Response of the High Granularity Calorimeter HGCAL and Characterisation of the Higgs Boson

This book highlights the most complete characterization of the Higgs boson properties performed to date in the "golden channel," i.e., decay into a pair of Z bosons which subsequently decay into four leptons. The data collected by the CMS experiment in the so-called Run-II data-taking period of the LHC are used to produce an extensive set of results that test in detail the predictions of the Standard Model.

Given the remarkable predictive power of the SM when including the Higgs boson, possible new physics will require even more extensive studies at higher statistics. A massive upgrade of the detectors is necessary to maintain the current physics performance in the harsh environment of the High-Luminosity LHC (HL-LHC) project, expected to start by the end of 2027. The CMS Collaboration will replace the current endcap calorimeters with a High Granularity Calorimeter (HGCAL). The HGCAL will be the very first large-scale silicon-based imaging calorimeter ever employed in ahigh-energy physics experiment. This book presents the results of the analysis of the test beam data collected with the first large-scale prototype of the HGCAL. The results of this analysis are used to corroborate the final design of the HGCAL and its nominal physics performance expected for the HL-LHC operations.

Highlights most complete characterization of Higgs boson properties in the HZZ decay channel performed in CMS to date Corroborates validation of the design and assessment of the physics performance of the CMS High Granularity Calorimeter Provides fundamental inputs in the characterization of the Higgs boson and in the preparation of the Phase II of CMS

Auteur

Matteo Bonanomi is a particle physicist from Italy.

After obtaining a Master of Science in Physics at the University of Milano-Bicocca with a thesis on the design and validation of an innovative experiment to measure the hadronic contributions to the anomalous magnetic moment of the muon, Matteo joined the CMS Collaboration in 2018 for his Ph.D.

He worked on his Ph.D. thesis at the Laboratoire Leprince Ringuet (LLR) at the École Polytechnique in France, studying the performance of the CMS High Granularity Calorimeter (HGCAL) with test beam data and measuring the properties of the Higgs boson in the "golden channel," where the Higgs boson decays into a pair of Z bosons.

He is currently a postdoctoral researcher at the University of Hamburg, and his main research interests are the precision measurements of the Higgs boson properties and the searches for additional bosons that could unveil the presence of physics beyond the Standard Model.

Contenu
Introduction.- The CMS detector at the LHC.- The CMS endcap calorimeters upgrade for the HL-LHC.- The "golden channel" and its properties.- Events selection and categorization.- Signal and background modelling.- The Higgs boson properties in the "golden channel".- Conclusions