It has been proposed several times in the past that one can obtain an equivalent, but in many aspects simpler description of fermions by first reformulating their first-order (Dirac) Lagrangian in terms of two-component spinors, and then integrating out the spinors of one chirality (e.g.primed or dotted). The resulting new Lagrangian is second-order in derivatives, and contains two-component spinors of only one chirality. The new second-order formulation simplifies the fermion Feynman rules of the theory considerably, e.g. the propagator becomes a multiple of an identity matrix in the field space. The aim of this thesis is to work out the details of this formulation for theories such as Quantum Electrodynamics, and the Standard Model of elementary particles. After having developed the tools necessary to establish the second-order formalism as an equivalent approach to spinor field theories, we proceed with some important consistency checks that the new formulation is required to pass, namely the presence or absence of anomalies in their perturbative and non-perturbative description, and the unitarity of the S-Matrix derived from their Lagrangian. Another aspect which is studied is unification, where we seek novel gauge-groups that can be used to embed all of the Standard Model content: forces and fermionic representations. Finally, we will explore the possibility to unify gravity and the Standard Model when the former is seen as a diffeomorphism invariant gauge-theory.

We study the chiral anomaly by solving the Dirac equation for fermions in parallel electric and magnetic fields. In such case, only the lowest-energy Landau levels are relevant to the anomaly. Specifically, for massless fermions, the chiral anomaly is a result of the production of particles of one chirality, and no creation of particles of the other chirality. For massive fermions, we find that the chiral anomaly equation can be simply obtained via a proper regularization of the range of the momentum. We extend the method to anomaly cancellation, and conclude that the conservation of the baryon number plus lepton number must be violated as a quantum anomaly in the context of the Standard Model. Accordingly, such baryon number non-conservation can play a vital role during the electroweak transition to achieve the baryon asymmetry of the Universe. Through real-time lattice simulations, we refine the implementation of ensemble fermions for a cold electroweak transition, involving the SU (2) gauge field, Higgs field and one generation of fermions. We find that the dynamics and most observables converge quickly with a reasonable number of fermion realizations, and the method of ensemble fermions for the entire electroweak sector becomes numerically tractable. We apply the method to the computation of the effective preheating temperature during a fast electroweak transition, relevant for Cold Electroweak Baryogenesis. We find that the fermion temperature is never below 20 GeV, and this can indirectly rule out Standard Model CP -violation as the origin of the baryon asymmetry of the Universe, as Standard Model cold baryogenesis requires a temperature of at most of order of 1 GeV. For this reason, new CP -violation source from physics beyond the Standard Model is required in order to explain the baryon asymmetry. We further present a first-principles numerical computation of the baryon asymmetry in electroweak-scale baryogenesis, where the CP -violation is obtained as a consequence of including another Higgs doublet. For one particularly favourable scalar potential that could provide a high sphaleron transition rate, we calculate the asymmetry through large-scale computer simulations. The numerical signal is at the boundary of what is numerically discernible with the available computer resources, but we tentatively find an asymmetry of |η| ≤ 3.5 × 10−7 . We also find it is attainable to include the complete electroweak SU (2) × U (1) gauge fields in the reduced Standard Model that we are using in practical simulations, so that in further studies we can measure the cosmic magnetic field generated during the electroweak phase transition.

