[Truncated abstract] This thesis presents the design, construction and operation of a new rotating mod- ern Michelson-Morley test of Lorentz invariance. The experiment measures the isotropy of the speed of light by comparing the frequencies of two orthogonally ori- ented cryogenic sapphire whispering gallery mode resonators. Putative violations of Lorentz invariance will manifest as periodic variations in the difference frequency between the two resonators, related to the changing orientation of the experiment with respect to a preferred cosmological frame. Actively rotating the experiment is advantageous for three reasons. Firstly, by careful selection of the rotation frequency in the laboratory we are able to sample the isotropy of the speed of light at a rate that coincides with the optimal frequency instabilities of the oscillators (18 seconds). Secondly, the statistics of this exper- iment are improved with respect to non-rotating (stationary) experiments, which rely on the motion of the Earth to sample the isotropy of the speed of light. This results from integrating over more periods of rotation per unit of time, compared to the sidereal rotation experienced by stationary experiments. ... Many noise sources and systematic disturbances have been characterized and the operation of the experiment optimized. Two frequencies are generated at 10 GHz with 226 kHz separation, exhibiting a fractional frequency instability of less than 2x10-14 from 5 to 500 seconds. Furthermore, the work includes a detailed analysis of the experiment within the Standard Model Extension and Robertson, Mansouri and Sexl frameworks. The sensitivity of the experiment to violations of Lorentz invariance has been derived in each of these frameworks, for both short data set and the complete full year analysis. The data has been analysed using two separate data analysis techniques, which were optimised for noise present in the data. We have operated the experiment over the course of more than one year, collect- ing data more than 30 percent of the time. By analysing over 1 year of data we were able to set the first independent limits on 8 parameters in the photon sector of the Standard Model Extension as low as 10-16 for Ke- and 10-12 for Ko+ parameters, improving upon previous non-rotating experiments by up to an order of magnitude. We have also set new a new limit on the isotropy parameter PMM = 9.4(8.1)x10-11 of the Robertson, Mansouri and Sexl framework, which is a factor of 25 improvement.

The search for a theory of quantum gravity has persisted through the last century. Although many beautiful theories such as string theory and loop quantum gravity have been proposed, experimental evidence to support or refute these theories has been difficult to obtain. Searching for Lorentz invariance violation (LIV) is one of a limited number of experimental tests which can be used to search for evidence of quantum gravity since new physics may only be observable at energies well beyond those present in the most energetic astrophysical objects, which are far greater than the energies accessible in a terrestrial laboratory. One method of searching for LIV is to look for energy-dependent time delays in the arrival of high-energy photons from distant astrophysical sources. We search for Lorentz invariance violation (LIV) using VERITAS, an imaging atmospheric Cherenkov telescope (IACT) located in southern Arizona. Significant TeV gamma ray flaring activity was detected from the blazar Markarian 421 on the night of February 17, 2010 (MJD 55244), which presented a good opportunity to search for delays in the energetic emission. We demonstrate the performance of two different dispersion estimation algorithms and apply these algorithms to our data to search for LIV. We find that while the emission from Markarian 421 contains significant variability, a necessary condition for an LIV detection, the presence of a constant background flux severely limits our sensitivity. We expect our findings to be useful for guiding future LIV studies, especially those using IACT data. In the latter part of this work we discuss the alignment of ground-based gamma-ray telescopes and present a digital autocollimator which will be used in the alignment system of a next-generation IACT. The configuration of our autocollimator enables measurement of the angle formed between the planar surface of a distant reflector and the line of sight over a range of ±0.126° with a precision better than 5 arcsec. We present a detailed description of the instrument and its data acquisition software that was used during laboratory testing.

