The subject of this thesis is "the fundamental structure of matter, that is, the quest of understanding the deepest level of the physical world, and the interactions relevant at that level. The hope is that, as one goes deeper, the laws are going to be simpler, not necessarily in mathematical terms, but in conceptual terms. The goal is fewer and fewer ad hoc assumptions, inspiring and driving the pursuit for the fundamental structure of matter. The thesis consists of an introductory part, giving a broad overview of where the subject stands today, and of a more detailed part, containing our own contributions to the advances of this knowledge. Six reproduced papers are appended at the end. There we treat the fundamental structure of matter on three different levels. The first three papers are concerned with the inner structure of particles (hadrons) that interact via the strong nuclear force. Here we have investigated the interactions of the so-called quarks inside hadrons, taking into account also their spin structure. Besides protons and neutrons, we have also studied more exotic particles containing quarks, so-called mesons, that are only produced in high-energy collision processes. Om a more fundamental, but speculative, level we have constructed a new model for an underlying substructure common to both quarks and leptons (particles unaffected by the strong interaction), i.e., all particles that build up matter. We also investigate some of the physical consequences of this model, particularly the possibility of radiative neutrino decay. On the large scale, we analyse the origin of the so-called dark matter in the Universe, which we propose is composed out of enormous lumps exclusively made of quarks, without any "normal" hadrons. We also explore the connection of this phenomenon to the mysterious bursts of gammarays seen in astrophysics. / Godkänd; 1998; 20061123 (haneit)

We set out on the ambitious journey to fuse inflation and string theory. We first give a somewhat extensive, yet free from the most complicated details, review of string inflation, discussing concepts as flux compactifications, moduli stabilization, the η-problem and reheating. Then, we consider two specific configurations of type II supergravity; type IIB on T6 with D3-branes and O3-planes, and type IIA on a twisted torus with D6-branes and O6-planes. In both cases, we calculate the scalar potential from the metric ansatzes, and try to uplift it to one of de-Sitter (dS) type. In the IIA-case, we also derive the scalar potential from a super- and Kähler potential, before we search for stable dS-solutions.

The Light Wave Synthesizer 20 (LWS20) is an Optical Parametric Synthesizer (OPS) system used for relativistic attosecond physics research. The LWS20 performs OPS through the means of multiple two-color pumped Noncollinear Optical Parametric Chirped Pulse Amplification (NOPCPA) stages. NOPCPA is basedon the nonlinear optical effect Optical Parametric Amplification (OPA) which is only described analytically through simplified expressions. A natural route around this difficulty is through the means of numerical models. In this thesis a (2+1) dimensional simulation software [1], [2] is used to simulate the four currently present NOPCPA stages of the LWS20, operated under two different options. The simulationwill be key to the planned upgrade of the LWS20, propelling the system fromthe current 16 TW power [3] to the wanted 100 TW power domain. It is shown that the used software is able to, with some caveats, emulate the results achieved in a laboratory environment and that the two operational options are optimized under slightly different settings. Furthermore, some barely documented, albeit crucial, features of the simulation software have been exposed, indicating that it is not very well optimized for simulating the OPA processes of the LWS20. By increasing the pump energy of the simulation beyond the realisticlevel it is still possible to attain relatively realistic amplification and thus the software ought to prove a valuable tool for the planned system upgrade. Some alternative approaches to the continuation of the simulations are presented which would further increase the software’s usefulness in the process of expanding theLWS20. Historically, the LWS20 has been operated successfully under the sameconditions under the two possible operational options, but the simulations clearly show that an optimized set-up for one option is far from optimal for the other option. Therefore, there is a possibility to further optimize the LWS20, an idea worth pursuing in future experiments.

