Recent lbnl_ps_ns items

Imaging nuclear shape through anisotropic and radial flow in high-energy heavy-ion collisions

Mon, 31 Aug 2026 00:00:00 +0000

Most atomic nuclei exhibit ellipsoidal shapes characterized by quadrupole deformationβ₂and triaxialityγ, and sometimes even a pear-like octupole deformationβ₃. The STAR experiment introduced a new 'imaging-by-smashing' technique ((STAR Collaboration) 2024Nature63567; Jia 2025Rep. Prog. Phys.88092301) to image the nuclear global shape by colliding nuclei at ultra-relativistic speeds and analyzing outgoing debris. Features of nuclear shape manifest in collective observables like anisotropic flowv_nand radial flow via mean transverse momentum[pT]. We present new measurements of the variances ofv_n(n = 2, 3, and 4) and[pT], and the covariance ofvn2with[pT], in collisions of highly deformed²³⁸U and nearly spherical¹⁹⁷Au. Ratios of these observables between the two systems effectively suppress common final-state effects, isolating the strong impact of...

Dielectron production in central Pb-Pb collisions at sNN=5.02TeV

Mon, 31 Aug 2026 00:00:00 +0000

The first measurement of the pair production at midrapidity and low invariant mass in central Pb-Pb collisions at at the Large Hadron Collider is presented. The yield of pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass ( ) and pair transverse momentum ( ) ranges and . For the ratio of data to the cocktail of hadronic contributions amounts to and , including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal pairs from the hadronic and partonic phases. In the intermediate-mass range ( ), the pair transverse impact parameter of the pairs ( , where “DCA” denotes “distance of closest approach”) is used for the first time in Pb-Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point....

D0-meson-tagged jet axes difference in proton-proton collisions at s=5.02 TeV

Mon, 31 Aug 2026 00:00:00 +0000

Heavy-flavor quarks produced in proton-proton (pp) collisions provide a unique opportunity to investigate the evolution of quark-initiated parton showers from initial hard scatterings to final-state hadrons. By examining jets that contain heavy-flavor hadrons, this study explores the effects of both perturbative and nonperturbative QCD on jet formation and structure. The angular differences between various jet axes, , offer insight into the radiation patterns and fragmentation of charm quarks. The first measurement of -tagged jet axes differences in pp collisions at by the ALICE experiment at the LHC is presented for jets with transverse momentum and mesons with . In this -meson-tagged jet measurement, three jet axis definitions, each with different sensitivities to soft, wide-angle radiation, are used: the standard axis, soft drop groomed axis, and winner-takes-all axis. Measurements of the radial distributions of mesons with respect to the jet axes, , are reported,...

Measurement of ω meson production in pp and p-Pb collisions at sNN=5.02 TeV

Mon, 31 Aug 2026 00:00:00 +0000

We present the measurement of the -differential production cross section of mesons in and -Pb collisions at TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor for mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the and . Within the measured range, the of mesons is compatible with no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published ratios at lower and higher collision energies in collisions suggests a decreasing trend of the ratio above = 4 GeV/ with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA 8, EPOS LHC, and DPMJET event generators, revealing significant shortcomings in these...

A Search for Millimeter-bright Blazars as Astrophysical Neutrino Sources

Mon, 31 Aug 2026 00:00:00 +0000

The powerful jets of blazars have been historically considered as likely sites of high-energy cosmic-ray acceleration. However, the particulars of the launched jet and the locations of leptonic and hadronic jet loading remain unclear. In the case when leptonic and hadronic particle injection occur jointly, a temporal correlation between synchrotron radiation and neutrino production is expected. We use a first catalog of millimeter wavelength (95–225 GHz) blazar light curves from the Atacama Cosmology Telescope for a time-dependent correlation with 12 yr of muon neutrino events from the IceCube South Pole Neutrino Observatory. Such millimeter emission traces activity of the bright jet base, which is often self-absorbed at lower frequencies and potentially gamma-ray opaque. We perform an analysis of the population, as well as analyses of individual, selected sources. We do not observe a significant signal from the stacked population. TXS 0506+056 is found as the most significant,...

