Advances in theoretical and computational techniques for advancing concepts in nanophotonics along with major development in nanofabrication technologies has enable the realization of nanoscale optical device with unprecedented ability to control light such as plasmonic metasurface. Fabrication of plasmonic devices, however, has long been relying on conventional lithography technique such as electron beam lithography (EBL), focused ion beam (FIB) milling and photolithography (PL). While these lithography techniques have enable construction of sub-wavelengths nanostructures, their reliance on the interaction between charged particles or light beam with polymer resist during pattern writing process require intricate control systems and usually require high operating and maintenance cost. In fact, for FIB and EBL, the writing time can be very slow depending on the pattern area. These approaches, therefore, are unsuitable for industrial scale production thus hindering commercial uptake of metasurfaces. Therefore, there is a need for an alternative low-cost, high-throughput nano-manufacturing approach to overcome the bottleneck in conventional lithography methods. With this motivation in mind, this thesis focused on utilizing the nanoimprint lithography (NIL) technique for fabrication of the designated plasmonic device. NIL uses pattern transfer approach whereby a predefined pattern on a mould is used to replicate the pattern onto another surface. NIL offers scalability and high-throughput large area manufacturing of nanostructures. In this thesis, the versatility and capability of NIL for producing plasmonic device, particularly plasmonic colours, with a potential of scalability is investigated. This includes the investigation of the dynamic flow of the resist during the nanoimprinting process through various process parameters. With this information, it will be shown that NIL is capable of producing multi height, grayscale-like structures through a careful control of the flow of the resist, without relying on control of charged particle or light beams. This novel technique was then utilised as a method to print the plasmonic colouration device, with ability of controlling the hue and saturation of the resulting colours via tuning of the vertical gap size of the structure. Additionally, an investigation of multispectral, polarisation-selective iridescence plasmonic colour will also be shown in this thesis. This was achieved via the elongation of the spatial dimension of plasmonic structure which results in multiple resonances in both visible and infrared region of the spectrum. Such multispectral system will be very useful especially for optical security device. Finally, a novel plasmonic colour designed to preserve the vividness of the resulting colour under unpolarised ambient lighting condition will be demonstrated in this thesis. This involves production of polarization-independent plasmonic structure featuring symmetric cross structures. It will be shown that this device produced excellent colours with preserved hue and vividness, regardless of polarization state of light

X-ray Absorption Spectroscopy (XAS) is the study of quantum interference of the photoelectron emitted upon ionisation of an absorbing atom by an incident x-ray. XAS is one of the most popular techniques of synchrotron science and most modern synchrotrons have several dedicated beamlines for this purpose. The overwhelming majority of research in this field measures secondary fluorescence photons emitted by the sample of interest. This type of measurement suffers from the dominant systematic error of self-absorption of the fluorescence photon which compromises accuracy, analysis and insight. This work presents a novel self-consistent methodology to correct for this systematic error. These results represent an enormous improvement over any previous attempt to correct for this systematic error. This method (and accompanying software package) can be applied to any fluorescence XAS data set leading to a widely-applicable general solution. XAS is an invaluable tool in the interpretation of much organometallic chemical physics including stereochemistry and quantum structure. Ferrocene is arguably the archetypal organometallic. The 1973 Nobel Prize in Chemistry was awarded on the basis of its discovery and for the identification of its extraordinary nanostructure. Subsequently, its nanostructure has been the subject of dozens of experimental investigations using widely-ranging techniques and a continued source of debate for over 6 decades since its discovery. I have successfully investigated the nanostructure of the isolated ferrocene molecule using a novel combination of Fourier Transform Infrared (FTIR) spectra processing techniques. Detailed analysis of experimental data was undertaken using modern Density Functional Theory (DFT) calculations for high-accuracy hypothesis testing. In this way, the most compelling evidence yet of the existence of the ‘eclipsed’ conformer of ferrocene is presented.

