Recent lbnl_cs items

DESI DR1 Lyα 1D power spectrum: Validation of estimators

Tue, 4 Aug 2026 00:00:00 +0000

The Data Release 1 (DR1) of the Dark Energy Spectroscopic Instrument (DESI) is the largest sample to date for small-scale Lyα forest cosmology, accessed through its one-dimensional power spectrum (P 1D). The Lyα forest P 1D is extracted from quasar spectra that are highly inhomogeneous (both in wavelength and between quasars) in noise properties due to intrinsic properties of the quasar, atmospheric and astrophysical contamination, and also sensitive to low-level details of the spectral extraction pipeline. We employ two estimators in DR1 analysis to measure P 1D: the optimal estimator and the fast Fourier transform (FFT) estimator. To ensure robustness of our DR1 measurements, we validate these two power spectrum and covariance matrix estimation methodologies against the challenging aspects of the data. First, using a set of 20 synthetic 1D realizations of DR1, we derive the masking bias corrections needed for the FFT estimator and the continuum fitting bias needed for both estimators....

Combined tracer analysis for DESI 2024 BAO

Tue, 4 Aug 2026 00:00:00 +0000

This paper demonstrates how the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1) and future baryon acoustic oscillations (BAO) analyses can optimally combine overlapping tracers (galaxies of distinct types) in the same redshift range. We make a unified catalog of Luminous Red Galaxies (LRGs) and Emission Line Galaxies (ELGs) in the redshift range 0.8 < z < 1.1 and investigate the impact on the BAO constraints. DESI DR1 contains ∼ 30% of the final DESI LRG sample and less than 25% of the final ELG sample, and the combination of LRGs and ELGs increases the number density and reduces the shot noise. We developed a pipeline to merge the overlapping tracers using galaxy bias as an approximately optimal weight and tested the pipeline on a suite of Abacus simulations, calibrated on the final version of the DESI Early Data Release. When applying our pipeline to the DESI DR1 catalog, we find an improvement in the BAO constraints of 11% for α iso and ∼ 7.0% for α AP...

Galaxy-multiplet clustering from DESI DR2

Tue, 4 Aug 2026 00:00:00 +0000

ABSTRACT We present an efficient estimator for higher order galaxy clustering using small groups of nearby galaxies, or multiplets. Using the Luminous Red Galaxy sample from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2, we identify galaxy multiplets as discrete objects and measure their cross-correlations with the general galaxy field. Our results show that the multiplets exhibit stronger clustering bias as they trace more massive dark matter haloes than individual galaxies. When comparing the observed clustering statistics with the mock catalogues generated from the N-body simulation AbacusSummit, we find that the mocks underpredict multiplet clustering despite reproducing the galaxy two-point autocorrelation reasonably well. This discrepancy indicates that the standard Halo Occupation Distribution (HOD) model is insufficient to describe the properties of galaxy multiplets, revealing the greater constraining power of this higher order statistic on galaxy–halo...

The Backup Program of the Dark Energy Spectroscopic Instrument’s Milky Way Survey

Tue, 4 Aug 2026 00:00:00 +0000

The Milky Way Backup Program (MWBP), a survey currently underway with the Dark Energy Spectroscopic Instrument (DESI) on the Nicholas U. Mayall 4 m Telescope, works at the margins of the DESI Main surveys to obtain spectra of millions of additional stars from the Gaia catalog. Efficiently utilizing times between ∼12° and 18° twilight and poor weather conditions, the MWBP extends the range of stellar sources studied to both brighter magnitudes and lower Galactic latitude and declination than the stars studied in DESI’s Main Milky Way Survey. While the MWBP prioritizes candidate giant stars selected from the Gaia catalog (using color and parallax criteria), it also includes an unbiased sample of bright stars (i.e., 11.2 ≲ G < 16 mag) as well as fainter sources (to G ≲ 19 mag). As of 2025 March 1, the survey had obtained spectra of ∼7 million stars, approximately 1.2 million of which are included in the DESI Data Release 1. The DESI spectra cover the wavelength range from 3600...

DESI DR2 reference mocks: clustering results from Uchuu-BGS and LRG

Tue, 4 Aug 2026 00:00:00 +0000

The aim of this work is to construct mock galaxy catalogues that accurately reproduce the redshift evolution of galaxy number density, clustering statistics, and baryonic properties, such as stellar mass for luminous red galaxies (LRGs) and absolute magnitude in the r-band for the bright galaxy sample (BGS), based on the first three years of observations from the Dark Energy Spectroscopic Instrument (DESI). To achieve this, we applied the subhalo abundance matching (SHAM) technique to the Uchuu N-body simulation, which follows the evolution of 2.1 trillion particles within a volume of 8 h -3 Gpc3, assuming a Planck base-ΛCDM cosmology. Using SHAM, we populated Uchuu subhalos with LRGs and BGS-BRIGHT (r < 19.5) galaxies up to redshift z = 1.1, assigning stellar masses to LRGs and luminosities to BGS galaxies (up to M r ≤ 20). Furthermore, we analyzed the clustering dependence on stellar mass and luminosity for each tracer. Our results show that the Uchuu BGS-BRIGHT and LRG mocks...

H 0 without the sound horizon (or supernovae): A 2% measurement in DESI DR1

Tue, 4 Aug 2026 00:00:00 +0000

The sound horizon scale rs is a key source of information for measurements of H 0 from early-time data, and is therefore a common target of new physics proposed to solve the Hubble tension. We present a sub-2% measurement of the Hubble constant that is independent of this scale, using data from the first data release of the Dark Energy Spectroscopic Instrument (DESI DR1). Building on previous work, we remove dependency on the sound horizon size using a heuristic rescaling procedure at the power spectrum level. A key innovation is the inclusion of uncalibrated (agnostic to rs ) post-reconstruction BAO measurements from DESI DR1, as well as using the CMB acoustic scale θ * as a high-redshift anchor. Uncalibrated type-Ia supernovae are often included as an independent source of Ωm information; here we demonstrate the robustness of our results by additionally considering two supernova-independent alternative datasets. We find somewhat higher values of H 0 relative to our previous...

DESI Strong Lens Foundry. III. Keck Spectroscopy for Strong Lenses Discovered Using Residual Neural Networks

Tue, 4 Aug 2026 00:00:00 +0000

We present spectroscopic data of strong lenses and their source galaxies using the Keck Near-Infrared Echellette Spectrometer (NIRES) and the Dark Energy Spectroscopic Instrument (DESI), providing redshifts necessary for nearly all strong-lensing applications with these systems, especially the extraction of physical parameters from lensing modeling. These strong lenses were found in the DESI Legacy Imaging Surveys using residual neural networks and followed up by our Hubble Space Telescope program, with all systems displaying unambiguous lensed arcs. With NIRES, we target eight lensed sources at redshifts difficult to measure in the optical range and determine the source redshifts for six, between zs = 1.675 and 3.332. DESI observed one of the remaining source redshifts, as well as an additional source redshift within the six systems. The two systems with nondetections by NIRES were observed for a considerably shorter 600 s at high airmass. Combining NIRES infrared spectroscopy...

The DESI DR1 peculiar velocity survey: growth rate measurements from the maximum likelihood fields method

Tue, 4 Aug 2026 00:00:00 +0000

We present the constraint on the growth rate of structure from the combination of DESI DR1 BGS sample, Fundamental Plane, and Tully-Fisher peculiar velocity catalogues using the maximum likelihood fields method. The combined catalogue contains 415,523 galaxy redshifts and 76,616 peculiar velocity measurements. To handle the large amount of data in the DESI DR1 peculiar velocity catalogue, we significantly improve the computational efficiency by rewriting the algorithm with JAX. After removing outliers and Tully-Fisher galaxies that are affected by systematics, we find f σ 8 = 0.483-0.043 +0.080(stat) ± 0.018(sys), consistent within 1σ with the power spectrum and correlation function analysis using the same dataset. Combining all three measurements with appropriate correlations, the consensus measurement is f σ 8 (z eff = 0.07) = 0.450±0.055, consistent with Planck +ΛCDM cosmology (f σ 8 = 0.449 ± 0.008). Combining with the high redshift growth rate of structure measurements from...

DESI 2024 II: sample definitions, characteristics, and two-point clustering statistics

Tue, 4 Aug 2026 00:00:00 +0000

We present the samples of galaxies and quasars used for DESI 2024 cosmological analyses, drawn from the DESI Data Release 1 (DR1). We describe the construction of large-scale structure (LSS) catalogs from these samples, which include matched sets of synthetic reference `randoms' and weights that account for variations in the observed density of the samples due to experimental design and varying instrument performance. We detail how we correct for variations in observational completeness, the input `target' densities due to imaging systematics, and the ability to confidently measure redshifts from DESI spectra. We then summarize how remaining uncertainties in the corrections can be translated to systematic uncertainties for particular analyses. We describe the weights added to maximize the signal-to-noise of DESI DR1 2-point clustering measurements. We detail measurement pipelines applied to the LSS catalogs that obtain 2-point clustering measurements in configuration and Fourier...

DESI Strong Lens Foundry. I. HST Observations and Modeling with GIGA-Lens

Tue, 4 Aug 2026 00:00:00 +0000

We present the Dark Energy Spectroscopic Instrument (DESI) Strong Lens Foundry. We discovered ∼3500 new strong gravitational lens candidates in the DESI Legacy Imaging Surveys using residual neural networks (ResNet). We observed a subset (51) of our candidates using the Hubble Space Telescope (HST). Except for one ambiguous case, we have confirmed 50 of the 51 candidates to be strong lenses. We also briefly describe spectroscopic follow-up observations by DESI and Keck NIRES programs. From this very rich data set, a number of studies will be carried out, including evaluating the quality of the ResNet search candidates and lens modeling. In this paper, we present our initial effort in these directions. In particular, as a demonstration, we present the lens model for DESI-165.4754−06.0423, with imaging data from HST, and lens and source redshifts from DESI and Keck NIRES, respectively. In this effort, we have applied a fully forward-modeling Bayesian approach (GIGA-Lens), using...

DESI DR2 Galaxy luminosity functions

Tue, 4 Aug 2026 00:00:00 +0000

ABSTRACT We present galaxy luminosity functions (LFs) for the Dark Energy Spectroscopic Instrument (DESI) DR2 Bright Galaxy Survey (BGS) in the g, r, z, and $w1$ bands over $0.002\lt z\lt 0.6$. Our analysis uses updated k-corrections and evolutionary corrections, including new polynomial kcorrection fits derived from BGS Year 1 data that supersede earlier GAMA-based prescriptions. Exploiting the statistical power of DESI, we measure LFs to very faint magnitudes, reaching $^{0.1}M_r-5\log h\sim -10$. Independent measurements from the North and South survey regions show excellent agreement around the LF knee, but the very small statistical uncertainties reveal that simple analytic forms fail to capture the full LF shape. The bright end departs from a pure exponential decline, while the faint end exhibits complex, non-powerlaw behaviour, including a pronounced upturn at $^{0.1}M_r-5\log h\gtrsim -15$, which is stronger for red galaxies than for blue. We show that our LFs are largely...

