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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Mechanical form factors and densities of nonrelativistic fermions

The hadron physics community has been actively debating the interpretation of so-called mechanical properties of hadrons. Nonrelativistic quantum-mechanical systems like the hydrogen atom have been appealed to in these debates as analogies. Since such appeals are likely to continue, it is important to have Galilei-covariant expressions for matrix elements of the energy-momentum tensor. In this work, I obtain Galilei-covariant breakdowns of such matrix elements into mechanical form factors, with a special focus on spin-half states. I additionally study the spatial densities associated with these form factors, using the pilot wave interpretation to guide their breakdown into contributions from internal structure and from quantum-mechanical effects such as wave packet dispersion. For completeness, I also obtain nonrelativistic Breit frame densities.

form factors↗
NASA NTRS1974

Hadron star models

The properties of fully relativistic rotating hadron star models are discussed using models based on recently developed equations of state. All of these stable neutron star models are bound with binding energies as high as about 25%. During hadron star formation, much of this energy will be released. The consequences, resulting from the release of this energy, are examined.

Cohen, J. M.↗
DOE OSTI2025

Integrating particle flavor into deep learning models for hadronization

Hadronization models used in event generators are physics-inspired functions with many tunable parameters. Since we do not understand hadronization from first principles, there have been multiple proposals to improve the accuracy of hadronization models by utilizing more flexible parametrizations based on neural networks. These recent proposals have focused on the kinematic properties of hadrons, but a full model must also include particle flavor. In this paper, we show how to build a deep learning-based hadronization model that includes both kinematic (continuous) and flavor (discrete) degrees of freedom. Our approach is based on generative adversarial networks and we show the performance within the context of the cluster hadronization model within the erwig event generator.

Chan, Jay↗
DOE OSTI2022

Status of Lattice QCD Calculations of One and Two-Nucleon Matrix Elements

Lattice QCD calculations of basic hadronic quantities are now often performed with systematic control over the physical pion mass, continuum and infinite volume limits. This progress signals a new era in which lattice QCD will be used to compute basic properties of hadrons, nucleons and light nuclei directly from the Standard Model (SM). In particular, we will be able to use lattice QCD, combined with Effective Field Theory, to make quantitative statements about the interaction of SM matter and potential beyond the SM physics ranging from direct dark matter detection to permanent electric dipole moments. I will briefly review the status and challenges of lattice QCD calculations of select one- and two-nucleon matrix elements. These calculations are significantly more challenging than the basic quantities computed with all systematics controlled, but substantial progress is being made.

Walker-Loud, Andre↗
DOE OSTI2025

Experimental impact of jet fragmentation reference frames at particle colliders

In collider physics, the properties of hadronic jets are often measured as a function of their lab-frame momenta. However, jet fragmentation must occur in a particular rest frame defined by all color-connected particles. Since this frame may not be the lab frame, the fragmentation of a jet depends on the properties of its sibling objects. This non-factorizability of jets has consequences for experimental jet techniques such as jet tagging, boosted boson measurements, and searches for physics Beyond the Standard Model. In this paper, we will describe the effect and show its impact as predicted by simulation.

