Observation of tWZ Production at the CMS Experiment

Area of Science:

• High Energy Physics
• Particle Physics
• Collider Physics

Background:

• Single top quark production is a fundamental process in quantum chromodynamics.
• The associated production of a single top quark with W and Z bosons (tWZ) is a rare electroweak process predicted by the Standard Model.
• Observing tWZ production provides a stringent test of the Standard Model and probes new physics beyond it.

Purpose of the Study:

• To report the first observation of single top quark production in association with W and Z bosons (tWZ).
• To measure the tWZ production cross sections at center-of-mass energies of 13 and 13.6 TeV.
• To enhance sensitivity to this rare process using advanced analysis techniques.

Main Methods:

• Analysis of proton-proton collision data collected by the CMS detector at the CERN Large Hadron Collider (LHC).
• Selection of events containing three or four charged leptons (electrons or muons).
• Application of advanced machine-learning algorithms and improved reconstruction techniques for enhanced sensitivity.

Main Results:

• The first observation of tWZ production is established with a statistical significance of 5.8 standard deviations.
• Measured cross sections for tWZ production are 248±52 fb at 13 TeV and 242±77 fb at 13.6 TeV.
• The observed significance exceeds the expected significance of 3.5 standard deviations.

Conclusions:

• The observation of tWZ production marks a significant advancement in particle physics.
• The measurements provide crucial data for testing Standard Model predictions.
• This finding opens new avenues for exploring electroweak interactions and potential new physics.