Nucleon Form Factors and their Modification in the Nuclear Medium 
by G. Ron (Nuclear Science Division, Lawrence Berkeley National Lab)
 
Electromagnetic form factors of the nucleon are model-independent observables 
which encode our ignorance of its complex internal structure. 
In recent years significant attention has been drawn to these observables 
due to the discovery of unexplained deviations from previously measured 
results. 

Recoil polarization measurements and high precision cross section measurements 
are allowing the electric to magnetic form factors ratios be determined 
with unprecedented precision. New results from MIT-BLAST and, 
more recently, from Hall A at Jefferson Lab indicate that there is an unexpected 
decrease in the proton form factor ratio at low Q2. Even newer data 
is expected to come from MAINZ and JLab experiments in the near future. 
Nucleon modifications in the nuclear matter have been suggested as possible 
explanation of different phenomena, such as the EMC effect and quenching 
of the Coulomb sum rule, beyond the N-N interaction. Unambiguous 
evidence these modifications has yet to be found. A sensitive probe 
for such modification, which is predicted to minimize the effects of final 
state interactions and meson exchange currents, is the ratio of the electric 
to magnetic nucleon form factors. 

This talk will address the measurement, and interpretation, of the nucleon 
form factors, present new results of the proton form factors as a probe of 
the proton peripheral structure, and discuss the probing of the nucleon 
modification in the medium using measurements of the EM form factors.