Antonios Tsapalis (Athens):

Nucleon deformation from Lattice QCD

Abstract:

The issue of nucleon and Delta(1232) deformation is discussed through the evaluation of the N to Delta electromagnetic transition and Delta electromagnetic form factors in Lattice QCD. The momentum dependence of the  form factors is studied using 2+1 staggered dynamical flavors at pion masses as low as 350 MeV and compared to results obtained in the Wilson quenched and two-flavor dynamical theory at similar pion masses. The measurement of small non-zero quadrupole amplitudes, in agreement to recent experiments, establishes the existence of deformation in the N and Delta states.

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