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Submitted by Vasti Diniz (vastijpa@hotmail.com) on 2017-09-18T12:14:57Z No. of bitstreams: 1 arquivototal.pdf: 2895129 bytes, checksum: 572a06d99b50bb3cd9314e80d1c5b3c7 (MD5) / Made available in DSpace on 2017-09-18T12:14:57Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2895129 bytes, checksum: 572a06d99b50bb3cd9314e80d1c5b3c7 (MD5) Previous issue date: 2017-07-27 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / In this dissertation, we study the possibility of violation of the Lorentz invariance taking into account some terms of the standard extended model, more specifically, the part of this model that deals with the extended quantum electrodynamics. We perform quantum corrections in the fermionic sector of the usual quantum electrodynamics added with terms that violate the Lorentz symmetries and in two different configurations. First, the coefficient added and that causes the Lorentz symmetry breaking is introduced th­rough the constant pseudo-tensor Ic juvAp And we treat the constant electric and magnetic fields, that is, we do not evaluate as external leg between the coupling of the photon and fermions, evaluating the field FAp Without opening in term of the gauge field. In the second case, we investigated the operators governed by the coefficient of interaction FAp open in term of the gauge field. In the second case, we investigated the mixed contribu­tion of the minimum and non-minimum coupling. We immediately know that for each coupling evaluated will have their respective vertices. For both cases, we calculate the quantum corrections in a loop. In the first case, the theory with the coefficient Ic juvAp and field FAp without being opened at the end of the gauge field AP, The contribution of a loop and we calculate the counter-ter, having a CPT-par characteristic, which will be useful to be introduced in action to eliminate divergences. In the second case, we examined the contribution of a loop, considering the mixture of minimum and non-minimum coupling, that is, and and and an external one AP, having a CPT-par characteristic, One related to the non-minimum coupling and another to the minimum, respectively and verifying the vertex correction also having the contribution of its counter-term. / Nesta dissertagao, estudamos a possibilidade de violagao da invariancia de Lorentz le­vando em conta alguns termos do modelo padrao estendido, mais especificamente da parte do modelo que trata da eletrodinamica quantica estendida. Realizamos corregoes quanticas no setor fermiOnico da eletrodinamica quantica usual adicionada de termos que violam as simetrias de Lorentz e em duas configuragoes diferentes. Primeiramente, o co­eficiente adicionado e que ocasiona a quebra de simetria de Lorentz é introduzida atraves do pseudo-tensor constante is juvAp e tratamos os campos eletricos e magneticos constantes, ou seja, nao avaliamos como perna externas entre o acoplamento do fOton e fermions, avaliando o campo FAp sem abrir em termo do campo de gauge. No segundo caso, investi­gamos a contribuigao mista do acoplamento minim° e nao-minimo. De imediato sabemos que para cada acoplamento avaliado tera seus respectivo vertices. Para os dois casos, cal­culamos as corregoes quanticas em um lago. No primeiro caso, a teoria com o coeficiente I c juvAp e campo FAp sem ser aberto em termo do campo de gauge AP, a contribuigao de um lago e calculamos a pega de polo, tendo uma caracteristica CPT-par, que sera iltil para ser introduzida na agao para eliminar as divergencias. No segundo caso, nos examinamos a contribuigao de um lago, considerando a mistura dos acoplamento minimo e nao-minimo, ou seja, um Fill, e um externo AP, tendo como caracteristica CPT-impar um relacionado ao acoplamento nao-minimo e outro ao minimo, respectivamente e verificando a corregao de vertice tendo tambem a contribuigao do seu contra termo.

This thesis addresses the issue of the time variability of the fine structure constant, alpha. Recent claims of a varying alpha are set against the established standards of quantum electrodynamical theory and experiments. A study of the feasibility of extracting data on the time dependence of alpha using particles in Penning traps is compared to the results obtained by existing methods, including those using astrophysical data and those obtained in atomic clock experiments. Suggestions are made on the nature of trapped particles and the trapping fields.

We present an algorithm for the calculation of scalar and tensor one- and two-loop integrals that contribute to the virtual corrections of 2 →2 partonic scattering. First, the tensor integrals are related to scalar integrals that contain an irreducible propagator-like structure in the numerator. Then, we use Integration by Parts and Lorentz Invariance recurrence relations to build a general system of equations that enables the reduction of any scalar integral (with and without structure in the numerator) to a basis set of master integrals. Their expansions in e = 2-D/2 have already been calculated and we present a summary of the techniques that have been used to this end, as well as a compilation of the expansions we need in the different physical regions. We then apply this algorithm to the direct evaluation of the Feynman diagrams contributing to the O(α4/8) one- and two-loop matrix-elements for massless like and unlike quark-quark, quark-gluon and gluon-gluon scattering. The analytic expressions we provide are regularised in Convensional Dimensional Regularisation and renormalised in the MS scheme. Finally, we show that the structure of the infrared divergences agrees with that predicted by the application of Catani's formalism to the analysis of each partonic scattering process. The results presented in this thesis provide the complete calculation of the one- and two-loop matrix-elements for 2 2 processes needed for the next-to-next-to-leading order contribution to inclusive jet production at hadron colliders.