The central thread of this thesis describes the testing and commissioning of the optical fibre beam-loss monitor (oBLM) for use at the Australian Synchrotron. The four 125 m long silica fibres that form the sensitive detectors of the oBLM are installed on the Aus- tralian Synchrotron and provide complete baseline coverage of the accelerator, from the electron gun to the end of the storage ring. This configuration provided a range of testing environments in which to characterise the oBLM and investigate potential use cases. The results of these procedures demonstrated that the oBLM was able to objectively discern losses above 200 fC or approximately 10^6 electrons. The timing resolution as averaged from measurements using multiple fibres at several loss locations was determined to be 1.22 +/- 0.19 ns at FWHM across the working range of the fibres. When the oBLM is operated in time of flight mode this corresponds to a spatial resolution of 0.13 +/- 0.02 m, which is smaller than the average component spacing of lattice elements at the Australian Synchrotron and demonstrates that the oBLM is capable of attributing losses to specific errant devices. Potential and productive use cases of the oBLM were then explored and a range of operational techniques were developed, after which the oBLM was integrated into the injection efficiency monitoring and optimisation system. Where it was used, in time of flight mode, to characterise spontaneous losses along the length of the Australian Synchrotron injection and storage ring systems. The diagnostic information it provided from these measurements was employed in the tuning of the injection system and as a consequence the injection efficiency between the linac and booster ring was increased by 60 %. Based on the findings of this thesis an optimised configuration, that best enables the oBLM to address the usage scenarios identified, was created and presented in this thesis.

In modern-day technology, silicon and silicon-based materials play a key role in the production of computing parts, specifically, the transistors within the chips. The exponential densification of transistors has caused the excess heat generated during operation to significantly hamper chip performance. This has led to the rise of hyperbolic language which refers to this problem as the `silicon apocalypse', and the material as `dark silicon', on account of each chip mostly being turned off to limit heating. The focus of this work lies in creating a silicon-based heterostructure with diamond, which has an unparalleled thermal conductivity, to effectively extract and dissipate heat directly from the chip. To realise such a structure, this work explored the usage of single crystal diamond as a substrate for silicon growth. As diamond had been previously grown on silicon carbide with limited coherence, shown in literature by other authors, the work begins by investigating the interface between 3C-SiC and a diamond substrate both experimentally and theoretically. It was found that 3C-SiC could form a coherent interface with diamond across several nanometres and that, through atomistic simulation, it was possible to realise greater regions of coherence. In the fabrication process, which involved heating thermally deposited silicon within an ultra high vacuum chamber, it was discovered that thin film dewetting became a major hurdle for long range coherence. This dewetting phenomenon and the behaviour of silicon on diamond during annealing then became the second major focus of this thesis to better understand how, or if, a coherent interface could be achieved between these two materials. To diminish the possibility of dewetting, which occurs with very thin films, PECVD silicon was chosen as an accessible method to time-efficiently deposit thicker layers. In spite of the benefits of PECVD silicon, crystallisation through annealing did not yield single crystal silicon. Instead, minimal interaction was found below 600C between the diamond substrate and silicon, which exhibited behaviour in line with PECVD silicon on other substrates as reported in the literature. However, at elevated temperatures around 1000C, a novel form of diamond etching was observed. The results gleaned from this work indicated that 3C-SiC/diamond heterostructures with a coherent interface could be produced, and thus, future applications are possible. The formation of a silicon and diamond heterostructure, however, was hampered by thin film dewetting and so further testing is needed to determine whether a coherent interface could be achieved using processing techniques applied in the case of 3C-SiC, but with thicker layers. By utilising a more accessible deposition method, namely PECVD, thicker layers became readily available on diamond substrate. Under thermal treatment, the PECVD silicon was found to crystallise into a polycrystalline layer, and at temperatures exceeding 1000C, even begin etching the diamond substrate. These series of studies bring to light several fundamental details of a silicon and diamond interface that are a prerequisite to the utilisation of diamond substrates in the future, especially with silicon-based materials.

