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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 541 records · Page 30
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DOE OSTI2011

Complete Photo-production Experiments

The extraction of resonance parameters from meson photo-reaction data is a challenging effort, that would greatly benefit from the availability of several polarization observables, measured for each reaction channel on both proton and neutron targets. In the aim of obtaining such complete experiments, polarized photon beams and targets have been developed at facilities, worldwide. We report on the latest results from the LEGS and GRAAL collaborations, providing single and double polarization measurements on pseudo-scalar meson photo-production from the nucleon.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Strangeness Production at COSY

The paper gives an overview of strangeness-production experiments at the Cooler Synchrotron COSY. Results on kaon-pair and {phi} meson production in pp, pd and dd collisions, hyperon-production experiments and {Lambda}p final-state interaction studies are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent Results from the WASA-at-COSY Experiment

Studies of light meson decays are the key experiments for the WASA detector at COSY-Juelich. One of the world largest data samples of the {eta} meson decays have been recently collected in the pd {yields}{sup 3}He{eta} and in the pp {yields} pp{eta} reactions. The status of the analysis of various decay channels and the further plans for the light meson decay program are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent Results from CLEO

The CLEO Experiment, utilizing symmetric e{sup +}e{sup -} collisions provided by the Cornell Electron Storage Ring (CESR) in the charmonium and bottomonium regions, has a wide-reaching program in the study of hadrons and the strong force. This review briefly summarizes recent contributions the CLEO Collaboration has made in the study of: (1) light quark systems (rare decays of the {eta}'); (2) charmonium radiative decays to light quarks (J/{psi} and {psi}(2S) radiative decays to the {eta} and {eta}'); (3) mesons with open charm (the D and D{sub s} decay constants); (4) charmonium transitions (a multipole analysis of {psi}(2S) {yields} {gamma}{chi}{sub c1,2} and {chi}{sub c1,2} {yields} {gamma}J/{psi}); and (5) bottomonium spectroscopy (confirming evidence for the discovery of the {eta}{sub b}(1S)).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Elastic electron-deuteron scattering in the light-front Hamiltonian dynamics

Within the Light-Front Hamiltonian Dynamics, we are extending our investigation of the deuteron electromagnetic properties by adding new, dynamical two-body terms to the one-body current operator, introduced in previous works. These two-body contributions are generated in a four-dimensional Yukawa model (two fermions interacting through a pion) from an analysis of the Light-Front-projected current that acts on the three-dimensional valence component and fulfills the Ward-Takahashi identity. Preliminary results for the magnetic moment and the non valence probability are shown.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Photoproduction of K{Sigma}(1385) from the nucleon

The reactions of K{Sigma}(1385) photoproduction, i.e., {gamma}p {yields} K{sup +}{Sigma}{sup 0}(1385) and {gamma} {yields} K{sup +}{Sigma}{sup -}(1385), are investigated in the resonance energy region for studying the role of the nucleon and {Delta} resonances of masses around 2 GeV. The Lagrangians for describing the decays of these resonances into the K{Sigma}(1385) channel are constructed and the decay amplitudes are obtained, which allows us to determine the coupling constants using the predictions of quark models or the data listed by the Particle Data Group. The resulting cross sections are compared to the data from the Thomas Jefferson National Accelerator Facility and the SPring-8, which indicates nontrivial contributions from the two-star-rated resonances in the Particle Data Group as well as from some missing resonances predicted by a quark model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The energy dependence of the pp {yields} K{sup +}n{Sigma}{sup +} reaction

The energy dependence of the total cross section for the pp {yields} K{sup +}n{Sigma}{sup +} reaction has been investigated at the magnetic spectrometer COSY-ANKE. Signals from the production of the {Sigma}{sup +} hyperon were searched for in three simultaneously measured spectra. The values obtained for the total production cross section {sigma}({Sigma}{sup +}) are slightly below those of {sigma}({Sigma}{sup 0}) at the same excess energies. They follow a phase space dependence and do not show any evidence for strong threshold effects or a significant n{Sigma}{sup +} final state interaction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Effect of {Lambda}(1405) on structure of multi-antikaonic nuclei

