Ph.D. Theses

This interdisciplinary dissertation investigates several key physical and computational challenging inherent in high-energy physics analyses of top quark pair (tt) production. As the heaviest known elementary particle, the top quark occupies a unique position within the Standard Model (SM), serving as a critical probe for new physics. [...]

The main objective of this thesis is to elucidate the role of induced wireless bipolar electrochemistry in the field of energy storage, never tackled before in the field. New applications for wireless electrochemistry have been found recently from wireless electrodeposition to oscillating reactions related to local changes in resistance of the bipolar electrode. [...]

Double molybdates have demonstrated high variability and tunability in their luminescence properties and therefore have instigated considerable research activities aimed at identification of their potential for application in lighting, laser physics, remote thermometry, and radiation detection. In this work, the luminescence phenomena were investigated in detail in several novel rare-earth-based double molybdates, such as K₅RE(MoO₄)₄, KRE(MoO₄)₂ and KRE₅(MoO₄)₈, where RE = Tb, Eu, Nd. [...]

Light has fascinated humanity for centuries, not only for its beauty but also for its practical value in illumination and healing. Recent research shows that specific wavelengths can be used against treatment of tumors. [...]

This thesis explores ultrafast dynamics in atomic and molecular systems using pump–probe techniques at the free-electron laser (FLASH), with the goal of achieving the high temporal resolution required to resolve processes on the order of 100 fs and below. To address this challenge, an active feedback scheme based on a laser arrival time monitor is implemented to improve synchronization between optical laser and FEL pulses. [...]

Conformal field theories (CFTs) and supersymmetric field theories constitute special classes of quantum field theories with applications ranging from critical phenomena and confinement to quantum gravity via holography. Their large symmetry groups make them ideal testing grounds for theoretical developments, enabling the use of powerful and elegant methods. [...]

This thesis provides new non-perturbative numerical methods and exact analytic constructions in the context of low-dimensional conformal field theory and holography.The main results are a six-point extension of the numerical conformal bootstrap and the identification of the holographic dual of anti-de Sitter (AdS) D-branes in minimal pure NSNS AdS$_3$.On the numerical side, the thesis introduces a six-point bootstrap framework that exploits positivity in decompositions of six-point correlation functions into products of four-point correlators to derive rigorous bounds on solutions to six-point crossing equations.The resulting optimisation problem involves semi-definite programming (SDP) with infinite-dimensional constraint matrices.By employing sparse SDP techniques, the problem is recast into a numerically tractable form.As a proof of concept, the method is implemented for conformally invariant correlation functions in one dimension, providing e.g.~a non-perturbative handle on correlations of holographic boundary modes in interacting quantum field theories defined on AdS$_2$.On the analytic side, the thesis introduces a family of one-dimensional holographic interfaces between symmetric product orbifolds.These interfaces are first analysed algebraically via explicit boundary states in the folded theory.In this framework, the partition function of interface-changing operators is computed and exactly matched with the annulus partition function of AdS$_2$ branes in the Eberhardt–Gaberdiel–Gopa\-kumar tensionless limit of superstring theory on pure NSNS AdS$_3 \times S_3 \times \mathbb{T}^4$.Finally, an alternative description of the interfaces in terms of a novel class of generalised covering maps is provided, which yields significantly improved control over interface correlators and higher-genus partition functions.With this new handle on the interface correlators, a 't Hooft-like expansion is established which structurally matches string perturbation theory to all orders in the string coupling..

Despite the Standard Model's ability to describe collider data from all experiments conducted around the world, several questions about the history of the Universe, including the hierarchy problem, the baryon asymmetry, and the dark matter density, remain open. To address these unresolved issues, the particle physics community agrees on the need to construct a next-generation collider that could probe the Standard Model with higher accuracy and potentially reveal deviations from the predictions of this fundamental theory. [...]

In this thesis, a comprehensive investigation of the electronic energy structureand associated radiation- and photostimulated processes in a wide class of perovskite-based scintillation materials is presented. The research encompasses the study ofinorganic crystals Cs₂MCl₆ (M = Hf, Zr), CsPbX₃ (X = Cl, Br, I), as well as organic-inorganic perovskites with the general formula MAPbX₃ (X = Cl, Br, I).The crystal structure of inorganic Cs₂HfCl₆ and Cs₂ZrCl₆ perovskites wasinvestigated. [...]

This thesis investigates the interplay between integrability, defects, and renormal-ization group (RG) flows, in quantum field theories in 2 and 4 dimensions.In the first part, we study the analytic properties and integrable structure of the meson spectrum in the large Nc limit of two-dimensional QCD. In this regime, the integral equation governing meson masses is shown to be equivalent to a TQ-Baxter equation, characteristic of integrable models. [...]