Zeroing in on supersymmetric radiation amplitude zeros

Radiation amplitude zeros have long been used to test the standard model. Here, we consider the supersymmetric radiation amplitude zero in chargino-neutralino associated production, which can be observed at the luminosity upgraded LHC. Such an amplitude zero only occurs if the neutralino has a large wino fraction and hence this observable can be used to determine the neutralino eigenstate content. We find that this observable can be measured by comparing the p _T spectrum of the softest lepton in the trilepton χ1±χ20 decay channel to that of a control process such as χ1+χ1- or χ20χ20. We test this technique on a previously generated model sample of the 19 dimensional parameter space of the phenomenological minimal supersymmetric standard model, and find that it is effective in determining the wino content of the neutralino.