Short- and long-distance contributions to the rare decay K_L-->mu+ mu-

Abstract

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.

Comments: 4 pages, 1 figure, talk given at the Euroconference QCD 98, Montpellier, France, July 1998