Off-forward parton distributions and impact parameter dependence of parton structure

The connection between parton distributions as a function of the impact parameter and off-forward parton distributions is discussed in the limit of vanishing skewedness parameter $\zeta$, i.e. when the off-forwardness is purely transverse. For the $2^{nd}$ moment it is also illustrated how to relate $\zeta\neq 0$ data to $\zeta=0$ data, which is important for experimental measurements of these observables.