Fragmentation into hadrons↗
DOE OSTI2026

Measuring spin correlation between quarks during QCD confinement

The vacuum is now understood to have a rich and complex structure, characterized by fluctuating energy fields and a condensate of virtual quark–antiquark pairs. The spontaneous breaking of the approximate chiral symmetry, signalled by the nonvanishing quark condensate $\langle$$q\bar{q}$$\rangle$, is dynamically generated through topologically nontrivial gauge configurations such as instantons. The precise mechanism linking the chiral symmetry breaking to the mass generation associated with quark confinement remains a profound open question in quantum chromodynamics (QCD)—the fundamental theory of strong interaction. High-energy proton–proton collisions could liberate virtual quark–antiquark pairs from the vacuum that subsequently undergo confinement to form hadrons, whose properties could serve as probes into QCD confinement and the quark condensate. Here we report evidence of spin correlations in $Λ\bar{Λ}$ hyperon pairs inherited from spin-correlated strange quark–antiquark virtual pairs. Measurements by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory reveal a relative polarization signal of (18 ± 4)% that links the virtual spin-correlated quark pairs from the QCD vacuum to their final-state hadron counterparts. Crucially, this correlation vanishes when the hyperon pairs are widely separated in angle, consistent with the decoherence of the quantum system. Our findings provide a new experimental model for exploring the dynamics and interplay of quark confinement and entanglement.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Production of light-flavor hadrons in pp collisions at $\sqrt{s}~=~7\text { and }\sqrt{s} = 13 \, \text { TeV} $

The production of \(\pi ^{\pm }\) , \(\mathrm{K}^{\pm }\) , \(\mathrm{K}^{0}_{S}\) , \(\mathrm{K}^{*}(892)^{0}\) , \(\mathrm{p}\) , \(\phi (1020)\) , \(\Lambda \) , \(\Xi ^{-}\) , \(\Omega ^{-}\) , and their antiparticles was measured in inelastic proton–proton (pp) collisions at a center-of-mass energy of \(\sqrt{s}\) = 13 TeV at midrapidity ( \(|y|<0.5\) ) as a function of transverse momentum ( \(p_{\mathrm{T}}\) ) using the ALICE detector at the CERN LHC. Furthermore, the single-particle \(p_{\mathrm{T}}\) distributions of \(\mathrm{K}^{0}_{S}\) , \(\Lambda \) , and \(\overline{\Lambda }\) in inelastic pp collisions at \(\sqrt{s} = 7\) TeV are reported here for the first time. The \(p_{\mathrm{T}}\) distributions are studied at midrapidity within the transverse momentum range \(0\le p_{\mathrm{T}}\le 20\) GeV/ c , depending on the particle species. The \(p_{\mathrm{T}}\) spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower \(\sqrt{s}\) and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high \(p_{\mathrm{T}}\) with increasing collision energy is observed, which is similar for all particle species under study. The transverse mass and \(x_{\mathrm{T}}\equiv 2p_{\mathrm{T}}/\sqrt{s}\) scaling properties of hadron production are also studied. As the collision energy increases from \(\sqrt{s}\) = 7–13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of \(\sqrt{s}\) , while ratios for multi-strange hadrons indicate enhancements. The \(p_\mathrm{{T}}\) -differential cross sections of \(\pi ^{\pm }\) , \(\mathrm {K}^{\pm }\) and \(\mathrm {p}\) ( \(\overline{\mathrm{p}}\) ) are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for \(\pi ^{\pm }\) and \(\mathrm{p}\) ( \(\overline{\mathrm{p}}\) ) at high \(p_\mathrm{{T}}\) .

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Thermal energy of a charm-meson molecule in a pion gas

The thermal corrections to the propagator of a loosely bound charm-meson molecule in a pion gas are calculated to next-to-leading order in the heavy-meson expansion using a zero-range effective field theory. Ultraviolet divergences in the charm-meson-pair self energy are canceled by corrections to the charm-meson-pair contact vertex. Terms that are singular at the charm-meson-pair threshold can be absorbed into thermal corrections to the rest energies and kinetic masses of the charm-meson constituents. The remaining terms reduce to a thermal correction to the binding momentum that is proportional to the pion number density and suppressed by the pion/charm-meson mass ratio. The correction gives a tiny decrease in the binding energy of the charm-meson molecule relative to the charm-meson-pair threshold in the pion gas and a change in its thermal width that is small compared to the thermal widths of the charm-meson constituents. These results are encouraging for the prospects of observing X(3872) and $T$$^{+}_{cc}$ (3875) in the expanding hadron gas produced by heavy-ion collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Estimating the color lifetime of energetic quarks

