Search for Large Extra Dimensions Using Dielectron and Diphoton Events in pbar{p} Collisions at sqrt{s}=1.8 TeV

Arkani-Hamed, Dimopoulous, and Dvali have proposed a model of low-scale quantum gravity featuring large extra dimensions. In this model, the exchange of Kaluza-Klein towers of gravitons can enhance the production rate of electron and photon pairs at high invariant mass in proton-antiproton collisions. The amount of enhancement is characterized by the parameter $M_S$, the fundamental Planck scale in the bulk extra dimensions. We have searched for this effect using 100 pb$^{-1}$ of diphoton data and 110 pb$^{-1}$ of dielectron data collected with the Collider Detector at Fermilab at $\sqrt{s}=1.8$ TeV during the 1992-1996 run. In the absence of a signal, we place 95% confidence-level limits on $M_S$ of 905 GeV/$c^2$ and 826 GeV/$c^2$, for the case of constructive and destructive graviton interference respectively.