Physics Backgrounds to Supersymmetric Signals with Two Photons and Missing Mass at LEP

Abstract

We calculate the event rates for the Standard Model production of two photons plus missing mass through the process electron positron to gamma gamma nu nubar, where nu is any of the three neutrino flavors, at LEP energies. This process can be a background to new physics signatures, such as that expected from supersymmetry with a higgsino or gravitino LSP. The missing mass distribution is presented for several sets of kinematic cuts at beam energies of 161, 172, 184, and 194 GeV. The effect of initial state photon radiation is also studied, and is found to be significant, approximately doubling the event rates.