanning 1984 to 2025. Additionally, we examined the
star's spectral variability using data obtained at the Shamakhy Astrophysical Observatory (ShAO) between 2020 and 2024. The three deepest brightness minima were detected in 1990, 2013, and 2023, with amplitudes of approximately ~2 mag in the U-band and up to ~1 mag in other bands. All three observed deep minima were accompanied by smaller brightness dips occurring both before and after the main event. The main light curve and color-magnitude diagrams show the "blueing" effect, which is characteristic of UXOR
stars. A quasi-periodic occurrence of deep brightness minima with a period of P = 3759 +/- 35 days was detected for the first time. Our spectral observations were performed before the last deep light fading, which occurred in 2023. We show that the observed spectral variability, specifically the strengthening of emission lines and the reduction in depths and widths of absorption lines, is primarily related to the
star's brightness variations. We have shown for the first time that the main reason for the UXOR-like brightness dip of the HAeBe
star AS 442A can be explained by a periodic eclipse in a binary system. A close companion as a late-type secondary
star with an orbit semimajor axis (a>7.5 au) likely drives the observed
stellar variability.
Read the full abstract ▾
All authors Nariman Ismailov, Faida Surkhai Huseynova, Volkan Bak{\i}ş, Namiq Serdar Dzhalilov, Sabahaddin Amanulla Alishov, Shafaq Kamal Ismayilova
Cosmology and Nongalactic Astrophysics
Robust Ly$\alpha$ forest constraints on reionization from semi-analytic galaxy formation models
Yuxiang Qin and J. Stuart B. Wyithe
The high-
redshift Ly$\alpha$ forest provides one of the most sensitive probes of the final stages of reionization, but its interpretation can depend on how the ionizing sources are modelled. We test the robustness of Ly$\alpha$ forest-inferred reionization histories using Meraxes, a semi-analytic model of
galaxy formation and reionization applied to a cosmological volume of $(210h^{-1}{\rm cMpc})^3$ with merger trees augmented down to the atomic-cooling threshold. We construct a suite of source models in which the
galaxy escape fraction, $f_{\rm esc}^{\rm gal}$, is parameterized as a function of
halo mass,
stellar mass,
star formation rate, specific
star formation rate, or
star-forming disc surface density. We also consider models in which accreting blackholes contribute ionizing
photons, or dense circumgalactic gas further attenuates the escape of ionizing
photons. Each model is calibrated to the observed distribution of Ly$\alpha$ effective optical depths from XQR-30+. These prescriptions redistribute the escaping
photon budget across
halo mass and UV luminosity, introduce scatter in $f_{\rm esc}^{\rm gal}$ at fixed
halo mass, and allow modest variation in the early
evolution of reionization. Nevertheless, all viable calibrated models recover a late and extended EoR, with the midpoint occurring at $z\sim6.2$–6.9 and the final stages at $z\sim5.36$–5.57. Our results indicate that the late reionization history inferred from Ly$\alpha$ forest is robust to physically motivated scatter in the
galaxy–
halo connection, modest AGN contributions, and phenomenological CGM attenuation.
Read the full abstract ▾
Astrophysics of Galaxies
SKAO-ALMA Synergies in Star Formation Science
Jan Forbrich, Gary A. Fuller, Mark A. Thompson et al. (+7 more)
We highlight the potential for synergies between the SKA
telescopes and ALMA, which will begin to be significant already with SKA Early Science. Broadly within
star formation science, we focus on 1) (simultaneous) time domain and variability studies (e.g., of (proto-)
stars), which is systematically opening a new observing window that will enable us to better constrain the physics of extreme
stellar flares and their interplay with mass
accretion in young
stars, 2) possibilities for complementary coverage of different transitions of molecules as tracers of the ISM (e.g., H2CO to trace density and temperature), and 3)
radio recombination lines to trace ionised gas at different densities. Furthermore, we address synergies in terms of the spatial resolution of both observatories and new capabilities not only on the SKAO side but extending to the ALMA2030 wideband sensitivity upgrade.
