Filtyp
In this thesis we investigate the properties of a specific two Higgs Doublet Model (2HDM) that can be used to explain the data on B->Dtu and B->D*tu, which deviate from the Standard Model (SM) by 3.4 sigma. The 2HDM is the simplest extension of the Standard model scalar sector. Phenomenologically it is very rich with 4 new Higgs bosons: 2 neutral and an electromagnetic charged pair. The 2HDMs exhi
Throughout this work we investigate a trinification-based grand unification theory (GUT) with a global family symmetry, as a radiative origin of the Standard Model (SM). We show that after spontaneous symmetry breaking of the trinification gauge group, we can in theory construct an effective left-right symmetric model (LRSM) which breaks to the SM gauge group through radiative breaking induced by
An analysis of two-particle angular correlations was recently performed on measurements taken from pp collisions at $\sqrt{s}$ = 7 TeV by ALICE at the LHC. The correlations for mesons are in good agreement with simulations performed in Monte Carlo event generators such as PYTHIA and PHOJET, but there is a significant difference for baryons. We here investigate particle production mechanisms in PYT
In this Master thesis, two directions have been explored to improve the current parton shower algorithm of the event generator Pythia. Firstly, three choices of transverse-momentum-ordered evolution variable have been studied for final-state radiation in order to allow more flexibility within the algorithm. These three choices turn out to be valid but they lead to more technical implementations th
In recent years, the BaBar, Belle and LHCb experiments have observed an excess of $B\to D^{(*)}\tau\nu$ decays compared to Standard Model predictions. In this thesis, we investigate if it is possible to explain this excess with a two Higgs doublet model using the Froggatt-Nielsen framework. Two Higgs doublet models allow new decays at tree-level and the Froggatt-Nielsen mechanism gives an explanat
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
The black hole information paradox is of central importance in the study of quantum gravity. The paradox states that quantum fields surrounding a black hole behave in ways that run into conflict with the unitarity of quantum mechanical time evolution. In the course of the past two years, new theoretical discoveries have made progress towards the paradox’s resolution, suggesting that unitarity can
Some of the shortcomings of the Standard Model of particle physics are the 'unnatural' value of the mass of the Higgs boson and the fact that the model cannot account for the process of baryogenesis - a mechanism which generates the observed asymmetry between matter and anti-matter in the Universe. The former is related to the fundamental scalar nature of the Higgs boson, connected to quad
We study the key properties of the quantum SU(2) Yang-Mills ground state and its possible role in the early Universe, in particular, as a driver of Cosmic Inflation. Using the effective action approach and separating the Yang-Mills field potential into homogeneous (condensate) and inhomogeneous (fluctuations) components, we reproduce the conformal-time solutions for the two different types of the
This thesis gives an introduction to the basic formalism of one-dimensional supersymmetric quantum mechanics. The factorization of a Hamiltonian is used to create a supersymmetric partner Hamiltonian. The connections between the energy spectra and wave functions of these partner Hamiltonians are deduced and examined for the case of broken and unbroken supersymmetry. An extension to hierarchies of
This thesis considers the low-energy effective field theory of a new technicolor extension. The extension preserves the Standard Model Higgs boson and introduces a chirally symmetric technifermion sector, in the framework of the gauged linear sigma model. In the nearly conformal limit, the considered extension leads to a common origin of the Higgs- and Technisigma vacuum expectation values, relate
In this thesis a chirally symmetric technicolor model is investigated as an extension to the Standard Model. The extension is based on low-energy QCD, with a linear sigma model used to induce the additional degrees of freedom corresponding to the lightest particles of the new techni-sector. The main goal is to incorporate the Standard Model Higgs into the new model, as to explain its vacuum expect
High energy particle collisions involve complex physics, beyond analytical control. Instead, Monte Carlo event generators like Pythia have been used to simulate particle collisions since decades. A study of the production of heavy quarks (namely, charm and bottom) is presented for two different scenarios: lepton (e+e−) and hadron (pp) collisions. Electron- positron collisions at the Z0 resonance a
In this thesis a method for decomposing QCD colour structures into multiplet bases is described. The method is applicable for any number of gluons and quarks. To achieve the decomposition requires the knowledge of group theoretical weights, so-called Wigner 3j and 6j coefficients. The number of required coefficients have been calculated for up to 12 external gluons, and been shown to scale well in
We have studied left-right-symmetric (LR) model building in two specific instances: the Minimal Left-Right-Symmetric Model (MLRM), with gauge group SU(3)_C × SU(2)_L × SU(2)_R × U(1)_{B-L} and parity as the LR symmetry; and a non-supersymmetric, trinified theory, with gauge structure SU(3)_L × SU(3)_R × SU(3)_C × Z_3 and an additional, novel, SU(3) family symmetry. For the MLRM, we have rederive
We review the factorization theorem for the production of a heavy color-neutral final state with a transverse momentum much smaller than its invariant mass in the framework of soft collinear effective field theory (SCET). This phase space region is plagued by large logarithms of widely separated scales, including large logarithms of rapidity ratios, that need to be resummed for sensible results. I
