In particle physics the semileptonic decay of a hadron refers to a decay through the weak interaction in which one lepton (and the corresponding neutrino) is produced in addition to one or more hadrons.
An example of a semileptonic decay is
This is to be contrasted with purely hadronic decays, such as K0
→ π+
+ π−
, which are also mediated by the weak force.
Semileptonic decays of neutral kaons have been used to study kaon oscillations.