Search for single-top production with the ZEUS detector at HERA

TL;DR

This paper reports a search for anomalous single-top production at HERA using the ZEUS detector, finding no evidence but setting new constraints on FCNC couplings that improve upon previous limits.

Contribution

First search for single-top production via FCNC at HERA, providing new constraints on the t-u-gamma coupling beyond existing experimental limits.

Findings

No evidence for single-top production was observed.

Constraints on FCNC t-u-gamma coupling were significantly improved.

Excluded a large region of parameter space not previously ruled out.

Abstract

A search for anomalous single-top production, ep -> etX, t -> Wb, has been made with the ZEUS detector at HERA using an integrated luminosity of 130 pb^-1. No evidence for top-quark production was found in either the leptonic or the hadronic decay channel of the W boson. The resulting constraints on single-top production via quark-flavour changing neutral current (FCNC) transitions exclude a substantial region in the FCNC t-u-gamma coupling not ruled out by other experiments.