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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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DOE OSTI2017

Off-forward gluonic structure of vector mesons

Here, the spin-independent and transversity generalized form factors (GFFs) of the Φmeson are studied using lattice QCD calculations with light quark masses corresponding to a pion mass m π ~ 450(5) MeV . One transversity and three spin-independent GFFs related to the lowest moments of leading-twist spin-independent and transversity gluon distributions are obtained at six nonzero values of the momentum transfer up to 1.2 Ge V 2 . These quantities are compared with the analogous spin-independent quark GFFs and the electromagnetic form factors determined on the same lattice ensemble. In conclusion, the results show quantitative distinction between the spatial distribution of transversely polarized gluons, unpolarized gluons, and quarks and point the way towards further investigations of the gluon structure of nucleons and nuclei.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

High Statistics Analysis of All-Neutral Decays of Vector Mesons with the Radphi Experiment

The differential cross section and spin density matrix elements for w(782) meson photoproduction in the reaction 9Be(yp,pw)8Li have been measured in the energy range 4.4 - 5.4 GeV using the Radphi detector. Radphi used a 9Be target, and identified the final state by triggering on the recoil proton plus neutrals. At the kinematics of this experiment, the observed nuclear cross section is consistent with the p cross section measured by prior experiments when multiplied by 4 for the number of protons in the nucleus, in agreement with a naive spectator model. However, the spin observables show some deviation from a spectator model, particularly approaching the low-t limit of the experimental acceptance. Besides the cross sections, spin density matrix elements in Gottfried Jackson and Helicity frame have been measured. The data selection is discussed and the acceptance is examined and quantified.

Mokaya, Fridah↗