Short- and long-distance contributions to the rare decay K_L-->mu+ mu-
  The interplay between short- and long-distance contributions to the K_L-->mu+ mu- decay amplitude is analyzed. The long-distance piece is estimated using chiral perturbation theory techniques and large-N_C considerations, leading to a consistent description of the pi^0-->e+ e-, eta-->mu+ mu- and K_L-->mu+ mu- branching ratios. 
D. Gomez Dumm, A. Pich