Nucleon and Pion-nucleon Form Factors from Lattice Qcd
چکیده
The isovector Nucleon electromagnetic form factors GE(q ) and GM(q ) are evaluated in Lattice QCD using Wilson fermions. A lattice of spatial extent 3 fm is used in the quenched theory allowing the extraction of the form factors for momentum transfer squared between 0.1 and 2 GeV for lowest pion mass of about 400 MeV. The calculation is also performed using two degenerate dynamical flavors of Wilson quarks for pion masses comparable to those in the quenched theory allowing a direct comparison. An effective chiral theory is used for the extrapolation of the magnetic moment and isovector radii at the physical limit. In addition, we present recent results from the calculation of the momentum dependence of the axial form factors GA(q ) and Gp(q ) along with the calculation of the GπNN form factor on the same set of lattices. This enables us to test the Goldberger-Treiman relation and compare to the experimental value of the pion-nucleon strong coupling constant gπNN .