lepton

noun

Etymology: From Ancient Greek λεπτός (leptós) + -on. Coined by Dutch-American physicist Abraham Pais in 1947.

1. An elementary particle that has a spin of 1/2 (i.e., is a fermion) and does not interact via the strong nuclear force; examples include the electron, the muon, the neutrino and the tauon.

   “In the present paper we deal with the second order radiative correction to the beta disintegration of nucleon, assuming the Fermi's interaction between necleon and lepton fields, and show that there appears such an ultraviolet divergence as can not be removed by the procedure of renormalization of mass and coupling constant, so far as a single type of coupling is assumed for the decay Hamiltonian.”