Using a simple geometric framework with a realistic nuclear density distribution, we fit published HERMES data to determine fundamental properties of hadronization using the nuclear medium as a spatial analyzer. Our approach uses a fit to the transverse momentum broadening observable and the hadronic multiplicity ratio; the simultaneous fit to two different observables strongly constrains the outcome. Using the known sizes of the target nuclei, we extract the color lifetime, finding a z h -dependent range of values from 2 to 8 fm/c for these data. We also extract estimates for the qˆ transport coefficient characterizing the strength of the interaction between the quark and the cold nuclear medium, finding an average value of 0.035±0.011 GeV 2 /fm. With a three-parameter model we obtain satisfactory fits to the data with a goodness-of-fit parameter χ 2 /dof of 1.1 or less. In a secondary fit of the results from that model we independently find a value for the Lund String Model string tension of 1.00±0.05 GeV/fm. We evaluated the sensitivity for extracting quark energy loss and effective in-medium hadronic cross sections using four-parameter variants of the model, finding large uncertainties in both cases. Our results suggest that hadronic interaction of forming hadrons in the nuclear medium is the primary dynamical cause of meson attenuation in the HERMES data, with quark energy loss playing a more minor role.

Electron-ion collider↗
DOE OSTI2024

Measurements of $\pi ^\pm $, $K^\pm $, p and $\bar{p}$ spectra in $^{40}\hbox {Ar+}^{45}\hbox {Sc}$ collisions at 13A to 150A $\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c$

The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $\pi ^\pm $, $K^\pm $, p and $\bar{p}$ produced in $^{40}\hbox {Ar+}^{45}\hbox {Sc}$ collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A $\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c$. The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the $K^\pm $/$\pi ^\pm $ ratios as well as of inverse slope parameters of the $K^\pm $ transverse mass distributions are placed in between those found in inelastic $p+p$ and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Longitudinal double helicity asymmetry $A_{LL}$ from direct photon, jet and charged pion production in polarized $\vec{p}+\vec{p}$ collisions

Understanding the proton spin composition from the quarks and gluons spin polarization and their motion is important to test various kinds of sum rules and nonperturbative properties of hadrons. At the Relativistic Heavy Ion Collider (RHIC), we collide longitudinally polarized proton beams and measure the double helicity asymmetry A_{LL} A L L , which is an important physical quantity for extracting the polarized parton distribution functions (PDFs) of the proton. Direct photon, jet and charged pion production are good channels to probe the gluon spin polarization inside the proton, with the ability to probe also the sign of the gluon spin. Direct photon production is the theoretically ``cleanest’’ channel, with little fragmentation contribution, but limited by statistics. On the other hand, jet and charged pion production have more statistics, but include more hard processes and hadronization effects. I will present the recent measurements of direct photon, jet and charged pion A_{LL} A L L s at PHENIX and show their complementary roles in extracting the gluon spin.

Ji, Zhongling↗
DOE OSTI2023

Properties of first-order hadron-quark phase transition from inverting neutron star observables

By inverting the observational data of several neutron star observables in the three-dimensional parameter space of the constant speed of sound (CSS) model while fixing all hadronic equation-of-state parameters at their currently known most probable values, we constrain the three parameters of the CSS model and their correlations. Using two lower radius limits of $R$ $2.01$ = $11.41$ km and $R$ $2.01$ = $12.2$ km for PSR J0740+6620 obtained from two independent analyses using different approaches by the Neutron Star Interior Composition Explorer (NICER) Collaboration, the speed of sound squared $c$ $^2_{QM}$ in quark matter is found to have a lower limit of 0.35 or 0.43 in units of $c$ $2$ , above its conformal limit of $c$ $^2_{QM}$ < $1/3$. Furthermore, an approximately linear correlation between the first-order hadron-quark transition density $ρ$ $t$ and its strength $Δε$ is found. Moreover, the presence of twin stars is deemed improbable by the present work.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Comparison of integral equations used to study ${T}_{cc}^{+}$ for a stable D *

