  We study lepton flavour violating two- and three-body decays of pseudoscalar
mesons in Effective Field Theory (EFT). We give analytic formulae for the decay
rates in the presence of a complete basis of QED and QCD-invariant operators.
The constraints are obtained at the experimental scale, then translated to the
weak scale via one-loop RGEs. The large RG-mixing between tensor and
(pseudo)scalar operators weakens the constraints on scalar and pseudoscalar
operators at the weak scale.
