Does anybody know what interpretation the invariant corresponding to the global U(1) invariance of the Dirac Lagrangian is? I have always had it in my head that it's charge, but then I realized that uncharged free particles such as neutrinos satisfy this equation too! Any thoughts much appreciated.(adsbygoogle = window.adsbygoogle || []).push({});

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# Global U(1) invariant of Dirac Lagrangian

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