We perform a detailed comparison between three formalisms used in recent studies of DD* scattering at heavier-than-physical pion masses, which aim to understand the properties of the doubly-charmed tetraquark, ${T}_{cc}^{+}$ (3875). These methods are the three-particle relativistic field theory (RFT) formalism, the two-body Lippmann-Schwinger (LS) equation with chiral effective field theory potentials, and the two-particle relativistic framework proposed by Baião Raposo and Hansen (BRH approach). In a simplified single-channel setting, we derive the conditions under which the infinite-volume integral equations from the RFT and BRH approaches reduce to the LS form. We present numerical examples showing that differences between these methods can be largely removed by adjusting short-range couplings. We also address a number of technical issues in the RFT approach.

Hadronic Spectroscopy↗
DOE OSTI2025

Scaling Properties of φ -Meson and Light Charged Hadron Production in Small and Large Systems at PHENIX

Recent results on the identified charged-hadron (π ± , K ± , p, p¯) production vat midrapidity region (|η| < 0.35) have been measured by the PHENIX experiment in p + Al, 3 He + Au, Cu + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U + U collisions at $\sqrt{s_{NN}}$ = 193 GeV. These measurements are presented through the invariant transverse-momentum (p T ) and transverse-mass (m T ) spectra for different collision centralities. The averaged freeze-out temperature value for different systems was found to be 166.1 ± 2.2 MeV, and do not exhibit any dependence on the collision centrality and $\langle$N parti $\rangle$ values. The particle ratios of K/π and p/π have been measured in different centrality ranges of large and small collision systems. The values of K/π ratios measured in all considered collision systems were found to be consistent with those measured in p+p collisions. Furthermore, the identified charged-hadron nuclear-modification factors (R AB ) are also presented. Enhancement of proton R AB values over meson R AB values was observed in central 3 He+Au, Cu+Au, and U+U collisions. The proton R AB values measured in p+Al collision system were found to be consistent with R AB values of Φ, π ± , K ± , and π 0 mesons, suggesting that the size of the system produced in p+Al collisions is too small for recombination to cause a noticeable increase in proton production.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Physics Division Strategic Plan Fiscal Years 2020-2024

