Search for Single Top Production at HERA

TL;DR

This paper reports a comprehensive search for single top quark production at HERA using the full dataset, setting upper limits on production cross section and anomalous couplings, and analyzing related W boson properties.

Contribution

It provides the first complete search for single top production at HERA, establishing new upper limits and exploring tau lepton events and W polarization.

Findings

Upper limit on top production cross section: < 0.16 pb

Upper bound on anomalous magnetic coupling: < 0.14

Constraints on W boson polarization fractions

Abstract

A search for single top production in ep collisions using the complete high energy data from HERA is presented. This search is based on the analysis of events containing isolated leptons (electrons or muons) and missing transverse momentum PTmiss. In the absence of a signal, an upper limit on the top production cross section sigma_ep -> etX < 0.16 pb is established at the 95% confidence level, corresponding to an upper bound on the anomalous magnetic coupling kappa_tug < 0.14. The search is complemented by a search for events containing an isolated tau lepton and PTmiss and the measurement of W boson polarisation fractions.