Speaker
Description
Signals of QCD instanton-induced processes are searched for in
deep-inelastic scattering (DIS) at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable $x> 0.001$, the inelasticity $0.2< y< 0.7$ and the photon virtuality $150< Q^2<15000$ GeV$^2$. The search is performed using H1 data corresponding to an integrated luminosity of 350 pb$^{-1}$. Several observables of the hadronic final state of the events are exploited to identify a potentially instanton-enriched domain. Two Monte Carlo models, RAPGAP and ARIADNE, are used to estimate the background from the standard DIS processes, and the instanton-induced scattering processes are modeled by the program QCDINS. In order to extract the expected signal a multivariate data analysis technique is used. Exclusion limits on instanton production are reported, excluding cross sections larger than 2 pb. Limits are also reported as a function of parameters used to regularize the perturbative instanton model.