Read the full abstract ▾
All authors Jan Forbrich, Gary A. Fuller, Mark A. Thompson, Eleonora Bianchi, Jaime E. Pineda, Marta De Simone, Tomoya Hirota, Katharine Johnston, Steven N. Longmore, Giovanni Sabatini
Atmospheric and Oceanic Physics
Small-scale polarization variations in near-inertial deep Mediterranean horizontal waterflow
Hans van Haren
Deep-sea observations are reported of horizontal waterflow differences with typical amplitudes of 0.02 m s-1 over 50-m small scales so that relative vorticity reaches values of the inertial frequency f. The timeseries observations are made using a complex mooring system deployed in the 2500-m deep Mediterranean Sea, where vertical density stratification is extremely weak, with buoyancy frequency O(f), and the slow waterflow with total speeds <0.07 m s-1 is dominated by inertial internal waves and sub-mesoscale eddies. Horizontal waterflow differences increase when polarization, i.e. direction of traversal of
elliptic oscillatory motion, switches sign. Common anticyclonic polarization of inertial motions is predominantly found under near-homogeneous conditions. It alternates with uncommon cyclonic polarization under stratified-water conditions, varyingly over 50-m distances. The alternation is in line with predictions from non-traditional inertio-
gravity wave theory, but only when relatively strong turbulent convection causes local reduced stratification, as observed.
Read the full abstract ▾
High Energy Physics (Theory)
The coupling flow for supergravity
Federico Arrighi, Saurish Khandelwal and Olaf Lechtenfeld
Quantum correlation functions in supersymmetric field theories can be encoded in the Nicolai map. The infinitesimal inverse map provides their response to a change in a coupling constant through a "flow equation". We investigate the flow in the gravitational constant $\kappa$ for four-dimensional Poincaré supergravity via its superconformal formulation. By expressing the full superconformal off-shell action as a supervariation we derive a "flow operator" in the effective vierbein theory, whose exponentiation yields the gauge-invariant part of an all-order (inverse) Nicolai map for supergravity. Alas, the BRST gauge fixing adds to this functional differential flow operator a multiplicative term, which ruins its derivational property and therefore jeopardizes its connection with the Nicolai map. We argue and present an example, however, that such multiplicative flow contributions might be rewritable as derivational ones with the help of Wick's
theorem in the free effective theory where the Nicolai-transformed correlators are ultimately evaluated. At least in the Landau gauge, the supergravity flow equation is shown to be regular at $\kappa=0$, allowing for a perturbative expansion around Minkowski geometry. Therewith, we have overcome two of the three obstacles met in an earlier attempt towards a Nicolai map for Poincaré supergravity. Finally, we compare with the direct on-shell construction of a Nicolai map to leading order in $\kappa$.
Read the full abstract ▾
Materials Science
Laser induced optical reconfiguration in Ge_Sb_Te Films with composition dependent response
M. Zhezhu, A. Vasilev, M. Sukiasyan et al. (+5 more)
Phase change Ge_Sb_Te (GST) materials exhibit pronounced optical contrast and tunability driven by structural transformations, enabling a diverse range of photonic and optoelectronic applications. GST materials undergo reversible amorphous crystalline phase transitions during which the refractive index and extinction coefficient increase significantly in the crystalline phase across a broad spectral range. However, a systematic correlation between local composition, crystalline microstructure, and broadband optical response within as deposited crystalline GST films has not been established, particularly for films spanning various compositions within a single growth process and in the absence of amorphous-crystalline transitions. Here, we report a systematic study of composition resolved optostructural property relationships in as-deposited crystalline GST films spanning Ge3Sb2Te6, Ge2Sb2Te5, and GeSb2Te4 within a single CVD process, avoiding intermediate phase transitions. This enables direct correlations between composition, microstructure, morphology, and broadband optical response across 400-1700 nm. Specifically, the compositional gradient results in a shift of the absorption minimum from 815.9 nm to 889.8 nm, accompanied by a 5.9 fold change in the intensity, reflecting the strong dependence of optical behavior on composition and microstructure. We further show that femtosecond
laser irradiation enables spatially selective tuning of the optical response. These findings establish crystalline GST films as a platform for broadband-tunable, spatially programmable photonic elements, controllable through both compositional design and localized
laser processing.