AT2025ulz and S250818k: Leveraging DESI Spectroscopy in the Hunt for a Kilonova Associated with a Subsolar-mass Gravitational-wave Candidate

Tue, 4 Aug 2026 00:00:00 +0000

On 2025 August 18, the LIGO–Virgo–KAGRA collaboration reported a subthreshold gravitational-wave candidate detection consistent with a subsolar-mass neutron star merger, denoted S250818k. An optical transient, AT2025ulz, was discovered within the localization region. AT2025ulz initially appeared to meet the expected behavior of kilonova emission, the telltale signature of a binary neutron star merger. The transient subsequently rebrightened after ∼5 days and was classified as a Type IIb supernova. In this work, we analyze the observations of its host galaxy obtained by the Dark Energy Spectroscopic Instrument (DESI). From the DESI spectrum, we obtain a secure redshift of z = 0.084840 ± 0.000006. If S250818k has an astrophysical origin, this places the transient within 2σ of the gravitational-wave distance and results in an integral overlap between the gravitational-wave alert and the transient location of log10I≈3.9−4.2 . Our analysis of the host galaxy’s spectral energy distribution...

Measurements of Quasar Proximity Zones with the Lyα Forest of DESI Y1 Quasars

Tue, 4 Aug 2026 00:00:00 +0000

The intergalactic medium (IGM) around a quasar is shaped by its dense environment and by its excess ionizing radiation, which form a “quasar proximity zone” whose size and anisotropy depend on the quasar’s halo mass, luminosity, age, and radiation geometry. Using over 10,000 quasar pairs from the Dark Energy Spectroscopic Instrument (DESI) Year 1 data, with projected comoving separations r⊥ < 2h−1 Mpc, we investigate how the proximity zone of foreground quasars at z ∼ 2–3.5 affects Lyα absorption in their background quasars. The large DESI sample enables unprecedented precision in measuring this “transverse proximity” effect, allowing a detailed investigation of the signal’s dependence on the projected separation of quasar pairs and the luminosity of the foreground quasar. We find that enhanced gas clustering near quasars dominates over their ionizing effect, leading to stronger absorption on neighboring sightlines. Under the assumption that quasar ionizing luminosity is isotropic...

Extensive analysis of reconstruction algorithms for DESI 2024 baryon acoustic oscillations

Tue, 4 Aug 2026 00:00:00 +0000

Reconstruction of the baryon acoustic oscillation (BAO) signal has been a standard procedure in BAO analyses over the past decade and has helped to improve the BAO parameter precision by a factor of ∼2 on average. The Dark Energy Spectroscopic Instrument (DESI) BAO analysis for the first year (DR1) data uses the “standard” reconstruction framework, in which the displacement field is estimated from the observed density field by solving the linearized continuity equation in redshift space, and galaxy and random positions are shifted in order to partially remove non-linearities. There are several approaches to solving for the displacement field in real survey data, including the multigrid (MG), iterative Fast Fourier Transform (iFFT), and iterative Fast Fourier Transform particle (iFFTP) algorithms. In this work, we analyze these algorithms and compare them with various metrics including two-point statistics and the displacement itself using realistic DESI mocks. We focus on three...

Study of the connected four-point correlation function of galaxies from the DESI Data Release 1 luminous red galaxy sample

Tue, 4 Aug 2026 00:00:00 +0000

We present a measurement of the non-Gaussian four-point correlation function (4PCF) from the DESI DR1 luminous red galaxy (LRG) sample. For the gravitationally induced parity-even 4PCF, we detect a signal with a significance of using our fiducial setup. We assess the robustness of this detection through a series of validation tests, including auto and cross-correlation analyses, sky partitioning across multiple patch combinations, and variations in radial scale cuts. Due to the low completeness of the sample, we find that differences in fiber assignment implementation schemes can significantly impact estimation of the covariance and introduce biases in the data vector. After correcting for these effects, all tests yield consistent results. This is one of the first measurements of the connected 4PCF on the DESI LRG sample; the good agreement between the simulation and the data implies that the amplitude of the density fluctuation inferred from the connected 4PCF is consistent...

DESI EDR: Calibrating the Tully–Fisher Relationship with the DESI Peculiar Velocity Survey

Tue, 4 Aug 2026 00:00:00 +0000

We calibrate the Tully–Fisher relation (TFR) with data from the DESI Peculiar Velocity (PV) Survey taken during the Survey Validation (SV) period of the DESI galaxy redshift survey. Placing spectroscopic fibers on the centers and major axes of spatially extended spiral galaxies identified in the 2020 Siena Galaxy Atlas using the DESI Legacy Surveys, we measure the rotational velocities at 0.33R26 for 1155 (1128 + 27 dwarf) spiral galaxies observed during SV. Using 39 spiral galaxies observed in the Coma cluster, we find a slope for the TFR of −8.32 ± 0.15 AB mag in the r band, with a scatter about the TFR of 1.12 ± 0.03 AB mag. We calibrate the zero-point of the TFR using galaxies with independent distances measured using type Ia supernovae (SNe Ia) via the cosmological distance ladder. From the SN Ia distances, we measure a zero-point of −19.21−0.31+0.30 AB mag in the r band. We produce a public catalog of the distances to these 1128 spiral galaxies observed during DESI SV as...

Probing the Environment around GW170817 with DESI: Insights on Galaxy Group Peculiar Velocities for Standard Siren Measurements

Tue, 4 Aug 2026 00:00:00 +0000

We present a new measurement of the Hubble constant, H0, following the gravitational-wave event GW170817 and Dark Energy Spectroscopic Instrument (DESI) observations. A standard siren measurement with a nearby (luminosity distance ∼40 Mpc) event such as GW170817 is typically sensitive to the peculiar motion of the host galaxy owing to local dynamics. Previous measurements from this event have taken advantage of peculiar velocity measurements of nearby galaxies, including a handful of objects in the galaxy group that the host of the event, NGC 4993, has been associated with. Still, the group’s properties and NGC 4993’s membership were debated. We present DESI observations of thousands of galaxies in the vicinity of NGC 4993, resulting in 39 group galaxies and a fivefold increase in galaxies compared to previous observations, with many contributing to a peculiar velocity measurement. Examining the local dynamics, our observations support the presence of a galaxy group of which NGC...

Towards a Verifiable Domain-Specific Language for Hardware-Accelerated Stencils

Thu, 30 Jul 2026 00:00:00 +0000

Defining a domain-specific language (DSL) that supports vector-calculus abstractions eases the porting of partial differential equation (PDE) solvers to specialized architectures. Sufficiently high-level abstractions empower users to express universal laws with sufficient generality that the laws must always hold true within their domain of validity. A broad class of PDE solvers employs stencil-based algorithms, the target domain of Berkeley Lab's stencil accelerator chip co-design project. First released as open-source in January 2026, the Formal software framework lays a foundation for defining an embedded DSL based on composable operators that implement mimetic numerical methods -- stencil algorithms that guarantee satisfaction of discrete versions of important vector calculus theorems. The Formal DSL will be the frontend to a new class of stencil-PDE accelerators developed jointly by LBNL, UHCL, and UC Berkeley through the DOE Competitive Portfolios for Computer Science Project....

The Persistent Challenge of Data Locality in the Post-Exascale Era

Thu, 30 Jul 2026 00:00:00 +0000

The era of exascale computing, exemplified by systems like Frontier achieving exaflop-level performance, marks a milestone. However, the quest for sheer compute power leads to strong imbalance in system design. Hence, scaling advancements in memory, network bandwidth, and storage are also necessary and pose challenges, with a crucial need to address data locality issues. This article underscores the fundamental importance of data locality as a key abstraction for optimizing application performance. Despite notable software solutions, the growing complexity of parallelism and memory hierarchy demands performance-portable data locality solutions across diverse computing platforms. The article revisits data locality aspects, covering hardware considerations, application perspectives, software stack abstractions, and tool support. It concludes with insights into data locality challenges and opportunities, emphasizing the ongoing significance of collaborative research for progress...

Data Cards for Standardized Metadata Across DOE-Aligned Data Initiatives: Toward Transparent, Interoperable, and Governed Dataset Documentation

Wed, 29 Jul 2026 00:00:00 +0000

Data Cards for Standardized Metadata Across DOE-Aligned Data Initiatives: Toward Transparent, Interoperable, and Governed Dataset Documentation

Characterizing Lossless GPU Data Compression Across AMD CDNA and RDNA Architectures

Wed, 29 Jul 2026 00:00:00 +0000

Data movement remains a major bottleneck in high-performance computing workflows, making GPU-accelerated compression an increasingly important optimization. While NVIDIA platforms benefit from mature compression libraries such as nvCOMP, the performance of practical lossless compression on AMD GPUs remains undercharacterized. This paper addresses that gap by porting LZ4, Snappy, and Cascaded from CUDA to HIP and evaluating them across four AMD GPUs spanning three CDNA generations (MI50, MI210, MI300X) and RDNA 3 (RX 7900 XT), using both synthetic datasets and seismic simulation data. Our study makes three contributions. First, we provide a cross-generational characterization of lossless GPU compression on recent AMD accelerators. Second, we present a functional CUDA-to-HIP port of three widely used algorithms, establishing an open baseline for future AMD-specific optimization. Third, we analyze how architectural differences shape compression and decompression behavior across algorithms...

Streamlining HDF5’s AI Workloads Benchmarking

Wed, 29 Jul 2026 00:00:00 +0000

Rapid adoption of artificial intelligence (AI) in scientific computing requires new tools to evaluate I/O performance effectively. HDF5 is one of the data formats frequently used not only in HPC but also in modern AI applications. However, existing benchmarks are insufficient to address the current challenges posed by AI workloads. This paper introduces an extension to the existing HDF5 benchmark, called h5bench, by incorporating the workload characteristics from the MLPerf Storage - DLIO benchmark. This extension allows users to test AI workloads together with traditional HPC benchmarks in the same context without the complexities of installing various machine learning libraries. Our experimental analysis demonstrates that the extension can replicate the existing I/O patterns with easily customizable configurations to perform various scaling tests.

Combined effective field theory interpretation of measurements sensitive to quartic gauge boson couplings in pp collisions at s = 13 TeV with the ATLAS detector

Tue, 28 Jul 2026 00:00:00 +0000

A combination of measurements sensitive to anomalous quartic electroweak gauge boson couplings is presented using proton–proton collision data collected by the ATLAS detector at s = 13 TeV at the LHC. Contributing analyses include measurements of vector-boson scattering in numerous final states as well as a tri-boson measurement. The combined measurement is used to constrain anomalous electroweak boson quartic self-couplings that result from dimension-8 operators in the Éboli model using an effective field theory. Results are presented as 68% and 95% confidence level intervals parameterised by one or two Wilson coefficients, both with and without unitarity constraints applied. Theoretical bounds from unitarity and positivity are overlaid where relevant. Confidence intervals obtained from simultaneous profiled fits to all Wilson coefficients are also presented.

