Canonical Quantization of Scalar Fields — Mark Srednicki
Physics — QFT · standard-model-lepton-sector
Problem
Show that the sum of eqs.\,(88.32) and (88.33), when rewritten in terms of fields of definite mass, has a global symmetry U(1)×U(1)×U(1). The corresponding charges are called electron number, muon number, and tau number; the sum of the charges is the lepton number. List the value of each charge for each Dirac field EI and NLI.