Srednicki — Quantum Field Theory · Problem 39.2

Canonical Quantization of Scalar Fields — Mark Srednicki

Physics — QFT · canonical-quantization-spinor-fields-ii

Problem

Use [Ψ(x),Mμν]=−i(xμ∂ν−xν∂μ)Ψ(x)+SμνΨ(x)[\Psi(x), M^{\mu\nu}] = -i(x^\mu\partial^\nu - x^\nu\partial^\mu)\Psi(x) + S^{\mu\nu}\Psi(x), plus whatever spinor identities you need, to show that Jz bs†(pz^)∣0⟩=12s bs†(pz^)∣0⟩ ,J_z\, b_s^\dagger(p\hat{\mathbf{z}})|0\rangle = \tfrac{1}{2}s\, b_s^\dagger(p\hat{\mathbf{z}})|0\rangle\,, Jz ds†(pz^)∣0⟩=12s ds†(pz^)∣0⟩ ,(39.38)J_z\, d_s^\dagger(p\hat{\mathbf{z}})|0\rangle = \tfrac{1}{2}s\, d_s^\dagger(p\hat{\mathbf{z}})|0\rangle\,, \tag{39.38} where p=pz^\mathbf{p} = p\hat{\mathbf{z}} is the three-momentum, and z^\hat{\mathbf{z}} is a unit vector in the zz direction.

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