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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Interplay of femtoscopic and charge-balance correlations

Correlations driven by the constraints of local charge conservation have been shown to provide insight into the chemical evolution and diffusivity of the high-temperature matter created in ultrarelativistic heavy ion collisions. Two-particle correlations driven by final-state interactions have allowed the extraction of critical femtoscopic space-time information about the expansion and dissolution of the same collisions. Whereas correlations from final-state interactions mainly appear at small relative momenta, a few tens of MeV/c, charge-balance correlations extend over a range of hundreds of MeV/c. In nearly all previous analyses, this separation of scales is used to focus solely on one class or the other. So the purpose of this study is to quantitatively understand the degree to which correlations from final-state interactions distort the interpretation of charge-balance correlations and vice versa.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Process Dependent Sivers Function and Implication for Single Spin Asymmetry in Inclusive Hadron Production

We study the single transverse spin asymmetries in the single inclusive particle production within the framework of the generalized parton model (GPM). By carefully analyzing the initial- and final-state interactions, we include the process-dependence of the Sivers functions into the GPM formalism. The modified GPM formalism has a close connection with the collinear twist-3 approach. Within the new formalism, we make predictions for inclusive {pi}{sup 0} and direct photon productions at RHIC energies. We find the predictions are opposite to those in the conventional GPM approach.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

First saturation correction in high energy proton-nucleus collisions. Part III. Ensemble averaging

In high energy proton-nucleus collisions, the gluon saturation effects from the nucleus are fully incorporated into the light-like Wilson lines. The gluon saturation effects from the proton, which are anticipated to be important either in the extreme high energy limit or towards the dense-dense (nucleus-nucleus) collision regimes, have been studied perturbatively within the Color Glass Condensate effective theory in previous papers of this series. A configuration-by-configuration expression for the single inclusive semi-hard gluon production including the first saturation correction was obtained. In this paper, we perform ensemble averaging in the McLerran-Venugopalan model and the Dipole Approximation. We find that, in the saturation correction, the effects of the initial state interactions are negligible while the final state interactions play most important role and give a positive-valued contribution to the semi-hard gluon spectrum. Furthermore, we show that the single gluon spectrum scales approximately 1/$k$$^{4}_{⊥}$ at small k ⊥ , suggesting that a resummation of higher order saturation corrections is required to regulate the infrared region of the gluon spectrum.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Inclusive charged-current neutrino-nucleus scattering in the quasielastic region

We study inclusive charged-current reaction through total cross sections of neutrino-nucleus scattering within the framework of a relativistic single-particle model in the quasielastic region. To describe the final-state interaction between knocked-out nucleons and the residual nucleus, a real potential of final nucleons, which is generated by a relativistic mean field, is used with the assumption of no loss of flux, which leads to current conservation and gauge invariance. We calculate ({nu}{sub {mu},{mu}}{sup -}) and ({nu}-bar{sub {mu},{mu}}{sup +}) reactions. In these calculations, {sup 12}C, {sup 40}Ca, and {sup 208}Pb are used as target nuclei and the incident neutrino (antineutrino) energies are exploited up to 4 GeV. We find that the effect of the final-state interaction by the real potential of the knocked-out nucleons reduces cross sections by about 15%, similar to the effect of electron scattering. Furthermore, the effect of the Coulomb distortion for the outgoing leptons is shown to be different from the electron scattering. Finally, our total cross sections by scaling number of participated nucleons are presented to compare with experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Evaluation of the γn→π⁻p differential cross section in the Δ-isobar region

Differential cross sections for the process γn→π⁻p have been extracted from MAMI-B measurements of γd→π⁻pp, accounting for final-state interaction effects, using a diagrammatic technique taking into account the NN and πN final-state interaction amplitudes. Results are compared to previous measurements of the inverse process, π⁻p→nγ, and recent multipole analyses.

Briscoe, W. J.↗
DOE OSTI2015

Comparison of GiBUU calculations with MiniBooNE pion production data

Background: Neutrino-induced pion production can give important informationon the axial coupling to nucleon resonances. Furthermore, pion production represents a major background to quasielastic-like events. one pion production data from the MiniBooNE in charged current neutrino scattering in mineral oil appeared higher than expected within conventional theoretical approaches. Purpose: We aim to investigate which model parameters affect the calculated cross section and how they do this. Method: The Giessen Boltzmann–Uehling–Uhlenbeck (GiBUU) model is used for an investigation of neutrino-nucleus reactions. Results: Presented are integrated and differential cross sections for 1π{sup +} and 1π{sup 0} production before and after final state interactions in comparison with the MiniBooNE data. Conclusions: For the MiniBooNE flux all processes (QE, 1π-background, Δ, higher resonance production, DIS) contribute to the observed final state with one pion of a given charge. The uncertainty in elementary pion production cross sections leads to a corresponding uncertainty in the nuclear cross sections. Final state interactions change the shape of the muon-related observables only slightly, but they significantly change the shape of pion distributions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Quasielastic scattering with the relativistic Green’s function approach

