Discovery Potential for GMSB Supersymmetry in ATLAS using the $Z\gamma + \not E_T$ Final State at a center of mass energy of $\sqrt{s}$=10 \TeV

We have studied the sensitivity of the ATLAS detector for supersymmetric neutralino signals in the $Z\gamma +\notE_{T}$ final state in a GMSB model in which the Higgsino-like neutralino is NLSP. This study considers the reaction of $pp \ra \tilde{\chi}^{0}_{1} \tilde{\chi}^{0}_{1} \ra Z(\ra \ell^{+}\ell^{-})\gamma \tilde{G}\tilde{G}$, where $\ell = \mu/e$, at a center of mass energy of $\sqrt{s}$=10 \TeV using fully simulated ATLAS Monte Carlo events both for the signal and background. Based on the GMSB Model Line E predictions, we expect that, for an integrated luminosity of less then 3 fb$^{-1}$, ATLAS could detect the GMSB signal from the Higgsino-like neutralino that has a mass of 134.7 \GeV in the $Z\gamma +\notE_{T}$ final state with a significance of 5$\sigma$, assuming 20% systematic uncertainty.