Ph.D. Theses

A search for gluino pair production with events using 35.9 fb−1of data from ppcollisions at a center-of-mass energy of 13 TeV in 2016 is presented. Two differentcascade decay modes of gluinos are considered, and separate analyses for each of themodels are performed [...]

A search for pairs of light bosons produced from decays of the 125 GeV Higgs boson is presented. The search covers the light boson mass region where the particle could have an enhanced decay rate to a pair of τ leptons, according to different models and scenarios.The leptonic decay channels corresponding to the 4τ and 2μ2τ final states are used. [...]

In this thesis measurements of the $t\bar{t}$ pair production at the very high transverse momentum are presented. When a top quark is produced with very high momentum the decay products are collimated in the direction of the quark, and they can be clustered within a single large cone size jet. [...]

Laser-wakefield accelerators enable the generation of electron beams with initially nm-small emittances and GeV-level beam energies within cm-scale distances and are thereforepromissing candidates for drivers of future experiments. However, the percent-level energy-spreads and shot-to-shot fluctuations in beam quality can pose a limit to the transportability of plasma-generated beams, and further impete the measurement of the beam emittance using conventional methods.In the framework of this thesis, two energy-resolved phase-space diagnostics, a single-shot and a multi-shot method, have been implemented at the LUX laser-plasma accelerator.Electron beams from ionization injection are imaged by a compact quadrupole doublet from a virtual source into a dispersive electron spectrometer, which allows to measurethe beam emittance, beam size, divergence and phase-space correlation on the singleenergy-slice level. [...]

In this thesis we investigate two questions that shed new light on fundamentalproperties of supersymmetric gauge theories.Our first topic deals with the question, which implications results for N = 4 Super-Yang-Mills have on theories with less symmetry. Specifically we conjecture that thedilatation operator in the SU(2, 1|1) sector of any N = 1 superconformal gauge theorycan be found from the one for N = 4 Super-Yang-Mills by a redefinition of the couplingconstant. [...]

Natural essential oils are complex mixtures containing several compounds of structural similarity.They are well known for their wide range of applications in different areas, frommedicine to cosmetics. One of the conventional methods for their quantitative analysis is gaschromatography (GC). [...]

In this thesis we propose intensity correlation enhanced imaging techniques in two major areas of imaging with light. The first area is diffractive imaging. [...]

The study of molecular dynamics involves observations of the motion of nuclei and electrons. While nuclear motion is usually on the picosecond or femtosecond timescale, attosecond precision is necessary to directly observe the motion of electrons. [...]

The time scale of the dynamics in atoms and molecules varies from attoseconds (10-18) to picoseconds (10-12) depending on the size of the particles. To study such dynamics, ultrafast light pulses are needed to trigger and capture the reaction. [...]

Shape resonances are a ubiquitous phenomenon in electron–molecule scattering, in which the impinging electron is resonantly captured in a pseudo-bound state that is supported by the molecular potential. To study the electron scattering dynamics, we use time- and angle- resolved photoelectron spectroscopy here. [...]