Carbon nanotubes (CNTs) have attracted an immense attention of the research community since reporting on this system by S. Ijima in 1991. A "single-walled" CNT (SWCNT) can be considered as a rolled-up single-layer graphene - a one atom-thick layer of carbon atoms arranged in a hexagonal lattice. This cylindrical object being just about 1 nm in diameter and up to a few centimeters long can be considered as a quasi-one-dimensional system. Several nanotubes "inserted" one into another build a so-called multi-walled CNT. CNTs exhibit outstanding mechanical, thermal and electronic properties which make this material a promising candidate for numerous applications - reinforced composite materials, nano-electronics, molecular sensors and drug delivery systems to name just a few. CNTs possess tensile strength 10 and 5 times higher than that of steel and Kevlar, respectively, that creates a great prospective for their use as reinforcing units in materials subjected to high-impact dynamic loads/stress (bullet-proof jackets, for example). Nonetheless, to date there are no reports on experimental study of CNTs behavior at extreme dynamic loads which may substantiate such prospective. In addition, several theoretical predictions indicate a possibility of CNTs transformation into new structural forms at extreme pressures. The goal of this work is a systematic study of structural properties and exploration possibility of synthesis of new materials from CNTs under extreme pressures/stress.In a set of experiments purified SWCNTs were subjected to high dynamic (shock) pressures up to 52 GPa. Recovered from each pressure step sample was characterized by High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. We observed a gradual increase of defects concentration on the CNT surface with pressure along with shortening and "un-zipping" of the tubes and an onset of the complete CNT destruction at 26 GPa shock which sets-up a limit for certain practical applications of this kind of material. Further increase of the dynamic load to 35 and 52 GPa led to CNT transformation into a mixture of disordered sp²/sp³- bonded carbon atoms with nano-sized graphene clusters. No CNT polymerization or coalescence was observed contrary to some theoretical predictions. For comparison, we conducted a separate experiment on the same CNT material under static compression up to 36 GPa in a diamond anvil cell (DAC). The system evolution was monitored in-situ during the high-pressure run using Raman spectroscopy. Examination of the material recovered from high pressure revealed that certain fraction of the CNTs survived exposure to 36 GPa though similar damages were introduced to the nanotubes as in the shock experiments evidenced by the Raman spectra. This result testifies a substantial difference in the processes of CNT destruction by dynamic vs static compression.A separate set of experiments in DACs was aimed at in-situ monitoring of the Raman spectra (in particular G-band) during pressure evolution and establishing the level of static pressure which causes a complete destruction of SWCNTs from the same batch as used in similar experiments at the dynamic compression. Pressure dependence of G-band, G(p), exhibited several peculiarities at approximately 15, 45 and 60 GPa which we associate with collapse of large (1.2 nm) and small (∼1 nm) diameter CNTs, and an onset of nanotubes transformation to a new phase respectively. Raman spectra of the sample recovered after 58 GPa static compression exhibit no RBM signal, large G-band broadening and high D/G peak intensity ratio that testifies for CNT destruction. Pressure increase to 100 GPa resulted in a substantial altering of Raman spectrum of the recovered sample - appearance of characteristic features of highly disordered sp²-and sp³-bonded carbons which may stem from interlinked nano-sized graphene clusters.Change of CNTs structure results in the altering of their electronic properties thus structure evolution of the CNTs with pressure may be followed by monitoring electrical resistance change with pressure. In a series of experiments we conducted in-situ electrical resistance (R) measurements of the SWCNTs under static pressures up to 45 GPa (temperature range 293 - 395 K) in a conductive DAC. Isobaric temperature dependence of the resistance indicated that the nanotube sample is comprised predominantly of semiconducting CNTs. A set of anomalies observed in R(p) at room temperature we interpret as a sequential, diameter-dependent collapse of the CNTs. Raman characterization of the samples after the pressure cycling confirmed reversibility of these structural transitions for at least certain CNT species accompanied by a substantial increase of CNT defects density. No indication of nanotubes polymerization was observed.Although thermal conductivity of individual CNTs is excellent (5 times better than that of copper) heat conduction becomes far less efficient in "conventional" system, i.e. when the tubes form bundles/ropes which may lead to a risk of CNT destruction by overheating. Therefore probing CNTs response to extreme heat (temperature) is important both for testing capabilities of the nanotube material and developing methods of its proper characterization. We followed temporal evolution of the Raman spectra of bundled SWCNTs exposed to high laser irradiance in both air and argon atmosphere. Temperature threshold for CNT destruction in air appeared to be lower than that in Ar, the fact indicating importance of the CNTs oxidation for their structural integrity. We show that primary damage occurs in resonant with excitation laser CNTs which act as photon energy absorbers. We show that smaller diameter and metallic nanotubes are less stable to high irradiance/heat flux than their large diameter/semiconducting counterparts. Remarkably, some small diameter, non-resonant CNTs were destroyed indirectly, i.e. via overheating induced by neighbor CNTs in resonance (photon absorbers). We demonstrate the importance of laser heating effects on Raman characterization of nanotubes.Even though carbon nanotubes exhibit susceptibility to extreme pressure/stress and high laser irradiance/overheating their potential for use in very demanding applications is not yet challenged: for example SWCNT destruction under dynamic compression occurs at pressure exceeding 20 times the typical threshold levels in ballistic impact. Cold compression of nanotubes also opens up perspectives of synthesis of new carbon phases with superior mechanical properties. / Godkänd; 2014; 20141216 (maxnoe); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Maxime Noël Ämne: Fysik/Physics Avhandling: Physical Properties and Structural Stability of Carbon Nanotubes Under Extreme Conditions Opponent: Professor David Dunstan, School of Physics and Astronomy, Queen Mary, University of London, London, Ordförande: Professor Alexander Soldatov, Avd för materialvetenskap, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 30 januari, kl 10.00 Plats: E231, Luleå tekniska universitet

