Abstract.
Signals of QCD instanton-induced processes are searched for in deep-inelastic scattering (DIS) at the electron-proton collider HERA in a kinematic region defined by the Bjorken-scaling variables x > 10-3, 0.1 < y < 0.6 and photon virtualities \(10 \lesssim Q^2 < 100 GeV2. Several observables characterising hadronic final state properties of QCD instanton-induced events are exploited to identify a potentially instanton-enriched domain. While an excess of events with instanton-like topology is observed it cannot be claimed significant given the uncertainty of the standard DIS background simulation. Upper limits on the cross-section for instanton-induced processes of between 60 pb and 1000 pb are set dependent on the kinematic domain considered. The data do not exclude the cross-section predicted by instanton perturbation theory for small instanton sizes. At large instanton sizes a naive extrapolation of instanton perturbation theory yields a cross-section in the range of sensitivity of this study. Such a cross-section is not observed, in agreement with non-perturbative lattice simulations of the QCD vacuum.
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Received: 27 May 2002 / Published online: 24 September 2002
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The H1 Collaboration., Adloff et al., C. Search for QCD instanton-induced processes in deep-inelastic scattering at HERA. Eur. Phys. J. C 25, 495–509 (2002). https://doi.org/10.1140/epjc/s2002-01039-8
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DOI: https://doi.org/10.1140/epjc/s2002-01039-8