Electromagnetic properties of diquarks

摘要

Diquark correlations play an important role in hadron physics. The properties of diquarks can be obtained from the corresponding bound-state equation. Using a model for the effective quark-quark interaction that has been proved successfully in the light meson sector. we solve the scalar diquark Bethe-Salpeter equations and use the obtained Bethe-Salpeter amplitudes to compute the diquarks' electromagnetic form factors. The scalar ud diquark charge radius is about 8 % larger than the pion charge radius. indicating that these diquarks are somewhat larger in size than the corresponding mesons. We also provide analytic fits for the form factor over a moderate range in Q(2), which may be useful, for example, in building quark-diquark models of nucleons.