Spinor azimuth convention
= Spinor azimuth convention
With $X_{12}=x+iy$, a <spinor> whose components have phases $e^{-i\phi/2}$ and $e^{i\phi/2}$ has $x+iy\propto e^{-i\phi}$, so its physical <azimuth> is $-\phi$. The usual positive <azimuth> for those phases uses $X_{12}=x-iy$. Both conventions are valid if used consistently.