Combined effective field theory interpretation of Higgs boson, electroweak vector boson, top quark, and multijet measurements

Mon, 31 Aug 2026 00:00:00 +0000

Constraints on Wilson coefficients (WCs) corresponding to dimension-6 operators of the standard model effective field theory (SMEFT) are determined from a simultaneous fit to seven sets of CMS measurements probing Higgs boson, electroweak vector boson, top quark, and multijet production. Measurements of electroweak precision observables are also included and provide complementary constraints to those from the CMS experiment. The CMS measurements, using LHC proton-proton collision data at s=13Te$$\sqrt{s}=13\,\text {Te}\text {V} $$, corresponding to integrated luminosities of 36.3 or 138fb-1$$\,\text {fb}^{-1}$$, are chosen to provide sensitivity to a broad set of operators, for which consistent SMEFT predictions can be derived. These are primarily measurements of differential cross sections which are parameterized as functions of the WCs. In measurements targeting t(t¯)X$${\text {t}} (\bar{\textrm{t}})\text {X} $$ production, SMEFT effects are modelled at the detector level. Individual...

Mass of Sn101 and Bayesian extrapolations to the proton drip line

Tue, 25 Aug 2026 00:00:00 +0000

The favorable energy configurations of nuclei at magic numbers of N neutrons and Z protons are fundamental for understanding the evolution of nuclear structure. The Z=50 (tin) isotopic chain is a frontier for such studies, with particular interest at and around the doubly magic Sn100 isotope, for which the mass is a topic of debate. Precise mass values for neutron-deficient isotopes provide necessary anchor points for mass models to test extrapolations near the proton drip line, where experimental studies remain out of reach. In this work, we report a Penning trap mass measurement of Sn101. The determined mass excess of −59889.89(96) keV for Sn101 represents a factor-of-300 improvement over the current precision and indicates that Sn101 is less bound than previously thought. Mass predictions from a recently developed Bayesian model combination framework employing statistical machine learning and nuclear masses computed within seven global models based on nuclear density functional...

Global Bayesian analysis of J/ψ photoproduction on proton and lead targets

Fri, 21 Aug 2026 00:00:00 +0000

We perform a global Bayesian analysis of diffractive production in and collisions using a color glass condensate (CGC) based calculation framework. As past calculations have shown that CGC-based models typically overpredict the production in collisions at high center of mass energy, we address the question of whether it is possible to describe coherent and incoherent diffractive data from collisions at Hadron–Electron Ring Accelerator (HERA) and the LHC, and from collisions at the LHC simultaneously. Our results indicate that a simultaneous description of and data is challenging, with results improving when an overall -factor—scaling and cross sections to absorb model uncertainties—is introduced.

Nuclear Structure and Decay Data for A=169 Isobars

Fri, 21 Aug 2026 00:00:00 +0000

Experimental data pertaining to all nuclei with mass number A=169 (Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt) have been evaluated. Level schemes from both radioactive decay and reaction studies are presented, along with associated tables of experimental data and adopted properties for levels and γ rays. The present evaluation for A=169 supersedes the 2008 evaluation, 2008Ba31, by C.M. Baglin. A few highlights of this evaluation: More extensive work on ε decay from 169W is needed and new experimental work will be required to resolve a discrepancy between the J π values deduced for a 180-keV level in 169Ta based on extensive band structure from (HI,xnγ) work (J π =1/2−) and TDPAD measurements (J=5/2). Low lying states of 169Os were studied via fine structure of 173Pt α decay in 2014ThZZ. The Eαs feeding the g.s. of 169Os in 2008Ba31 are separated well into two consistent groups to feed the g.s. and the newly proposed state at 34.84 keV. Based on the studies of...

Intrinsic energy and time resolution of the Jefferson Lab Hall C Neutral Particle Spectrometer

Fri, 21 Aug 2026 00:00:00 +0000

The Neutral Particle Spectrometer (NPS) is an advanced calorimeter designed to measure neutral electromagnetic particles with high precision in energy, time, and position, under conditions of high luminosity and significant background. Integrated into the experimental setup of Hall C at Thomas Jefferson National Accelerator Facility, the NPS plays a critical role in studies of nucleon structure through exclusive and semi-inclusive reaction channels. This paper presents an assessment of the detector’s performance characteristics, specifically its energy and timing resolution, derived from elastic electron–proton scattering data. We report an energy resolution between 1.2% and 1.3% in the 4.5–7.3 GeV range, and an intrinsic timing resolution better than 200 ps for energies above 500 MeV. These results serve as a reference for current and future precision measurements in hadronic physics.

RADAI: A Large-Scale Realistic Dataset for Radiation Detection Algorithm Development

Thu, 20 Aug 2026 00:00:00 +0000

Open, realistic datasets are essential for developing and benchmarking radiation detection algorithms, yet they remain scarce. The Radiological Anomaly Detection and Identification (RADAI) project was develop to create datasets that meet the training and testing needs for sophisticated radiation detection algorithms. The RADAI dataset is a large-scale synthetic resource that integrates high-fidelity Monte Carlo simulations with realistic urban scenarios to capture both background variability and source signatures. RADAI models construction-material NORM, people and vehicles, urban clutter, and dynamic environmental effects such as cosmic-ray and rain-induced transients, and they provide list-mode detector data with motion and response modeling suitable for algorithm training and evaluation. The RADAI project resulted in three publicly-released complementary datasets together with an online scoring portal for standardized performance assessment and an open software toolkit that...

