Search for Universal Extra Dimensions in the Two Photon and Missing Transverse Energy Final State with the ATLAS Detector

A search for diphoton events with large missing transverse energy is conducted using 3.1 pb$^{-1}$ of integrated luminosity of proton-proton collisions at center of mass energy $\sqrt{s}$=7 TeV. The data were collected with the ATLAS detector at the CERN Large Hadron Collider during the period from March 30, 2010 until August 30, 2010. No excess of such events is observed above the Standard Model background prediction. This result is interpreted in the context of a gravity mediated One Universal Extra Dimension model with $\Lambda R=20, N=6 and M$_{D}$=5 TeV, where $\Lambda$ is the cutoff scale, N is the number of large extra dimensions and M$_{D}$ is the Planck scale in the higher dimensional theory. The compactification radius of the Universal Extra Dimension, R, is excluded for values of 1/R < 728 GeV at 95\% CL, providing the most stringent limit on this model at the time of publication.