Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “properties of Hadrons”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Measurement of ψ (2S) production as a function of charged-particle pseudorapidity density in pp collisions at $ \sqrt{s}$ = 13 TeV and p–Pb collisions at $ \sqrt{s_{\textrm{NN}}}$ = 8.16 TeV with ALICE at the LHC

Production of inclusive charmonia in pp collisions at center-of-mass energy of $ \sqrt{s}$= 13 TeV and p–Pb collisions at center-of-mass energy per nucleon pair of $ \sqrt{s_{\textrm{NN}}}$ = 8.16 TeV is studied as a function of charged-particle pseudorapidity density with ALICE. Ground and excited charmonium states (J/ψ, ψ(2S)) are measured from their dimuon decays in the interval of rapidity in the center-of-mass frame 2.5 < y cms < 4.0 for pp collisions, and 2.03 < y cms < 3.53 and –4.46 < y cms < –2.96 for p–Pb collisions. The charged-particle pseudorapidity density is measured around midrapidity (|η| < 1.0). In pp collisions, the measured charged-particle multiplicity extends to about six times the average value, while in p-Pb collisions at forward (backward) rapidity a multiplicity corresponding to about three (four) times the average is reached. The ψ(2S) yield increases with the charged-particle pseudorapidity density. The ratio of ψ(2S) over J/ψ yield does not show a significant multiplicity dependence in either colliding system, suggesting a similar behavior of J/ψ and ψ(2S) yields with respect to charged-particle pseudorapidity density. Results for the ψ(2S) yield and its ratio with respect to J/ψ agree with available model calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

On extraction of twist-two Compton form factors from DVCS observables through harmonic analysis

We investigate the exercise of locally extracting the real and imaginary parts of the four twist-2 Compton form factors (CFFs) {$\mathcal{H,E,\tilde H,\tilde E}$} which arise in the deeply virtual Compton scattering (DVCS) process e + p → e + p + y. Neglecting dynamical higher-twist contributions, we find that there are a sufficient number of DVCS observables and degrees of freedom to extract all 8 leading quantities model-independently, exploiting the azimuthal dependence of the absolute cross sections across all possible beam and target polarizations at a common kinematical point in {Q, t,x b , y}. As an example, for typical JLab lab-frame kinematics, we simplify the reduced DVCS observables to their dominant terms, providing a sufficient number of equations for local determination of the twist-2 CFFs. We demonstrate the feasibility using harmonic fitting to both cross sections and beam spin asymmetries with both real and pseudo-data.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Heavy-quark spin symmetry breaking in the Born-Oppenheimer approximation

Heavy-quark spin symmetry is explicitly broken by the mass splitting between a heavy-light pseudoscalar meson and its vector partner. This fact plays a pivotal role in the physics of states whose mass lies close to the threshold of an open-flavor meson pair, like X (3872). We show that this source of heavy-quark spin symmetry breaking can be systematically included within the diabatic representation of the Born-Oppenheimer approximation. We verify that including all the appropriate coupled channels guarantees conservation of total angular momentum, parity, and charge-conjugation parity. This marks a fundamental step towards a unified, first-principles study of quarkonia and meson molecules with hidden flavor.

properties of hadrons↗
DOE OSTI2022

Generalized parton distributions through universal moment parameterization: zero skewness case

We present a global analysis program for the generalized parton distributions (GPDs) based on conformal moment expansion. We apply the strategy of universal moment parameterization to fit both the collinear parton distribution functions (PDFs) from phenomenology and generalized form factors from lattice calculations, and show that the parameterization is flexible enough to accommodate these constraints. In addition, we can also fit direct lattice calculations of GPDs from large-momentum effective theory. In this work we focus on the analysis of t-dependent PDFs which correspond to GPDs in the ξ → 0 limit. The strategy also applies to the ξ ≠ 0 region with extra parameters, and therefore can be fitted to experimental observables in the future. With a demonstrative example of fitted GPDs, we exhibit the quark transverse angular momentum densities of the proton as well as the impact parameter space distributions of quarks in both unpolarized and transversely polarized protons.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Perturbative calculations of gravitational form factors at large momentum transfer

We perform a perturbative QCD analysis of the gravitational form factors (GFFs) of nucleon at large momentum transfer. We derive the explicit factorization formula of the GFFs in terms of twist-3 and twist-4 light-cone distribution amplitudes of nucleon. Power behaviors for these GFFs are obtained from the leading order calculations. Numeric results of the quark and gluon contributions to various GFFs are presented with model assumptions for the distribution amplitudes in the literature. We also present the perturbative calculations of the scalar form factor $\langle P$' $|F^2|P \rangle$ for pion and proton at large momentum transfer.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Generalized parton distributions and gravitational form factors at large momentum transfer

