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We have searched for exclusive γγ production in proton-antiproton collisions at s=1.96TeV, using 532pb-1 of integrated luminosity taken by the run II Collider Detector at Fermilab. The event signature requires two electromagnetic showers, each with transverse energy ET>5GeV and pseudorapidity |η|<1.0, with no other particles detected in the event. Three candidate events are observed. We discuss the consistency of the three events with γγ, π0π0, or ηη production. The probability that other processes fluctuate to 3 events is 1.7×10-4. An upper limit on the cross section of pp̄→p+γγ+p̄ production is set at 410 fb with 95% confidence level. © 2007 The American Physical Society.

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Physical Review Letters