Cosmological constraints from a joint DESI DR1 Full-Shape and DR2 BAO

Tue, 28 Jul 2026 00:00:00 +0000

We present a cosmological analysis combining full-shape (FS) clustering measurements from the Dark Energy Spectroscopic Instrument (DESI) DR1 with baryon acoustic oscillation (BAO) measurements from DESI DR2. To achieve a robust combination that accounts for the correlation between the two data releases, we employ the ShapeFit compression method and estimate the joint covariance using EZmocks. This compressed approach inherently mitigates the prior volume effects that have previously dominated Bayesian constraints from DESI data with minimal external priors. Consequently, we obtain — for the first time within a Bayesian framework — reliable DESI-only constraints on extensions to ΛCDM using only a Big Bang Nucleosynthesis prior on the baryon density and a wide prior on the spectral index. In flat ΛCDM, we find Ω m = 0.3035 ± 0.0085, h = 0.6876 ± 0.0059, and σ 8 = 0.822 ± 0.034. For the w 0 wa CDM dynamical dark energy model, we measure w 0 = -0.49 ± 0.25 and wa = -1.52 ± 0.77,...

Fast solvers for tokamak fluid models with PETSc

Tue, 28 Jul 2026 00:00:00 +0000

Multigrid (MG) is widely recognized as a highly effective solver for the model problem, the Laplacian, but textbook MG fails on most problems of interest. MG methods have been applied to complex, real-world applications with careful consideration of the physical model and discretization. This work develops the first step in applying MG methods to science and engineering relevant magnetohydrodynamics (MHD) tokamak models in the M3D-C1 (https://m3dc1.pppl.gov) fusion energy science code. The semi-implicit time integrator in M3D-C1 is composed of many linear solves. The implicit advance of the momentum equation is the most challenging and is the focus of this work. The current production solver in M3D-C1 is a block Jacobi (BJ) preconditioner within a Krylov solver, where blocks group degrees of freedom on planes of constant toroidal coordinate. BJ convergence degrades as the number of planes increases due to the spectral properties of the matrix preconditioned with BJ. The partially...

Search for electroweak tt¯Wj production in multileptonic final states at s=13 TeV with the ATLAS detector and bounds on effective field theory operators

Tue, 28 Jul 2026 00:00:00 +0000

A search is presented for the electroweak production of a top-quark pair in association with a boson and at least one additional jet known as the process. This process has embedded within it a -scattering vertex, which is probed directly for the first time. The collision data were collected with the ATLAS detector during Run 2 of the LHC and correspond to an integrated luminosity of at . The search uses same-charge pairs of electrons and muons together with jets, of which at least one is -tagged. The properties of the most forward jet relative to the rest of the event are used to discriminate the electroweak production process from its strong production counterpart. A measured (expected) 95% CL upper limit on the cross section is set at (230 fb), to be compared with the expected Standard Model (SM) cross section of 47.7 fb. Limits are set on the SM effective field theory (EFT) operators and , which modify the electroweak couplings of the top quark through...

Search for emerging jets in pp collisions at s=13TeV with the ATLAS experiment

Tue, 28 Jul 2026 00:00:00 +0000

A search is presented for emerging jets using 140fb-1$$140~\textrm{fb}^{-1}$$ of proton–proton collision data at s=13TeV$$\sqrt{s} = 13~\textrm{TeV}$$, collected by the ATLAS experiment between 2015 and 2018. The search looks for the existence of a dark sector with symmetries similar to those in quantum chromodynamics. This dark sector is populated with dark quarks, which undergo showering similar to quarks in the Standard Model, leading to a high multiplicity of long-lived dark hadrons within a dark jet. These dark hadrons subsequently decay to Standard Model particles via a new heavy scalar mediating particle ϕ$$\phi $$. This results in jets which contain multiple displaced vertices, known as emerging jets. This analysis targets four-jet topologies, with two emerging jets and two Standard Model jets, resulting from the decay of pair-produced scalar mediators. No significant excess above the Standard Model background is observed. For dark pion proper decay lengths of 20mm$$20~\textrm{mm}$$,...

Combination of Measurements of CP Properties of Higgs Boson Interactions with Vector Bosons Using Proton-Proton Collisions at s=13 TeV with the ATLAS Detector

Tue, 28 Jul 2026 00:00:00 +0000

A combination of measurements of the properties of Higgs boson interactions with electroweak gauge bosons is presented, using of proton-proton collisions at recorded by the ATLAS detector. Results from vector boson fusion , inclusive , and channels are combined. No evidence of violation is observed, and constrains on the -violating operators in the Standard Model effective field theory framework (SMEFT) are set in the Warsaw basis. The results from the combination improve by over 40% on previous individual limits on and, for the first time, simultaneous constraints on three coefficients , , and are set. These limits are the most stringent constraints to date on the relevant Wilson coefficients in the SMEFT framework with minimum model dependence.

Search for Higgs bosons produced in association with a high-energy photon via vector-boson fusion and decaying to a pair of b-quarks in the ATLAS detector

Mon, 27 Jul 2026 00:00:00 +0000

A search for Standard Model Higgs bosons produced in association with a high-energy photon and decaying to b b ¯ is performed using 133 fb − 1 of s = 13 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider at CERN. The photon requirement reduces the multijet background, and the H → b b ¯ decay is the dominant decay mode. Event selection requirements target events produced by vector-boson fusion, the dominant production mode in this channel. Several improvements enhance the search sensitivity compared to previous measurements. These improvements include better background modelling and characterization, the use of a neural-network classifier, and an updated signal extraction strategy adopting a direct binned-likelihood fit to the classifier output. With these improvements, the Higgs boson signal strength is measured to be 0.2 ± 0.7 relative to the Standard Model prediction. This corresponds to an observed significance of 0.3 standard deviations, compared...

Elastic and resonance structures of the nucleon from the hadronic tensor in lattice QCD: Implications for neutrino-nucleon scattering and hadron physics

Wed, 22 Jul 2026 00:00:00 +0000

We compute the Euclidean hadronic tensor from charge density operators and extract elastic and resonance structures by employing exponential fits to the four-point function correlator, as well as a Bayesian reconstruction inverse algorithm to obtain the corresponding spectral density for qualitative comparison. We present the determination of the nucleon’s Sachs electric form factor using the hadronic tensor formalism and verify that it is consistent with that from the conventional three-point function calculation. Beyond the elastic peak, we observe a structure located approximately 0.5–0.7 GeV above the nucleon mass in the Bayesian reconstruction. This structure is interpreted as a mixture of the Roper resonance [ N ( 1440 ) ], and states with both positive and negative parities in this mass region, as well as multihadron...

Ab initio many-fermion structure calculations on a quantum computer

Wed, 22 Jul 2026 00:00:00 +0000

To overcome the limitations of existing algorithms for solving self-bound quantum many-body problems—such as those encountered in nuclear and particle physics—that access only a restricted subset of energy levels and provide limited structural information, we introduce and demonstrate a novel quantum-classical approach capable of resolving the complete bound-state spectrum. This method also provides the total angular momentum J associated with each eigenstate. Our approach is based on expressing the Hamiltonian in second-quantized form within a novel input model combined with a scan scheme, enabling broad applicability to configuration-interaction calculations across diverse fields. We apply this hybrid method to compute, for the first time, the bound-state spectrum together with corresponding J values of O20 using a realistic strong-interaction Hamiltonian. Our approach applies to hadron spectra and J values solved in the relativistic basis light-front quantization approach.

Polynomial-time preparation of low-temperature Gibbs states for two-dimensional toric code

Tue, 21 Jul 2026 00:00:00 +0000

We propose a polynomial-time algorithm for preparing the Gibbs state of the two-dimensional toric code Hamiltonian at any temperature, starting from any initial state, significantly improving upon prior estimates that suggested exponential scaling with inverse temperature. We prove that fast mixing at low temperature for the two-dimensional toric code can be achieved by augmenting local jump operators with simple global jump operators, which enable efficient transitions between logical sectors. To establish tight lower bounds on the spectral gap, we introduce a new reduction method that eventually maps the problem to estimating the spectral gap of a perturbed graph Laplacian on a stair graph. Our proof also shows that the Lindblad dynamics with a digitally implemented low-temperature local Davies generator is able to efficiently drive the quantum state toward the ground state manifold.

Measurement of the W-boson angular coefficients and transverse momentum in pp collisions at s=13 TeV with the ATLAS detector

Thu, 16 Jul 2026 00:00:00 +0000

The angular distributions of Drell–Yan lepton pairs provide sensitive probes of the underlying dynamics of quantum chromodynamics (QCD) effects in vector-boson production. This paper presents for the first time the measurement of the full set of angular coefficients together with the differential cross-section as a function of the transverse momentum of the W boson, in the full phase space of the decay leptons. The measurements are performed separately for the W-$$W^-$$ and W+$$W^+$$ channels. The analysis uses proton–proton collision data recorded by the ATLAS experiment at the Large Hadron Collider in 2017 and 2018, during special low-luminosity runs with a reduced number of interactions per bunch crossings (pile-up). The data correspond to an integrated luminosity of 338 pb-1$$^{-1}$$ at a centre-of-mass energy of s=13$$\sqrt{s} = 13$$ TeV. The low pile-up environment provides excellent experimental conditions for high-precision measurements of W-boson production....

Search for the Higgs boson decay to a Z boson and a photon in pp collisions at s = 13 TeV and 13.6 TeV with the ATLAS detector

Thu, 16 Jul 2026 00:00:00 +0000

A search for the Higgs boson decay to a Z boson and a photon in the ℓℓγ ( ℓ = e , μ ) final state is performed using pp collisions at s = 13.6 TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022–2024, corresponding to an integrated luminosity of 165 fb − 1 . The signal yield, normalised to the Standard Model prediction, is measured to be μ = 0 . 9 − 0.6 + 0.7 , compatible with the expected value of μ = 1.0 ± 0.7 . This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations under the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb − 1 of s = 13 TeV pp collisions to provide the best expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of μ = 1 . 3 − 0.5 + 0.6 ( μ = 1 . 0 − 0.5 + 0.6 ), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model...

Study of Higgs boson pair production in the H H → b b ‾ γ γ final state with 308 fb − 1 of data collected at s = 13 TeV and 13.6 TeV by the ATLAS experiment

Thu, 16 Jul 2026 00:00:00 +0000

A search for Higgs boson pair production in the b b ¯ γ γ final state is performed. The proton–proton collision dataset corresponds to an integrated luminosity of 308 fb − 1 , consisting of two samples, 140 fb − 1 at a centre-of-mass energy of s = 13 TeV and 168 fb − 1 at s = 13.6 TeV , recorded between 2015 and 2024 by the ATLAS detector at the CERN Large Hadron Collider. In addition to a larger dataset, this analysis improves upon the previous search in the same final state through several methodological and technical developments. The Higgs boson pair production cross section divided by the Standard Model prediction is found to be μ H H = 0 . 9 − 1.1 + 1.4 ( μ H H = 1 − 1.0 + 1.3 expected), which translates into a 95% confidence-level upper limit of μHH  < 3.7. At the same confidence level the Higgs self-coupling modifier is constrained to be in the range − 1.6 < κ λ < 6.6 ( − 1.8 < κ λ < 6.9 expected).