This thesis proposes that the nuclear age offered high modernity and technological nationalism a central position in the making of modern Canada. The nuclear age influenced modern Canada’s social, economic, and political history and it did so by telling Canadians they were, essentially, a modern people governed by a modern state. From the 1940s to the end of the 1970s, Canada’s development of the nuclear industry reflected the pursuit of science and technology to create modern forms of energy production. Canadians were urged to see in nuclear power a way of remaining competitive in a changing global order. It offered them new industries at many stages of the nuclear cycle. The post-war era reflected a changing direction in the country’s central ideological direction – one defined since the 1840s by liberalism and a subordinate role in the British Empire. The creation of the Canadian nuclear cycle signified a transition to a new stage in which Canada, now imagined by some to be a nation, actively sought out modern forms of social and economic progress. Nuclear energy systems came to fruition at a moment when Canada was establishing new directions as a sovereign state vying for greater global political and economic influence on the global stage. This thesis argues that this pattern was no mere coincidence: this technological nationalism was the logical outcome of deep-seated tendencies. Yet, many citizens remained skeptical of the nuclear age’s possibilities. Although the federal government had established its nuclear cycle to develop the peaceful uses of atomic energy, its birth in the shadows of the Second World War and the Manhattan Project also provoked a widespread sense of discomfort. The dropping of the atomic bomb in 1945 solidified fears of nuclear energy long before the AECL built its first reactor on the shores of Lake Huron. Canadians en masse rejected the country’s participation in the development of nuclear weapons and, as Lester Pearson learned to his cost in 1963, were adamant that Canada should remain a nuclear-weapons-free nation. Successive governments in the 1950s and 1960s faced public backlash regarding Canada’s complicity in the stockpiling of nuclear arms, the production of uranium for American weapons, and its involvement in weapons tests. Born out of the peace movements and ecological movements of the 1960s, anti-nuclear groups emerged in the 1970s to oppose the nuclear industry. These groups shared members, ideas, and momentum, and the chasm between anti-war and environmental activism was progressively bridged as the 1970s proceeded. Both the anti-nuclear and anti-bomb activists were essential to challenging the path and direction of the Canadian nuclear system and its role in creating political and environmental uncertainty. Such fears remained a constant social reminder throughout the post-war era of the mutually assured destruction associated with atomic energy and the Cold War arms race. Indeed, Canada’s peaceful nuclear program did not always seem so peaceable, as activists in both camps argued more and more empathetically. Canada’s nationalistic pursuit of a nuclear modernity also entailed the quest of a narrow form of utopianism – one in which a future-oriented Canada provided greater social and economic freedoms under the aegis of liberal democracy. At the community level, nuclear energy symbolized the changing senses and sensibilities of living through modernity – the perception that the core structures of society were giving way to new social realities and that the relations of time and space were shifting. While nuclear energy symbolized the social and economic benefits of the cultural revolution of the nuclear age, it also aroused the concerns and fears about modernity. The conflicts between the pro- and anti-nuclear movements of the 1970s and 1980s were in many respects an extension of debates over high modernity and techno-nationalism. / Thesis / Candidate in Philosophy / This thesis explores the history of Canada’s nuclear age between 1942 and 1979 and examines how both Canadians and the state perceived the development of the country’s nuclear industry. It examines how Canada gained entrance into the nuclear club – joining the ranks of the Manhattan Project – its post-war developments in nuclear power, and the ways in which nuclear energy bolstered a form of nationalism predicated on technological prowess. The need to develop Canada’s nuclear industry reflected the larger social, political, and economic changes occurring in the post-war era. In many ways, the history of Canada’s nuclear age is the history of how societies act and react to modernity – the radical transformation of perceptions of space and time. This thesis examines that process of change and its influence on Canadians’ responses to the modern world around them.

<p> The Three Beam Gamma Densitometers developed by AECL-WNRE for measurement of void fraction in flowing steam/water mixtures were investigated to determine the major causes of drift and slow response to changes in void fraction. Available remedies were evaluated. The study indicated the following: (1) Using the existing current mode system, considerable reductions in drift and response time may be possible through the following inexpensive modifications: (a) design changes in the photo multiplier tube high voltage circuit, (b) replacement of the detectors with Cadmium Telluride semi-conductor detectors, (c) replacement of the scintillation phosphor with one which exhibits no afterglow such as Bismuth Germanate or Cesium Fluoride, (d) matching voltages of photo multiplier tube outside wall and photocathode, (e) improved stabilization of high voltage and detector temperature. (2) Drift would probably be reduced to less than 0.1%/hour if the existing current mode system were replaced with a simple integral counting mode system at an approximate cost of $5,200 per densitometer. (3) Additions to the above counting mode system of a single channel analyser (S.C.A.) and an automatic gain control unit which uses a reference light would probably completely eliminate drift as well as substantially improve system response. This would require an additional $4,900 per densitometer. </p> <p> It is recommended that these modifications be implemented in the same order as above, on a trial basis, as far as further expenditure is justified.</p> / Thesis / Master of Engineering (MEngr)

This thesis examines multiple different molecular networks adsorbed on several different substrates, namely, highly oriented pyrolytic graphite (HOPG), Au(111) and graphene. STM investigations into hydrogen-bonded structures formed by closely related tetracarboxylic acid molecules were performed. The molecule pterphenyl-3,5,3,5-tetracarboxylic acid (TPTC), which is known to form random tiling networks, was observed on a graphene on copper substrate. The network formed from deposition of TPTC from nonanoic acid was examined statistically. Aqueous solutions of TPTC were also examined on HOPG where a new structure, distinct from the random tiling, was observed. Aqueous solutions of related molecules biphenyl-3,3',5,5'-tetracarboxylic acid (BPTC) and quaterphenyl-3,3',5,5'-tetracarboxylic acid (QPTC), were also studied on HOPG. QPTC formed a similar structure to the aqueous solutions of TPTC, but BPTC formed two different phases, one of which was a kagome network. Addition of nonanoic acid to a dried network of TPTC deposited from aqueous solution resulted in solvent induced recrystallisation into a random tiling network comparable to that observed on graphene on copper, which was statistically analysed. Studies investigating the potential for covalent bonded molecular networks identified two distinct phases of the molecule 1,3,5-Tri(4-bromophenyl-benzene (TBPB)) adsorbed on Au(111). Concentration variation indicates an island based growth mechanism for these domains from solution. Dimerisation of TBPB was achieved by deposition onto heated substrates and a discussion of possible reasons for the reaction termination at dimers is provided. Attempts to repeat the TBPB experiments on graphene on copper failed due to excessive corrosion. Variations using larger molecules failed due to lack of solubility. Preliminary experiments on 10,10'-dibromo-9,9'-bianthryl (DBrBA) showed promise but were irreproducible, however micron scale dendritic structures were observed suggesting poor compatibility with the solvent. Finally, a discussion of the development of a nickel catalysis based graphene fabrication method is given and the limits of what is achievable with this method are discussed. The results from this thesis highlight the importance of solvent selection for the future understanding of molecular network fabrication. We also demonstrated the feasibility of covalently bonded networks prepared in ambient conditions.

