Soft factors and interaction vertices from light-cone actions

TL;DR

This paper explores soft emission factors in gauge theories and gravity within the light-cone gauge, applying inverse-soft methods to construct amplitudes and deriving a key quartic interaction vertex in N=8 supergravity.

Contribution

It introduces universal soft factors in light-cone gauge and provides a compact form for the quartic interaction vertex in N=8 supergravity.

Findings

Derived universal soft factors in light-cone gauge

Reviewed inverse-soft construction of amplitudes

Obtained a compact quartic vertex in N=8 supergravity

Abstract

Universal factors associated with the emission of a soft boson in gauge theories and gravity, formulated in the light-cone gauge, are presented. The inverse-soft method, for constructing higher-point amplitudes from lower-point ones, using these factors is reviewed. These ideas are then examined in (light-cone) superspace and applied to both the N=4 super Yang-Mills and N=8 supergravity theories. One highlight is a compact result for the quartic interaction vertex in N=8 supergravity, a crucial ingredient for finiteness analyses.