The purely electroweak process $\mathrm{qq}\to \mathrm{qqZ}$ (via $t$-channel $\frac{\gamma }{Z}$ or $W$ exchange) provides a copious and fairly clean source of color-singlet exchange events in $\mathrm{pp}$ collisions at the CERN LHC. A judicious choice of phase-space region allows the suppression of QCD backgrounds to the level of the signal. The color-singlet-exchange signal can be distinguished from QCD backgrounds by the radiation patterns of additional minijets in individual events. A rapidity-gap trigger at the minijet level enhances substantially the signal versus the background. Analogous features of weak-boson scattering events make $Z+2\mathrm{}$-jet events at the CERN LHC an ideal laboratory for investigation of the soft-jet activity expected in weak-boson scattering events.

• Received 30 May 1996

DOI:https://doi.org/10.1103/PhysRevD.54.6680