Within the soft collinear effective theory (SCET), we derive a factorization theorem which resums Sudakov logarithms (α s ln 2 ( –t)) n to all orders in the quark-in-quark generalized parton distribution (GPD) at large momentum transfer t, and perform a consistency check to one-loop. We show that the same Sudakov factor appears in the ‘Feynman’ contribution to the GPDs of the nucleon. Our result enables the resummation of all the large logarithms ln Q 2 and ln 2 t in exclusive processes with two hard scales Λ$^{2}_{QCD}$ ≪ |t| ≪ Q 2 . We also present a SCET power counting analysis of the Feynman contributions to the GPDs and show that the x-dependence of GPDs factorizes at large-t with controlled corrections. This in particular implies that any ratio of GPD moments such as the electromagnetic and gravitational form factors (GFF) is perturbatively calculable in this approximation. Furthermore, we identify a novel order α s power-law t-dependence in the GPD and the D-type GFF that will dominate over the standard order α$^{2}_{s}$ ‘leading twist’ asymptotic contribution in the phenomenologically relevant region of t.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Detecting nuclear mass distribution in isobar collisions via charmonium

Abstract The collective properties of final state hadrons produced in the high statistics $$_{44}^{96}$$ 44 96 Ru + $$_{44}^{96}$$ 44 96 Ru and $$_{40}^{96}$$ 40 96 Zr + $$_{40}^{96}$$ 40 96 Zr collisions at $$\sqrt{s_\textrm{NN}} = 200~\textrm{GeV}$$ s NN = 200 GeV are found to be significantly different. Such differences were argued to be precise probes of the difference in nucleon distribution in the isobar nuclei. We investigate the $$J/\psi $$ J / ψ production in the isobar collision via a relativistic transport approach. By comparing the isobar systems according to equal centrality bin and equal multiplicity bin, we find that the yield ratio of $$J/\psi $$ J / ψ is sensitive to the differences in both the number of binary collisions and the medium evolution. Besides, the elliptic flow $$v_2$$ v 2 of $$J/\psi $$ J / ψ is qualitatively different from the light hadrons, and the ratio between Ru + Ru and Zr + Zr collisions is sensitive to the medium evolution. The charmonium production provides an independent probe to study the nucleon distribution in the isobar system.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Unravelling the extreme universe [Slides]

A journey to the early universe includes stops that examine the Quark Gluon plasma of the early universe 10 -6 seconds after the Big Bang and its extraordinary properties, the emergence of hadrons (like the proton and neutron) and light nuclei 1 second after the Big Bang, and the elusive neutrinos, in addition to the primordial ones that are also produced during star formation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Measurement of Charged-Pion Production in Deep-Inelastic Scattering off Nuclei with the CLAS Detector

Background: Energetic quarks in nuclear deep-inelastic scattering propagate through the nuclear medium. Processes that are believed to occur inside nuclei include quark energy loss through medium-stimulated gluon bremsstrahlung and intranuclear interactions of forming hadrons. More data are required to gain a more complete understanding of these effects. Purpose: To test the theoretical models of parton transport and hadron formation, we compared their predictions for the nuclear and kinematic dependence of pion production in nuclei. Methods: We have measured charged-pion production in semi-inclusive deep-inelastic scattering off D, C, Fe, and Pb using the CLAS detector and the CEBAF 5.014-GeV electron beam. We report results on the nuclear-to-deuterium multiplicity ratio for π + and π - as a function of energy transfer, four-momentum transfer, and pion energy fraction or transverse momentum—the first three-dimensional study of its kind. Results: The π + multiplicity ratio is found to depend strongly on the pion fractional energy z and reaches minimum values of 0.67 ± 0.03, 0.43 ± 0.02, and 0.27 ± 0.01 for the C, Fe, and Pb targets, respectively. The z dependencies of the multiplicity ratios for π + and π - are equal within uncertainties for C and Fe targets but show differences at the level of 10% for the Pb-target data. The results are qualitatively described by the GIBUU transport model, as well as with a model based on hadron absorption, but are in tension with calculations based on nuclear fragmentation functions. Conclusions: These precise results will strongly constrain the kinematic and flavor dependence of nuclear effects in hadron production, probing an unexplored kinematic region. They will help to reveal how the nucleus reacts to a fast quark, thereby shedding light on its color structure and transport properties and on the mechanisms of the hadronization process.

