UV considerations on scattering amplitudes in a web of theories

Understand

The scattering predictions of a web of theories including Yang-Mills (YM), gravity, bi-adjoint scalar, the non-linear sigma model (NLSM), Dirac-Born-Infeld-Volkov-Akulov (DBI-VA) and the special Galileon (sGal) form a class of special objects with two fascinating properties: they are related by the double-copy procedure, and they can be defined purely by on-shell constraints.

• We expand on both of these properties.
• First we show that NLSM tree-level amplitudes are fully determined by imposing color-dual structure together with cyclic invariance and locality.
• We then consider how hard-scaling can be used to constrain the predictions of these theories, as opposed to the usual soft-scaling.