Quantum devices that leverage the manufacturing techniques of silicon-based classical computers make them strong candidates for future quantum computers. However, the demands on device quality are much more stringent given that quantum states can decohere via interactions with their environment. In this thesis, a detailed investigation of ion implantation induced defects generated during device fabrication in a regime relevant to quantum device fabrication is presented. We identify different types of defects in Si using various advanced electrical characterisation techniques. The first experimental technique, electrical conductance, was used for the investigation of the interface state density of both n- and p-type MOS capacitors after ion implantation of various species followed by a rapid thermal anneal. As precise atomic placement is critical for building Si based quantum computers, implantation through the oxide in fully fabricated devices is necessary for some applications. However, implanting through the oxide might affect the quality of the Si/SiO_2 interface which is in close proximity to the region in which manipulation of the qubits take place. Implanting ions in MOS capacitors through the oxide is a model for the damage that might be observed in other fabricated devices. It will be shown that the interface state density only changes significantly after a fuence of 10^13 ions/cm^2 except for Bi in p-type silicon, where significant increase in interface state density was observed after a fuence of 10^11 Bi/cm^2. The second experimental technique, deep level transient spectroscopy, was used to study the defects in the substrate of Si after ion implantation. As Er has the potential of interfacing electrical and optical properties of Si based quantum computers, it is important to know what defects will be present after the implantation because of its large atomic mass. H and Er implantation damages were compared to demonstrate the more complex defect evolution for Er implantation. Although defects were still present after a 400 C anneal, the concentration was reduced by at least one order of magnitude. The last experimental technique, charge pumping, was used on MOSFETs to study the interface state density directly in device structures that can be directly used in, for example, magnetic resonance and quantum sensing applications. Charge pumping has the potential of allowing measurement and manipulation of both electronic and magnetic properties of the interface defects and defects in the MOSFET channel. For such applications it may be necessary to operate the device close to absolute zero temperature. The work presented here represents a first step towards device and technique development with the ultimate aim of pushing measurements to mK temperatures where quantum device operations typically operate.

Establishing a baryogenesis mechanism, a dynamical origin of the baryon asymmetry, remains an open problem in physics. Electroweak baryogenesis is one such mechanism that is often touted for its inherent testability at current and near future experiments. Taking this notion to heart, here we will examine the collider and dark matter phenomenology of three models motivated by electroweak baryogenesis and novel electroweak phase transitions. In chapter 2, we extend the standard model with two real scalar singlets and one vector-like lepton doublet and examine the collider phenomenology, phase transition history, and baryogenesis mechanism. We find that such a model is capable of generating sufficient baryon asymmetry while satisfying electron electric dipole moment and collider phenomenology constraints. In chapter 3, we study the phenomenology of a hypercharge-zero SU(2) triplet scalar whose existence is motivated by two-step electroweak symmetry-breaking models. If the neutral component of the triplet is stable, we find that this model is strongly constrained by disappearing charged track searches and dark matter direct detection experiments. Conversely, if it is unstable, we find that this model is constrained by multilepton collider searches, such that a triplet with a mass less than 230 GeV is almost excluded at 95% confidence. In chapter 4, we examine the collider and dark matter phenomenology of the standard model extended by a hypercharge-zero SU(2) triplet scalar and a gauge singlet scalar. In particular, we study the scenario where both of the new scalars are charged under a single Z2 symmetry. We find that such an extension is capable of generating the observed dark matter density, while also modifying the collider phenomenology such that the lower bound on the mass of the triplet is smaller than in minimal triplet scalar extensions to the standard model.

This thesis focuses on the development of implantable neural interfaces to perform multifunctional neural recording, neural stimulation and biochemical sensing. Neural interfacing devices using penetrating electrodes have emerged as an important tool in both neuroscience research and medical applications. These implantable electrodes enable communication between man-made devices and the nervous system by detecting and/or evoking neuronal activities. Recent years have seen a rapid development of electrodes fabricated using flexible, ultrathin microwires/microfibers. Compared to the arrays fabricated with rigid materials and larger cross sections, these microwires/microfibers have been shown to reduce foreign body response after implantation, with improved signal-to-noise ratio for neural recording and enhanced resolution for neural stimulation. Carbon fibers (CFs) are considered for implant into particular tissue types since they have small size, cause less tissue damage, and are flexible. CF recording electrodes have shown promise as recording electrodes and have the properties necessary to form sensing electrodes. Micron-scale electrodes such as CFs are expected to evoke localized neural responses due to localized electric fields. CFs are traditionally used with fast-scan cyclic voltammetry to study rapid neurotransmitter changes in vivo and in vitro, as they allow real-time detection of catecholamines with high sensitivity and selectivity. However, they possess narrow usable voltage range, which limits their application for neural stimulation. Additionally, surface fouling occurs with certain neurochemicals potentially obstructing further neurotransmitter adsorption onto the electrode surface. Therefore, they need to be coated with other materials to boost their electrochemical properties for neural stimulation. In this thesis, diamond and diamond-like materials, in particular nitrogen doped ultrananocrystalline diamond (NUNCD) hybrid and boron doped carbon nanowall (B-CNW) are considered as coatings for CFs to enhance properties towards neural interface applications. A focus is finding acceptable properties for recording, stimulation and neurochemical sensing. Novel fabrication techniques were developed to deposit the films onto the surface of CFs. Firstly, the surface of CFs was amine-functionalised and covalent bonds were formed with oxygen terminated nanodiamonds. Films were grown on the treated/seeded fibers using plasma-assisted chemical vapor deposition. To fabricate single fiber electrodes, individual fibers were insulated with capillary glass with 100 micrometer of fiber exposed. The physical and chemical properties of NUNCD hybrid and B-CNW were characterized and studied. The results from electrochemical characterization, in conjunction with both in vitro and in vivo assessments, suggest that these electrodes offer a highly functional alternative to conventional electrode materials for both recording and stimulation, yielding safe charge injection capacities up to 25.08 +-12.37 mC/cm2. To test the capability of electrodes for neural stimulation in vitro, explanted wholemount rat retina was used. The electrodes could elicit localized stimulation responses in the explanted retina. These electrodes with micron -scale cross sections have the potential to improve the spatial resolution for stimulation while minimizing axon bundle activation. In vivo and in vitro single-unit recording showed that the electrodes could detect signals with high signal-to-noise ratios up to 8.7. NUNCD hybrid coated CFs were able to electrochemically detect dopamine with high sensitivity and selectivity. Such electrodes are needed for the next generation of miniaturized, closed-loop implants that can self-tune therapies by monitoring both electrophysiological and biochemical biomarkers.

