Speaker
Prof.
Egle Tomasi-Gustafsson
(IPN Orsay)
Description
The study of electromagnetic nucleon form factors is object of
experimental and theoretical studies since decades. At moderate
values of the momentum transfer squared, q^2, the individual
determination of the electric and magnetic FFs strongly constrain
the nucleon models, whereas at larger q^2 the validity of analyticity
and of the asymptotic properties predicted by QCD can be tested.
New possibilities are opened by the recent advances in accelerator
technology and polarimetry. The challenges opened by FFs
measurements at high values of transferred momentum and/or in the
search of better precision are related to the validity of radiative
corrections, the modelization of the background and to the
interpretation, which is related to the description of the
internal structure of the nucleon. At the accelerator complex
FAIR (Darmstadt, Germany) a program of measurements of electromagnetic
proton form factors is foreseen in the time-like region, with the
detector PANDA. The high intensity and high energy antiproton beams
will open the possibility to determine these form factors in a wide
kinematical range, through the annihilation reaction
pbarp -> e+e- and also accessing for the first time the unphysical
region. In the space-like region, the polarization method has been
recently applied. The very precise data show an unexpected behavior, in contradiction with most of the nucleon models. The time-like data,
together with the information from the space-like region, will provide the experimental ground for a unified view of the electromagnetic structure
of the proton as observed in scattering and annihilation reactions.
The present status and future perspectives in this field will be presented.