Moran, S.↗
DOE OSTI2025

Exotic hidden-heavy hadrons and where to find them

The Born-Oppenheimer potentials for QCD with light quarks include adjoint-hadron potentials that are repulsive at short distances and heavy-hadron-pair potentials that approach thresholds at large distances. The adjoint-hadron potentials must connect smoothly to the heavy-hadron-pair potentials at intermediate distances. We identify exotic hidden-heavy hadrons as bound states and resonances in adjoint-hadron potentials that cross below a heavy-hadron-pair threshold before approaching it. This explains why many exotic hidden-charm and hidden-bottom hadrons have energies near heavy-hadron-pair thresholds. The remarkable properties of some exotic hidden-heavy mesons can be explained by fine tunings of adjoint-meson energies in QCD.

Born-Oppenheimer approximation↗
DOE OSTI2024

Search for production of a single vectorlike quark decaying to t H or t Z in the all-hadronic final state in p p collisions at s = 13 TeV

A search for electroweak production of a single vectorlike T quark in association with a bottom ( b ) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at s = 13 TeV collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of 138 fb - 1 . The T quark is assumed to have charge 2 / 3 and decay to a top ( t ) quark and a Higgs ( H ) or Z boson. Hadronic decays of the t quark and the H or Z boson are reconstructed from the kinematic properties of jets, including those containing b hadrons. No deviation from the standard model prediction is observed in the reconstructed t H and t Z invariant mass distributions. The 95% confidence level upper limits on the product of the production cross section and branching fraction of a T quark produced in association with a b quark and decaying via t H or t Z range from 1260 to 68 fb for T quark masses of 600–1200 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Measurements of Lund subjet multiplicities in 13 TeV proton-proton collisions with the ATLAS detector

This Letter presents a differential cross-section measurement of Lund subjet multiplicities, suitable for testing current and future parton shower Monte Carlo algorithms. This measurement is made in dijet events in 140 fb -1 of $\sqrt{s}$ =13 TeV proton–proton collision data collected with the ATLAS detector at CERN's Large Hadron Collider. The data are unfolded to account for acceptance and detector-related effects, and are then compared with several Monte Carlo models and to recent resummed analytical calculations. The experimental precision achieved in the measurement allows tests of higher-order effects in QCD predictions. Most predictions fail to accurately describe the measured data, particularly at large values of jet transverse momentum accessible at the Large Hadron Collider, indicating the measurement's utility as an input to future parton shower developments and other studies probing fundamental properties of QCD and the production of hadronic final states up to the TeV-scale.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Underlying-event studies with strange hadrons in pp collisions at √s = 13 TeV with the ATLAS detector

Properties of the underlying-event in pp interactions are investigated primarily via the strange hadrons $K^0_S$, $\Lambda$, and $\bar\Lambda$, as reconstructed using the ATLAS detector at the LHC in minimum-bias pp collision data at √s = 13 TeV. The hadrons are reconstructed via the identification of the displaced two-particle vertices corresponding to the decay modes $K^0_S$ → π⁺π⁻, Λ → π⁻p and $\bar\Lambda$ → $\pi^+\overline{p}$. These are used in the construction of underlying-event observables in azimuthal regions computed relative to the leading charged-particle jet in the event. None of the hadronisation and underlying-event physics models considered can describe the data over the full kinematic range considered. Events with a leading charged-particle jet in the range of 10 < p T ≤ 40 GeV are studied using the number of prompt charged particles in the transverse region. The ratio N(Λ + $\bar\Lambda$/N($K^0_S$) as a function of the number of such charged particles varies only slightly over this range. This disagrees with the expectations of some of the considered Monte Carlo models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Common femtoscopic hadron-emission source in pp collisions at the LHC