Search for GeV-scale dark matter from the Galactic Center with IceCube-DeepCore

Wed, 19 Aug 2026 00:00:00 +0000

Models describing dark matter as a novel particle often predict that its annihilation or decay into Standard Model particles could produce a detectable neutrino flux in regions of high dark matter density, such as the Galactic Center. In this work, we search for these neutrinos using ∼9 years of IceCube-DeepCore data with an event selection optimized for energies between 15 to 200 GeV. We considered several annihilation and decay channels and dark matter masses ranging from 15 GeV up to 8 TeV. No significant deviation from the background expectation from atmospheric neutrinos and muons was found. The most significant result was found for a dark matter mass of 201.6 GeV annihilating into a pair of bb¯ quarks assuming the Navarro–Frenk–White halo profile with a post-trial significance of 1.08σ. We present upper limits on the thermally averaged annihilation cross section of the order of 10-24 cm3 s-1, as well as lower limits on the dark matter decay lifetime up to 1026 s for dark...

Identification and denoising of radio signals from cosmic-ray air showers using convolutional neural networks

Wed, 19 Aug 2026 00:00:00 +0000

Radio pulses generated by cosmic-ray air showers can be used to reconstruct key properties like the energy and depth of the electromagnetic component of cosmic-ray air showers. Radio detection threshold, influenced by natural and anthropogenic radio background, can be reduced through various techniques. In this work, we demonstrate that convolutional neural networks (CNNs) are an effective way to lower the threshold. We developed two CNNs: a classifier to distinguish radio signal waveforms from background noise and a denoiser to clean contaminated radio signals. Following the training and testing phases, we applied the networks to air-shower data triggered by scintillation detectors of the prototype station for the enhancement of IceTop, IceCube’s surface array at the South Pole. Over a four-month period, we identified 554 cosmic-ray events in coincidence with IceTop, approximately five times more compared to a reference method based on a cut on the signal-to-noise ratio. Comparisons...

Observation of flow vector fluctuations in p–Pb collisions at $\sqrt{{s}_{NN}}=5.02$ TeV

Tue, 18 Aug 2026 00:00:00 +0000

Measurements of transverse momentum (pT) and pseudorapidity (η) dependent flow vector fluctuations in p–Pb collisions at $$\sqrt{{s}_{NN}}=5.02$$ TeV at the CERN Large Hadron Collider are presented. By studying long-range two-particle correlations with a template fit method, potential biases from non-flow effects such as jets and resonance decays are effectively suppressed. Significant pT- and η-dependent fluctuations of the second-harmonic flow vector are observed with more than 5σ confidence in p–Pb collisions, similar to the observations in Pb–Pb collisions. The influence of residual non-flow effects has been evaluated and cannot account for the observed fluctuations, thereby confirming the observation of flow vector fluctuations in small collision systems at the LHC. Comparisons to model calculations from 3DGlauber+MUSIC+UrQMD and the parton transport model from AMPT are also presented. The measurements provide constraints on the theoretical modelling of the three-dimensional...

Strangeness enhancement at its extremes: multiple (multi-)strange hadron production in pp collisions at $\sqrt{s}=5.02$ TeV

Tue, 18 Aug 2026 00:00:00 +0000

The probability to observe a specific number of strange and multi-strange hadrons (nS), denoted as P(nS), is measured by ALICE at midrapidity (|y| < 0.5) in $$\sqrt{s}=5.02$$ TeV proton-proton (pp) collisions, dividing events into several multiplicity-density classes. Exploiting, for the first time, a technique based on counting the number of strange-particle candidates event-by-event, this measurement allows one to extend the study of strangeness production beyond the mean of the distribution. This constitutes a new test bench for production mechanisms, probing events with a large imbalance between strange and non-strange content. The analysis of a large-statistics data sample makes it possible to extract P(nS) up to a maximum nS of 7 for $${\text{K}}_{\text{S}}^{0}$$, 5 for Λ and $$\overline{\Lambda }$$, 4 for Ξ− and $${\overline{\Xi } }^{+}$$, and 2 for Ω− and $${\overline{\Omega } }^{+}$$. From this, the probability of producing strange hadron multiplets per event is calculated,...

Observation of deuteron and antideuteron formation from resonance-decay nucleons