A relativistic model for quasielastic (QE) lepton-nucleus scattering is presented. The effects of final-state interactions (FSI) between the ejected nucleon and the residual nucleus are described in the relativistic Green’s function (RGF) model where FSI are consistently described with exclusive scattering using a complex optical potential. The results of the model are compared with experimental results of electron and neutrino scattering.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

K{sub l3{gamma}}{sup +} decays revisited: Branching ratios and T-ODD momenta correlations

We calculate the branching ratios of the K{sup +} {yields} {pi}{sup 0}l{sup +}{nu}{sub l{gamma}} (l = e, Micro-Sign ) decays, and the T-odd triple momenta correlations {xi} = q {center_dot} [p{sub l} Multiplication-Sign p{sub {pi}}]/M{sub K}{sup 3}, due to the electromagnetic final-state interaction, in these processes. The contributions on the order of {omega}{sup -1} and {omega}{sup 0} to the corresponding amplitudes are treated exactly. For the branching ratios, the corrections on the order of {omega} are estimated and demonstrated to be small. We compare the results with those of other authors. In some cases our results differ considerably from the previous ones.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The In-medium Mass and Widths of Light Vector Mesons

Partial restoration of chiral symmetry in ordinary nuclear matter suggests the modification of properties of vector mesons, such as a shift in mass and/or a change of width. Photoproduction of vector mesons off nuclei were performed at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). The properties of the {rho}, {omega} and {phi} mesons were investigated via their rare leptonic decay to e+e-. This decay channel has an advantage over hadronic modes as it eliminates final state interactions in the nuclear matter. After subtracting the combinatorial background, the meson mass distributions were extracted for each of the nuclear targets. No significant mass shift is observed, however substantial increase in the widths of the mesons is reported.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Isospin symmetry violating effects and scattering length extraction from kaon decays

The isospin symmetry breaking effects in the charged kaons decays to two or three pions are considered. In semileptonic decay K{sup {+-}} {yields} {pi}{sup +}{pi}{sup -}e{sup {+-}}{nu} (called K{sub e4}) these effects turn out to be crucial for correct extraction of {pi}{pi} scattering lengths. Taking in account electromagnetic interaction between the pions in the final state and isospin symmetry breaking due to different masses of charged and neutral pions allows to adjust the values of scattering lengths obtained from experimental data on K{sub e4} decay and predictions of Chiral Perturbation Theory (ChPT). Final state interactions of pions in the decay K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{pi}{sup 0} leading to the anomaly (cusp) in the {pi}{sup 0}{pi}{sup 0} invariant mass distribution in the vicinity of charged pions' threshold are discussed and recent results of accounting of the electromagnetic interaction among charged pions leading to {pi}{sup +}{pi}{sup -} bound states (pioniumatom) just under the charged pions' threshold are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Progress on Neutron-Target Multipoles above 1 GeV

We report a new extraction of nucleon resonance couplings using π{sup -} photo-production cross sections on the neutron. The world database for the process γn → π{sup -}p above 1 GeV has quadrupled with the addition of new differential cross sections from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab in Hall B. Differential cross sections from CLAS have been improved with a new final-state interaction determination using a diagrammatic technique taking into account the SAID phenomenological NN and πN final-state interaction amplitudes. Resonance couplings have been extracted and compared to previous determinations. With the addition of these new cross sections, significant changes are seen in the high-energy behavior of the SAID cross sections and amplitudes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Study of the Hyperon-Nucleon Interaction in Exclusive Λ Photoproduction off the Deuteron

The study of final-state interactions in exclusive hyperon photoproduction off the deuteron is a promising approach to extract information about the hyperon-nucleon (YN) interaction. First preliminary results on the azimuthal asymmetry ∑, as well as the polarization transfer coeffcients Ox, Oz, Cx, and Cz for the reaction γd → K+ Λn initiated with linearly and circularly polarized photon beam are presented. The data were taken with the CLAS detector in Hall B of Jefferson Lab during the E06-103 experiment. The large kinematic coverage of the CLAS, combined with the exceptionally high quality of the experimental data, allows identifying and selecting final-state interaction events to extract single- and double-polarization observables and their kinematical dependencies.

