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Search for QCD-instanton induced events in deep inelastic ep scattering at HERA

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Abstract.

A search for QCD-instanton-induced events in deep inelastic ep scattering has been performed with the ZEUS detector at the HERA collider, using data corresponding to an integrated luminosity of 38 pb-1. A kinematic range defined by cuts on the photon virtuality, Q 2 > 120 GeV2, and on the Bjorken scaling variable, x > 10-3, has been investigated. The QCD-instanton induced events were modelled by the Monte Carlo generator QCDINS. A background-independent, conservative 95% confidence level upper limit for the instanton cross section of 26 pb is obtained, to be compared with the theoretically expected value of 8.9 pb.

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Received: 17 December 2003, Published online: 2 April 2004

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The ZEUS Collaboration. Search for QCD-instanton induced events in deep inelastic ep scattering at HERA. Eur. Phys. J. C 34, 255–265 (2004). https://doi.org/10.1140/epjc/s2004-01735-3

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