[Jlab-seminars] Physics Seminar Announcement

[Luci Collins]

*Physics Seminar
Friday, Oct. 21, 2011
11:00AM
CC Auditorium
Cookies & Coffee 10:45AM

**Christian Weiss
Jefferson Lab *

*"Quantifying the Nucleon's Meson Cloud with Transverse Charge Densities"*

The transverse charge and current densities provide an objective spatial 
representation of the nucleon's elastic form factors and contain 
essential information on its partonic structure in QCD. They are usually 
obtained as the two-dimensional Fourier transforms of the form factors 
measured in electron scattering at spacelike momentum transfer. We 
present a novel approach in which the transverse densities are 
represented as dispersion integrals of the form factors in the timelike 
region. This formulation relates the transverse distribution of quarks 
in the nucleon's periphery to the well-known hadronic exchange 
mechanisms and permits a fully quantitative assessment of traditional 
notions such as the "pion cloud" and "vector meson dominance." We 
summarize the present knowledge and outline how future form factor 
measurements at JLab and other facilities could further explore the role 
of mesons in the nucleon's periphery. We also show that the transverse 
charge density in the pion can be reconstructed with unprecedented 
accuracy from the timelike form factor measured in e+e- annihilation 
experiments and reveals the presence of pointlike quark-antiquark 
configurations at the center. [PRC82 (2010) 042201; PRC84, 045205 
(2011); PRD83 (2011) 013006] *
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