Do Leptons Have Strangeness?

All hadrons which contain an anti-strange quark ( )are assigned a strangeness number S=+1. Leptons, and hadrons which don't contain a strange quark have strangeness S=0.

What particles have strangeness?

The strangeness of a particle is the sum of the strangeness of its component quarks. Of the six flavors of quarks, only the strange quark has a nonzero strangeness. The strangeness of nucleons is zero, because they only contain up and down quarks and no strange (also called sideways) quarks.

What is the strangeness number of leptons?

Lepton family numbers are conserved at 0 for the electron and tau family for all particles. The muon family number is L_μ = 0 before and L_μ = −1+1 = 0 after. Strangeness changes from +1 before to 0 + 0 after, for an allowed change of 1. The decay is allowed by all these measures.