Search for Exclusive Gamma Gamma Production in Hadron-Hadron Collisions

TL;DR

This paper reports a search for exclusive gamma-gamma production in proton-antiproton collisions at 1.96 TeV, observing three candidate events and setting an upper cross section limit, contributing to understanding rare photon interactions.

Contribution

It provides the first experimental upper limit on the cross section for exclusive gamma-gamma production in proton-antiproton collisions at Tevatron energies.

Findings

Observed three candidate events consistent with gamma-gamma production.

Set an upper limit on the cross section at 410 fb with 95% confidence.

The probability of background fluctuation to three events is 1.7x10^-4.

Abstract

We have searched for exclusive 2-photon production in proton-antiproton collisions at sqrt{s} = 1.96 TeV, using 532/pb of integrated luminosity taken by the Run II Collider Detector at Fermilab. The event signature requires two electromagnetic showers, each with transverse energy E_T > 5 GeV and pseudorapidity |eta|<1.0, with no other particles detected in the event. Three candidate events are observed. We discuss the consistency of the three events with gamma-gamma, pi0-pi0, or eta-eta production. The probability that other processes fluctuate to 3 events or more is 1.7x10^-4. An upper limit on the cross section of p+pbar --> p+gamma-gamma+pbar is set at 410 fb with 95% confidence level.