This is a mathematical study of certain aspects of the interacting electron system in very high perpendicular magnetic field. We analyse restrictions imposed upon the density correlation functions of this system and propose a set of sum rules which they must obey. We study the possibility of building a bosonisation scheme for the projected density operators in the lowest Landau level. We suggest a second order bosonisation, along with an approximation scheme, which may be useful for carrying out calculations in the lowest Landau level. We analyse the possible ground states of the system. We suggest a set of variational wavefunctions which can have lower energy than the Laughlin state for sufficiently soft interaction potentials. We study the collective excitations of the system, paying particular attention to its symmetries. We suggest a set of variational excited states and discuss their applicability to finite as well as infinite systems.

The effective theory of gravity coupled to matter represents a fully consistent low energy theory of quantum gravity coupled to the known particles and forces of the standard model. In recent years this framework has been extensively used to make physical predictions of phenomena in high energy physics and cosmology. In this thesis we use theoretical tools and experimental data to place constraints on various popular models which utilise this framework. We speciffically derive unitarity bounds in grand unified theories, models of low scale quantum gravity, models with extra dimensions and models of Higgs inflation. We also derive a bound on the size of the Higgs boson's non-minimal coupling to gravity. This represents an important area of research because it helps us to better understand the theories and models that many physicists are currently working on and crucially it can inform us where we can reliably use the effective theory approach and where it breaks down.

Ultracold atomic gases have proven to be an excellent tool for research in quantum systems. A Bose gas can be trapped on an atom chip using very well defined and tunable spatially-dependent potentials. The proximity of the atoms to the chip permits the use of low currents allowing for highly accurate temporal changes. Excellent experimental apparatus is needed to achieve Bose-Einstein condensation with a sufficient atom number to study low-dimensional physics. The setup described in this document utilises a set of current-carrying structures on top of which an atom chip sits. For improved atom loading rate, a two-dimensional loading stage was added, extending the lifetime of the magnetic trap. From this loading stage to the atom chip, Bose-Einstein condensation of 105 Rubidium-87 atoms was achieved in less than 30 s, allowing for a large rate of experimental cycles. The high spatial and temporal tunability of this setup results in the ability to split the atomic cloud and quench the trapping potential geometry. Maximising the ratio between trapping frequencies for different spatial directions leads to the system presenting features of a one-dimensional gas. Manipulating the coherence dynamics of a one-dimensional Bose-Einstein condensate creates fluctuations in the phase properties of the wavefunction. These fluctuations are observed as atom density perturbations after releasing the trapping potentials, and are a tool for temperature measurements. When the cloud of atoms is positioned at a few tens of micrometres from the surface of the atom chip, corrugations in the microstructures of the chip affect the trapping potentials at very low temperatures 1 μK. This effect is simulated and quantified in the thesis, with the aim of improving future setups. Additionally, the effect is explored for microscopy purposes. The behaviour of a Bose-Einstein condensate, especially the expansion rate, has long been studied. In this thesis, the Gross-Pitaevskii Equation is introduced, finding its numerical solutions to the two-dimensional and three-dimensional forms, using the Split-Step Fourier Method. The results show very good agreement with the experimental results, as well as with other well- established theories of condensates. The creation of such a toolbox opens up the opportunity to further investigate the coherence dynamics of low-dimensional systems.

The prompt production of &chi / c quarkonia is studied in proton-proton collisions at 7 TeV, using data collected by CMS in 2011 corresponding to an integrated luminosity of 4.6 fb &minus / 1. The &chi / c mesons are reconstructed through their radiative decays to J/&psi / and photon with J/&psi / &rarr / &mu / +&mu / &minus / . The photons are reconstructed through their conversion in electron-positron pairs in the tracking detector which gives a mass resolution sufficient for resolving these states. The ratio of the prompt production cross sections for the &chi / c1 and &chi / c2 states, &sigma / (&chi / c2)/&sigma / (&chi / c1), has been determined as a function of the J/&psi / transverse momentum between 7 and 25 GeV/c.

Scherk-Schwarz reductions are a generalization of Kaluza-Klein reductions in which the higher dimensional fields are allowed to have a dependence on the compactiifed coordinates. This is possible only if the higher dimensional theory has a global symmetry and the dependence is dictated by this symmetry. In this thesis we consider generalised Scherk Schwarz reductions of supergravity and superstring theories with twists by electromagnetic dualities that are symmetries of the equations of motion but not of the action, such as the S-duality of $D=4, N=4$ super-Yang-Mills coupled to supergravity. The reduction cannot be done on the action itself, but must be done either on the field equations or on a duality invariant form of the action, such as one in the doubled formalism in which potentials are introduced for both electric and magnetic fields. The resulting theory in odd dimensions has massive form fields satisfying a self-duality condition $dA sim m*A$. We apply these methods to theories in $D=4,6,8$, and obtain new gauged supergravity theories with massive form fields, with Chern-Simons like couplings and with a scalar potential in $D=3,5,7$.