Probing Hard Color-Singlet Exchange in $pp$ Collisions at $s = 630$ GeV and 1800 GeV

Abstract We present results on dijet production via hard color-singlet exchange in proton-antiproton collisions at s =630 GeV and 1800 GeV using the DO detector. The fraction of dijet events produced via color-singlet exchange is measured as a function of jet transverse energy, separation in pseudorapidity between the two highest transverse energy jets, and proton-antiproton center-of-mass energy. The results are consistent with a color-singlet fraction that increases with an increasing fraction of quark-initiated processes and inconsistent with two-gluon models for the hard color-singlet.