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The aim of this thesis is to get a better understanding of the evolution of the Milky Way stellar disc by looking at the abundance ratios for neutron-capture elements in thin and thick disc stars. In this project the formation of our Galaxy’s thin and thick disc was studied by analysing 10 different neutron-capture elements in field stars measured by Gaia-ESO. The methodology to determine if this
The first part of this thesis deals with the dynamical estimation of the Oort constants using proper motions and parallaxes provided from the Gaia-DR1 TGAS catalogue. The photometric information was provided by the 2MASS catalogue. The Oort constants calculated from the TGAS catalogue are compared to those obtained from the original Hipparcos catalogue in order to attempt to estimate how well Gaia
The orbital approximation for stellar streams is the assumption that all stars in a stream can be described as following the same orbit. In this thesis, I evaluate this approximation as a method for constraining the potential of the Milky Way. I wrote a program in MATLAB which integrates the orbits of test particles in a potential model which resembles that of the Milky Way's halo and disc. Th
Abstract The idea of the spread of life through the galaxy is, in most minds, considered science fiction. Yet, scientists argue that most galaxies have had more than enough time for civilisation development and space travel. In this thesis I simulate how civilisations can spread through the galaxy via close encountering stars, assuming they travel at sub-relativistic speeds. A defined region arou
One of the biggest mysteries astronomers wish to unveil is the formation and evolution of galaxies. Properties of our own galaxy, the Milky Way, can provide great insight into these. The star formation rate (SFR) and whether it varies with distance from the galactic centre (GC), is one of these properties. Studies indicate that the SFR is higher in the bulge region than in the local thick disk of
The observed high orbital eccentricities of many giant exoplanets is thought to be the result of gravitational scattering between planets. Outcomes of planet-planet scattering can result in some planets being lost by ejections into interstellar space, or collisions between planets or with the star. The likelihood of collisions for a planet with a certain mass, increases with larger radii. After p
The use of reliable distance estimates is key to derive accurate three-dimensional velocities of celestial objects. Systematic overestimation and large uncertainties in the distances will thus provide misleading information of an object's kinematics. In turn, astronomers will get a flawed understanding of dynamical properties of substructures in the Milky Way. In this paper, we employ the imp
A selection of the latest and most frequently used PDFs is incorporated in Pythia8, including the MC-adapted PDFs from the MSTW and CTEQ collaborations. This thesis examines the differences in PDFs as well as the effect they have on results of simulations. The results are also compared to data collected by the CDF experiment.
The problems of the standard model are reviewed and the motivations for introducing supersymmetry are discussed. The basic theory behind supersymmetry is described briefly, followed by an introduction of two realistic supersymmetric models; the Minimal SuperSymmetric Model (MSSM) and its proposed extension, the NMSSM. Some details of the NMSSM are stated and some constraints on parameters are desc
The increased capacity of elementary particle accelerators raises the demand for the simulation data of the experiments. One of the bottlenecks in the simulations is the QCD color structure calculation, which is usually treated using non-orthogonal and overcomplete sets of bases. The computational cost could be decreased significantly if orthogonal bases, such as the multiplet bases, were used ins
High energy particle collisions often produce large numbers of partons in the final state, which are clustered together in collimated sprays called jets. A recent paper [1] introduces the concept of jet entropy, which is an observable that quantifies the entanglement between the resolved and unresolved parts of a jet. We derive an analytic expression for the entropy of a gluon jet and compare the
The purpose of this thesis was to implement an alternative method to calculate the overlap function, which describe to what extent two protons overlap with each other spatially, into PYTHIA8 in order to determine how it affected the average number of multiparton interactions. The new overlap function is based on an explicit impact parameter picture, whereas PYTHIA8s overlap function uses an implic
Finite-volume corrections to the Lattice Quantum Chromo Dynamics (LQCD) calculation of the hadronic vacuum polarization are here considered to one loop, for the simplified case of one and two propagators of equal mass. Simplifications in the calculations are sought for by comparing computations in momentum space, time-momentum space and position space. The derivation of the finite-volume correctio
In this thesis I extend the chirality-flow method to the full standard model at tree-level by including massive particles and electroweak interactions. The chirality-flow method is a new diagrammatic method for calculating Feynman diagrams that is based on the spinor-helicity formalism, that before this thesis was written had been worked out for massless QED and QCD at tree-level. I summarize what
Recently, a number of experiments have been proposed with the aim of finding light dark matter. In particular, the proposed LDMX experiment is meant to utilize electron scattering off metal nuclei to excite dark matter emissions. Motivated by this, we construct an event generator for electrons scattering off metal nuclei. The relevant kinematics are presented in detail. The matrix element for the
We have studied the main features and the phenomenological consistency of a family-nonuniversal Three Higgs Doublet Model (3HDM) with a softly broken U(1)xZ2 family symmetry that enforces the flavour hierarchies in the Standard Model (SM) while implementing a tree-level Flavour Changing Neutral Current (FCNC) suppression in a Branco-Grimus-Lavoura way. Furthermore, the alignment limit is imposed i