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Background: Fluoroscopy is a common imaging technique which uses X-ray to derive a real time imaging of patient anatomy to determine diagnosis and positioning of patients for interventional procedures. It is therefore important that the fluoroscopy systems maintain their performance. Assessment of image quality parameters (such as: low contrast resolution, uniformity, homogeneity and detection of defective pixels and artifacts) is one way to assess if they maintain their performance. This study aims to develop and implement a Matlab script to do a remote Quality Control (QC) and set up tolerance levels on different types of fluoroscopy systems.                                        Method: Three fluoroscopy systems were used in this project, Siemens Axiom Artis Zee MP, Siemens Cios Alpha and Ziehm Vision RFD. There were two setups used in the study for image acquisition by adding a 2 mm Cu filter as the attenuating material placed directly on the X-ray tube. A Cylindrical aluminum contrast detail of dimension 4 mm thick and 6 mm diameter was placed in the middle of X-ray field (Setup 1 on patient couch and setup 2 directly on the flat panel detector). The fluoroscopic images were acquired with and without contrast detail over a period of six month. The image quality parameter SNR2rate was determined from signal and background images while other quality parameters such as kerma-area product rate PKA, rate, uniformity, homogeneity, low contrast resolution, SNR, defective pixels and artefact detection were examined and determined from the background images. Two additional supporting experiments were performed, one with a chest phantom and 13 cm PMMA and the other one a human visual detection 4-AFC experiment.                 Result: The image quality index SNR2rate and the dose rate index PKA, rate, the low contrast resolution parameter (LCRP), uniformity, homogeneity and SNR values were within ±2 standard deviation for repeated measurements in each system. Nevertheless, the result indicates that Siemens Axiom Artis Zee MP has the best performance while Ziehm Vision RFD has the worst performance between these three systems. The result from the defective pixel method indicate that for 20 % tolerance there were no defective pixels for Siemens Axiom and Cios Alpha. Ziehm Vision had also no defective pixels for 30 % tolerance. The artefact detection shows that artefact level is high for fluoroscopy systems and Ziehm Vision RFD has artefact level more than 50 % tolerance.  The chest phantom experiment indicate that SNR2rate varies considerably over the lung anatomy as expected.           The 4-AFC experiment indicates that the effective time was 0.14 s for human observers to integrate the information in the live image.           Conclusion: The methods developed and implemented in this project were successfully able to determine and assess the image quality parameters such as SNR2rate,PKA, rate, low contrast resolution, uniformity, homogeneity, SNR and detection of defective pixels. Further effort is needed for installation of Matlab script on our local server, connection with Excel program and internal website (SharePoint) and adding more clinical fluoroscopy systems to do remote QC in Region Östergötland.