The femtoscopic study of pairs of identical pions is particularly suited to investigate the effective source function of particle emission, due to the resulting Bose–Einstein correlation signal. In small collision systems at the LHC, pp in particular, the majority of the pions are produced in resonance decays, which significantly affect the profile and size of the source. In this work, we explicitly model this effect in order to extract the primordial source in pp collisions at $\sqrt{s}$ = 13 TeV from charged π–π correlations measured by ALICE. We demonstrate that the assumption of a Gaussian primordial source is compatible with the data and that the effective source, resulting from modifications due to resonances, is approximately exponential, as found in previous measurements at the LHC. The universality of hadron emission in pp collisions is further investigated by applying the same methodology to characterize the primordial source of K–p pairs. The size of the primordial source is evaluated as a function of the transverse mass (m T ) of the pairs, leading to the observation of a common scaling for both π–π and K–p, suggesting a collective effect. Further, the present results are compatible with the m T scaling of the p–p and p–Λ primordial source measured by ALICE in high multiplicity pp collisions, providing additional evidence for the presence of a common emission source for all hadrons in small collision systems at the LHC. This will allow the determination of the source function for any hadron–hadron pairs with high precision, granting access to the properties of the possible final-state interaction among pairs of less abundantly produced hadrons, such as strange or charmed particles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Measurement of the nuclear modification factor for muons from charm and bottom hadrons in Pb+Pb collisions at 5.02 TeV with the ATLAS detector

Heavy-flavour hadron production provides information about the transport properties and microscopic structure of the quark–gluon plasma created in ultra-relativistic heavy-ion collisions. A measurement of the muons from semileptonic decays of charm and bottom hadrons produced in Pb+Pb and pp collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV with the ATLAS detector at the Large Hadron Collider is presented. The Pb+Pb data were collected in 2015 and 2018 with sampled integrated luminosities of 208 μb –1 and 38 μb –1 , respectively, and pp data with a sampled integrated luminosity of 1.17 pb –1 were collected in 2017. Muons from heavy-flavour semileptonic decays are separated from the light-flavour hadronic background using the momentum imbalance between the inner detector and muon spectrometer measurements, and muons originating from charm and bottom decays are further separated via the muon track's transverse impact parameter. Differential yields in Pb+Pb collisions and differential cross sections in pp collisions for such muons are measured as a function of muon transverse momentum from 4 GeV to 30 GeV in the absolute pseudorapidity interval |n| < 2. Nuclear modification factors for charm and bottom muons are presented as a function of muon transverse momentum in intervals of Pb+Pb collision centrality. The bottom muon results are the most precise measurement of b quark nuclear modification at low transverse momentum where reconstruction of B hadrons is challenging. The measured nuclear modification factors quantify a significant suppression of the yields of muons from decays of charm and bottom hadrons, with stronger effects for muons from charm hadron decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of b -quark fragmentation properties in jets using the decay $B^±$ → $J/ψK^±$ in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The fragmentation properties of jets containing b-hadrons are studied using charged B mesons in 139 fb -1 of pp collisions at $\sqrt{s}$ = 13 TeV, recorded with the ATLAS detector at the LHC during the period from 2015 to 2018. The B mesons are reconstructed using the decay of B ± into J/ψK ± , with the J/ψ decaying into a pair of muons. Jets are reconstructed using the anti-k t algorithm with radius parameter R = 0.4. The measurement determines the longitudinal and transverse momentum profiles of the reconstructed B hadrons with respect to the axes of the jets to which they are geometrically associated. These distributions are measured in intervals of the jet transverse momentum, ranging from 50 GeV to above 100 GeV. The results are corrected for detector effects and compared with several Monte Carlo predictions using different parton shower and hadronisation models. The results for the longitudinal and transverse profiles provide useful inputs to improve the description of heavy-flavour fragmentation in jets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Observables for scattering on targets with arbitrary spin

Starting from the Weinberg formalism for fields of arbitrary spin, we discuss a method for the decomposition of matrix elements of QCD operators (local currents, quark/gluon bilinears) for targets with arbitrary spin. This procedure is advantageous for the systematic study of the structure of hadrons and nuclei, particularly in the case of spin-dependent observables. As higher spin targets exhibit new features in their hadronic structure, the investigation of these properties can enhance our understanding of the strong force. The construction allows for a unified framework to discuss spin > 1/2 very similar to the spin 1/2 case, without subsidiary conditions for the wave functions. Different types of spinors (canonical, helicity, light-front helicity) can be easily accommodated. Its numerical implementation is simple and can be entirely reduced to objects familiar from the rotation group. A natural sl(2,C) multipole decomposition emerges, enabling a physical interpretation of non-perturbative objects that multiply spinor bilinears as Generalized Form Factors. To demonstrate the efficacy of this method, we apply it to the description of a spin 1 target, such as the deuteron. We discuss extensions of the formalism to hard exclusive processes on the deuteron and beyond.

Vera, Frank↗