Regional Earthquake Ground Motion Simulations for Southern California With EQSIM: Insights From the 2008 Chino Hills, 2024 Highland Park, and 2021 Carson Earthquakes

Thu, 16 Jul 2026 00:00:00 +0000

This study presents physics‐based, 3D simulations using the EQSIM framework for several earthquakes in the Los Angeles region. The primary objective was to assess the ability of deterministic physics‐based ground motion simulations to reproduce the observed motions from historical events. The selected events included the 5.4 2008 Chino Hills, the 4.4 2024 Highland Park, and the 4.3 2021 Carson events. The simulated motions were evaluated by comparing the recorded and simulated seismograms, as well as the Fourier amplitude spectra, across multiple seismic stations. The SCEC 3D velocity model, CVM‐S4.26.M01, was used to represent the regional geology, and ground motion simulations were carried out with a resolution of up to 5 Hz. The results indicate that the simulated motions captured the recorded motions up to approximately 4 Hz. While careful iterations regarding source parameters and corner frequencies were required, and, for the case of the Highland Park event, some of the...

Measurement of differential t-channel single top (anti)quark production cross-sections at 13 TeV with the ATLAS detector

Thu, 16 Jul 2026 00:00:00 +0000

The production of single top quarks and top antiquarks via the t-channel exchange of a virtual W boson is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider. The full Run 2 data sample recorded with the ATLAS detector in the years 2015–2018 is used, corresponding to an integrated luminosity of 140 fb−1. The absolute and normalised production cross-sections are measured differentially as a function of the transverse momentum and absolute rapidity of the top quark and top antiquark. In addition, the ratio of top quark to top antiquark production cross-sections is measured. The measured distributions are compared with next-to-leading-order quantum chromodynamics predictions obtained with different combinations of matrix-element generators, parton-shower programs and proton parton distribution functions, as well as to next-to-next-to-leading-order calculations. Overall, good agreement is observed between the measurements and the...

Precise measurement of the tt¯ production cross-section and lepton differential distributions in eμ dilepton events from s=13TeVpp collisions with the ATLAS detector

Thu, 16 Jul 2026 00:00:00 +0000

The inclusive top quark pair (tt¯$$t\bar{t}$$) cross-section σtt¯$$\sigma _{t\bar{t}}$$ has been measured in proton–proton collisions at s=13TeV$$\sqrt{s}=13\,\text {TeV}$$, using 140fb-1$$140\,{\text {fb}^{-1}} $$ of data collected by the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge eμ$$e\mu $$ pair and b-tagged jets, the cross-section is measured to be: σtt¯=829.3±1.3(stat)±8.0(syst)±7.3(lumi)±1.9(beam)pb,$$\begin{aligned} \sigma _{t\bar{t}} & = 829.3\pm 1.3\,\mathrm {(stat)}\ \pm 8.0\,\mathrm {(syst)}\ \pm 7.3\,\mathrm {(lumi)}\ \\ & \quad \pm 1.9\,\mathrm {(beam)}\,\textrm{pb}, \end{aligned}$$where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the proton beam energy, giving a total uncertainty of 1.3%. The result is used to determine the top quark pole mass via the dependence of the predicted cross-section on mtpole$${m_{t}^\textrm{pole}}$$,...

Reflections on the Shifting Experiences of Scientific Infrastructure

Wed, 15 Jul 2026 00:00:00 +0000

Infrastructure of all types is fundamental to modern work and life. Computing for scientific work, especially, extends from distributed local research sites, often at the edges of other major systems, outward into globally connected high-performance facilities and infrastructures. This commentary reviews longstanding research on the social characteristics of infrastructure. We reflect on social concerns that affect the ongoing development, use, and maintenance of a wide range of scientific computing and data resources. Reflecting on the social nature of infrastructure is timely for Computing in Science & Engineeering readers, given continued emphasis on developing even more expansive platforms for data and artificial intelligence work in science (e.g., the United States Genesis Mission). We assert that, regardless of technological advances, the complex nature of scientific research and data will require continued understanding of longstanding and nascent social practices across...

Efficient Tensor Completion Algorithms for Highly Oscillatory Operators

Wed, 15 Jul 2026 00:00:00 +0000

We address the problem of recovering highly oscillatory operators, represented as (Formula presented.) matrices with a fixed set of observed entries. Given that these matrices can be well compressed by butterfly matrix decomposition of (Formula presented.) levels requiring only (Formula presented.) degrees of freedom, we propose a novel reformulation of the butterfly structure as a compact tensor network. Specifically, we reshape the input matrix as an order (Formula presented.) dense tensor, and cast its butterfly decomposition as a tensor network consisting of order (Formula presented.) dense tensors. This enables efficient utilization of the existing software infrastructure for dense and sparse tensor computations. Next, we propose several tensor completion algorithms based on the tensor reformulation of butterfly format, and compare them against algorithms using the quantized tensor train (QTT) format. These algorithms leverage popular completion methods such as alternating...

A sharp interface method for two-phase incompressible flow with surface tension

Wed, 15 Jul 2026 00:00:00 +0000

We present a sharp-interface method for resolved two-phase incompressible viscous flow based on embedded boundary finite volume discretizations of the individual phase domains. The numerical algorithm is a fractional step method, in which incompressibility is enforced at the half-step and the full-step by solving coupled Hodge projections that respect the jump boundary conditions in pressure and pressure gradient at the interface. Surface tension enters through these boundary conditions. The viscous term in the momentum equations is solved implicitly using a Crank-Nicholson time discretization, respecting the jump conditions on velocity and velocity gradient. The method is implemented with block-structured adaptive mesh refinement. We demonstrate stable behavior in 2D and 3D, with the velocity converging in all norms as measured using Richardson extrapolation. The method successfully models spherical cap bubble shapes and velocities, showing good agreement with a range of experiments.

Search for a resonance decaying into a scalar particle and a Higgs boson in the final state with two bottom quarks and two photons with 199 fb − 1 of data collected at s =13 and 13.6 TeV with the ATLAS detector

Wed, 15 Jul 2026 00:00:00 +0000

A search for the resonant production of a heavy scalar X decaying into a lighter scalar S and a Higgs boson, through the process X → S ( → b b ¯ ) H ( → γ γ ) , where the two photons are consistent with the Higgs boson decay, is performed. The search is conducted using integrated luminosities of 140 and 59 fb − 1 of proton–proton collision data at centre-of-mass energies of 13 and 13.6 TeV, respectively, recorded with the ATLAS detector at the LHC. The search is performed over the mass ranges of 170  ≤  mX  ≤  1000 GeV and 15  ≤  mS  ≤  500 GeV. No significant excess over the Standard Model background predictions is observed and limits at 95% confidence level are set on the product of cross section and branching fraction for the process X → S ( → b b ¯ ) H ( → γ γ ) at 13 TeV, ranging from 9 fb to 0.06 fb.

Search for higgsinos in compressed mass spectra using low-momentum tracks in pp collisions at s=13 TeV with the ATLAS detector

Tue, 14 Jul 2026 00:00:00 +0000

This paper presents two searches for the electroweak production of higgsinos with compressed mass spectra using 140 fb−1 of s=13$$ \sqrt{s}=13 $$ TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider. Events are required to feature an energetic jet, large missing transverse momentum, and at least one low-momentum charged particle that serves as a candidate higgsino decay product. In the first search, targeting higgsino mass splittings in the range of 0.3–1 GeV, the higgsinos are expected to predominantly decay into pions that are identified as low-momentum charged particles with large transverse impact parameters due to the long higgsino lifetime (cτ ≈ ?(0.1–10 mm)), and neural networks are used to discriminate between signal and background processes. The second search targets larger mass splittings in the range of 1–3 GeV, where the higgsinos are expected to decay promptly into low-momentum leptons, one of which is identified by dedicated...

Measurement of the azimuthal anisotropy of charged particles in sNN=5.36TeV O16+O16 and Ne20+Ne20 collisions with the ATLAS detector

Tue, 14 Jul 2026 00:00:00 +0000

This paper presents the first measurements of the azimuthal anisotropy coefficients , which quantify the -order Fourier modulation of charged-particle azimuthal distributions, for in and collisions recorded with the ATLAS detector at the CERN Large Hadron Collider in 2025. The coefficients are measured as a function of transverse momentum ( ), collision centrality, and event multiplicity. They are extracted using two complementary methods: two-particle correlations with a template-fit subtraction of short-range nonflow contributions, and four-particle subevent cumulants, which intrinsically suppress nonflow effects and provide sensitivity to flow fluctuations. The results show a clear hierarchy and a nonmonotonic dependence on , reaching a maximum around , consistent with trends observed in heavy-ion collisions. Detailed comparisons between the two collision systems reveal an enhanced in central collisions, consistent with theory expectations based on the predicted...

Search for dimuon resonance in the 35 to 75 GeV mass range using 140 fb−1 of 13 TeV pp collisions with the ATLAS detector

Tue, 14 Jul 2026 00:00:00 +0000

A model-independent search for low-mass resonances decaying into pairs of oppositely charged muons is presented. The analysis uses proton-proton collision data corresponding to an integrated luminosity of 140 fb−1, recorded by the ATLAS detector at the Large Hadron Collider between 2015 and 2018. The search targets hypothetical dimuon resonances in the invariant mass range from 35 GeV to 75 GeV. The modelling of this mass region is particularly challenging for conventional analytic background parameterisations. To address this, a Gaussian process regression technique is used to model the background. The dimuon mass spectrum is analysed for potential signals, and no statistically significant excess is observed. Upper limits at the 95% confidence level are set on the fiducial production cross-section of new resonances decaying promptly into muons, ranging from 20 fb to 110 fb, depending on the resonance mass. These results are further interpreted in the context of dark-photon and...

Observation of structures in the J/ψ+ψ(2S) mass spectrum with the ATLAS detector

Tue, 14 Jul 2026 00:00:00 +0000

A search for resonant structures in the mass spectrum is performed using proton-proton collision data at , corresponding to an integrated luminosity of , recorded by the ATLAS experiment at the LHC. The decay channels of and are analyzed. An excess near 6.9 GeV is observed in both channels with a combined significance of . No significant signal is observed near 7.2 GeV, and an upper limit on its yield relative to is provided. A simultaneous fit with the di- channel is carried out under assumptions regarding the resonance interferences, yielding a ratio of the partial decay widths between the and di- channels of for the resonance near 6.9 GeV.

Differential cross-section measurements of D± and Ds± meson production in proton-proton collisions at s = 13 TeV with the ATLAS detector

Tue, 7 Jul 2026 00:00:00 +0000

The production of D± and Ds±$$ {D}_s^{\pm } $$ charmed mesons is measured using the D±/Ds±$$ {D}_s^{\pm } $$→ ϕ(μμ)π± decay channel with 137 fb−1 of s$$ \sqrt{s} $$ = 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider during the years 2016–2018. The charmed mesons are reconstructed in the range of transverse momentum 12 < pT < 100 GeV and pseudorapidity |η| < 2.5. The differential cross-sections are measured as a function of transverse momentum and pseudorapidity, respectively, and compared with next-to-leading- order QCD predictions. The predictions are found to be consistent with the measurements in the visible kinematic region within the large theoretical uncertainties.

