- #1

nrqed

Science Advisor

Homework Helper

Gold Member

- 3,572

- 192

## Main Question or Discussion Point

If anyone is familiar with the calculation of scattering amplitudes using momentum twistors. I am working through the book "Scattering Amplitudes in Gauge Theory and Gravity" by Elvang and Huang.

I am completely stumped by one step that should be simple. My question is about Eq. (5.45). My question is on the last step, which is

[tex] \biggl( |i \rangle^{\dot{b}} ~\langle i-1|_{\dot{a}} ~ - ~ |i-1 \rangle^{\dot{b}} \, \langle i |_{\dot{a}} \biggr) y_i^{\dot{a} a} = \langle i-1, i \rangle \, y_i^{\dot{b}a} [/tex]

I am stumped, conservation of momentum or the Schouten identity does not help here.

I can provide more details with the various quantities here, but probably someone already quite familiar with the notation will be able to help.

I am completely stumped by one step that should be simple. My question is about Eq. (5.45). My question is on the last step, which is

[tex] \biggl( |i \rangle^{\dot{b}} ~\langle i-1|_{\dot{a}} ~ - ~ |i-1 \rangle^{\dot{b}} \, \langle i |_{\dot{a}} \biggr) y_i^{\dot{a} a} = \langle i-1, i \rangle \, y_i^{\dot{b}a} [/tex]

I am stumped, conservation of momentum or the Schouten identity does not help here.

I can provide more details with the various quantities here, but probably someone already quite familiar with the notation will be able to help.