PROMPT PHOTON PAIR PRODUCTION IN ASSOCIATION WITH TOP ANTITOP PAIRS - AN IMPORTANT BACKGROUND TO INTERMEDIATE MASS HIGGS DETECTION

The reaction pp --> tt-gamma-gammaBAR is studied for 80 less-than-or-equal-to M-gamma-gamma less-than-or-equal-to 140 GeV, as a possible background to the detection of an intermediate mass standard model Higgs in the rare l-nu-gamma-gamma final state. If the top is not too heavy the prompt photon production, integrated over a window of 6 GeV in M-gamma-gamma around the Higgs mass, can be larger than the production of photon pairs from Higgs decay. Standard isolation cuts can effectively dispose of this background for m(t) greater-than-or-equal-to 150 GeV. For m(t) approximately 100 GeV approximately the same number of background and signal events pass the cuts.