The Epoch of Reionization marks the transitional period of our Universe where the emergent growth of luminous structure begin to ionize the surrounding medium of neutral hydrogen gas. The characterisation of these luminous sources; galaxies or accreting black holes (i.e. quasars) play an important role by tracing sites of early structure formation, thus forms an integral aspect to our overall understanding in galaxy formation and evolution. In this thesis, we investigate the key properties of the rarest, brightest objects that are easily accessible by contemporary means; its large-scale environment and its number density, in the specific context of how stochasticity can affect the measured statistics of these rare objects. In the first part of this thesis, we investigate the impact of luminosity scatter in measurements of galaxy clustering, under the premise that luminosity scatter facilitates the odds for a common halo to contain an over-luminous outlier. We construct a Monte Carlo simulation of mock Hubble Space Telescope field-of-views to collect statistics of visible galaxy neighbours. We find that galaxy luminosity scatter is important in the overall clustering statistics within a field-of-view. However, current observations of weak clustering is consistent with our modeling predictions due to Poisson noise. There is scope in using future clustering measurements as a method to constrain luminosity scatter. The impact of luminosity scatter has a profound impact on the number distribution of luminous objects by broadening the bright end of the luminosity function. We extend the semi-empirical model for the evolution of the galaxy luminosity function by accounting for stochasticity in galaxy luminosities. Our model shows that a non-zero scatter in galaxy luminosities results in a departure from the Schechter function, and the amount of scatter can be constrained by additional large area observations of very bright galaxies. In the second part of the thesis, we extend our analysis of galaxy luminosity stochasticity to quasars. We investigate how quasar luminosity evolves with halo mass under different assumptions of quasar luminosity scatter and quasar duty cycle. We find that quasar luminosity scatter is linked to AGN and star formation feedback in our modeling. With a duty cycle of unity, we find that feedback acts on black holes and galaxies independently. Alternatively, a lower duty cycle favours the interpretation of a common feedback source. We conduct a similar Monte Carlo analysis on the weak clustering around $z\sim6$ quasars. We find that a duty cycle of unity places constraints on galaxy luminosity scatter in order to maintain consistency with observations, while a lower duty cycle does not have any restrictions on galaxy luminosity scatter. The quasar luminosity scatter is not strongly constrained by the field-of-view clustering measurements. Finally, we develop a single parameter semi-empirical model of the evolution for the quasar luminosity function that accounts for quasar luminosity scatter. Our model shows excellent agreement with the $z=3-6$ quasar luminosity functions and is capable of reproducing the $z=0-2$ luminosity functions assuming a small evolution in quasar luminosity scatter. Future measurements of the $z>6$ quasar luminosity function will be essential in validating the robustness of this model.

