# Charged pion decay and spin conservation

Charged pions $\pi^\pm$ decay via an intermediate $W$ to (e.g.) a lepton-neutrino pair.

The pions being scalar (spin-0) particles and the intermediate $W$ having spin 1, how is spin conserved in this interaction?

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Aren't the spins of the lepton and the neutrino both $\frac{1}{2}$? –  Kyle Kanos Jul 10 at 15:47
Yes, they are. But my question is not about spin conservation between initial and final state, but in between. –  fuenfundachtzig Jul 10 at 17:55