Read the full abstract ▾
All authors M. Zhezhu, A. Vasilev, M. Sukiasyan, A. Kutuzyan, N. Anosov, M. Yaprintsev, D. A. Ghazaryan, H. Gharagulyan
Lattice Field Theory
Radiative decays of the $h_c$ meson from lattice QCD
Mischa Batelaan, Jozef J. Dudek and Robert G. Edwards
We explore, for the first time in
lattice QCD, the radiative decays to $\gamma \eta$ and $\gamma \eta'$ of the $J^{PC}=1^{+-}$ charmonium state, $h_c$. This work expands upon a previous calculation of $J/\psi$ decays to the same final states, incorporating novel technology to access the $h_c$ where it is an excited state and to separate the independent electric dipole and longitudinal form–factors. Results for the radiative decay rates, computed on three-
flavor lattices with $m_\pi \sim $ 391 MeV show a suppression relative to experiment that is similar to that observed in the prior calculation of $J/\psi \to \gamma \eta^{(\prime)}$. The timelike $Q^2$ dependence of both form–factors together influence the Dalitz decays, $h_c \to \ell^+ \ell^- \eta^{(\prime)}$, which are as yet unmeasured experimentally.
Read the full abstract ▾
Quantum Physics
Verifiable blind probabilistic error cancellation
Bo Yang, Elham Kashefi and Harold Ollivier
Quantum error mitigation (QEM) is an essential tool for mitigating hardware noise without incurring space overhead. Yet, its reliability depends on modeling, calibration, and implementation, leaving end-to-end security on untrusted
quantum hardware unresolved. We address this problem by introducing verifiable blind probabilistic error cancellation (VBPEC), the first secure verification protocol against a fully malicious adversary that integrates QEM. VBPEC brings probabilistic error cancellation (PEC), a widely studied QEM technique, within the scope of composable security by formalizing delegated mitigation as a cryptographic resource in the abstract cryptography framework. The protocol performs PEC with perfect blindness and an exponentially small security error. VBPEC retains the absence of
quantum-space overhead from recent statistically-secure verified
quantum computation protocols and from PEC. The only overhead takes the form of additional repetitions due to the QEM procedure. To achieve this, we extend trap-based verification from deterministic pass/fail checks to statistical tests that benefit from QEM and develop a new proof technique that integrates the corresponding additional deviation sources. Rather than merely tolerating honest noise below a fixed threshold, VBPEC actively cancels it, enabling correctly mitigated estimates to be accepted with high probability without compromising security. Our framework thus establishes an essential route towards secure, reliable, and practical delegated
quantum computation on near-future
quantum hardware: VBPEC fundamentally improves the practicality of verification.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Simulation-based tension quantification of the cosmic dipole
Mali Land-Strykowski, Harry T. J. Bevins, Oliver T. Oayda et al. (+1 more)
The
cosmic dipole measured in surveys of cosmologically distant sources consistently exceeds the expectation derived from the
cosmic microwave background, posing a significant challenge to the standard $\Lambda$CDM cosmology. In the era of precision cosmology, quantifying robust tensions is constrained by our ability to model complex, non-linear effects that often result in intractable likelihood functions. In this paper, we present a flexible simulation-based inference (SBI) architecture for measuring the
cosmic dipole tension using Neural Ratio
Estimators (NREs). We design and train an ensemble of NREs to evaluate the log
Bayesian evidence ratio and measure $N\sigma$ tension. We validate our approach against nested sampling, demonstrating that it accurately recovers the ground-truth. Under the kinematic interpretation of the dipole, we apply our approach to Planck, the NRAO VLA Sky Survey (NVSS), the Rapid ASKAP Continuum Survey (RACS), and the Wide-field Infrared Survey Explorer catalogue (CatWISE). Here, leveraging SBI, we measure a $\approx5.7\sigma$ tension between CatWISE and Planck. We demonstrate the extensibility of our approach by applying it to forward-modelled simulations of the CatWISE Eddington bias, revealing a $\approx6.7\sigma$ tension. The methodology proposed here enables robust tension quantification as we enter the era of LSST, Euclid, and the SKA.
