  QCD instantons are arguably the best motivated yet unobserved nonperturbative
effects predicted by the Standard Model. A discovery and detailed study of
instanton-generated processes at colliders would provide a new window into the
phenomenological exploration of QCD and a vastly improved fundamental
understanding of its non-perturbative dynamics. Building on the optical
theorem, we numerically calculate the total instanton cross-section from the
elastic scattering amplitude, also including quantum effects arising from
resummed perturbative exchanges between hard gluons in the initial state,
thereby improving in accuracy on previous results. Although QCD instanton
processes are predicted to be produced with a large scattering cross-section at
small centre-of-mass partonic energies, discovering them at hadron colliders is
a challenging task that requires dedicated search strategies. We evaluate the
sensitivity of high-luminosity LHC runs, as well as low-luminosity LHC and
Tevatron runs. We find that LHC low-luminosity runs in particular, which do not
suffer from large pileup and trigger thresholds, show a very good sensitivity
for discovering QCD instanton-generated processes.
