DOI: 10.1140/epjc/s2002-01039-8
Search for QCD instanton-induced processes in deep-inelastic scattering at HERA
The H1 Collaboration(Received: 27 May 2002 / Published online: 24 September 2002 )
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
.
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-sec tion for instanton-induced processes of
between
and
are set dependent on the kinematic domain considered.
The data do not exclude the cross-sec tion predicted by instanton perturbation theory for small instanton sizes.
At large instanton sizes a naive extrapolation of instanton perturbation theory yields a cross-sec tion in the range of sensitivity
of this study. Such a cross-sec tion is not observed, in agreement with non-perturbative lattice simulations of the QCD vacuum.
© Società Italiana di Fisica, Springer-Verlag 2002
