The anapole form factor of the nucleon
  The anapole form factor of the nucleon is calculated in chiral perturbation theory in leading order. To this order, the form factor originates from the pion cloud, and is proportional to the non-derivative parity-violating pion-nucleon coupling. The momentum dependence of the form factor - and in particular, its radius - is completely determined by the pion mass. 
C. M. Maekawa and U. van Kolck (Kellogg Radiation Laboratory of   California Institute of Technology)