Master Theses

This thesis presents measurements of charm and beauty quark production in proton–proton collisions at a center-of-mass energy of √s = 5 TeV using the CMS detector at the LargeHadron Collider at CERN.Heavy-flavor production cross sections test perturbative Quantum Chromodynamics and constrain parameters such as heavy-quark masses and the proton parton distribution functions.In this work, the double-differential production cross sections of D∗ mesons are measured as functions of the transverse momentum pT and the absolute rapidity |y|, reaching very low transverse momenta. The kinematic region covered by CMS is complementary to previous measurements at the LHC. [...]

This thesis presents a precision measurement of the CP properties of the Higgs tau Yukawa coupling, focusing on the H → τ τ → μa3pr 1 +3ν decay channel with ggF and VBF production.The study uses proton–proton collisions data recorded by CMS in 2022 and 2023 at √s = 13.6TeV, corresponding to an integrated luminosity of 62.4 fb−1. The CP-mixing angle αHττ is determined via the coplanarity angle ϕCP . [...]

Among other restrictions, vacuum stability is a theoretical constraint for vacuumconfigurations in BSM theories to be allowed or excluded. But due to multidimensionalfield spaces, computing the vacuum stability is a challenging task. [...]

As the search for physics beyond the Standard Model continues, this thesis presentsan analysis in the long-lived particle (LLP) supersymmetry sector. A Boosted DecisionTree (BDT) classifier was developed to enhance the search for long-lived supersymmetricpartner particles of the tau lepton (stau) particles in the muon-hadronic tau channel at theCMS detector in LHC, motivated by Gauge Mediated Supersymmetry Breaking (GMSB)scenarios. [...]

This thesis evaluates a b-tagging algorithm optimized to identify low pT (soft) b-hadrons in theATLAS experiment at the LHC. The algorithm, called the NewVrtSecInclusiveTool, reconstructssoft secondary vertices (SSVs), which can be connected to the decay of a soft b-hadron [...]

(di-Higgs) events using simulated data from the ATLAS detector at the Large Hadron Collider ata center-of-mass energy of √s = 13TeV and an integrated luminosity of 140 fb−1. In the studiedchannel, one Higgs boson decays into a bottom quark-antiquark pair (b¯b), the other into two photons(γγ) [...]

In the endeavour to understand the fundamental components of the universe, the search for newparticles beyond the Standard Model of particle physics is a pivotal task. Axion-like particles (ALPs)are among the prime targets of this search, arising in various theoretical frameworks, includingquantum chromodynamics, supersymmetric extensions of the Standard Model of particle physics orstring theory. [...]

Palladium nanoparticles are widely studied in various fields of science. In biology, Pd parti-cles are studied for possible medical applications, in chemistry the particles are often synthe-sised in solution and then applied to a support via, for example, spin coating. [...]