TY - JOUR
T1 - Search for QCD instanton-induced processes in deep-inelastic scattering at HERA
AU - Adloff, C
AU - Coppens, Yves
AU - Dowell, John
AU - Faulkner, Peter
AU - Fleming, Yves
AU - Garvey, John
AU - Johnson, Carrie
AU - Kenyon, Ian
AU - Lamb, David
AU - Newman, Paul
AU - Rizvi, Syed
AU - Thompson, Paul
AU - Woehrling, Ethan-Etienne
PY - 2002/11/1
Y1 - 2002/11/1
N2 - 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 less than or similar to 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.
AB - 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 less than or similar to 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.
U2 - 10.1140/epjc/s2002-01039-8
DO - 10.1140/epjc/s2002-01039-8
M3 - Article
SN - 1434-6044
VL - 25
SP - 495
JO - European Physical Journal C
JF - European Physical Journal C
IS - 4
ER -