Dortmund 2021 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 8: Top quark production I

T 8.5: Vortrag

Montag, 15. März 2021, 17:00–17:15, Th

Differential Measurement of the Associated Production of a Single Top Quark and a Z Boson at the CMS Experiment — •David Walter, Abideh Jafari, and Nicolas Tonon — DESY, Hamburg, Germany

The top quark is the heaviest particle of the standard model (SM) and can be produced through strong interactions in top quark-antiquark pairs, or polarised as a single top quark (or antiquark) via the electroweak interaction. The associated production of a single top quark and a Z boson (pp → tZq) includes the tZ coupling as well as the coupling of three vector bosons (WWZ) and is therefore a unique process to study the couplings of heavy particles in the SM. As early as 2018, the CMS Collaboration observed the production of tZq in its final state with three leptons. It was found to be in agreement with the SM prediction.

In an ongoing analysis, a differential tZq cross section measurement is being carried out. This can give more detailed insight into the modeling of the process in the SM while some of the distributions are also sensitive to beyond-SM effects. The analysis makes use of 137 fb⁻¹ of pp collision data, collected at the LHC with the CMS experiment at a center of mass energy of √s = 13 TeV. A full event reconstruction is performed and multivariate analysis techniques are exploited to isolate the signal from various background contributions. A maximum likelihood based unfolding is performed to extract the differential cross section at parton level and to correct for detector effects and hadronization effects.