The second-order effects (SOE) including a pole contribution of the {Lambda}(1405)({Lambda}*) and range terms on the structure of multi-antikaonic nuclei are investigated in a relativistic mean-field theory coupled with the nonlinear effective chiral Lagrangian. It is shown that, due to the attractive interaction from the {Lambda}*-pole contribution, the K{sup -} mesons and the protons are more attracted each other than the case without the SOE. On the other hand, the density distribution for neutron is pushed outward due to the repulsive effect from the range terms. The SOE on the formation of the bound state of K{sup -} mesons are also discussed associated with modification of relevant kaonic modes in a dense medium.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Kaonic Atoms

The precision spectroscopy of kaonic hydrogen and kaonic helium x-rays offers a unique possibility to precisely determine the K{sup -}N strong interaction in the low energy limit. Results and status of modern experiments using silicon drift x-ray detectors (SDDs), namely, KEK E570, SIDDHARTA at DA{Phi}NE and E17 at J-PARC, are discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Precision spectroscopy of light kaonic atom X-rays in the SIDDHARTA experiment

The KN system at rest makes a sensitive testing ground for low energy QCD. At the DA{Phi}NE electron-positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons from {Phi}-mesons decaying nearly at rest. The DEAR (DA{Phi}NE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. SIDDHARTA is the first experiment on kaonic helium-3 and deuterium ever, and kaonic hydrogen was remeasured with improved precision.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Precision spectroscopy of kaonic {sup 3}He X-rays at J-PARC

We will measure the X-rays from kaonic {sup 3}He 3d {yields} 2p transition with a precision below 2 eV. It can provide crucial information on the kaon-nucleus strong interaction. The experiment (J-PARC E17) will be performed as Day-1, which is one of the first experiments in the J-PARC hadron facility in the year 2011. An overview and the present status of the J-PARC E17 experiment are described.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Study of the {gamma}d {yields} K{sup +}K{sup -}np reaction and an alternative explanation for the ''{Theta}{sup +}'' peak

We look for an explanation of the peak in the K{sup +}n invariant mass distribution of the {gamma}d {yields} K{sup +}K{sup -}n p reaction that was associated to the {Theta}{sup +}(1540) pentaquark at LEPS. For this we develop a theoretical model adapted to the experiment. The study shows that the method used in the experiment to associate momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K{sup +}n invariant mass in the region of the claimed {Theta}{sup +}(1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2{sigma} significance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A measurement of double spin asymmetry A{sub LT} in semi-inclusive pion electroproduction on a transversely polarized {sup 3}He target

The double spin asymmetry A{sub LT} for {sup 3}He was measured for the first time at Jefferson Lab Hall A in the semi-inclusive {sup 3}He{up_arrow}({sup {yields}e},{pi}{sup +/-}X reactions, using a 6 GeV polarized electron beam on a transversely polarized {sup 3}He target. The produced charged pions were detected in coincidence with the scattered electrons by the high-resolution spectrometer and the BigBite spectrometer, respectively. The kinematic coverage was focused on the valence quark region, x {approx} 0.13-0.41, Q{sup 2}{approx} 1.31-3.10 (GeV/c){sup 2}. When combined with the world data, this new data will provide constraints on the g{sub 1T}{sup q} distribution functions, which describe the longitudinal polarization of quarks in a transversely polarized nucleon. The status of the current analysis and the preliminary results are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent Results on Hadron Spectroscopy and Charmonium from BESIII

pp-bar mass threshold enhancement is studied using the data sample of J/{psi} and y(2S) collected with BESIII detector in 2009. The enhancement is evident in J/{psi} radiative decay, which is consistent with BESII results. No significance narrow enhancement is observed in {psi}(2S) radiative decay. The structure of Xlpar;1835 is also confirmed in J/{psi} = {gamma}{eta}'{pi}{sub +}{pi}{sup -} at BESIII. The spin-singlet P-wave charmonium state h{sub c}(1P) is studied at BESIII, the mass spectra recoiling against the {pi}{sup 0} in the decay {psi}(2S) = {pi}{sup 0}h{sub c} both in h{sub c} inclusive decay and in the final states with a tagged E1-transition photon from h{sub c} {yields} {gamma}{eta}{sub r} are fitted to extract the number of hc signals.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Diffractive Dissociation into {pi}{sup -{pi}-{pi}+} Final States at COMPASS

