Medida da largura invisível do bóson Z utilizando os dados abertos do experimento CMS.

Abstract

This work presents a measurement of the invisible width of the Z boson, a fundamental parameter of the Standard Model, using CMS Open Data from proton-proton collisions at a center-of-mass energy of √ s = 13TeV, corresponding to an integrated luminosity of 16,290 fb−1. The invisible width of the Z boson, associated with the decay Z → ν¯ν, is inferred from the missing transverse momentum observed in Z +jets events. This approach provides insight into the coupling of the Z boson to neutrinos. The result obtained is compared with previous measurements published by the CMS Collaboration. In addition, the study includes an exploratory investigation of event selection using machine learning techniques, employing Graph Neural Networks (GNNs) as an alternative to traditional cut-based selection methods. The research also involves technical contributions to the upgrade of the CMS muon system, focusing on the assembly and testing of the Improved Resistive Plate Chambers (iRPCs). These gaseous detectors, designed for high-precision timing, will be installed in the endcap regions of the detector to extend pseudorapidity coverage and significantly enhance muon detection and tracking efficiency, particularly in the high-luminosity environment expected in future LHC upgrades.