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Nucleon axial coupling constants and QCD sum rules

Description: QCD sum rules are used to obtain the isovector and isoscalar'' axial vector coupling constants, g{sub A} and g{sub A}{sup S}. We find g{sub A} = 1.26 {plus minus} 0.08, g{sub A}{sup S} = 0.13 {plus minus} 0.08 with sum results for g{sub A}{minus}1 and g{sub A} + g{sub A}{sup S}. These sum rules also show that in the limit of chiral symmetry restoration, g{sub A} {yields} 1 and g{sub A}{sup S} {yields} {minus}1.
Date: January 1, 1991
Creator: Henley, E.M. (Washington Univ., Seattle, WA (United States)); Hwang, W.Y.P. (National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Physics) & Kisslinger, L.S. (Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Measurement of Pressure Dependent Fluorescence Yield of Air: Calibration Factor for UHECR Detectors

Description: In a test experiment at the Final Focus Test Beam of the Stanford Linear Accelerator Center, the fluorescence yield of 28.5 GeV electrons in air and nitrogen was measured. The measured photon yields between 300 and 400 nm at 1 atm and 29 C are Y(760 Torr){sup air} = 4.42 {+-} 0.73 and Y(760 Torr){sup N{sub 2}} = 29.2 {+-} 4.8 photons per electron per meter. Assuming that the fluorescence yield is proportional to the energy deposition of a charged particle traveling through air, good agreement with measurements at lower particle energies is observed.
Date: July 6, 2005
Creator: Belz, J.W.; Burt, G.W.; Cao, Z.; Chang, F.Y.; Chen, C.C.; Chen, C.W. et al.
Partner: UNT Libraries Government Documents Department

Techniques of the FLASH Thin Target Experiment

Description: The fluorescence yield in air is reported for wavelength and pressure ranges of interest to ultra-high energy cosmic ray detectors. A 28.5 GeV electron beam was used to excite the fluorescence. Central to the approach was the system calibration, using Rayleigh scattering of a nitrogen laser beam. In atmospheric pressure dry air, at 304 K the yield is 20.8 {+-} 1.6 photons per MeV.
Date: October 30, 2007
Creator: Abbasi, R.; Abu-Zayyad, T.; Belov, K.; Belz, J.; U., /Utah; Bergman, D.R. et al.
Partner: UNT Libraries Government Documents Department