Search for QCD Instanton-Induced Processes in DIS at HERA

Apr 12, 2016, 2:25 PM
SR1 (DESY Hamburg)


DESY Hamburg

QCD and Hadronic Final States WG2 QCD and Hadronic Final States


Stanislav Mikocki (Institute of Nuclear Physics Polish Academy of Sciences)


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 < Q2 < 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.

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