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Self-gravity in superradiance clouds: Implications for binary dynamics and observational prospects
No full textSpinning black holes could produce ultralight particles via the superradiance instability. These particles form a dense cloud around the host black hole, introducing new opportunities for the detection of ultralight new physics. When the black hole is part of a binary system, the binary can trigger transitions among different states of the cloud configuration. Such transitions backreact on the orbital dynamics, modifying the frequency evolution of the emitted gravitational waves. Based on this observation, black hole binaries were proposed as a way to test the existence of ultralight particles. We investigate the effects of the self-gravity of the cloud on the orbital evolution and on the gravitational wave emission. We find that cloud self-gravity could lead to a density-dependent modification of the energy levels of ultralight particles and that it could alter the order of hyperfine energy levels. The crossing of hyperfine levels prevents binaries from triggering resonant hyperfine transitions, and allows them to approach radii that could trigger resonant transitions of fine levels. We study the implications of these findings, especially in the context of future space-borne gravitational wave observatory, the Laser Interferometer Space Antenna (LISA). For quasicircular, prograde, and equatorial orbits, we find that LISA could probe ultralight particles in the mass range 10-15 eV–10-13 eV through gravitational wave observations
Quenching induced depolarization delay and structure evolution in (1-x)NaBiTiOBiFeO ceramics
No full textAs a relaxor, Na1/2Bi1/2TiO3 (NBT) presents limitations in high temperature application because of thermally induced depolarization. Stabilizing the polar ferroelectric phase is key for deferring the temperature dependent depolarization. In this work, a transition from relaxor to ferroelectric is induced by incorporating BiFeO3 (BFO) in NBT. The transition is characterized by temperature dependent dielectric and piezoelectric properties, and supported by mechanical stress-strain tests and in-situ electric field dependent synchrotron XRD analysis. To improve the depolarization temperature (Td) further, 40NBT-60BFO (60BFO) is subject to a quenching treatment. Td of 60BFO increases from 300 °C to 520 °C upon quenching. The significant increase in Td is explained by analyzing the average and local structure changes. It is found that the ordered Bi and Na ions and the intensified Bi-O bonding upon quenching contribute to the increase in Td. This work clarifies the mechanism of quenching induced enhancement Td in NBT-BFO ceramics
Microstructural evolution of laser-processed CuZrTi alloy during liquid metal dealloying
No full textThe possibility of topology modification at the design stage makes metal additive manufacturing (AM) a promising approach for coupling with liquid metal dealloying (LMD) to synthesize novel hierarchical materials. However, elemental microsegregation in the precursor fabricated by AM leads to compositional and phase heterogeneity, which inevitably affects the dealloying process. In this work, the AM–LMD process chain is pioneered to explore the microstructural evolution of a laser-processed CuZrTi precursor, synthesized via powder bed fusion, on the dealloying kinetics and the formation of ligament microstructure. The results demonstrate that the dealloying of laser-processed materials is strongly affected by compositional heterogeneity. According to a systematic analysis, the size of the ligament varies up to 2.6 μm in the region corresponding to the 2nd stage of dealloying and correlates with the observed heterogeneity inside the laser-processed precursor. A heterogeneous stepwise (two-stage) dealloying reaction is observed. The formation of the 2nd dealloying stage is attributed to the saturation of the Mg channels by Cu during the 1st stage, which is unique for each dealloying condition. For the same immersion time, the average atomic fraction of Cu dissolved in Mg during the 1st stage of dealloying increases with temperature. This study provides insight into the effects of compositional heterogeneity in laser-processed materials during LMD, highlighting new challenges in achieving compositional homogeneity and phase stability
Strong Stabilization of Co Nanoparticles by CeO Clusters in Inverse CeO/Co Catalysts for Enhanced CO Methanation
No full textInverse catalysts, where metal oxide species are dispersed over metallic nanoparticles, represent a promising class of materials for accelerating various chemical reactions. However, stabilizing metal nanoparticles with a small amount of oxide clusters remains a significant challenge, as the metallic phase tends to sinter under reaction conditions due to insufficient immobilization. In this study, flame spray pyrolysis is employed to synthesize uniformly sized inverse CeOx/Co catalysts for CO2 methanation (Sabatier reaction). It is found that small, highly reducible CeO2-x clusters effectively stabilize metallic cobalt nanoparticles, thereby preventing sintering even during hydrogen reduction at 500 °C and during CO2 hydrogenation. Detailed operando characterization demonstrates that this stabilization leads to a high density of metallic Co sites interfaced with CeO2-x clusters, which facilitates CO2 activation into carbonyl (CO*) intermediates, resulting in significantly enhanced CH4 formation rates. Notably, an inverse CeOx/Co catalyst containing 20 mol% Ce exhibits a methanation rate an order of magnitude higher than that of a CeO2-free Co catalyst. These findings highlight the dual role of CeO2-x clusters in both stabilizing Co nanoparticles and enhancing catalytic performance, offering a robust strategy for improving CO2 hydrogenation performance
