19 research outputs found
Longitudinal-Transverse Separations of Structure Functions at Low for Hydrogen and Deuterium
We report on a study of the longitudinal to transverse cross section ratio,
, at low values of and , as determined from
inclusive inelastic electron-hydrogen and electron-deuterium scattering data
from Jefferson Lab Hall C spanning the four-momentum transfer range 0.06 GeV. Even at the lowest values of , remains
nearly constant and does not disappear with decreasing , as expected. We
find a nearly identical behaviour for hydrogen and deuterium.Comment: 4 pages, 2 gigure
Measurements of electron-proton elastic cross sections for
We report on precision measurements of the elastic cross section for
electron-proton scattering performed in Hall C at Jefferson Lab. The
measurements were made at 28 unique kinematic settings covering a range in
momentum transfer of 0.4 5.5 . These measurements
represent a significant contribution to the world's cross section data set in
the range where a large discrepancy currently exists between the ratio of
electric to magnetic proton form factors extracted from previous cross section
measurements and that recently measured via polarization transfer in Hall A at
Jefferson Lab.Comment: 17 pages, 18 figures; text added, some figures replace
Transverse momentum dependence of semi-inclusive pion production
Cross sections for semi-inclusive electroproduction of charged pions
() from both proton and deuteron targets were measured for
, GeV, , and GeV. For
GeV, we find the azimuthal dependence to be small, as expected
theoretically. For both and , the dependence from the
deuteron is found to be slightly weaker than from the proton. In the context of
a simple model, this implies that the initial transverse momenta width of
quarks is larger than for quarks and, contrary to expectations, the
transverse momentum width of the favored fragmentation function is larger than
the unfavored one.Comment: 15 pages, 4 figures. Fit form changed to include Cahn effect Minor
revisions. Added one new figur
Nuclear transparency from quasielastic A(e,e'p) reactions uo to Q^2=8.1 (GeV/c)^2
The quasielastic (e,ep) reaction was studied on targets of
deuterium, carbon, and iron up to a value of momentum transfer of 8.1
(GeV/c). A nuclear transparency was determined by comparing the data to
calculations in the Plane-Wave Impulse Approximation. The dependence of the
nuclear transparency on and the mass number was investigated in a
search for the onset of the Color Transparency phenomenon. We find no evidence
for the onset of Color Transparency within our range of . A fit to the
world's nuclear transparency data reflects the energy dependence of the free
proton-nucleon cross section.Comment: 11 pages, 6 figure
Cross sections and Rosenbluth separations in 1H(e, e'K+)Lambda up to Q2=2.35 GeV2
The kaon electroproduction reaction 1H(e,e'K+)Lambda was studied as a
function of the virtual-photon four-momentum, Q2, total energy, W, and momentum
transfer, t, for different values of the virtual- photon polarization
parameter. Data were taken at electron beam energies ranging from 3.40 to 5.75
GeV. The center of mass cross section was determined for 21 kinematics
corresponding to Q2 of 1.90 and 2.35 GeV2 and the longitudinal, sigmaL, and
transverse, sigmaT, cross sections were separated using the Rosenbluth
technique at fixed W and t. The separated cross sections reveal a flat energy
dependence at forward kaon angles not satisfactorily described by existing
electroproduction models. Influence of the kaon pole on the cross sections was
investigated by adopting an off-shell form factor in the Regge model which
better describes the observed energy dependence of sigmaT and sigmaL.Comment: 5 pages, 4 figures. Submitted to Physical Review C, Rapid
Communication
Electroproduction of Eta Mesons in the S11(1535) Resonance Region at High Momentum Transfer
The differential cross-section for the process p(e,e'p)eta has been measured
at Q2 ~ 5.7 and 7.0 (GeV/c)2 for centre-of-mass energies from threshold to 1.8
GeV, encompassing the S11(1535) resonance, which dominates the channel. This is
the highest momentum transfer measurement of this exclusive process to date.
The helicity-conserving transition amplitude A_1/2, for the production of the
S11(1535) resonance, is extracted from the data. Within the limited Q2 now
measured, this quantity appears to begin scaling as 1/Q3 - a predicted, but not
definitive, signal of the dominance of perturbative QCD, at Q2 ~ 5 (GeV/c)2.Comment: LaTeX, 30 pages, 29 figures, uses longtable.sty, slashbox.sty,
ifthen.sty; (v2) corrected figure inclusions; (v3) changes in filenames for
prc and added Report-no; (v4) correction based on comments from referee
{small changes to abstract and conclusion, inserted figure 9, other small
changes to the text} (v5) very minor additions to improve clarit