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Example – Particle moving in z direction. Eigenstate of Momentum (Plane wave approximation). Spinor. Spinors. Properties:. Orthogonality. Density increase as volume decreases. Completeness. Proof:. Transform back into rest frame. Projection Operators.
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Example – Particle moving in z direction Eigenstate of Momentum (Plane wave approximation) Spinor
Spinors Properties: Orthogonality Density increase as volume decreases
Completeness Proof: Transform back into rest frame
Projection Operators • Break projection operator into two parts: • Electron/positron part; and • Spin up/down part. +=electrons (upper states) - =positrons (lower states) Property for projection operators:
Electron/Positron Projections Since: Projection operators are complete.
Spin Projection Non-relativistic spin Projection operator: Relativistic z-direction (in rest frame): Spin direction is opposite for positrons Conventions:
Define Electron and Positron States Electron wave functions ε=+1 Positron wave functions ε=-1 Projection Operators