Search for single-top production in ep collisions at HERA

A search for single-top production, ep --> etX, has been made with the ZEUS\ndetector at HERA using an integrated luminosity of 130.1 pb-1. Events from both\nthe leptonic and hadronic decay channels of the W boson resulting from the\ndecay of the top quark were sought. For the leptonic mode, the search was made\nfor events with isolated high-energy leptons and significant missing transverse\nmomentum. For the hadronic decay mode, three-jet events in which two of the\njets had an invariant mass consistent with that of the W were selected. No\nevidence for top production was found. The results are used to constrain\nsingle-top production via flavour-changing neutral current (FCNC) transitions.\nThe ZEUS limit excludes a substantial region in the FCNC t-u-gamma coupling not\nruled out by other experiments.\n Comment: 28 pages, 4 figures, 2 tables, final version (minor changes in text)\n Addendum with new limits included