Finite size effects on $M_\pi$ in QCD from Chiral Perturbation Theory
  We present a determination of the shift $M_\pi(L)-M_\pi$ due to the finite spatial box size $L$ by means of $N_f=2$ Chiral Perturbation Theory and L\"uscher's formula. The range of applicability of the chiral prediction is discussed. 
G. Colangelo, S. D\"urr, R. Sommer