On the solutions of the scattering equations

Understand

This paper addresses the question, whether the solutions of the scattering equations in four space-time dimensions can be expressed as rational functions of the momentum twistor variables.

• This is the case for $n\le5$ external particles.
• For general $n$ there are always two solutions, which are rational functions of the momentum twistor variables.
• However, the remaining solutions are in general not rational.