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Context. Large scale chemical abundance gradients in the Galactic disks, small-scale abundance structures, and the mean chemical abundance values in the Solar vicinity, are important constraints to Galactic chemo-dynamical formation and evolution models. The formation and evolution of stars, and interstellar gas and dust depends on the distribution and evolution of matter in the Galaxy. Therefore,
Protoplanetary discs surround young stars for the first few million years after their formation and they are the birthplaces of planetary systems. The thermal structure of the discs is regulated by their dust content and the opacity that it provides. The aim of this project is to investigate the effect grain growth has on the structure of the protoplanetary discs. Hydrodynamical simulations have b
Researchers in the field of Galactic Archaeology have entered the era of industrial revolution. Upcoming surveys are planning on observing tens of millions of stars and high precision and accuracy must be ensured when deriving their stellar parameters and elemental abundances. Unconventional data-driven techniques hold the promise of efficiently dealing with these vast collections of data while st
Purpose: even in the era of exponential increase in the amount of stellar data gathered, binaries are still often overlooked in observational data due to the special handling they require. The goal of this work is to develop a method capable of automatically and efficiently identifying and extract double-lined spectroscopic binaries (SB2) from a spectroscopic survey, while being scalable and techn
Purpose: In order to study the Galactic Chemical Evolution, elemental abundances are needed. The purpose of this work is to investigate the chemical evolution of the Milky Way by determining several elemental abundances of giants in the local disk. Large surveys are up and coming, and several surveys are already working, and with these, the aim is high quality abundance measurements of several ele
27 oktober 2025 10:00 till 12:00 | Seminarium The world is crossing the 1.5°C global warming limit, perhaps exceeding 2°C soon after. What is to be done when these boundaries, set by the Paris Agreement, have been passed? In the overshoot era, schemes proliferate for muscular adaptation or for new technologies to turn the heat down at a later date by removing carbon dioxide from the air or blocki
https://www.lu.se/evenemang/book-launch-long-heat-climate-politics-when-its-too-late - 2026-10-06
In this Master thesis we extend the Standard Model with an additional $U(1)$ gauge group and an additional Higgs doublet with a lepton specific $\mathbb{Z}_2$ symmetry. This is used in a gauged version of the Froggatt-Nielsen mechanism to describe the observed masses and mixings among fermions. To reproduce these observables and satisfy the anomaly constraints posed by the new gauge symmetry metho
The Schwarzschild metric and the Kerr metric describe the gravitational fields around static and rotating black holes, respectively. Here, we derive the Kerr metric in a simpler way than how it was derived originally and determine the stability of the Schwarzschild metric. The Kerr metric was derived by using the Einstein-Hilbert action as well as directly from the Einstein field equations. In ord
The purpose of this thesis is to study what effect a photon field has on the equations of motion and the decay of a charged scalar field in thermal equilibrium at finite temperature and outside of thermal equilibrium. To do this we calculate the two-particle irreducible effective action for the mean fields and propagators and derive their equations of motion. The functional representations of up t
This thesis will investigate the possibility to have SU(2) gauge fields as the source to the Cosmic Inflation and/or to the Dark Energy. It will be explained that, under certain conditions, the Universe can be filled with vector fields without violating its isotropy. Those conditions are naturally fulfilled within the SU(2) gauge theory. Both Einstein's equations and the equations of motion
Chiral perturbation theory is an efficient effective theory to describe meson-meson scattering at low energy. An effective theory naturally introduces low energy constants and they are used, for example, to solve the ultraviolet divergences. The aim of this master thesis is to focus on meson-meson scattering to find some theoretical bounds on the coupling constants, based mainly on arguments from
One approach to understanding the observed hierarchy in quark masses is by using the Froggatt-Nielssen mechanism. In this model new exotic (and presumable yet undetected) particles are introduced. By forcing the particles of the Standard Model to interact with the postulated particles it is possible to create a mass suppression mechanism which can explain the observed quark mass relations. The me
In this thesis, a holographic model for quantum chromodynamics (QCD) is used to estimate the electromagnetic contribution to the kaon mass difference. The principal ideas of the model are inspired by the AdS/CFT correspondence, which is believed to be exact. The calculation is first performed theoretically, highlighting the expansion of the result into a diagrammatic structure referred to as Witte
We take a look at the properties of scalar fields in anti--de--Sitter space in five dimensions. More specifically we define bulk--to--boundary and bulk--to--bulk propagators for a five--dimensional scalar field and use these to calculate four--point functions. Finally we take a look at two--point functions and three--point functions and numerically calculate masses, residues and decay constants fo
We present a generalisation of the flavour-ordering method applied to the chiral nonlinear sigma model with any number of flavours. We use an extended Lagrangian with terms containing any number of derivatives, organised in a power-counting hierarchy. The method allows diagrammatic computations at tree-level with any number of legs at any order in the power-counting. Using an automated implementat