Gross-Llewellyn Smith sum rule from lattice QCD
No full textWe compute the Gross-Llewellyn Smith sum rule, i.e., the lowest odd moment of the parity-violating structure function, F3, of the nucleon from a lattice QCD calculation of the Compton amplitude. Our calculations are performed on 483×96 lattices at the SU(3) symmetric point for two lattice spacings. We extract the moments for several values of the current momenta in the range 0.5≲Q2≲10 GeV2, covering both the nonperturbative and perturbative regimes. We compare our moments to the Gross-Llewellyn Smith sum rule and discuss the implications for higher-twist effects, a determination of αs(Q2) from a hadronic quantity complementing the phenomenological and other lattice approaches, and electroweak box contributions crucial for Cabibbo–Kobayashi–Maskawa matrix unitarity studies
Cross-Geometry Transfer Learning in Fast Electromagnetic Shower Simulation
No full textAccurate particle shower simulation remains a critical computational bottleneck for high-energy physics. Traditional Monte Carlo methods, such as Geant4, are computationally prohibitive, while existing machine learning surrogates are tied to specific detector geometries and require complete retraining for each design change or alternative detector. We present a transfer learning framework for generative calorimeter simulation models that enables adaptation across diverse geometries with high data efficiency. Using point cloud representations and pre-training on the International Large Detector detector, our approach handles new configurations without re-voxelizing showers for each geometry. On the CaloChallenge dataset, transfer learning with only 100 target-domain samples achieves a improvement on the geometric mean of Wasserstein distance over training from scratch. Parameter-efficient fine-tuning with bias-only adaptation achieves competitive performance while updating only of model parameters. Our analysis provides insight into adaptation mechanisms for particle shower development, establishing a baseline for future progress of point cloud approaches in calorimeter simulation
Multi-goal-oriented anisotropic error control and mesh adaptivity for time-dependent convection-dominated problems
No full textIn this work, we present an anisotropic multi-goal error control based on the Dual Weighted Residual (DWR) method for time-dependent convection-diffusion-reaction (CDR) equations. This multi-goal oriented approach allows for an accurate and efficient error control with regard to several quantities of interest simultaneously. Using anisotropic interpolation and restriction operators, we obtain elementwise error indicators in space and time, where the spatial indicators are additionally separated with respect to the single directions. The directional error indicators quantify anisotropy of the solution with respect to the goals, and produce adaptive, anisotropic meshes that efficiently capture layers. To prevent spurious oscillations the streamline upwind Petrov-Galerkin (SUPG) method is applied to stabilize the underlying system in the case of high P\'{e}clet numbers. Numerical examples show efficiency and robustness of the proposed approach for several goal quantities using established benchmarks for convection-dominated transport
Live‐Cell RNA Imaging via Clickable Tri PPP ro Nucleotide Reporters
No full textUnderstanding RNA synthesis and dynamics in cells requires efficient labeling strategies that are not only compatible with cellular environments but can be performed in living cells. We developed a robust, bio-orthogonal approach for live-cell RNA labeling using TriPPPro (triphosphate prodrug) chemistry. This strategy enables the intracellular delivery of sterically demanding nucleoside triphosphates modified with inverse electron-demand Diels–Alder (IEDDA)-reactive groups, specifically trans-cyclooctene (2TCOa) and bicyclo[6.1.0]nonyne (BCN). Once hydrolyzed inside cells, these TriPPPro-modified uridines and cytidines are metabolically incorporated into nascent RNA by endogenous RNA polymerases. Subsequent IEDDA reaction with a dual-fluorogenic tetrazine-cyanine styryl dye conjugate allows wash-free, high-contrast imaging of RNA synthesis in cells. We demonstrate efficient RNA labeling, including nucleolar localization and specificity for newly transcribed RNA, validated by transcriptional inhibition and colocalization with ribosomal RNA. Comparative analyses confirm that TriPPPro delivery surpasses conventional transporter-based systems in both labeling efficiency and cellular compatibility. This platform offers a modular, non-genetic, and highly specific method for real-time RNA imaging, with broad applicability for RNA biology and antiviral research
ATLAS results on top, and associated cross-sections
No full textThe exceptionally large dataset collected by the ATLAS detector at the highest proton-proton collision energies provided by the LHC enables precision testing of theoretical predictions using an extensive sample of top quark events. Recent measurements include total and differential top quark cross sections, as well as measurements of associated top quark production. This contribution presents the latest highlights from the ATLAS top quark physics program, including key measurements from Run II, and new results using Run III data