Observation of exclusive electron-positron production in hadron-hadron collisions

We present the first observation of exclusive e(+)e(-) production in hadron-hadron collisions, using p (p) over bar collision data at root s=1.96 TeV taken by the run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb(-1). We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy E(T)> 5 GeV and pseudorapidity vertical bar eta vertical bar < 2. With these criteria, 16 events are observed compared to a background expectation of 1.9 +/- 0.3 events. These events are consistent in cross section and properties with the QED process p (p) over bar -> p+e(+)e(-)+(p) over bar through two-photon exchange. The measured cross section is 1.6(-0.3)(+0.5)(stat)+/- 0.3(syst) pb. This agrees with the theoretical prediction of 1.71 +/- 0.01 pb.