Diese Arbeit präsentiert ein modernes Michelson-Morley Experiment, welches genauere Grenzwerte für Testparameter liefert, die eine Verletzung der Lorentzinvarianz modellieren. Die Messung setzt einen oberen Grenzwert für eine Anisotropie der Lichtgeschwindigkeit im Bereich von dc/c ~10^-16. Das Experiment vergleicht die Frequenzen zweier optischer Hoch-Finesse Resonatoren, wobei einer dieser Resonatoren kontinuierlich auf einem Drehtisch rotiert. Um die Eigenfrequenzen der Resonatoren abzufragen, werden die Frequenzen zweier Nd:YAG-Laser auf die Resonatoren stabilisiert. Die relative Frequenzstabilität auf der Zeitskala einer Tischdrehung (~45s) liegt bei ~1x10^-14, limitiert durch das thermische Rauschen der Resonatorspiegel. Die Messung erstreckt sich über einen Zeitraum von einem Jahr, wobei mehr als 10^5 Tischumdrehungen eingehen. Ausführlich werden die systematischen Effekte und ihre Unterdrückung auf Signalamplituden unter 1 Hz dargestellt. Im Vergleich zu vorhergehenden Messungen konnten diese systematischen Effekte um einen Faktor 10 bis 100 reduziert werden. Zwei verschiedene Testtheorien wurden herangezogen, um ein Signal für eine Anisotropie der Lichtgeschwindigkeit als Folge einer Verletzung der Lorentzinvarianz zu modellieren: eine die Lorentzinvarianz verletzende Erweiterung des Standardmodells und die Testtheorie von Robertson, Mansouri und Sexl. Es wird eine Analyse der Daten im Rahmen beider Testtheorien präsentiert, und Grenzwerte auf die relevanten Parameter werden bestimmt. Diese Grenzwerte schränken eine Anisotropie der Lichtgeschwindigkeit im Bereich von 10^-16 ein, d.h. etwa 10 mal genauer als die Ergebnisse vorangegangener Messungen. Schließlich wird ein Ausblick auf einen verbesserten Aufbau gegeben, welcher neue Resonatoren zum Einsatz bringt, und es werden erste verbesserte Resultate präsentiert. Damit steht der Weg offen für eine Langzeit-Messung, welche die Grenze für eine Anisotropie der Lichtgeschwindigkeit bis in den Bereich von dc/c~10^-17 drücken wird. / This thesis presents a modern Michelson-Morley experiment, which provides improved limits on test parameters that model a violation of Lorentz invariance in electrodynamics. The measurement sets an upper limit on an anisotropy of the speed of light at a level of dc/c~10^-16. The experiment compares the resonance frequencies of two optical high-finesse cavities, one of them continuously rotating on a turntable. To read out their resonance frequencies, two Nd:YAG lasers are frequency-stabilized to these cavities. On the timescale of a turntable rotation (~45s), a relative frequency stability of ~1x10^-14 is achieved, limited by thermal noise of the cavity mirrors. The measurement extends over one year and includes ~10^5 rotations. The systematic effects compromising the measurement are described in detail, together with the measures that have been taken to suppress systematic effects below 1 Hz. This is a reduction by a factor of up to 100 as compared to preceding experiments. Two different test theories are applied to derive a signal for an anisotropy of the speed of light as a consequence of a violation of Lorentz invariance: a Lorentz violating extension of the standard model and the test theory by Robertson, Mansouri and Sexl. An analysis of the data within these two test models is presented, and limits on the relevant test parameters are deduced. These limits restrict an anisotropy of the speed of light at a level of 10^-16, which is a factor of ten more stringent as compared to results of previous such measurements. Finally, an outlook on an improved setup with new cavities and and first results from this setup are presented. This setup should allow for another order of magnitude improvement of the experiment''s sensitivity within a following long-term measurement aiming for the dc/c ~10^-17 level of accuracy.

