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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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44 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Analyzing Unfavored Fragmentation Functions Using NJL-Jet Model

The Nambu-Jona-Lasinio (NJL)-jet model provides a sound framework for calculating the fragmentation functions in an effective chiral quark theory, where the momentum and isospin sum rules are satisfied without the introduction of ad hoc parameters. The most recent version of the model includes the fragmentation of the light and strange quarks to pions, kaons, nucleons, and antinucleons; where the effects of the production of secondary pions and kaons from the vector mesons {rho}, K* and {phi} are also calculated. The results for the model fragmentation function exhibit a qualitative agreement with the empirical parameterizations. The results also allow to test, within the model assumptions, several assumption in parametrizations of the unfavored fragmentation functions used in empirical fits to the experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Prospects for X(3872) Detection at P-barANDA

Monte-Carlo simulations for a resonance scan of the charmonium-like state X(3872) at P-barANDA are performed. Final state radiation hadronic background reactions are taken into account. The signal reconstruction uses a realistic pattern recognition (track finder and track fitter) and electron/pion discrimination.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Prediction of narrow N* and {Lambda}* with hidden charm

The interaction between various charmed mesons and charmed baryons, such as D-bar{Sigma}{sub c}-D-bar{Lambda}{sub c}, D-bar*{Sigma}{sub c}-D-bar*{Lambda}{sub c}, and related strangeness channels, are studied within the framework of the coupled channel unitary approach with the local hidden gauge formalism. Six narrow N* and {Lambda}* resonances are dynamically generated with mass above 4 GeV and width smaller than 100 MeV. These predicted new resonances definitely cannot be accommodated by quark models with three constituent quarks. We make estimates of production cross sections of these predicted resonances in p-barp collisions for PANDA at the forthcoming FAIR facility.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A systematic study of the strong interaction with P-barANDA

The theory of Quantum Chromo Dynamics (QCD) reproduces the strong interaction at distances much shorter than the size of the nucleon. At larger distance scales, the generation of hadron masses and confinement cannot yet be derived from first principles on basis of QCD. The PANDA experiment at FAIR will address the origin of these phenomena in controlled environments. Beams of antiprotons together with a multi-purpose and compact detection system will provide unique tools to perform studies of the strong interaction. This will be achieved via precision spectroscopy of charmonium and open-charm states, an extensive search for exotic objects such as glueballs and hybrids, in-medium and hypernuclei spectroscopy, and more. An overview is given of the physics program of the P-barANDA collaboration.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Hadron Physics with PANDA at FAIR

The recently established FAIR facility in Darmstadt has a broad program in the field of hadron and nuclear physics utilizing ion beams with unprecedented intensity and accuracy. The PANDA experiment, which is integrated in the HESR storage ring for antiprotons is at the center of the hadron physics program. It includes among others topics like hadron spectroscopy in the charmonium mass region and below, hyperon physics and electromagnetic processes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

THE DISCOVERY OF GEOMAGNETICALLY TRAPPED COSMIC-RAY ANTIPROTONS

The existence of a significant flux of antiprotons confined to Earth's magnetosphere has been considered in several theoretical works. These antiparticles are produced in nuclear interactions of energetic cosmic rays with the terrestrial atmosphere and accumulate in the geomagnetic field at altitudes of several hundred kilometers. A contribution from the decay of albedo antineutrons has been hypothesized in analogy to proton production by neutron decay, which constitutes the main source of trapped protons at energies above some tens of MeV. This Letter reports the discovery of an antiproton radiation belt around the Earth. The trapped antiproton energy spectrum in the South Atlantic Anomaly (SAA) region has been measured by the PAMELA experiment for the kinetic energy range 60-750 MeV. A measurement of the atmospheric sub-cutoff antiproton spectrum outside the radiation belts is also reported. PAMELA data show that the magnetospheric antiproton flux in the SAA exceeds the cosmic-ray antiproton flux by three orders of magnitude at the present solar minimum, and exceeds the sub-cutoff antiproton flux outside radiation belts by four orders of magnitude, constituting the most abundant source of antiprotons near the Earth.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Analysis of the meson-meson data in the framework of the dispersion D-matrix method

We describe the meson-meson data for the (IJ{sup PC}=00{sup ++}) wave at 280{<=}{radical}(s){<=}1900 MeV in two approaches: (i) the K-matrix approach and (ii) the dispersion relation D-matrix method. With a good description of low-energy data (at 280{<=}{radical}(s){<=}900 MeV) as well as the data of two-meson transition amplitudes and antiproton-proton annihilation into three pseudoscalar meson states (at 450{<=}{radical}(s){<=}1950 MeV) we have found the positions of the resonance poles: (i) for the {sigma} meson pole: M{sub {sigma}=}(390{+-}35)-i(235{+-}50) MeV; (ii) two poles for the f{sub 0}(980), on the second sheet (under the {pi}{pi} cut): M{sub I}=(1011{+-}5)-i(35{+-}5) MeV, and on the third sheet (under the {pi}{pi} and KK cuts), M{sub II}=(1035{+-}50)-i(460{+-}50) MeV; for the f{sub 0}(1370) meson, M=(1285{+-}30)-i(160{+-}20) MeV; for the f{sub 0}(1500) meson, M=(1488{+-}4)-i(53{+-}5) MeV; for the f{sub 0}(1790) meson, M=(1775{+-}25)- i(140{+-}15) MeV; and for the broad state f{sub 0}(1200-1600) M=(1540{+-}120)-i(550{+-}70) MeV. Our estimation of the scalar-isoscalar scattering length obtained under different parameterizations and assumptions about the quality of low-energy {pi}{pi} scattering data is a{sub 0}{sup 0}=(0.215{+-}0.040)m{sub {pi}}{sup -1}. We also discuss the idea according to which the {sigma} meson could be a remnant of the confinement singularity, 1/s{sup 2}, in a white channel.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Feynman scaling violation on baryon spectra in pp collisions at LHC and cosmic ray energies

A significant asymmetry in baryon/antibaryon yields in the central region of high energy collisions is observed when the initial state has nonzero baryon charge. This asymmetry is connected with the possibility of baryon charge diffusion in rapidity space. Such a diffusion should decrease the baryon charge in the fragmentation region and translate into the corresponding decrease of the multiplicity of leading baryons. As a result, a new mechanism for Feynman scaling violation in the fragmentation region is obtained. Another numerically more significant reason for the Feynman scaling violation comes from the fact that the average number of cut Pomerons increases with initial energy. We present the quantitative predictions of the Quark-Gluon String Model for the Feynman scaling violation at LHC energies and at even higher energies that can be important for cosmic ray physics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