Search for QCD-instanton induced events in deep inelastic ep scattering at HERA
European Physical Journal C 34:3 (2004) 255-265
Authors:
S Chekanov, M Derrick, D Krakauer, JH Loizides, S Magill, S Miglioranzi, B Musgrave, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, P Giusti, G Iacobucci, A Margotti, A Montanari, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, O Kind, U Meyer, E Paul, J Rautenberg, R Renner, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, GP Heath, T Namsoo, S Robins, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helbich, X Liu, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycień, L Suszycki, D Szuba, J Szuba, A Kotański, W Slomiński, V Adler, U Behrens, I Bloch, K Borras, V Chiochia
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, Q2 > 120 GeV 2, 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 8.9pb.
