5,465 research outputs found
Electromagnetic Form Factors and the Hypercentral CQM
New results about the electromagnetic form factors of the nucleon are
obtained with a semirelativistic version of the hypercentral constituent quark
model (hCQM) and a relativistic current. The complex structure of the
constituent quarks is taken into account implicitly by means of
phenomenological constituent quark form factors. We obtain a detailed
reproduction of the experimental data up to , moreover our findings
about constituent quark root mean square radii are of the same order than the
recent ones obtained analyzing the proton structure functions.Comment: 11 pages, 4 figure
A relativistic study of the nucleon form factors
We perform a calculation of the relativistic corrections to the
electromagnetic elastic form factors of the nucleon obtained with various
Constituent Quark Models. With respect to the non relativistic calculations a
substantial improvement is obtained up to Q^2 about 2 (GeV/c)^2.Comment: 10 pages, 6 figures (1a,1b,1c,2a,2b,2c), to be published on Z. Phys.
Electromagnetic Form Factors and the hCQM
We briefly report on results about the electromagnetic form factors of the
nucleon obtained with different models and then we concentrate our attention on
recent results obtained with the hypercentral constituent quark model (hCQM).Comment: 12 pages, 5 figures, Invited talk at 27th Symposium on Nuclear
Physics, Taxco, Guerrero, Mexico, 5-8 Jan 200
Single Spin Asymmetries in Semi-Inclusive Electroproduction: Access to Transversity
We discuss the quark transversity distribution function and a possible way to
access it through the measurement of single spin azimuthal asymmetry in
semi-inclusive single pion electroproduction on a transversely polarized
target.Comment: 5 pages, Latex using aipproc.sty (included), to appear in proceedings
of "Second Workshop on Physics with an Electron Polarized Light Ion
Collider", Sept. 14-16, 2000, MIT, Cambridge, US
Spin-independent and double-spin cos(phi) asymmetries in semi-inclusive pion electroproduction
We consider the cos(phi) dependence of the longitudinal double-spin asymmetry
for charged pion electroproduction in semi-inclusive deep inelastic scattering,
emphasizing intrinsic transverse momentum effects. This azimuthal asymmetry
allows to measure the cos(phi) moments of the unpolarized and double-spin
cross-section, simultaneously. The size of the asymmetry, in the approximation
where all twist-3 interaction-dependent distribution and fragmentation
functions are set to zero, is estimated for HERMES kinematics; both the
spin-independent and the double-spin cos(phi) moments are predicted to be
sizeable and negative.Comment: LaTeX, 4 pages, 4 figures. Discussion on the acceptance effects
added; recent parameterizations of distribution and fragmentation functions
used, figures replaced. Final version to appear in Physics Letters
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