Precision measurement of the B0 meson lifetime using B0→J/ψK∗0 decays with the ATLAS detector

Tue, 7 Jul 2026 00:00:00 +0000

A measurement of the B0$$B^{0}$$ meson lifetime using B0→J/ψK∗0$$ B^{0} \rightarrow J/\psi K^{*0} $$ decays in data from 13 TeV$$\text {TeV}$$ proton–proton collisions with an integrated luminosity of 140fb-1$$ 140~\mathrm {fb^{-1}} $$ recorded by the ATLAS detector at the LHC is presented. The measured effective lifetime is τ=1.5053±0.0012(stat.)±0.0035(syst.)ps.$$ \tau = 1.5053\pm 0.0012~\mathrm {(stat.)} \pm 0.0035~\mathrm {(syst.)~ps}. $$The average decay width extracted from the effective lifetime, using parameters from external sources, is Γd=0.6639±0.0005(stat.)±0.0016(syst.)±0.0038(ext.)ps-1,$$\begin{aligned} \Gamma _d = 0.6639\pm 0.0005~\mathrm {(stat.)} \pm 0.0016~\mathrm {(syst.)}\\ \pm 0.0038~\text {(ext.)} \text {~ps}^{-1}, \end{aligned}$$where the uncertainties are statistical, systematic and from external sources. The earlier ATLAS measurement of Γs$$\Gamma _s$$ in the Bs0→J/ψϕ$$B^{0}_{s} \rightarrow J/\psi \phi $$ decay was used to derive a value for the ratio...

Scalable Computation of Topological Abstractions for Scalar Data

Wed, 1 Jul 2026 00:00:00 +0000

Topological data analysis has become an important tool for large scale scalar data analysis and visualization, efficiently extracting the inherent structure and features of interest of the data. However, with growing dataset sizes and complexity, it is increasingly becoming infeasible to compute topological abstractions of interest in serial and on single machines. This paper presents the state of the art in the scalable computation of topological abstractions on scalar data, in shared memory parallel on single machines, and in distributed memory parallel on multiple machines. We highlight results for set‐based, graph‐based and complex‐based abstractions and organize the state of the art based on this taxonomy. The paper identifies parallelization and distribution techniques common in topological algorithms and highlights further areas of interest with underdeveloped efforts.

Estimation of backgrounds from jets misidentified as τ-leptons using the Universal Fake Factor method with the ATLAS detector

Wed, 1 Jul 2026 00:00:00 +0000

Processes with τ$$\tau $$-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes τ$$\tau $$-leptons produced in proton–proton collisions only through their decay products. Data analyses involving hadronically decaying τ$$\tau $$-leptons face challenges due to backgrounds from jets misidentified as τ$$\tau $$-leptons that are not modelled reliably by Monte Carlo simulations. Data-driven methods such as the fake-factor method allow such misidentified backgrounds to be predicted by measuring transfer factors, known as fake factors, in data from dedicated regions. This paper describes a refined technique for determining the fake factors, the Universal Fake Factor method. It evaluates the fake factors for a signal region by using fake factors from samples enriched in different sources of jets misidentified as τ$$\tau $$-leptons (light-quark, gluon, b-quark,...

Toward Unified Autonomous Scattering Experiments: A Cross-Facility Case Study at ALS and PETRA III

Wed, 1 Jul 2026 00:00:00 +0000

Autonomous experiments rely on the integration of control, data acquisition, analysis, and decision-making frameworks. While such systems have been demonstrated at individual facilities, adapting them to additional instruments remains challenging due to differences in local infrastructure. We present a modular workflow that connects existing open-source tools for data access (Tiled), workflow orchestration (Prefect), analysis and visualization (pyFAI, Plotly Dash), and Gaussian-process-based adaptive sampling (gpCAM) into a unified framework for autonomous scattering experiments. The same configuration operates across two synchrotron beamlines (ALS 7.3.3 and PETRA III P03) with only minimal facility-specific adjustments, as shown in proof-of-concept demonstrations. This validates that a consistent design emphasizing modularity and shared interfaces can ease deployment across diverse experimental environments. The resulting framework provides a flexible foundation for extending...

Optimized Auxiliary Functions for Robust Mitigation of Finite-Size Errors in Periodic Hybrid Density Functional Theory

Wed, 1 Jul 2026 00:00:00 +0000

When calculating properties of periodic systems at the thermodynamic limit (TDL), the dominant source of finite size error (FSE) arises from the long-range Coulomb interaction, and can manifest as a slowly converging quadrature error when approximating an integral in the reciprocal space by a finite sum. The singularity subtraction (SS) method offers a systematic approach for reducing this quadrature error and thus the FSE. In this work, we first investigate the performance of the SS method in the simplest setting, aiming at reducing the FSE in exact exchange calculations by subtracting the Coulomb contribution with a single, adjustable Gaussian auxiliary function. We demonstrate that a simple fitting method can robustly estimate the optimal Gaussian width and leads to rapid convergence toward the TDL. Furthermore, we suggest new forms of the auxiliary function, whose optimal parameters could also be determined through least-squares fitting. For a range of semiconductors and insulators,...

Existence and Regularity Results for a Nonlinear Fluid-Structure Interaction Problem with Three-Dimensional Structural Displacement

Wed, 1 Jul 2026 00:00:00 +0000

In this paper we investigate a nonlinear fluid-structure interaction (FSI) problem involving the Navier-Stokes equations, that describe the flow of an incompressible, viscous fluid in a 3D domain interacting with a thin viscoelastic lateral wall. The wall's elastodynamics is modeled by a two-dimensional plate equation with fractional damping, accounting for displacement in all three directions. The system is nonlinearly coupled through kinematic and dynamic conditions imposed at the time-varying fluid-structure interface, whose location is not known a priori. We establish three key results, particularly significant for FSI problems that account for vector displacements of thin structures. Specifically, we first establish a hidden spatial regularity for the structure displace ment, which forms the basis for proving that self-contact of the structure will not occur within a finite time interval. Second, we demonstrate temporal regularity for both the structure and fluid velocities,...

Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector

Mon, 29 Jun 2026 00:00:00 +0000

The existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter–antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb-1$$^{-1}$$ of 13 TeV proton–proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton’s mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes |Ue|2$$|U_{e}|^2$$ values above 8×10-5$$8\times 10^{-5}$$ and |Uμ|2$$|U_{\mu...

Operator-level quantum acceleration of non-logconcave sampling

Mon, 29 Jun 2026 00:00:00 +0000

Sampling from probability distributions of the form [Formula: see text], where [Formula: see text] is a continuous potential, is a fundamental task across physics, chemistry, biology, computer science, and statistics. However, when [Formula: see text] is nonconvex, the resulting distribution becomes non-logconcave, and classical methods such as Langevin dynamics often exhibit poor performance. We introduce a quantum algorithm that provably accelerates a broad class of continuous-time sampling dynamics. For Langevin dynamics, our method encodes the target Gibbs measure into the amplitudes of a quantum state, identified as the kernel of a block matrix derived from a factorization of the Witten Laplacian operator. This connection enables Gibbs sampling via singular value thresholding and yields up to a quartic quantum speedup over best-known classical Langevin-based methods in the non-logconcave setting. Building on this framework, we further develop the first quantum algorithm that...

Neural Posterior Unfolding

Fri, 26 Jun 2026 00:00:00 +0000

Differential cross section measurements are the currency of scientific exchange in particle and nuclear physics. The key challenge for these analyses is the correction for detector distortions known as deconvolution or unfolding. In the case of binned cross section measurements, there are many tools for regularized matrix inversion where the matrix governs the detector response going from pre- to post-detector observables. In this paper, we show how normalizing flows and neural posterior estimation can be used for unfolding. This approach has many potential advantages, including implicit regularization from the neural networks and fast inference from amortized training. We demonstrate this approach using simple Gaussian examples as well as a simulated jet substructure measurement at the Large Hadron Collider.

Search for Beyond the Standard Model physics with anomaly detection in multilepton final states in pp collisions at s=13TeV with the ATLAS detector

Fri, 26 Jun 2026 00:00:00 +0000

A model-agnostic search for Beyond the Standard Model physics is presented, targeting final states with at least four light leptons (electrons or muons). The search regions are separated by event topology and unsupervised machine learning is used to identify anomalous events in the full 140 fb-1$$^{-1}$$ of proton–proton collision data collected with the ATLAS detector during Run 2. No significant excess above the Standard Model background expectation is observed. Model-agnostic limits are presented in each topology, along with limits on several benchmark models including vector-like leptons, wino-like charginos and neutralinos, or smuons. Limits are set on the flavourful vector-like lepton model for the first time.

Learning earthquake ground motions via conditional generative modeling

Fri, 26 Jun 2026 00:00:00 +0000

Predicting high-fidelity ground motions for future earthquakes is crucial for seismic hazard assessment and infrastructure resilience. Conventional empirical simulations suffer from sparse sensor distribution and geographically localized earthquake locations, while physics-based methods are computationally intensive and require accurate representations of Earth structures and earthquake sources. We propose an artificial intelligence (AI) spectrogram generator, Conditional Generative Modeling for Ground Motion (CGM-GM). CGM-GM leverages earthquake magnitudes and geographic coordinates of earthquakes and sensors as inputs, when postprocessed with phase information, capturing spatially continuous Fourier amplitude spectra (FAS) as well as properties such as P and S arrivals, and waveform durations, without explicit physics constraints. This is achieved through a probabilistic autoencoder that extracts latent distributions in the time-frequency domain and variational sequential models...

Observation of t t ¯ γ γ production at s = 13 TeV with the ATLAS detector

Fri, 26 Jun 2026 00:00:00 +0000

This paper presents the first observation of top-quark pair production in association with two photons ( t t ¯ γ γ ). The measurement is performed in the single-lepton decay channel using proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider. The data correspond to an integrated luminosity of 140 fb − 1 recorded during Run 2 at a centre-of-mass energy of 13 TeV. The t t ¯ γ γ production cross section, measured in a fiducial phase space based on particle-level kinematic criteria for the lepton, photons, and jets, is found to be 2 . 42 − 0.53 + 0.58 fb , corresponding to an observed significance of 5.2 standard deviations. Additionally, the ratio of the production cross section of t t ¯ γ γ to top-quark pair production in association with one photon is determined, yielding ( 3 . 30 − 0.65 + 0.70 ) × 10 − 3 .

Gradient Flow for Parton Distribution Functions: First Application to the Pion

Thu, 25 Jun 2026 00:00:00 +0000

Parton distribution functions (PDFs) are central to precision QCD phenomenology. Their Mellin moments can be computed on the lattice, but direct determinations using local operators, besides ⟨x⟩, face severe challenges from reduced hypercubic symmetry, limiting results to the lowest moments. A recently proposed method resolves these issues using gradient flow. We demonstrate the efficacy of this method by computing ratios of flavor nonsinglet pion PDF moments up to ⟨x^{5}⟩ on four lattice spacings at m_{π}≃411 MeV. The moments and reconstructed PDF agree quantitatively with recent phenomenological extractions.

Moments of parton distribution functions of the pion from lattice QCD using gradient flow

Thu, 25 Jun 2026 00:00:00 +0000

We present a nonperturbative determination of the pion valence parton distribution function (PDF) moment ratios up to , using the gradient flow in lattice quantum chromodynamics (QCD). As a testing ground, we employ SU(3) isosymmetric gauge configurations generated by the OpenLat initiative with a pseudoscalar mass of . Our analysis uses four lattice spacings and a nonperturbatively improved action, enabling full control over the continuum extrapolation, and the limit of vanishing flow time, . The flowed ratios exhibit O( ) scaling across the ensembles, and the continuum-extrapolated results, matched to the scheme at using next-to-next-to-leading order matching coefficients, show only mild residual flow-time dependence. The resulting ratios, computed with a relatively small number of configurations, are consistent with phenomenological expectations for the pion’s valence distribution, with statistical uncertainties that are competitive with modern global fits. These findings...

