Search for single top quark production with a Z boson and a quark using 137 𝑓𝑏⁻¹ of data at √s = 13 TeV by the CMS detector at CERN

Abstract

A search for tZq production in association with a Z boson in dilepton final states is conducted by analysing 137.1 𝑓𝑏⁻¹ of data recorded by the CMS detector of the Large Hadron Collider at CERN. A hadronically-decaying W boson candidate from the decay of a top quark and a leptonically-decaying Z boson candidate are considered, where the dilepton is either a pair of electrons or muons. Across the entire dataset, the observed significances were found to be 2.85, 0.60 and 11.9_ for 2016, 2017 and 2018, respectively. In addition to being an important test for the predictions of the Standard Model. The tZq process forms an irreducible background to the tZq flavour changing neutral current (tZq-FCNC) production mechanism, which is predicted by Beyond the Standard Model Physics, the tZq dilepton cross section and signal strength measurements obtained could be useful for future Run 3 analyses.