This thesis investigates the interplay between explanatory issues in special relativity and the theory's metaphysical foundations. Special attention is given to the 'dynamical approach' to relativity, promoted primarily by Harvey Brown and collaborators, according to which the symmetries of dynamical laws are explanatory of relativistic effects, inertial motion, and even the Minkowskian geometrical structure of a specially relativistic world. The thesis begins with a review of Einstein's 1905 introduction to special relativity, after which brief historical introductions are given for the standard 'geometrical' approach to relativity and the unorthodox 'dynamical' approach. After a critical review of recent literature on the topic, the dynamical approach is shown to be in need of a metaphysical package that would undergird the explanatory claims mentioned above. It is argued that the dynamical approach is best understood as a form of relationalism - in particular, as a relativistic form of 'regularity relationalism', promoted recently by Nick Huggett. According to this view, some portion of a world's geometrical structure actually supervenes upon the symmetries of the best-system dynamical laws for a material ontology endowed with a primitive sub-metrical structure. To explore the plausibility of this construal of the dynamical approach, a case study is carried out on solutions to the Klein-Gordon equation. Examples are found for which the field values, when purged of all spatiotemporal structure but their induced topology, are still arguably best-systematized by the Klein-Gordon equation itself. This bolsters the plausibility of the claim that some system of field values, endowed with mere sub-metrical structure, might have as its best-systems dynamical laws a (set of) Lorentz-covariant equation(s), on which Minkowski geometrical structure would supervene. The upshot is that the dynamical approach to special relativity can be defended as what might be called an ontologically and ideologically relationalist approach to Minkowski spacetime structure. The chapters refer regularly to three appendices, which include a brief introduction to topological and differentiable spaces.

Le cinquième télescope (CT5) du réseau H.E.S.S. (High Energy Stereoscopic System) a été inauguré en 2012. H.E.S.S. est destiné à l’observation du ciel austral dans le domaine des rayons γ et CT5, dont le seuil est d’environ 30 GeV, a permis la détection du pulsar de Vela après 24 heures d’observations. Certains scénarios de gravitation quantique (QG) prédisent une violation d’invariance de Lorentz (LIV). Celle-ci se manifeste par l’ajout de termes ∝(E/EQG)n aux relations de dispersion du photon, où E est l’énergie du quanta de lumière, EQG l’énergie caractéristique des processus de QG et n l’ordre de la correction. Cette dépendance en énergie peut être testée par des mesures de temps de vol entre photons reçus de sources astrophysiques variables (noyaux actifs de galaxies), transitoires (sursauts γ) ou encore périodiques (pulsars). Cette thèse présente l’analyse des données recueillies par CT5 sur le pulsar de Vela. Une méthode de maximum de vraisemblance ayant déjà montré sa robustesse sur d’autres types de sources a été adaptée au cas du pulsar de Vela. Aucune déviation des relations de dispersion standard n’est observée, par conséquent des limites sont placées sur EQG. La plus contraignante est obtenue pour une correction linéaire superluminique aux relations de dispersion EQG > 7.0×1015 GeV. / The fifth telescope (CT5) of the H.E.S.S. array (High Energy Stereoscopic System) was inaugurated in 2012. H.E.S.S. is designed to scrutinize the southern γ ray sky and CT5, whose threshold is about 30 GeV, allowed the Vela pulsar detection in 24 hours observation time. Some quantum gravity (QG) scenarios predict a violation of Lorentz invariance (LIV). This could manifest by additional terms ∝(E/EQG)n to the photon dispersion relations, where E is the light quantum energy, EQG the typical scale at which QG processes are expected to occur and n the order of the correction. This energy dependence could be tested by time of flight measurements between photons emitted from variable (active galactic nuclei), transient (gamma ray bursts) or periodical (pulsars) astrophysical sources. This thesis presents the analysis of the CT5 collected data from the Vela pulsar. A maximum likelihood method already successfully applied to other source species has been adapted here to the Vela pulsar. No deviation from standard photon dispersion relations is observed, therefore limits have been placed on EQG. The most restrictive result has been obtained for a superluminal linear correction to the dispersion relations EQG > 7.0×1015 GeV.

The master's thesis is dedicated to studying the propagation of ultra-high energy proton cosmic rays under a hypothesis of Lorentz invariance violation. For this purpose, numerical methods were used. Our calculations indicated that the ef- fective horizon of ultra-high energy cosmic protons is significantly extended when Lorentz invariance violation is assumed. Further, we investigated the effects of Lo- rentz invariance violation on the Cosmic ray spectrum. We learned that measured cosmic ray spectra are a suitable tool for constraining the coefficients describing Lorentz invariance violation and we estimated an interval where the upper bound on the pion Lorentz invariance violating coefficient lies. Moreover, a correlation between free parameters of the analytical model of cosmic ray spectrum and coefficients, that describes Lorentz invariance violation, was found.