In this thesis high precision QCD-factorisation tests were performed. The branching ratios B(B → D π ) = (2.67±0.02±0.09)×10 and B(B → D K ) = (2.27±0.06±0.08)×10−4 were measured using (771.58±10.56)×106 B-meson pairs recorded by the Belle experiment. Both values are in tension with the theoretical expectation. The ratio of the branching ratio is measured in a way that allows for the cancellation of the systematic uncertainties arising from the D∗-meson reconstruction; the value of RK/π = B(B → D K )/B(B → D π ) = (8.41±0.24±0.13)×10 was found. Both B(B → D π ) and B(B → D K ) have shown deviations from the prediction, this suggests that the estimation of the Feynman diagrams contributing to the predictions may be inaccurate. The new measured branching ratios were used to perform a high precision QCD factorisation test by measuring ratios with respect to semi-leptonic branching ratios at fixed momentum transfers for different particle species. A deviation for the ratio Γ(B → D h )/dΓ(B → D l ν ̄)/dq of 16% from theoretical predictions was found, suggesting large non-factorisable contributions and/or new physics contributions. Furthermore, SU(3)-symmetry was tested by measuring ratios for pions and kaons of a21(K)/a21(π) = 1.05±0.05 as well as for different particle species. The found value is consistent with unity and therefore no evidence for SU(3)-symmetry breaking effects was found in this test to 5% precision. Thus, for RK/π one can rule out SU(3)- symmetry breaking effects as an explanation for the deviation. Finally, a new vertex fitting algorithm and its implementation for the Belle II software framework was reported. It can improve D∗-meson reconstruction, is com- putationally very efficient and is now the standard vertex fitting tool of the Belle II experiment.

Microscopy based on the nitrogen-vacancy centre in diamond is an emerging technology that may soon find regular application in characterising a broad range of systems. The development of nitrogen-vacancy microscopy has been benchmarked by key proof-of-concept experiments, each demonstrating the great potential of the technique, without necessarily delivering unique insights into the system studied. In this thesis, we aim to further the development of this emerging technology by applying it to study a range of delicate and complex condensed matter test systems. Specifically, we take a widefield approach which utilises a dense ensemble of near-surface nitrogen-vacancy centres to image magnetic and electric fields over a 100 um field of view with diffraction-limited resolution and good sensitivity. In each application presented, we study physics both intrinsic to the test systems and arising from their interaction with our imaging technique. These observations inspire refinements to our approach that enhance the utility of the technique. Chapter 1 reviews the physics underpinning microscopy with nitrogen-vacancy centres in diamond, and surveys key achievements in the literature. Chapter 2 details our approach to widefield nitrogen-vacancy microscopy. Chapter 3 applies widefield magnetic imaging to ultrathin depositions of nanoparticles on the diamond surface. We observe a strong magnetic noise associated with metallic depositions, even when the deposited material is less than 1 nm thick. This study demonstrates the great sensitivity of widefield nitrogen-vacancy microscopy, allowing the detection of minute sample volumes. Chapter 4 studies magnetic and electric fields associated with graphene field-effect transistors fabricated on the diamond surface. We demonstrate current density mapping under different doping conditions, a significant extension of device studies published at the time, and identify strong electric fields associated with the gating that affect both the spin resonances and photoluminescence of the sensing ensemble. These first two studies motivate the use of a deeper and thicker nitrogen-vacancy ensemble that protects against the short-range noise contributed by the metallic nanoparticles, which mimic common contaminants, and protects the sensing layer from device-related electric fields. Chapter 5 extends our widefield imaging technique to low temperatures (4 K) by incorporating a closed-cycle cryostat into the apparatus, which we use to study a low-critical-temperature system, superconducting niobium wires. By imaging Abrikosov vortices and superconducting transport at various laser powers, we quantify local heating in the sample caused by the excitation laser. This observation motivates a refined nitrogen-vacancy imaging substrate that includes a reflective metallic layer at the diamond surface and an insulating oxide layer, onto which the target sample is deposited. This design mitigates the local heating caused by the excitation laser, an essential component of the imaging technique, and leaves the sample electrically isolated, facilitating advanced studies of low-temperature physics. Chapter 6 deploys this refined nitrogen-vacancy substrate to characterise the magnetic properties of two free-standing ultrathin ferromagnetic materials. We directly quantify the layer-dependent magnetisation of a van der Waals ferromagnet, VI3; a capability lacking in established characterisation techniques. Finally, we identify a threshold size (20 nm) below which a non-layered ultrathin material, magnetite, ceases to show ferromagnetism. This thesis furthers the development of widefield imaging using nitrogen-vacancy centres in diamond, enabling a range of future applications.

