Observation of tWZ production at the CMS experiment

TL;DR

This paper reports the first observation of tWZ production in proton-proton collisions at the LHC, using advanced analysis techniques to achieve high sensitivity and measure the production cross sections with significant statistical confidence.

Contribution

It presents the first observation of tWZ production at the LHC, employing machine learning and improved reconstruction methods for enhanced detection sensitivity.

Findings

Measured cross sections of 248 ± 52 fb at 13 TeV and 242 ± 77 fb at 13.6 TeV

Signal significance of 5.8 standard deviations

Use of advanced machine learning algorithms for analysis

Abstract

The first observation of single top quark production in association with a W and a Z boson in proton-proton collisions is reported. The analysis uses data at center-of-mass energies of 13 and 13.6 TeV recorded with the CMS detector at the CERN LHC, corresponding to a total integrated luminosity of 200 fb$^{-1}$. Events with three or four charged leptons, which can be electrons or muons, are selected. Advanced machine-learning algorithms and improved reconstruction methods, compared to an earlier analysis, result in an unprecedented sensitivity to tWZ production. The measured cross sections for tWZ production are 248 $\pm$ 52 fb and 242 $\pm$ 77 fb for $\sqrt{s}$ = 13 and 13.6 TeV, respectively. The signal is established with a statistical significance of 5.8 standard deviations, with 3.5 expected, compared to the background-only hypothesis.