Measurement of coherent exclusive J/ψ → μ+μ− production in ultraperipheral Pb+Pb collisions at sNN=5.36 TeV with the ATLAS detector

Thu, 25 Jun 2026 00:00:00 +0000

The ATLAS experiment has performed a measurement of coherent exclusive J/ψ → μ+μ− production in ultraperipheral Pb+Pb collisions at sNN=5.36$$ \sqrt{s_{\textrm{NN}}}=5.36 $$ TeV. The data was recorded at the Large Hadron Collider (LHC) during 2023, and corresponds to an integrated luminosity of 79 μb−1. Exclusive J/ψ candidates were selected with a dedicated track-sensitive trigger based on the ATLAS transition radiation tracker. The analysis involves reconstruction of the dimuon invariant mass based on muon tracks from the inner detector, as the muon transverse momentum range of interest precludes the use of the standard muon reconstruction and identification algorithms. Differential cross sections are measured as a function of J/ψ rapidity and are compared with theoretical predictions. After extrapolation to sNN=5.02$$ \sqrt{s_{\textrm{NN}}}=5.02 $$ TeV, they are also compared with previous measurements performed by other experiments using data from LHC Run 2. While the results...

ReMU: regional minimal updating for model-based derivative-free optimization

Thu, 25 Jun 2026 00:00:00 +0000

Derivative-free optimization (DFO) problems are optimization problems where derivative information is unavailable or extremely difficult to obtain. Model-based DFO solvers have been applied extensively in scientific computing. Powell's NEWUOA (2004) [Powell, The NEWUOA software for unconstrained optimization without derivatives, in Large-Scale Nonlinear Optimization, Nonconvex Optimization and its Applications Vol. 83, G. Di Pillo and M. Roma, eds., Springer, 2006, pp. 255–297] and Wild's POUNDerS (2014) [Wild, Solving derivative-free nonlinear least squares problems with POUNDERS, in Advances and Trends in Optimization with Engineering Applications, T. Terlaky, M.F. Anjos, and S. Ahmed, eds., SIAM, 2017, pp. 529–540] explore the numerical power of the minimal norm Hessian (MNH) model for DFO and contributed to the open discussion on building better models with fewer data to achieve faster numerical convergence. Another decade later, we propose the regional minimal updating (ReMU)...

Search for signatures of electroweakinos with photons, jets, and large missing transverse momentum in s=13 TeV pp collisions with the ATLAS detector

Thu, 25 Jun 2026 00:00:00 +0000

A search for final states characterised by at least one isolated high transverse-momentum photon, jets and large missing transverse momentum is presented. Such a final state might occur in gauge-mediated supersymmetric models where a pair of binos and higgsinos mix to form neutralinos, one of which decays into a photon plus a gravitino while the other decays into a Higgs boson, a Z boson or a photon, plus a gravitino. The search is performed using the full Run-2 data sample of 140 fb−1 of s=13$$ \sqrt{s}=13 $$ TeV proton-proton collisions collected by the ATLAS detector at the Large Hadron Collider. No significant excess of events is observed above the Standard Model prediction and model-dependent exclusion limits at the 95% confidence level are set. These limits are interpreted in terms of the masses of gauginos, which are excluded up to 1.2 TeV depending on their branching ratios, and on their branching ratios as a function of their mass.

A multimodal large language model for materials science

Thu, 25 Jun 2026 00:00:00 +0000

Understanding and predicting the properties of inorganic materials is crucial for accelerating advancements in materials science and driving applications in energy, electronics and beyond. Integrating material structure data with language-based information through multimodal large language models (LLMs) offers great potential to support these efforts by enhancing human–artificial intelligence interaction. However, a key challenge lies in integrating atomic structures at full resolution into LLMs. In this work, we introduce MatterChat, a versatile structure-aware multimodal LLM that unifies material structural data and textual inputs into a single cohesive model. MatterChat uses a bridging module to effectively align a pretrained universal machine learning interatomic potential with a pretrained LLM, reducing training costs and enhancing flexibility. Our results demonstrate that MatterChat greatly improves performance in material property prediction and human–artificial intelligence...

Measurement of the top-quark mass using decays with a J/ψ meson at s=13 TeV with the ATLAS detector

Thu, 25 Jun 2026 00:00:00 +0000

The top-quark mass is measured using top-quark decays producing an isolated lepton and J/ψ meson reconstructed in its μ+μ− decay mode. The data sample was recorded with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of s=13$$ \sqrt{s}=13 $$ TeV during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb−1. The measurement is based on the invariant mass m(ℓμ+μ−) of the system made of the isolated lepton ℓ from the W boson decay and the non-isolated μ+μ− pair from a J/ψ decay of a b-hadron, exploiting its sensitivity to the top-quark mass. An unbinned maximum-likelihood fit to the m(ℓμ+μ−) distribution is performed to extract the top-quark mass. The top-quark mass is measured to be mtop = 172.17 ± 0.80 (stat) ± 0.81 (syst) ± 1.07 (recoil) GeV, with a total uncertainty of 1.56 GeV. The third uncertainty arises from changing the dipole parton shower gluon-recoil scheme used in top-quark decays.

Classification of dynamical Lie algebras generated by spin interactions on undirected graphs

Fri, 19 Jun 2026 00:00:00 +0000

Dynamical Lie algebras (DLAs) are a versatile tool for various topics that span from the expressibility-trainability of variational quantum algorithms (VQAs), to simulation of many body Hamiltonians. Quantum gates and most of the Hamiltonians of interest consist of local interactions; therefore, the analysis of all possible DLAs generated by 1- and 2-local operators is crucial for quantum simulation and VQAs on current hardware. Previously in [R. Wiersema et al., npj Quantum Inf. 10, 110 (2024)], we analyzed the DLAs on linear, circular and all-to-all topologies, and obtained results about their dimensions and algebraic structure. In this work, we extend our analysis into any possible hardware topology and provide a classification of all DLAs generated by Pauli strings on any undirected interaction graph. Our results indicate that the DLAs depend solely on whether the connectivity or interaction graph is bipartite or not. In addition, we find that the non-trivial polynomially...

Verification of an energy-conserving semi-implicit electrostatic particle-in-cell scheme for modeling high-density plasma at scale

Fri, 19 Jun 2026 00:00:00 +0000

A verification study of a semi-implicit energy-conserving electrostatic particle-in-cell algorithm is presented. The algorithm relaxes the time-step and mesh-size constraints that require resolution of the plasma period and Debye length associated with traditional explicit momentum-conserving particle-in-cell algorithms. Physical implications and applicability of using the semi-implicit scheme for modeling high-density plasmas are discussed. Where possible, numerical results are compared against analytical solutions. The simulation results indicate that the algorithm is stable at time steps larger than twice the inverse plasma frequency and cell sizes larger than the Debye length. It is found that the algorithm gives adequate results, provided that the distribution function and the spatiotemporal scales dictating the physics of the problem are resolved. As such, the algorithm may provide a robust method for kinetic modeling of high-density plasmas at scale.

Tree reconstruction guarantees from CRISPR-Cas9 lineage tracing data using Neighbor-Joining.

Fri, 19 Jun 2026 00:00:00 +0000

CRISPR-Cas9-based lineage tracing technologies have enabled the reconstruction of single-cell phylogenies from transcriptional readouts. However, developing tree-reconstruction algorithms with theoretical guarantees in this setting is challenging. In this work, we derive a reconstruction algorithm with theoretical guarantees using Neighbor-Joining (NJ) on distances that are moment-matched to estimate the true tree distances. We develop a series of tools to analyze this algorithm and prove its theoretical guarantees. When the parameters of the data generating process are known and there is no missing data, our results align with established results from common evolutionary models, such as Cavender-Farris-Neyman and Jukes-Cantor. However, to account for the realistic case where the parameters of the data generating process are not known and there is missing data, we develop new theory that shows for the first time that it is still possible to obtain reconstruction guarantees in...

Using Filter Methods to Guide Convergence for ADMM, with Applications to Nonnegative Matrix Factorization Problems

Fri, 19 Jun 2026 00:00:00 +0000

Nonconvex, nonlinear optimization problems arise naturally in parameter fitting and machine learning. While augmented Lagrangian methods have demonstrated robust convergence for classes of these problems, their convergence for block updates has been relatively unexplored outside of the context of the alternating direction method of multipliers (ADMM). ADMM has seen extensive use in these applications, but may exhibit uncertain convergence behavior in many practical nonconvex settings, and struggles with general nonlinear constraints. In contrast, filter methods have proved effective in enforcing convergence for sequential quadratic programming methods and interior point methods with feasibility criteria. We develop an ADMM-filter method for highly nonlinear and nonconvex problems. We show convergence under mild assumptions for several types of coordinate descent schemes, and demonstrate our algorithm on nonnegative matrix factorization and completion problems in imaging and chemical...

Edits for UTI 002: collective subroutine sequencing

Thu, 18 Jun 2026 00:00:00 +0000

This paper contains Fortran 202Y specification edits to explain and resolve problems with work item DIN1: Collectives over a specified team. It replaces critical sequencing requirements in the Fortran standard that govern the correctness of collective subroutine invocations. It passed by unanimous consent at the Jun 2026 meeting #240 of the INCITS/US Fortran Programming Language Standards Technical Committee.

Signs of nonmonotonic finite-volume corrections to gA

Wed, 17 Jun 2026 00:00:00 +0000

We study finite-volume (FV) corrections to determinations of via lattice quantum chromodynamics (QCD) using analytic results and numerical analysis. We observe that heavy Baryon chiral perturbation theory does not provide an unambiguous prediction for the sign of the FV correction, which is not surprising when one also considers large- constraints on the axial couplings. We further show that nonmonotonic FV corrections are naturally allowed when one considers either including explicit -resonance degrees of freedom or one works to higher orders in the chiral expansion. We investigate the potential impact of these FV corrections with a precision study of using models of FV corrections that are monotonic and nonmonotonic. Using lattice QCD data that is approximately at the 1% level of precision, we do not see significant evidence of nonmonotonic corrections. Looking forward to the next phase of lattice QCD calculations, we estimate that calculations that are between the 0.1%...

Quantifying Epistemic Uncertainty in Diffusion Models

Wed, 17 Jun 2026 00:00:00 +0000

To ensure high quality outputs, it is important to quantify the epistemic uncertainty of diffusion models. Existing methods are often unreliable because they mix epistemic and aleatoric uncertainty. We introduce a method based on Fisher information that explicitly isolates epistemic variance, producing more reliable plausibility scores for generated data. To make this approach scalable, we propose FLARE (Fisher-Laplace Randomized Estimator), which approximates the Fisher information using a uniformly random subset of model parameters. Empirically, FLARE improves uncertainty estimation in synthetic time-series generation tasks, achieving more accurate and reliable filtering than other methods. Theoretically, we bound the convergence rate of our randomized approximation and provide analytic and empirical evidence that last-layer Laplace approximations are insufficient for this task.

