Speaker
Description
The $N\pi$ state contribution to nucleon 3-pt functions involving the pseudoscalar density P(x) and the time component $A_{4}(x)$ of the axial vector current are computed to LO in ChPT. In case of the latter the $N\pi$ contribution is O($M_N$) enhanced compared to the single nucleon ground state contribution. In addition, a relative sign in two terms of the $N\pi$-state contribution leads an almost linear dependence on the operator insertion time, as it is observed in lattice data. In case of the pseudoscalar density the $N\pi$ contribution is strongly dependent on the momentum transfer, leading to a sizeable distortion of the pseudoscalar nucleon form factor. The role the $N\pi$ excited states play in violating the PCAC form factor relation is also discussed.
