Offene Themen für Abschlussarbei­ten

Quarkonia are unstable hadrons made up of identical quark-antiquark pairs, which decay according to the electromagnetic, strong or weak interactions. This project will work on improving the modelling of these decays in the simulation program "Sherpa" by updating branching ratios from measured results and implementing matrix elements for the most relevant decay channels.

The production of W boson pairs from photons are a very sensitive probe of the electroweak gauge structure. Data recorded by the ATLAS Experiment in the LHC run-2 are used to quantify the agreement of the theoretical predictions. This is done by constraining higher-dimensional beyond-the-Standard-Model operators that modify the γγWW vertex.

tbd (Mareen, Erik)

The complexity of matrix element calculations for final states with a high multiplicity is so high, that their computational cost often limits theory simulations for the LHC. In this project we want to extend a machine learning based approach to simplify these calculations by approximating the matrix elements. The goal is to study various parameters for the architecture and training of deep neural networks in this approach.

The simulation of different polarisation states allows us to study effects from physics beyond the Standard Model in more detail. In this project we want to study, how effective-field-theory extensions of the Standard Model will affect different polarisations of W bosons in W±W± pair production at the LHC.

The simulation of different polarisation states allows us to study effects from physics beyond the Standard Model in more detail. In this project we want to study, how effective-field-theory extensions of the Standard Model will affect different polarisations of W and Z bosons in WZ pair production at the LHC.

Triboson production V(->ll)V(->ll)V(->qq) is a component of the signal definition in vector boson scattering, but is sometimes ignored or generated as a separate process. This thesis should study the impact of the triboson component. In particular the effect of dim-8 EFT operators in the quartic vertex should be studied to quantify the effect of ignoring the triboson production in an EFT study.

In parallel to our analysis of WZ final states at high transverse momentum we want to search for deviations from the Standard Model from new heavy particles decaying into a WZ boson pair.

TODO

The simulation program Sherpa can currently only simulate decay cascades with up to 3 final state particles in each step. For decays of the Higgs boson into 4 fermions via WW or ZZ diagrams it becomes important to simulate the full 1->4 decay. This thesis is about implementing such decays and make phenomenological comparisons to existing calculations.

Tbd

The production of leptons from photons proceeds through purely electromagnetic interactions. The photons are radiated from protons colliding at the LHC. The key experimental signatures for the production of four leptons from photons uses the fact that the protons stay intact and no particles other than the leptons are produced in the interaction. The analysis is based on an earlier measurement of the production of W boson pairs from photons, published in https://arxiv.org/abs/2010.04019.

tbd

Im Netzwerk Teilchenwelt wurde umfangreiches Unterrichtsmaterial zur Teilchenphysik erstellt. Die Erkenntnisse des Standardmodells werden darin mithilfe des Konzepts von Ladungen und Wechselwirkungen beschrieben. Dieser Ansatz, der sich in der populärwissenschaftlichen Literatur und in Schulbüchern bislang kaum widerspiegelt, soll durch geeignete Arbeitsblätter ergänzt werden.

Diese Arbeit soll in Kooperation mit der Didaktik der Physik erstellt werden.

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