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High Energy Physics Seminars
| Special Nuclear and High Energy
Wednesday, April 16, 2003
Physics Building, Room 204
Note special time.
Prof. Xiangdong Ji
[Host: Xiaotong Song]
Univ. of Maryland
"Viewing the nucleon through "color" filters"
While the form factors and parton distributions provide separately
the shape of the proton in coordinate and momentum spaces, a more
powerful imaging of the proton structure can be obtained through
phase-space distributions. In this talk, I introduce the Wigner-type
quark and gluon distributions which depict a full-3D proton at every
fixed light-cone momentum, like what is seen through momentum
("color")-filters. After appropriate phase-space reductions, the
Wigner distributions are related to the generalized parton distributions
(GPD's) and transverse-momentum dependent parton distributions, which
are measurable in high-energy experiments. The new interpretation of
GPD's provides a classical way to visualize the orbital motion of the
quarks, which is known to be the key to the spin and magnetic moment
of the proton.
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