ERRATUM: Two-neutrino double electron capture of 124Xe in the first LUX-ZEPLIN exposure (2024 J. Phys. G: Nucl. Part. Phys. 52 015103)

Wed, 17 Jun 2026 00:00:00 +0000

Due to an error in production, the error margins of many values were incorrectly published. Table 1 details the locations of the errors and their corrections.

Track reconstruction as a service for collider physics

Wed, 17 Jun 2026 00:00:00 +0000

Optimizing charged-particle track reconstruction algorithms is crucial for efficient event reconstruction in Large Hadron Collider (LHC) experiments due to their significant computational demands. Existing track reconstruction algorithms have been adapted to run on massively parallel coprocessors, such as graphics processing units (GPUs), to reduce processing time. Nevertheless, challenges remain in fully harnessing the computational capacity of coprocessors in a scalable and non-disruptive manner. This paper proposes an inference-as-a-service approach for particle tracking in high energy physics experiments. To evaluate the efficacy of this approach, two distinct tracking algorithms are tested: Patatrack, a rule-based algorithm, and Exa.TrkX, a machine learning-based algorithm. The as-a-service implementations show enhanced GPU utilization and can process requests from multiple CPU cores concurrently without increasing per-request latency. The impact of data transfer is minimal...

Towards a distributed heterogeneous task scheduler for the ATLAS offline software framework*

Tue, 16 Jun 2026 00:00:00 +0000

With the increased data volumes expected to be delivered by the HLLHC, it becomes critical for the ATLAS experiment to maximize the utilization of available computing resources ranging from conventional GRID clusters to supercomputers and cloud computing platforms. To run its data processing applications on these resources, the ATLAS software framework must be capable of efficiently executing data processing tasks in heterogeneous distributed computing environments. Today, using the Gaudi Avalanche Scheduler, whose implementation is based on Intel TBB, we can efficiently schedule Athena algorithms to multiple threads within a single compute node. We aim to develop a new framework scheduler capable of supporting distributed heterogeneous environments, based on technologies like HPX or Ray. After the initial evaluation phase of these technologies, we began the development of a prototype distributed task scheduler for the Athena framework. This contribution describes this prototype...

Parton labeling without matching: unveiling emergent labelling capabilities in regression models

Tue, 16 Jun 2026 00:00:00 +0000

Parton labeling methods are widely used when reconstructing collider events with top quarks or other massive particles. State-of-the-art techniques are based on machine learning and require training data with events that have been matched using simulations with truth information. In nature, there is no unique matching between partons and final state objects due to the properties of the strong force and due to acceptance effects. We propose a new approach to parton labeling that circumvents these challenges by recycling regression models. The final state objects that are most relevant for a regression model to predict the properties of a particular top quark are assigned to said parent particle without having any parton-matched training data. This approach is demonstrated using simulated events with top quarks and outperforms the widely-used χ2$$\chi ^2$$ method.

AthenaTriton: A tool for running machine learning inference as a service in Athena

Tue, 16 Jun 2026 00:00:00 +0000

Machine learning (ML)-based algorithms play increasingly important roles in almost all aspects of the data analyses in ATLAS, including detector simulations, event reconstructions, and data analyses. These diverse ML models are being deployed in the ATLAS software framework, Athena. To harmonize the ML inference in both the Athena environment and the ROOT environment, a dual-use ML interface is defined and implemented with two distinct backends: the Open Neural Network Exchange (ONNX) Runtime and Inference as a Service. While ONNX Runtime serves as the primary inference backend in Athena, scalable inference strategies are required to address the growing demands of processing simulation and collision data, including maximizing event throughput and utilizing coprocessors like graphics processing units (GPUs). To meet this challenge, we introduce AthenaTriton, a solution that integrates the NVIDIA Triton Inference Server with Athena. In AthenaTriton, Athena operates as a Triton client...

Erratum to: Search for exclusive Higgs and Z boson decays to ϕγ and ργ with the ATLAS detector

Tue, 16 Jun 2026 00:00:00 +0000

One correction is noted for the paper. The calculation of an angle used to account for meson polarisation in the signal decays was not correct.

Search for massive, long-lived particles in events with displaced vertices and displaced muons in pp collisions at s = 13.6 TeV with the ATLAS experiment

Tue, 16 Jun 2026 00:00:00 +0000

A search is presented for massive long-lived particles in events featuring at least one displaced vertex and at least one displaced muon, using proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider from 2022 to 2024 at a centre-of-mass energy of 13.6 TeV. The data sample corresponds to an integrated luminosity of 164 fb − 1 . The analysis targets scenarios in which long-lived particles decay inside the ATLAS inner detector, resulting in a topology of at least one massive, displaced vertex (DV) with multiple associated tracks, and at least one muon with a large transverse impact parameter relative to the primary interaction point. The muon is not required to be associated with the DV. Two signal regions are defined by the transverse distance of the reconstructed DV from the interaction point. Background contributions are estimated by using fully data-driven techniques. No significant excess above the expected background is observed. Upper limits...

Correction: Application of geometric deep learning for tracking of hyperons in a straw tube detector

Tue, 16 Jun 2026 00:00:00 +0000

Correction: Application of geometric deep learning for tracking of hyperons in a straw tube detector

The Future of Scheduling in Athena on HPCs

Tue, 16 Jun 2026 00:00:00 +0000

The large increase in luminosity expected from Run 4 of the LHC presents the ATLAS experiment with a new scale of computing challenge, and we can no longer restrict our computing to CPUs in a High Throughput Computing paradigm. We must make full use of the High Performance Computing resources available to us, exploiting accelerators and making efficient use of large jobs over many nodes. Here we describe current developments in introducing these capabilities to Athena, ATLAS’s general software framework.

thornado+FLASH-X: A Hybrid Discontinuous Galerkin–Implicit-explicit and Finite-volume Framework for Neutrino-radiation Hydrodynamics in Core-collapse Supernovae

Wed, 10 Jun 2026 00:00:00 +0000

We present neutrino-transport algorithms implemented in the toolkit for high-order neutrino-radiation hydrodynamics (thornado) and their coupling to self-gravitating hydrodynamics within the adaptive mesh refinement–based multiphysics simulation framework FLASH-X. thornado, developed primarily for simulations of core-collapse supernovae (CCSNe), employs a spectral, six-species two-moment formulation with algebraic closure and special-relativistic observer corrections accurate to O(v/c) , and uses discontinuous Galerkin (DG) methods for phase-space discretization combined with implicit-explicit time stepping. A key development is a nonlinear neutrino–matter coupling algorithm based on nested fixed-point iteration with Anderson acceleration, enabling fully implicit treatment of collisional processes, including energy-coupling interactions such as neutrino–electron scattering and pair production. Coupling to finite-volume (FV) hydrodynamics is achieved through a hybrid DG-FV representation...

Quantum Filtering and Analysis of Multiplicities in Eigenvalue Spectra

Wed, 10 Jun 2026 00:00:00 +0000

Fine-grained spectral properties of quantum Hamiltonians, including both eigenvalues and their multiplicities, provide useful information for characterizing many-body quantum systems as well as for understanding phenomena such as topological order. Extracting such information with small additive error is #BQP-complete in the worst case. In this work, we introduce QFAMES (quantum filtering and analysis of multiplicities in eigenvalue spectra), a quantum algorithm that efficiently identifies clusters of closely spaced dominant eigenvalues and determines their multiplicities under physically motivated assumptions, which allows us to bypass worst-case complexity barriers. QFAMES also enables the estimation of observable expectation values within targeted energy clusters, providing a powerful tool for studying quantum phase transitions and other physical properties. We validate the effectiveness of QFAMES through numerical demonstrations, including its applications to characterizing...

EPOC Deep Dive Retrospective: A Brief Overview of 7 years of Science Engagement Discussions

Thu, 4 Jun 2026 00:00:00 +0000

Understanding the appropriate ways cyberinfrastructure can be designed, implemented, and executed for scientific use cases requires a deep understanding of the way that researchers and educators interact with technology, and how it may be best implemented to suit their needs. The Engagement and Performance Operations Center (EPOC) has conducted a series of scientific “Deep Dives” of use cases at partner institutions to better understand the requirements for modern scientific innovation across the United States research complex. The results of these activities have revealed gaps in the way that technology has been used to foster research activities. This gap in cyberinfrastructure support has impacts for the overall productivity and innovation possibilities for scientific users.

Search for long-lived particles using displaced vertices of oppositely charged leptons in 140 fb − 1 of pp collisions at s = 13 TeV with the ATLAS detector

Thu, 4 Jun 2026 00:00:00 +0000

A search is presented for long-lived particles decaying into an oppositely charged lepton pair, μ + μ − , e + e − , or e  ±  μ ∓, that form a vertex within the inner tracking system of the ATLAS detector at the Large Hadron Collider, displaced from the primary proton–proton interaction region. The analysis uses the 140 fb − 1 of Run-2 data collected at s = 13 TeV by the ATLAS experiment in 2015–2018. The results of the analysis are interpreted in the context of three benchmark models covering masses from 0.1 to 2.2 TeV and a range of mean proper lifetimes times the speed of light from 1 to 10 000 mm. The first model is a generic Z′ boson pair-produced by a new heavy scalar, with the Z′ decaying into lepton pairs. The remaining two models are R-parity violating supersymmetric models in which the lightest neutralino χ ˜ 1 0 decays into ℓ + ℓ ′ − ν ( ℓ , ℓ ′ = e , μ). The models differ by the mode of production of the χ ˜ 1 0 , which can be produced via the decay of pairs of gluinos...

Characterization of nuclear breakup as a function of hard-scattering kinematics using dijets measured by ATLAS in p+Pb collisions

Thu, 4 Jun 2026 00:00:00 +0000

This Letter analyzes the sensitivity of event geometry estimators to the initial-state kinematics of hard scattering in proton–lead collisions. This analysis uses dijets as a proxy for the parton–parton scattering configuration, correlating it with event geometry estimators, namely the energy deposited in the Zero-Degree Calorimeter and the transverse energy recorded in the Forward Calorimeter in the Pb-going direction. The analysis uses data recorded by the ATLAS detector at the Large Hadron Collider with a nucleon–nucleon center-of-mass energy of 8.16 TeV, corresponding to an integrated luminosity of 56 nb − 1 . The jets are measured within the pseudorapidity interval −2.8  <  η  <  4.5, where positive η values correspond to the direction of the proton beam. Results are presented as a function of the Bjorken-x of the parton originating from the proton, xp . Both event geometry estimators are found to be dependent on xp , with the energy deposited in the Zero-Degree Calorimeter...

Multiscale analysis of large twist ferroelectricity and swirling dislocations in bilayer hexagonal boron nitride

Thu, 4 Jun 2026 00:00:00 +0000

With its atomically thin structure and intrinsic ferroelectric properties, heterodeformed bilayer hexagonal boron nitride (hBN) has gained prominence in next-generation non-volatile memory applications. However, studies to date have focused almost exclusively on small-twist bilayer hBN, leaving the question of whether ferroelectricity can persist under small heterostrain and large heterodeformation entirely unexplored. In this work, we establish the crystallographic origin of ferroelectricity in bilayer hBN configurations heterodeformed relative to high-symmetry configurations such as AA-stacking and 21.786789° twisted configurations (Σ7), using Smith normal form bicrystallography. We then demonstrate out-of-plane ferroelectricity in bilayer hBN across configurations vicinal to both the AA and Σ7 stackings. Atomistic simulations reveal that AA-vicinal systems support ferroelectricity under both small twist and small strain, with polarization switching in the latter...

