Moments of the neutron charge form factor and the N --> Delta quadrupole transition.
Recent data allow a new parametrization of the neutron charge form factor GnE. A parameter-free quark-model relation between GnE and the N-->Delta quadrupole form factor G(N-->Delta)C2 is used to predict G(N-->Delta)C2 from GnE data. In particular, <r2n> is related to N-->Delta quadrupole moment Q(N-->Delta), while <r4n> connects to the N-->Delta quadrupole transition radius <r2(N-->Delta)>. From the latter we derive an experimental value for the charge radius of the light constituent quarks r(gamma(q)) = 0.8 fm. Finally, the C2/M1 ratio in pion electroproduction is predicted from the elastic neutron form factor data.
Grabmayr
P
P
Physikalisches Institut, Universität Tübingen, D-72076 Tübingen, Germany. grabmayr@pit.uni-tuebingen.de
Buchmann
A J
AJ