Read the full abstract ▾
All authors Mali Land-Strykowski, Harry T. J. Bevins, Oliver T. Oayda, Geraint F. Lewis
Quantum Physics
Benchmarking Optical Receivers for Quantum Communication and Randomness Certification
Hamid Tebyanian
The choice of optical receiver determines which properties of the transmitted states remain visible in the observed data and therefore affects the performance of different
quantum protocols. We compare continuous-variable,
photon-counting and hybrid receivers within the same prepare-and-measure framework, using semi-device-independent randomness generation as the main case study. The measurement device is left uncharacterised, while the source is described by the Gram
matrix of its pure signal states using an energy-derived overlap constraint, a magnitude-Gram
benchmark or the full complex Gram
matrix of a certified coherent phase-shift-keyed constellation. Within this framework, the observed receiver statistics are used to bound $H_{\min}(B|X,\Lambda)$ against classical side information correlated with the measurement device but independent of the input. For a fixed Gram
matrix, this bound is obtained from an exact semidefinite program, with complex multi-input cases treated in block-real form and checked through the corresponding dual certificate.
Photon counting alone is phase blind for fixed-modulus phase encoding and therefore certifies no worst-case randomness. Continuous-variable receivers give the highest certified
entropy at moderate energy, while under the nominal source calibration a hybrid receiver performs better at low energy when the beacon-region label is retained in the output. The same receiver statistics also provide receiver-level comparisons for discrete-modulated continuous-variable
quantum key distribution,
quantum reading, covert communication and
quantum-signature verification, without replacing the full security analysis required for each protocol.
Read the full abstract ▾
Solar and Stellar Astrophysics
Project Hephaistos – III. Characterizing anomalous infrared sources identified as Dyson-sphere candidates
Andreas J. Korn, Matías Suazo, Erik Zackrisson et al. (+3 more)
The infrared-flux excess of
stars harbouring Dyson spheres represent one potential technosignature of extraterrestrial intelligence. In a previous Project Hephaistos paper, we highlighted seven M
dwarfs within 300 pc with unusual infrared properties that seem to resemble those expected for Dyson spheres. In the present study, we present an analysis of photometric and, in some cases, spectroscopic data on these seven objects, plus three additional objects with similar properties, to further constrain their nature. The
stellar parameters, derived from calibrated empirical relationships for M
dwarfs, reveal no irregularities with respect to the overall M-
dwarf population of main-sequence
stars. While the infrared properties of our targets resemble those of circumstellar disks in a transitional state, the objects with spectroscopic data show no signs of youth usually associated with such objects. One of our spectroscopic targets does exhibit weak H$\alpha$ emission, but this is more likely attributed to
stellar activity than to the gaseous
accretion disk expected for a young
star. After this analysis, we still find no clear explanation for the infrared excess of these
stars, but note that observations with the JWST and/or the Atacama Large Millimeter/submillimeter Array would be able to probe scenarios in which the infrared excess is due to circumstellar
dust emission or an infrared-bright background source that remains undetected at shorter wavelengths. For two of our
stars, JWST observations have recently revealed superpositions with very red background
galaxies.
Read the full abstract ▾
All authors Andreas J. Korn, Matías Suazo, Erik Zackrisson, Pía Cortés-Zuleta, Adam D. Rains, Armin Nabizadeh
Quantum Physics
Counterfactual Quantum Sensing: What Interaction-Free Measurement Can and Cannot Buy
Christoph F. Wildfeuer
Interaction-free measurement infers the presence of an absorbing object from a
photon that, in the counterfactual sense, never interacted with it, and is widely described as a route to minimally invasive sensing. We ask what it actually buys, in estimation-theoretic terms. Written as a channel-estimation problem, the Elitzur-Vaidman interferometer carries exactly half the Fisher information about the object's transmissivity that direct transmission probing does, and the two schemes deliver identical Fisher information per absorbed
photon. For measuring how transparent something is, the interferometer buys nothing. The advantage lies in discrimination, and we show that what it requires is not that the object be opaque but that the competing hypothesis be the object's absence. Against empty space the Chernoff information per absorbed
photon grows almost linearly, as the number of Zeno cycles times its logarithm, even for a weakly absorbing object; between two partial transparencies it does not grow at all. Parasitic loss in the cycle caps the advantage. The number of conclusive interrogations per absorbed
photon reaches a maximum inversely proportional to the loss per cycle, at an optimal cycle number that is likewise inversely proportional to it, which identifies the loss per cycle as the figure of merit governing how far interaction-free sensing can be pushed. Finally, the negative result is not special to the interferometer. For a single
photon meeting a memoryless, non-dispersive object any number of times through arbitrary fixed optics, the accessible
quantum Fisher information never exceeds that of the same incident flux spent on independent single-pass probes, and is generically far below it. This recovers the bound of Massar, Mitchison and Pironio for this class, by a short argument that also identifies when it is tight.
