• Question: What exactly is "spin"? Do only leptons have spin, or do quarks also have spin?

    Asked by strangeness to Arttu, Ceri, James_M, Monica, Philip on 14 Jun 2011.
    • Photo: Arttu Rajantie

      Arttu Rajantie answered on 14 Jun 2011:

      Spin is an internal property of the particle, which behaves like angular momentum as if the particle was rotating. In fact, all elementary particles we know have spin: Leptons and quarks have spin 1/2 (in units of the Planck constant), and photon, gluon and W and Z bosons have spin 1. The Higgs boson would have zero spin, but we haven’t found it yet.