Tagging sneutrino resonances at a linear collider with associated photons

Abstract

Sneutrino resonances at a high-energy linear ${e}^{+}{e}^{\ensuremath{-}}$ collider may be one of the clearest signals of supersymmetry without $R$ parity, especially when the $R$-parity-violating coupling is too small to produce observable excesses in four-fermion processes. However, there is no guarantee that the sneutrino pole will lie anywhere near the machine energy. We show that associated photon production induces the necessary energy spread, and that the resonance then leaves a clear imprint in the photon spectrum. It follows that tagging of a hard monoenergetic photon for a variety of possible final states provides a realistic method of separating sneutrino resonance signals from the standard model backgrounds.