Read the full abstract ▾
Statistical Mechanics
Gravity-controlled non-equilibrium Casimir pressure in a binary liquid mixture
Marcin Piotr Pruszczyk, Roberto Cerbino and Andrea Gambassi
We investigate the non-
equilibrium Casimir pressure in an isothermal binary
liquid mixture maintained in a spatially constant and stationary concentration gradient parallel to
gravity and confined within a three-dimensional slab of thickness $L$, bounded by two infinite plates parallel to both the gravitational field and the imposed gradient. We assume that the
liquid mixture, under the same non-
equilibrium conditions, occupies both the interior and the exterior of the slab. Using fluctuating hydrodynamics, we show that the resulting finite-size excess pressure on the plates is described by a scaling function of the dimensionless variable $k_{\mathrm{RO}}L$, where $k_{\mathrm{RO}}$ is the
gravity-induced roll-off wavevector. At large separations, this Casimir pressure decays as $1/(k_{\mathrm{RO}}L)$. Depending on the thermodynamic properties of the mixture, the corresponding force can be either attractive or repulsive, while it vanishes for ideal solutions. Since the mixture is assumed to be far from its consolute critical point, the Casimir pressure investigated here is entirely of non-
equilibrium origin and it vanishes in the absence of the imposed concentration gradient. Finally, we propose an experimental setup where this force might be measured, consisting of two optically trapped colloidal particles immersed in a dense aqueous colloidal suspension diffusing into an overlying layer of pure water, estimating the expected magnitude of the resulting force.
Read the full abstract ▾
Astrophysics of Galaxies
Tracing Obscured AGN Contribution and Number Fraction Across 0 < z < 6 with JWST
Angel Rodriguez Barbosa, Tomotsugu Goto, Daryl Joe D. Santos et al. (+7 more)
Active
galactic nuclei (AGN) are key drivers of
galaxy evolution, yet many remain undetected in ultraviolet and optical surveys due to heavy
dust obscuration. In these systems, absorbed emission is re-radiated at infrared (IR) wavelengths, making IR observations essential for identifying the full AGN population. Tracking the AGN IR contribution and number fraction provides insight into both the dominance and prevalence of AGN activity across
cosmic time. Using the JWST Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES) and the JWST Advanced Deep Extragalactic Survey (JADES), we leverage continuous optical-to-mid-IR coverage (0.4-25 $\mu$m) in the GOODS-S field to identify obscured AGN via multi-wavelength SED fitting with CIGALE. Our sample includes 278 AGN across 0 < z < 6, representing a seven-fold increase in sample size relative to previous studies utilizing the
Cosmic Evolution Early Release Science (CEERS) survey due to the larger 15-pointing SMILES MIRI footprint. We find that both AGN IR contribution and number fraction increase with
redshift, with AGN fractions rising from $\lesssim$ 5% at z < 2 to ~ 30% at higher
redshifts, while the median AGN contribution increases by up to ~ 0.15. In contrast, as a function of total IR luminosity over $\log(L/L_{\odot}) \approx$ 8 - 12, the AGN contribution and AGN number fraction remain fundamentally static. These trends suggest that the prevalence of obscured AGN activity is dependent on
redshift while showing little to no dependence on total infrared luminosity. Our results highlight JWST's ability to uncover previously hidden AGN populations and provide new constraints on AGN-
galaxy co-
evolution.
