Resonant slepton production at the LHC in models with an ultralight gravitino

We examine resonant slepton production at the LHC with gravitinos in the final state. The slepton undergoes gauge decay into a neutralino and a lepton, the neutralino decays into a photon and a gravitino. By measuring the transverse masses of the gamma- G and the l-gamma- G subsystems it is possible to accurately reconstruct both the slepton and neutralino masses. In some regions of parameter space the slepton decays directly into a lepton and gravitino, giving an identical experimental topology to W production (l missing E_T). We present the novel matrix element squared for lepton-gravitino production. A peak in the tail of the lepton-missing momentum transverse mass distribution of the W provides a signature for the process and an accurate measurement of the slepton mass. We display the search reach for the LHC and 300 fb^{-1} of integrated luminosity.