DiracSpinorNormalization is an option for SpinorChainEvaluate, DiracSimplify and other functions. It specifies the normalization of the spinor inner products \bar{u}(p) u(p) and \bar{v}(p) v(p). Following values are supported:
"Relativistic" - this is the standard value corresponding to \bar{u}(p) u(p) = 2 m, \bar{v}(p) v(p) = - 2 m.
"Rest" - this sets \bar{u}(p) u(p) = 1, \bar{v}(p) v(p) = - 1.
"Nonrelativistic" - this sets \bar{u}(p) u(p) = \frac{m}{p^0}, \bar{v}(p) v(p) = - \frac{m}{p^0}.
Overview, DiracSimplify, SpinorChainEvaluate.
SpinorUBar[p, m] . SpinorU[p, m]
DiracSimplify[%]\bar{u}(p,m).u(p,m)
2 m
SpinorUBar[p, m] . SpinorU[p, m]
DiracSimplify[%, DiracSpinorNormalization -> "Rest"]\bar{u}(p,m).u(p,m)
1
SpinorUBar[p, m] . SpinorU[p, m]
DiracSimplify[%, DiracSpinorNormalization -> "Nonrelativistic"]\bar{u}(p,m).u(p,m)
\frac{m}{p^0}