The Radiation Valley and Exotic Resonances in $W\gamma$ Production at the LHC

The tree-level partonic angular distribution of Standard Model $W\gamma$ production possesses a feature known as the Radiation Amplitude Zero (RAZ) where destructive interference causes the cross section to vanish. At the proton level the exact cancellation disappears, however, one can find a dip in the central region of the angular distributions, here called the Radiation Valley (RV). In this paper, we show how the sensitivity for $W(\ell\nu)\gamma$ resonances can be significantly improved if one focuses on events in the RV region. Using this technique, we find that the LHC could probe a larger range of resonance masses, equivalent to increasing the luminosity by a factor of $2-3$ over conventional searches. The exact increase depends on the spin of the $W\gamma$ resonance and exactly how it couples to electroweak gauge bosons.