First Differential Measurements of tZq Production and Luminosity Determination Using Z Boson Rates at the LHC

This thesis describes two groundbreaking measurements in the precision frontier at the LHC: the first ever differential measurement of the Z-associated single top quark (tZq) production, and the luminosity measurement using Z boson production rate for the first time in CMS.

I studied physics at KIT in Karlsruhe, Germany with the main subjects on theoretical particle physics, experimental particle physics, and data analysis. In summer 2017 I joined the CMS experiment to work for my master's thesis project on improvements in deep neural network algorithms for the identification of jets with b quarks. I showed that by using novel machine learning techniques based on domain adaptation the difference between data and simulation can be mitigated. Afterward, I moved to Hamburg where I started my PhD at the DESY research center. My main project was the analysis of proton-proton collision data recorded by the CMS experiment, where I studied the production of a single top quark in association with a Z boson (tZq). During this time, I also co-supervised a graduate student on a related project. Today, I am a level 3 tX convener for CMS and organize by-weekly meetings and support and review analyses from the early stages. As the HepData contact person, I organize thedata preservation of analysis results. In the past and present, I contribute to the CMS experiment in the group responsible for luminosity determination. I developed a novel technique of measuring the luminosity using Z bosons decaying into muons. The approach requires a deep understanding of the reconstruction, identification, triggering, and efficiency determination of munos. The method is also used to validate the luminosity recorded in the just-started LHC Run 3 data acquisition, where I take a supervising role. In my current position as a postdoctoral scientific researcher, I joined the effort for a precision measurement of the W boson mass, a parameter of the standard model that was recently measured with tension to theory predictions. To cope with the demanding conditions for the planned High-Luminosity LHC, new innovative and cutting-edge technology will be needed. In the context of the Phase-2 upgrade of the CMS experiment, I’m performing test measurements of silicon sensors for the new High Granularity Calorimeter (HGCAL).