Problems
267
8.20 Starting from the expression
σ
μν
u ¯(p
′ )i
q ν u(p)
2M
′
1
where q = p − p and σ
μν = i[γ
μ , γ
ν ], use the Dirac equation and properties
2
of γ-matrices to prove the ‘Gordon decomposition’ of the current
(
)
′ )
μ
σ
μν
(p + p
q ν
u ¯(p
′ )γ
μ u(p) = ¯
u(p
′ )
+ i
u(p).
2M
2M
267
8.20 Starting from the expression
σ
μν
u ¯(p
′ )i
q ν u(p)
2M
′
1
where q = p − p and σ
μν = i[γ
μ , γ
ν ], use the Dirac equation and properties
2
of γ-matrices to prove the ‘Gordon decomposition’ of the current
(
)
′ )
μ
σ
μν
(p + p
q ν
u ¯(p
′ )γ
μ u(p) = ¯
u(p
′ )
+ i
u(p).
2M
2M