The vision of the Physics Division (PHY) at Argonne National Laboratory is to continue enhancing its role as a world-leading institution in basic nuclear physics research and its applications. Key to this vision is for PHY to continue to safely and effectively operate and evolve the capabilities of the Argonne Tandem Linac Accelerator System (ATLAS) facility to best serve its users. ATLAS is the Department of Energy (DOE) accelerator facility for low-energy nuclear physics research. The research carried out by PHY covers many themes in contemporary science but can be distilled into five areas of focus. These themes are interconnected, with continuously evolving synergies between the various groups and facilities in PHY and the broader Laboratory. This five-year strategic plan serves to illustrate our current capabilities and new directions related to these five areas of focus (ATLAS also develops an independent strategic plan): Accelerator research and design. The goal of this theme is to design, fabricate, test, and implement novel accelerator systems, with a focus on high-intensity ion and electron systems. These R&D activities have led to enhancements in the ATLAS accelerator system. Among others, the division’s accelerator systems are in use or planned for use at Fermilab, the Advanced Photon Source, and in a broad variety of applications at the Facility for Rare Isotope Beams (FRIB). Atom trapping and fundamental symmetries. The goal of this theme is to explore and exploit the uses of advanced laser cooling and trapping techniques to manipulate atoms. There are three main areas of focus. First is in the application of the atom trap trace analysis (ATTA) technique for age determination of groundwater and ice by using radio-krypton dating. The next two trapping-based programs involve tests of fundamental symmetries in nature: the cooling and trapping of radium-225 with the aim of determining limits on an observation of its electric dipole moment and precision measurements of the beta decay properties of helium-6 to set limits on the tensor coupling constant. This is complemented by measurements of similar properties in lithium-8 and boron-8. Nuclear astrophysics. The goal of this theme is to enhance our understanding of how elements are created in the universe via explosive nucleosynthesis and how stars evolve. To meet the challenges of this theme, many of the capabilities of ATLAS are being enhanced, including the development of new beams through a new in-flight separator (RAISOR) and the anticipated neutron-generator upgrade of the Californium Rare Isotope Breeder Upgrade facility (nuCARIBU). These are coupled to state-of-the-art instruments such as the Canadian Penning Trap, Helical Orbit Spectrometer, Gammasphere, GRETINA, Multi-Sampling Ionization Chamber, the Fragment Mass Analyzer, and Argonne Gas-filled Fragment Analyzer, and a new low-background experimental area for decay studies. Nuclear structure. The goal of this theme is to understand the structure of nuclei, both stable and radioactive, in terms of single-particle properties, their shapes, and the dynamics governing reactions between them. These include questions such as what are the limits of nuclear stability and what are the properties of super heavy nuclei. As with the nuclear astrophysics theme, the capabilities of ATLAS, guided by the ATLAS user community, are continuously being enhanced to this end. The Division has strategic initiatives to play a leading role in the development of instrumentation and research programs at the FRIB. Quantum chromodynamics (QCD) and hadron physics. The goal of this theme is to lead major research programs focused on revealing the quark and gluon structure of protons, neutrons, nuclei, and short-lived mesons and baryons. These involve major programs at Jefferson Lab, Fermilab, and smaller facilities. They are complemented by theoretical endeavors centered on the question of how hadrons and their properties emerge from QCD. Out of these activities arise strategic initiatives to play a major role in the forthcoming Electron-Ion Collider (EIC).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Measurement of inclusive charged-particle b-jet production in pp and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

A measurement of the inclusive b-jet production cross section is presented in pp and p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV, using data collected with the ALICE detector at the LHC. The jets were reconstructed in the central rapidity region |η| < 0.5 from charged particles using the anti-k T algorithm with resolution parameter R = 0.4. Identification of b jets exploits the long lifetime of b hadrons, using the properties of secondary vertices and impact parameter distributions. The p T -differential inclusive production cross section of b jets, as well as the corresponding inclusive b-jet fraction, are reported for pp and p-Pb collisions in the jet transverse momentum range 10 ≤ p T,ch jet ≤ 100 GeV/c, together with the nuclear modification factor, $R^{b-jet}_{pPb}$. The analysis thus extends the lower p T limit of b-jet measurements at the LHC. The nuclear modification factor is found to be consistent with unity, indicating that the production of b jets in p-Pb at $\sqrt{s_{NN}}$ = 5.02 TeV is not affected by cold nuclear matter effects within the current precision. The measurements are well reproduced by POWHEG NLO pQCD calculations with PYTHIA fragmentation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

A unified neural-network framework for nucleon imaging from numerical simulations of QCD

Parton distributions encode the momentum-space structure and, in their generalizations, the spatial tomography of quarks and gluons inside hadrons, the building blocks of visible matter. We present a unified neural-network approach that learns these distributions directly from matrix elements calculated via numerical simulations of quantum chromodynamics (QCD) on the lattice by fitting two complementary inputs simultaneously: data matched to physical quantities via known momentum-space and coordinate-space formalisms. Utilizing data from both methods stabilizes the extraction and mitigates biases that can arise when either is used alone. We validate the method on controlled mock data and apply it to lattice-QCD matrix elements to extract parton distribution functions (PDFs). We show benefits of such an approach for determining the physical quantities. We further extend the framework to zero-skewness generalized parton distributions and demonstrate nucleon tomography within the same neural-network parameterization. Our results provide an adaptable and systematically improvable approach for extracting partonic distributions from Euclidean correlators. It can incorporate polarization, additional channels, and future experimental constraints from current and future facilities, such as the Electron-Ion Collider.

Hadronic Spectroscopy↗