Zachariou, Nicholas↗
DOE OSTI2026

Inclusive Search for Anomalous Single-Photon Production in MicroBooNE

We present an inclusive search for anomalous production of single-photon events from neutrino interactions in the MicroBooNE experiment. The search and its signal definition are motivated by the previous observation of a low-energy excess of electromagnetic shower events from the MiniBooNE experiment. We use the Wire-Cell reconstruction framework to select a sample of inclusive single-photon final-state interactions with a final efficiency and purity of 7.0% and 40.2%, respectively. We leverage simultaneous measurements of sidebands of charged current 𝜈 𝜇 interactions and neutral current interactions producing 𝜋 0 mesons to constrain signal and background predictions and reduce uncertainties. We perform a blind analysis using a dataset collected from February 2016 to July 2018, corresponding to an exposure of 6.34 × 10 20 protons on target from the Booster Neutrino Beam at Fermilab. In the full signal region, we observe agreement between the data and the prediction, with a goodness-of-fit 𝑝 value of 0.11. We then isolate a subsample of these events containing no visible protons, and observe 93 ± 22⁢(stat) ±35⁢(syst) data events above prediction, corresponding to just above 2⁢𝜎 local significance, concentrated at shower energies below 600 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The pp{yields}p{Lambda}K{sup +} and pp{yields}p{Sigma}{sup 0}K{sup +} reactions with chiral dynamics

We report on a theoretical study of the pp{yields}p{Lambda}K{sup +} and pp{yields}p{Sigma}{sup 0}K{sup +} reactions near threshold using a chiral dynamical approach. The production process is described by single-pion and single-kaon exchange. The final state interactions of nucleon-hyperon, K-hyperon, and K-nucleon systems are also taken into account. We show that our model leads to a fair description of the experimental data on the total cross section of the pp{yields}p{Lambda}K{sup +} and pp{yields}p{Sigma}{sup 0}K{sup +} reactions. We find that the experimental observed strong suppression of {Sigma}{sup 0} production compared to {Lambda} production at the same excess energy can be explained. However, ignorance of phases between some amplitudes does not allow one to properly account for the nucleon-hyperon final state interaction for the pp{yields}p{Sigma}{sup 0}K{sup +} reaction. We also demonstrate that the invariant mass distribution and the Dalitz plot provide direct information about the {Lambda} and {Sigma}{sup 0} production mechanisms and may be tested by experiments at COSY or HIRFL-CSR.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Effect of three-pion unitarity on resonance poles from heavy meson decays

We study the final state interaction in 3{pi} decay of meson resonances at the Excited Baryon Analysis Center (EBAC) of JLab. We apply the dynamical coupled-channels formulation which has been extensively used by EBAC to extract N{sup *} information. The formulation satisfies the 3{pi} unitarity condition which has been missed in the existing works with the isobar models. We report the effect of the 3{pi} unitarity on the meson resonance pole positions and Dalitz plot.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Probing the High Momentum Component of the Deuteron at High Q{sup 2}

The {sup 2}H(e,e{sup '}p)n cross section at a momentum transfer of 3.5 (GeV/c){sup 2} was measured over a kinematical range that made it possible to study this reaction for a set of fixed missing momenta as a function of the neutron recoil angle {theta}{sub nq} and to extract missing momentum distributions for fixed values of {theta}{sub nq} up to 0.55 GeV/c. In the region of 35 deg. {<=}{theta}{sub nq}{<=}45 deg. recent calculations, which predict that final-state interactions are small, agree reasonably well with the experimental data. Therefore, these experimental reduced cross sections provide direct access to the high momentum component of the deuteron momentum distribution in exclusive deuteron electrodisintegration.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Testing the process dependence of the Sivers function via hadron distributions inside a jet

We study the process dependence of the Sivers function by considering the impact of color-gauge invariant initial and final state interactions on transverse spin asymmetries in proton-proton scattering reactions within the framework of the transverse momentum dependent (TMD), generalized parton model. To this aim, we consider the azimuthal distribution of leading pions inside a fragmenting jet as well as single inclusive jet asymmetry in polarized proton-proton collisions. In contrast to single inclusive pion production, in both cases we can isolate the Sivers contribution and thereby study its process dependence. The predictions for the Sivers asymmetry obtained with and without inclusion of color gauge factors are comparable in size but with opposite signs. We conclude that both processes represent unique opportunities to discriminate among the two approaches and test the universality properties of the Sivers function in hadronic scattering reactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