Read the full abstract ▾
All authors Angel Rodriguez Barbosa, Tomotsugu Goto, Daryl Joe D. Santos, Chih-Teng Ling, Tetsuya Hashimoto, Ece Kilerci, Priyanka Jalan, Terry Long Phan Deriyan Senjaya, Vignesh V.V. Rao, Bahareh S. Salmasi
Mesoscale and Nanoscale Physics
First-Principles Wannier Representation of Proximity Effects
Yaroslav Zhumagulov, Johan Félisaz, Stepan S. Tsirkin et al. (+2 more)
Proximity effects in layered
heterostructures are commonly represented by static parameters fitted to first-principles band structures, an approximation that usually discards the energy dependence of interlayer hybridization, momentum transfer, and spatial structure. We address this limitation by deriving a dynamical proximity operator directly from density functional theory by downfolding the
heterostructure Kohn-Sham
Hamiltonian onto a fixed low-energy target Wannier subspace. We demonstrate the method for three different
graphene heterostructures coupled to
magnetic and semiconducting substrates.
Graphene/hBN/Co(0001) exhibits proximity-induced exchange resonances driven by hybridization with Co states.
Graphene/PtSe$_2$ develops a sublattice-selective, intervalley-coherent, proximity-induced coupling. For
graphene/WSe$_2$, we identify the spatial modulation of both Rashba and valley-Zeeman proximity-induced
spin-orbit couplings. The method determines the full microscopic structure of the proximity coupling from first principles, providing input for transport and correlated-phase calculations.
Read the full abstract ▾
All authors Yaroslav Zhumagulov, Johan Félisaz, Stepan S. Tsirkin, Denis Kochan, Oleg V. Yazyev
Optics
Antichiral hinge states in a higher-order photonic nodal ring semimetal
Yuchen Peng, Deep Mondal, Yuting Yang et al. (+17 more)
Antichiral states propagate in the same direction on opposite boundaries, defying the conventional constraint that boundary modes must cancel net chirality. Previously found antichiral states have been limited to first-order topological semimetals. However, antichiral hinge states, the antichiral counterpart of recently discovered higher-order
chiral hinge states, remain elusive. Here, we report the observation of antichiral hinge states in a higher-order nodal-ring semimetal made of a three-dimensional gyromagnetic photonic
crystal. Near-field scanning measurements reveal a pair of hinge states at two parallel one-dimensional boundaries propagating unidirectionally along the same direction, with robust transport against metallic scatterers. Their spatial positions can be reconfigured by adding or removing photonic layers. The additionally observed antichiral and drumhead surface states manifest a hierarchy of first- and second-order topological boundary states within a single photonic system. Our work extends antichiral states to higher-order topological semimetals and has potential applications in robust and reconfigurable photonic routing.
Read the full abstract ▾
All authors Yuchen Peng, Deep Mondal, Yuting Yang, Wanting Wu, Bo Zhao, Shuaiyang Wei, Zhenzhi Liu, Wenrong Qi, Xiaokang Dai, Minqi Cheng, Weili Li, Xinyi Zhang, Fei-Fei Li, Rimi Banerjee, Minggui Wei, Jingyi Tian, Peiheng Zhou, Subhaskar Mandal, Baile Zhang, Gui-Geng Liu
Quantum Physics
Landau Levels on the Surface of a Cube
Almila Kura, Bayram Tekin and Mehmet Özgür Oktel
We study the
quantum mechanics of a charged particle confined to the surface of a cube enclosing a
magnetic monopole. The
magnetic field is chosen to have a constant magnitude on each face and to point along the outward normal, preserving the rotational
symmetry of the cube. We formulate the continuum problem using two gauge patches on the cube surface and show that consistency of the wavefunction gives the Dirac quantization condition. Since an explicit vector potential does not remain invariant under ordinary rotations, we construct gauge-modified rotation operators and use them to classify the eigenstates. Even monopole charges are described by the irreducible representations of the cubic rotation group O, while odd monopole charges require the spinorial representations of the binary octahedral group 2O. We compute the spectrum with a gauge-covariant finite-difference discretization and find Landau-level-like
manifolds whose degeneracies are split by the discrete cubic
symmetry. We also study the corresponding tight-binding Hofstadter problem on the discretized cube. The resulting spectrum contains the usual
magnetic subband structure together with additional gap states localized near the cube corners.
Read the full abstract ▾