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

TL;DR

This paper calculates the Standard Model background for two-photon plus missing mass events at LEP, considering initial state radiation effects, to aid in identifying potential supersymmetric signals.

Contribution

It provides detailed event rate calculations and missing mass distributions for various energies and cuts, including the impact of initial state radiation.

Findings

Initial state radiation approximately doubles event rates.

Missing mass distributions vary with energy and kinematic cuts.

Background estimates are crucial for supersymmetry searches 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.