Twistor-inspired construction of electroweak vector boson currents

We present an extension of the twistor-motivated MHV vertices and accompanying rules presented by Cachazo, Svrček and Witten to the construction of vector-boson currents coupling to an arbitrary source. In particular, we give rules for constructing off-shell vector-boson currents with one fermion pair and $n$ gluons of arbitrary helicity. These currents may be employed directly in the computation of electroweak amplitudes. The rules yield expressions in agreement with previously-obtained results for $Z,W,{\gamma }^{*}\to \overline{q}q+n$ gluons (analytically up to $n=3$, beyond via the Berends-Giele recursion relations). We also confirm that the contribution to a seven-point amplitude containing the nonabelian triple vector-boson coupling obtained using the next-to-MHV currents matches the previous result in the literature.