Measurement of the Anomalous Magnetic Moment of Tau Lepton with CMS Experiments and Improvements to the Zero Degree Calorimeters at CMS

Ultra Peripheral Collisions at the Large Hadron Collider (LHC) provide the best environment for testing high-energy quantum electrodynamic (QED) scattering processes since the shutdown of the Large Electron-Positron Collider. Measurements of the anomalous magnetic moment of leptons have recently gained interest owing to the tension between experimental measurements of the anomalous magnetic moment of muons am at the Muon g-2 experiment [1] and Standard Model predictions [2]. If physics beyond the standard model is responsible for this tension, the anomalous magnetic moment of the tau lepton at is expected to be 280 times more sensitive to the new physics due to the increased mass of the tau lepton [3]. This dissertation presents the measurement of the anomalous magnetic moment of the tau lepton, at, via the photon-fusion production of tau pairs in ultra-peripheral PbPb collisions, PbPb!Pb(gg !t+t?)Pb. The data for this measurement were collected by the CMS experiment in 2018 with an integrated luminosity of up to 1.70nb?1 and at a center-of-mass energy per nucleon pair of = 5.02TeV. This measurement is an improvement over a previously reported measurement from CMS using 2015 PbPb Data [4]. The new measurement improves on the previous measurement with increased luminosity and three additional tau decay channel measurements. This dissertation focuses on the decay channel in which tau leptons decay to an electron and three charged hadrons. Additionally, this dissertation presents improvements to the zero-degree calorimeter in the CMS experiment.

Name thesis:degree_name

Ph.D.

Discipline thesis:degree_discipline

Physics & Astronomy

Grantor dc:publisher

University of Kansas

Year dc:date.issued

2025

Author dc:creator

• Nickel, Matthew Thomas

Advisor dc:contributor.advisor

• Murray, Michael

• anomalous magnetic moment of tau
• ultra peripheral collisions
• zero-degree calorimeter

Language dc:language.iso

en

Dc Identifier Other

https://www.proquest.com/LegacyDocView/DISSNUM/32240079

OAI identifier oai:identifier

oai:kuscholarworks.ku.edu:1808/37851