Understanding Dark Matter (DM) is one of the foremost goals of modern day particle physics. This thesis is focused on interactions between DM and visible matter. We examine the phenomenology that arises when existing frameworks are extended to make them theoretically consistent, and explore novel means of detection. The first chapter summarises current DM literature and experimental searches, as well as the motivation for pursuing a gauge invariant description of the interactions between the dark and visible sectors. The second chapter considers a gauge invariant portal between the dark and visible sectors, and how the phenomenology of a self consistent model described in a gauge invariant framework differs from the simplified models previously considered in the literature. We consider features of the direct detection signals characteristic of such a gauge invariant model, as well as constraints on these models arising from electroweak precision data, stability of the scalar potential, and DM relic density production. In chapter 3, we consider models in which the tree level contributions to nuclear recoil direct detection experiments are strongly suppressed. In this case, the leading order contributions arise at loop level. We investigate the size of these contributions for both the gauge invariant model presented in the previous chapter, as well as an inelastic DM model. In the fourth chapter we consider the capture of DM particles in the Sun, and their subsequent annihilation to other dark sector particles. The decay of these dark annihilation products, outside the Sun, leads to a flux of gamma rays that we compare with recent solar gamma ray measurements. We analyse this scenario in a model independent way, demonstrating excellent sensitivity to both spin-dependent and spin-independent scattering. We also determine constraints in the context of a self consistent model in which both the scattering and annihilation processes involve dark photons.

The seesaw mechanism, where a hierarchy exists between the moduli of different entries of a mass mixing matrix, is a simple and theoretically attractive explanation for the observed large hierarchy between the neutral- and charged-fermion masses of the Standard Model. The simplest neutrino mass seesaw predicts that, upon diagonalisation, the physical mass states will either all be Majorana or all form pseudo-Dirac pairs. Non-minimal variants of this seesaw often generate a hybrid scenario with the physical mass states being a combination of both Majorana and pseudo-Dirac pairs. Such models often predict unique phenomenology and also allow for much lower mass scales of new physics. This thesis explores the implications such non-minimal variants can have beyond the simple generation of neutrino mass, particularly the possible role they may have in explaining the observed matter-antimatter asymmetry as well as implications for particular models of quark-lepton unification. Chapter 1 reviews the current experimental evidence for neutrino mass and discusses some possible tree-level origins. The matter-antimatter asymmetry is introduced and the conditions necessary for the dynamical generation of this observed asymmetry are reviewed. The idea of thermal leptogenesis is outlined as a simple mechanism for generating an asymmetry dynamically at an epoch between the the period of reheating and the electroweak phase transition of the early universe. Finally, the idea that quarks and leptons are related by hidden symmetries are discussed with a particular emphasis on the quark-lepton unifying Pati-Salam gauge group. In Chapter 2 we consider the leptogenesis implications for the Standard Model extended by two gauge-singlet fermions for each generation of charged lepton. We focus on the possibility of resonant scenarios without the need for inter-generational mass degeneracies and therefore do not require a possible flavour symmetry origin. The possible connection between neutrino parameters measureable in low-energy experiments and the generation of a matter-antimatter asymmetry is explored. In Chapter 3 we extend the analysis of the previous chapter and highlight how a flavour symmetry can allow for leptogenesis in a much wider region of parameter space for the extended seesaw used in \Cref{Chapter2}. The benefits of this extended seesaw, compared to the minimal seesaw scenario, when the proposed flavour symmetry is included are discussed and implications for low-energy flavour-violation experiments are explored. In Chapter 4 different possible Pati-Salam models are discussed with an emphasis on the connection between the scale of Pati-Salam breaking and the scale of heavy neutrino masses. Models allowing for the breaking scale to occur close to the electroweak scale are introduced. The dominant experimental probe of Pati-Salam is discussed and the current limits on the scale of breaking are calculated. Simple extensions of this model are proposed which both break an undesired mass degeneracy in the theory and allow for a significant reduction in the experimental limits on Pati-Salam breaking. A thorough analysis of the possible allowed parameter space in which both of these effects occur is explored and any possible connection to the symmetries of the theory is made. Chapter 5 briefly concludes.