Solutions to the Exercises
摘要
he sigma-matrix four-vector is defined as \((\bar {\sigma }^{\mu })^{\dot {\alpha } \alpha } := ({\mathbb{1} },-\boldsymbol {\sigma })^{\top }\) , where \(\boldsymbol {\sigma } = (\hat \sigma _1,\hat \sigma _2, \hat \sigma _3)\) is the list of the Pauli matrices \(\hat \sigma _i\) .