Macrocoherence is the concept of quantum mechanics being scaled up to the macroscopic level where everyday physical systems should inhibit quantum mechanical properties, however this is not what is observed. Through the use of Leggett-Garg inequalities, one can infer if there is a fundamental quantum mechanical behavior of the system being observed. Then, using violations of these inequalities, this paper discusses the possibility of extracting useful measures of how macroscopic a system can be. Utilizing an analogy with the measures of locality through Bell's inequalities, the scope of what a measure should consist of is discussed. A measure should be proper in the sense that a baseline of 0 should be obtained from system that never violates an LGI. Further, it is proposed that a measure should extend naturally to all orders of LGIs without ranking quantum systems differently. With these in mind two measures are proposed, one utilizing the integral over the violated area of a LGI over time whereas the other uses inner products over a matrix defined elementwise as a specified LGI. The measures scopes are discussed and their applications are showcased for some analytical quantum systems. Though functional, the measures are found to lack a resource tied to its value complicating the conceptualization of what is being measured. It is concluded that a new effort to find a true measure of macrocoherence should start from the concept of a resource.

This work explores the possibilities to use quantum computers and quantum based language models for machine translation. Precise translation requires vast expertise and knowledge of various languages, thus machine translationis still far from superseding humans. Quantum computers could improve machine translation due to their high computational power, as they benefit from properties such as superposition and entanglement to process data faster and in parallel. We focused our work on the DIStributional COmpositional CATegorical (DisCoCat) semantics and its python toolbox DisCoPy developed by [1]. We built and transformed simple, complex, and negative English and Spanish sentences to DisCoCat diagrams. Those diagrams are then used as input to quantum circuits, allowing us to perform calculations in NISQ devices providedby IBMQ. The calculations show that a quantum computer can understand the meaning of simple and complex sentences in different languages, and this is the first step to perform translation with Quantum Computers. In addition, we worked on preserving sentence meaning by measuring the cosine similarity between two vectorised sentences and obtained sentence similarities scores of 95%.

Dark matter is required in the universe to explain certain phenomenona, like the dynamics of stars and temperature fluctuations of the cosmic microwave background. This thesis focuses on the production of dark matter in the ATLAS experiment at the Large Hadron Collider, where the dark matter is detected through momentum conservation. The models of interest are simplified dark matter models consisting of a pair of top quarks produced together with a mediator. It is the mediator, scalar or pseudoscalar having a mass of 20 GeV  that decays to dark matter particles each having a mass of 1 GeV. The final state considered in this thesis consists of jets, one lepton and missing transverse momentum.  The coupling constants between the mediator and the top quarks and the mediator and the dark matter particles is set to 1.  The goal of the work presented in this thesis is  to improve the searches for dark matter of dark matter, by studying the distributions of variables that can separate the signal from various background processes. This is done by loosening the requirement on missing transverse momentum in the dark matter searches from 230 GeV to 70 GeV and study the low missing transverse momenta samples. This thesis then finds that the low missing transverse momentum scalar sample has the highest yield of all samples studied. Moreover, the transverse mass selection efficiency for the low missing transverse momentum sample is found to be low and needs to be improved. The last conclusion presented is that the azimuthal angle between the lepton and the missing transverse momentum can be used to differentiate the mediator types in both the low and high missing transverse momentum samples.

Equivariant localization is a technique can be used to reduce the dimensionality of integral for the manifold with a Lie group action on. Such technique can beapplied to simply the calculation of path integral with certain type of symmetries.In this thesis, we will first introduce the language of super algebra and supergeometry, then discuss the localization formula and Mathai-Quillen formalismaccording to supergeometry.In the last chapter, we will equivariantize the formalism we made and discuss how this being manifested in odd tangent bundleand holomorphic line bundle. Such methodology is very powerful in providing areasonable regularization to eradicate divergence and such regularization is basedon the intrinsic property of the system, in other word the symmetry.