QCD predicts gluonic excitations like hybrids to contribute to the meson spectrum in addition to qq-bar pair configurations. The most promising way to identify such states is the search for J{sup PC} quantum number combinations which are forbidden in the constituent quark model. The fixed target COMPASS experiment at CERN offers the opportunity to search for such states in the light quark sector with an unprecedented statistics.Diffractive reactions of 190 GeV/c pions on a lead target were studied by COMPASS during a pilot run in 2004. A Partial Wave Analysis (PWA) of the {pi}{sup -{pi}-{pi}+} final state with 42 waves including acceptance corrections through a phase-space Monte Carlo simulation of the spectrometer was performed. The exotic {pi}{sup 1}(1600) meson with quantum numbers J{sup PC} = 1{sup -+} has been clearly established in the rho-pi decay channel with a mass of 1660{+-}10(stat) MeV/c{sup 2} and a width of 269{+-}21(stat) MeV/c{sup 2}. The improved detector performance in 2008 allows us to study this channel with significantly higher statistics. First results of the ongoing analysis of the 2008 data taking period, using a 190 GeV/c pion beam on a liquid hydrogen target are presented in this paper.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Precision measurements of K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} decay at NA48/2 and search for CP violation

The direct emission (DE) and interference (INT) terms of the radiative decay K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} have been measured by the NA48/2 experiment at CERN SPS. About 6 10{sup 5} K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} decays have been selected from data collected during 2003 and 2004. The relative amounts of DE and INT with respect to the dominant Inner Bremsstrahlung (IB) contribution have been measured in the range 0<T{sub {pi}}{sup *}<80 MeV, where T{sub {pi}}{sup *} is the kinetic energy of the charged pion in the kaon rest frame, obtaining: Frac(DE) = (3.32 {+-}0.15{sub stat}{+-}0.14{sub syst})10{sup -2}, Frac(INT) = (-2.35 {+-}0.35{sub stat}{+-}0.39{sub syst}) 10{sup -2}. This is the first observation of an interference term in K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} decays. From this measurement the DE normalized electric and magnetic amplitudes are derived: X{sub E} = (-24 {+-}6) GeV{sup -4}, X{sub M} = (254 {+-} 9) GeV{sup -4}.In addition, the CP violating asymmetry in the K{sup +} and K- branching ratios for this channel has been determined to be less than 1.5 10{sup -3} at 90% confidence level.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Lattice Calculations of Nucleon Form Factors

We present recent results of calculation of the isovector electromagnetic and axial form factors of the nucleon using lattice QCD with three different lattice actions and pion masses down to m{sub {pi}} > or approx. 300 MeV. Because of the precision of our high-statistics calculations, we can test predictions of baryon chiral perturbation theory for the charge and axial radii of the nucleon. We find that currently available baryon ChPT calculations disagree with our data, indicating that the corresponding effective theory approximations are not valid above m{sub {pi}{approx_equal}3}00 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Two-pion exchange currents in photodisintegration of the deuteron

Chiral effective field theory (ChEFT) is a modern framework to analyze the properties of few-nucleon systems at low energies. It is based on the most general effective Lagrangian for pions and nucleons consistent with the chiral symmetry of QCD. For energies below the pion-production threshold it is possible to eliminate the pionic degrees of freedom and derive nuclear potentials and nuclear current operators solely in terms of the nucleonic degrees of freedom. This is very important because, despite a lot of experience gained in the past, the consistency between two-nucleon forces, many-nucleon forces and the corresponding current operators has not been achieved yet. In this presentation we consider the recently derived long-range two-pion exchange (TPE) contributions to the nuclear current operator which appear at next-to leading order of the chiral expansion. These operators do not contain any free parameters. We study their role in the deuteron photodisintegration reaction and compare our predictions with experimental data from Refs [3]. The bound and scattering states are calculated using five different chiral N2LO nucleon-nucleon (NN) potentials which allows to estimate the theoretical uncertainty at a given order in the chiral expansion. For some observables the results are very close to the reference predictions based on the AV18 NN potential and the current operator (partly) consistent with this force.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