Books

The structure and dynamics of four different colloidal systems are investigated usingcoherent X-ray scattering methods. The static structure of the samples is studied us-ing Small Angle X-ray Scattering (SAXS), while the dynamics are probed using X-rayPhoton Correlation Spectroscopy (XPCS). [...]

This thesis investigates loop integrands of correlation functions of scalar half-BPS operators in four-dimensional $\mathcal{N}=4$ supersymmetric Yang–Mills (SYM) theory. $\mathcal{N}=4$ SYM provides a central “theoretical laboratory” due to its high degree of symmetry, its role in the AdS/CFT correspondence, and the emergence of integrability in the planar limit.First, we study planar higher-point generating functions, which combine infinitely many fixed-charge correlators into unified expressions using ten-dimensional coordinates that merge spacetime and R-symmetry variables. [...]

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. [...]

Synchronization systems in free-electron laser facilities enable frontier experiments on (sub)molecular matter. This work comprises a control theoretic analysis of such systems, explicitly taking into account their inherent nature as distributed time-delay systems. [...]

ISI oder SCOPUS Publikationen mit DESY Autor sowie alle Dissertationen mit DESY Beteiligung

In this thesis the electroweak production of the Z boson in association with twojets is investigated focusing on its topology via the Vector Boson Fusion (VBF)mechanism and the determination of heavy boson parton densities.The first part presents a theoretical study of the Drell–Yan and electroweak Zjj pro-duction mechanisms and their particle-level comparison, demonstrating the domi-nance of the former and motivating the definition of a VBF-enhanced phase space toisolate electroweak contributions. The impact of electroweak corrections is discussedas a motivation for introducing electroweak (heavy boson) densities [...]

Monte Carlo simulation of particle interactions underpins nearly every aspect of modern collider experiments, yet its computational cost will exceed available resources as luminosities and detector complexities increase.Calorimeter shower simulation accounts for the dominant share of this cost, particularly for the highly granular designs planned for future facilities.Deep generative Machine Learning models offer a promising path toward addressing this bottleneck by learning from relatively small amounts of Monte Carlo data and then sampling new showers more efficiently.This work introduces CaloClouds, a generative model for fast electromagnetic shower simulation in highly granular sampling calorimeters, developed and evaluated using the silicon-tungsten electromagnetic calorimeter of the International Large Detector (ILD) as a case study.In contrast to previous approaches built on fixed voxel grids, CaloClouds represents showers as point clouds -- sets of energy-weighted coordinates with continuous spatial positions.This formulation minimizes the projection artefacts that arise when mapping grid-based outputs onto irregular detector readout geometries and enables the use of a single model across different detector positions with the same longitudinal structure.The model combines two complementary components: ShowerFlow, a normalising flow that captures global properties such as per-layer energies and number of energy depositions, and a diffusion model that generates individual energy depositions.A dedicated preprocessing pipeline converts Geant4 simulation steps into high-resolution point clouds, providing training data at finer granularity than the physical readout cells.To disentangle the contributions of data representation from model performance, this work introduces optimal shower generators constructed by projecting Geant4 steps onto virtual grids of varying resolution without generative modelling.Benchmarks against these references show that CaloClouds achieves fidelity close to the finest-grained optimal generator, indicating that the model reaches its maximum potential given the data representation.Simultaneously, comparisons with the coarse-grained optimal shower generators reveal fundamental limitations of fixed-grid representations independent of the generative model architecture.Full integration into the ILD software chain via the DDML library enables evaluation with standard reconstruction tools, including Pandora particle flow.Physics benchmarks span single-photon observables, di-photon separation, and $\pi^0$ reconstruction in $e^+e^-\rightarrow~\tau^+\tau^-$ events, with the majority demonstrating state-of-the-art agreement with Geant4.On CPU hardware, CaloClouds achieves more than 120-fold acceleration relative to full Geant4 simulation, while on GPU hardware, speedups of several thousand-fold are achievable.Taken together, these results establish CaloClouds as an effective solution that balances speed and accuracy for fast calorimeter simulation, providing a foundation for meeting the simulation demands of next-generation collider experiments..

Vector-like quarks are predicted in various scenarios in beyond the Standard Model (SM) theories. This work presents a search for a single vector-like top quark (T) decaying into a top quark and a SM Higgs boson (T!tH), in the T mass range from 600 GeV to 1200 GeV. [...]

The high global warming potential of CH4 makes the catalytic conversion of residual CH4 in exhaust gases vital for applications such as CH4 combus tion engines and turbines, power-to-gas or biomass plants. The most active heterogeneous catalyst system for complete CH4 oxidation at low temper atures (< 650K) in lean reaction gas mixtures (overstoichiometric oxygen content) is the class of Pd-based catalysts supported by (mixed) metal oxide supports. [...]