A Brief Survey of Data Streaming Technologies

Thu, 4 Jun 2026 00:00:00 +0000

Streaming data is data that is emitted at variable volumes in a continuous, incremental manner with the goal of low-latency processing often at a different physical location. Network infrastructure is used to facilitate the connection between data sources and sinks, and must be robust to handle the requirements of the workflow. The U.S. Department of Energy Office of Science (DOE SC) a federal agency supporting fundamental scientific research for energy and the Nation’s largest supporter of basic research in the physical sciences. DOE SC has the responsibility for operating $\mathbf{1 0}$ National Laboratories, and 28 scientific user facilities supporting advanced supercomputers, particle accelerators, large x-ray light sources, neutron scattering sources, and other specialized facilities for nanoscience and genomics. This paper investigates the state of streaming data workfows, and details some of the approaches to this challenging problem.

Dirac Fermions and Flat Bands in Phosphorus Carbide Nanotubes: Structural and Quantum Phase Transitions in a Quasi-One-Dimensional Material

Thu, 4 Jun 2026 00:00:00 +0000

Chemically realistic quasi-one-dimensional (1D) materials in which Dirac Fermions and highly degenerate flat bands coexist intrinsically at the Fermi level are exceedingly rare, while representing a highly desirable platform for correlated and topological quantum phenomena. Here, using specialized symmetry-adapted first-principles calculations we predict a new class of nanomaterials─phosphorus carbide nanotubes (P₂C₃NTs)─obtained by rolling monolayer P₂C₃, a two-dimensional material shown in a previous letter to host "double Kagome bands". Both armchair and zigzag P₂C₃NTs are stable at room temperature and feature the rare coexistence of Dirac crossings and multiple flat bands at the Fermi level inherited from the underlying honeycomb-Kagome lattice, with the flat bands resilient to elastic deformations. Under large strain, the structure transforms from honeycomb-Kagome to "brick-wall", accompanied by multiple coupled...

Measurement of the Higgs boson production in association with top quarks in multilepton final states in pp collisions at s=13 TeV with the ATLAS detector

Thu, 4 Jun 2026 00:00:00 +0000

A measurement of the associated production of a top-quark pair with the Higgs boson (tt¯H$$ t\overline{t}H $$) in multilepton final states is presented. The analysis is based on a data sample of proton-proton collisions at s=13$$ \sqrt{s}=13 $$ TeV recorded with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 140 fb−1. Six final states defined by the number and flavour of reconstructed charged leptons are combined in a simultaneous likelihood fit to extract the tt¯H$$ t\overline{t}H $$ signal and constrain the most relevant backgrounds. The measured tt¯H$$ t\overline{t}H $$ cross-section normalised to Standard Model (SM) prediction is σtt¯H/σSM=0.63−0.19+0.20$$ {\sigma}_{t\overline{t}H}/{\sigma}^{\mathrm{SM}}=0.{63}_{-0.19}^{+0.20} $$. This result corresponds to an observed (expected) significance of 3.3σ (5.3σ). Additionally, two other fits are used to measure the tt¯H$$ t\overline{t}H $$ cross-section differentially in bins...

Electroweak diboson production in association with a high-mass dijet system in semileptonic final states from pp collisions at s=13 TeV with the ATLAS detector

Thu, 4 Jun 2026 00:00:00 +0000

This paper reports the observation of electroweak diboson (WW/WZ/ZZ) production in association with a high-mass dijet system, in which final states with one boson decaying leptonically and the other boson decaying hadronically are studied. The hadronically decaying W/Z boson is reconstructed as either two small-radius jets or one large-radius jet with jet substructure requirements. The data analyzed correspond to an integrated luminosity of 140fb-1$$140 \ \text {fb}^{-1}$$ of proton–proton collisions at a center-of-mass energy of s=13$$\sqrt{s}=13$$ TeV collected with the ATLAS detector during the 2015-2018 data taking at the Large Hadron Collider. The electroweak production of WW/WZ/ZZ in association with two jets is observed in a phase space dominated by vector-boson scattering with a significance of 7.4σ$$7.4\sigma $$ (expected 6.1σ$$6.1\sigma $$) and the signal strength is determined to be 1.28-0.21+0.23$$1.28^{+0.23}_{-0.21}$$. The corresponding production cross section in...

Electronic structure prediction of medium and high entropy alloys across composition space

Thu, 4 Jun 2026 00:00:00 +0000

We propose machine learning (ML) models to predict the electron density — the fundamental unknown of a material’s ground state — across the composition space of concentrated alloys. From this, other physical properties can be inferred, enabling accelerated exploration. A significant challenge is that the number of descriptors and sampled compositions required for accurate prediction grows rapidly with species. To address this, we employ Bayesian Active Learning (AL), which minimizes training data requirements by leveraging uncertainty quantification capabilities of Bayesian Neural Networks. Compared to the strategic tessellation of the composition space, Bayesian-AL reduces the number of training data points by a factor of 2.5 for ternary (SiGeSn) and 1.7 for quaternary (CrFeCoNi) systems. We also introduce easy-to-optimize, body-attached-frame descriptors, which respect physical symmetries while keeping descriptor-vector size nearly constant as alloy complexity increases. Our...

Compact representation and long-time extrapolation of real-time data for quantum systems using the ESPRIT algorithm

Wed, 27 May 2026 00:00:00 +0000

Representing real-time data as a sum of complex exponentials provides a compact form that enables both denoising and extrapolation. As a fully data-driven method, the Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm is agnostic to the underlying physical equations, making it broadly applicable to various observables and experimental or numerical setups. In this work, we consider applications of the ESPRIT algorithm primarily to extend real-time dynamical data from simulations of quantum systems. We evaluate ESPRIT's performance in the presence of noise and compare it to other extrapolation methods. We demonstrate its ability to extract information from short-time dynamics to reliably predict long-time behavior and determine the minimum time interval required for accurate results. We discuss how this insight can be leveraged in numerical methods that propagate quantum systems in time, and we show how ESPRIT can predict infinite-time values...

Artificial intelligence methods for protein structure and interaction prediction: Recent advances and challenges

Wed, 27 May 2026 00:00:00 +0000

Recent advances in artificial intelligence have introduced novel methods for high-accuracy prediction of protein tertiary structures, protein complex structures, and interactions between proteins and other biomolecules, such as small molecules and nucleic acids. Such advancements are accelerating biomedical research and the development of new protein design and bioengineering methods among many other important biotechnology applications. In this review, we outline the recent advances in protein-centric biomolecular structure and interaction prediction, highlight some major challenges in the field, and discuss potential directions to address them.

Differential Fuzz Testing to Detect Tampering in Sensor Systems and Its Application to Arms Control Authentication

Thu, 21 May 2026 00:00:00 +0000

In future nuclear arms control treaties, it will be necessary to authenticate the hardware and software components of verification measurement systems. This article introduces the concept of physical differential fuzz testing as a challenge-response-style tamper indicator that can holistically and simultaneously test various components in a cyber-physical system. This concept is then applied to authenticating the radiation measurement equipment in nuclear weapon verification systems and conducting demonstration fuzz testing measurements with a sodium iodide (NaI) gamma ray spectrometer. We show that physical differential fuzz testing can detect two types of tamper attempts, and conclude that it is a promising framework for authenticating future cyber-physical systems in nuclear arms control, safeguards, and beyond.

AstraAI: LLMs, Retrieval, and AST-Guided Assistance for HPC Codebases

Thu, 21 May 2026 00:00:00 +0000

We present AstraAI, a command-line interface (CLI) coding framework for high-performance computing (HPC) software development. AstraAI operates directly within a Linux terminal and integrates large language models (LLMs) with Retrieval-Augmented Generation (RAG) and Abstract Syntax Tree (AST)-based structural analysis to enable context-aware code generation for complex scientific codebases. The central idea is to construct a high-fidelity prompt that is passed to the LLM for inference. This prompt augments the user request with relevant code snippets retrieved from the underlying framework codebase via RAG and structural context extracted from AST analysis, providing the model with precise information about relevant functions, data structures, and overall code organization. The framework is designed to perform scoped modifications to source code while preserving structural consistency with the surrounding code. AstraAI supports both locally hosted models from Hugging Face and...

Parallel Runtime Interface for Fortran (PRIF) Specification, Revision 0.8

Tue, 19 May 2026 00:00:00 +0000

This document specifies an interface to support the multi-image parallelism features of Fortran, named the Parallel Runtime Interface for Fortran (PRIF). PRIF is a solution in which a runtime library is primarily responsible for implementing coarray allocation, deallocation and accesses, image synchronization, atomic operations, events, teams and collective subroutines. The Fortran compiler is responsible for transforming the invocation of Fortran-level multi-image parallelism features into procedure calls to the necessary PRIF subroutines. The interface is designed for portability across shared- and distributed-memory machines, different operating systems, and multiple architectures. Implementations of this interface are intended as an augmentation for the compiler's own runtime library. With an implementation-agnostic interface, alternative parallel runtime libraries may be developed that support the same interface. One benefit of this approach is the ability to vary the communication...

Reverse segregation and self-organization in inclined chute flows of bidisperse granular mixtures

Fri, 15 May 2026 00:00:00 +0000

In the usual segregation scenario for stable inclined chute flows of bidisperse mixtures of fine and coarse spherical particles, coarse particles rise toward the free surface, forming a coarse-rich region atop the flowing pile. Beyond a threshold coarse-to-fine diameter ratio of approximately 4, conversely, the weight of the coarse particles exceeds the segregation driving forces, causing individual coarse particles to sink within the pile and producing a reversed segregation state. However, an understanding of the collective evolution of the pile structure is still lacking when the particle diameter ratio exceeds 4 and the coarse-particle mass fraction is appreciable. To explore this broadly bidisperse limit, we perform discrete element method simulations considering mean particle diameter ratios of up to 8 and coarse-particle mass fractions spanning 0.1 to 0.9. The steady-state flow profiles reveal several intriguing behaviors that depend on the diameter ratio and mass fraction....

Real-time estimators for scattering observables: A full account of finite-volume errors for quantum simulation

Thu, 14 May 2026 00:00:00 +0000

The real-time correlators of quantum field theories can be directly probed through new approaches to simulation, such as quantum computing and tensor networks. This provides a new framework for computing scattering observables in lattice formulations of strongly interacting theories, such as lattice quantum chromodynamics. In this paper, we prove that the proposal of real-time estimators of scattering observables is universally applicable to all scattering observables of gapped quantum field theories. All finite-volume errors are exponentially suppressed, and the rate of this suppression is controlled by the regulator considered, namely, a displacement of the spectrum of the theory into the complex plane. A partial restoration of Lorentz symmetry by averaging over different boosts gives an additional suppression of finite volume errors. Our results also apply to the simulation of wave packet scattering, where a similar averaging is performed to construct the wave packets that...