Advanced nuclear and electron magnetic resonance techniques (i.e. nuclear magnetic resonance (NMR), dynamic nuclear polarization (DNP), and magnetic resonance imaging (MRI)) were used to study the attitude and dynamics of TEMPO (2,2,6,6-tetramethylpiperidinyloxy)-substrate systems and the relaxivity properties of water-soluble trimetallic nitride template functionalized endohedral metallofullerenes (TNT-fMF). The attitude and average distance of interaction for each TEMPO-substrate system was determined from comparing density functional theory (DFT) calculation results with experimental hyperfine coupling constants leading to an improved understanding of solution dynamics. The short-lived solvent-solute interactions of the TEMPO-substrate molecules, such as transient complex formation, are governed by weak hydrogen-bonding interactions. The collisions in solution were explained by determining the favored orientations of the two molecules interacting using calculated relative energy minima and reproducibility of the experimental results by the calculated coupling constants. Water-soluble TNT-fMFs are studied as candidates for the next generation MRI contrast agents as diagnostic agents and also as possible therapeutic agents to kill cancer cells and decrease tumors. The TNT-fMFs are being studied as part of a multi-modal platform dependent upon which metal atoms are encapsulated inside: Gd — MRI contrast agent (diagnostic), Lu and Ho — radio labeled for use as a therapeutic agent, Tb – fluorescence, and Lu – x-ray contrast. The current commercial MRI contrast agent, OmniscanTM, contains one gadolinium atom; however, the metal is complexed to, not encapsulated in, the molecule. TNT-fMFs fully encapsulate three metal atoms to ensure the patient does not run the risk of metal poisoning. The r1 and r2 relaxivities of TNT-fMFs containing either Gd, Lu, Ho, or Sc metals were measured at 0.35T. The data for the Gd containing TNT-fMFs indicated the metallofullerene has significantly higher relaxivities than OmniscanTM, and can be the next generation MRI contrast agent. The Ho containing species has a high r2/r1 ratio compared to the other samples showing it is a potential T2 agent, and has therapeutic capabilities. / Ph. D.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho calculamos os fatores de forma e constantes de acoplamento para os vértices B*sBK, B*BsK e BsBK* usando as Regras de Soma da Cromodinâmica Quântica (QCD). Ainda estão incluídos os diagramas não perturbativos. Nós usamos a técnica de considerar dois mésons fora da camada de massa para obter dois fatores de forma diferentes a fim de diminuir as incertezas. Os cálculos das incertezas foram incluídos neste trabalho. / In this work, we calculate the Form Factors and the Coupling Constants for the vertices B*sBK, BsB*K and BsBK* using the QCD Sum Rules. We use the technique of considering two mesons of shell to obtaining two differents form factors in order to give less uncertainty to the obtaining of the coupling constant. The evaluation of the uncertaints were included in this work.

The hunt for Dark Matter plays a truly critical role in contemporary physics. At both the largest and smallest scales, deep questions are being raised about the fundamental nature of the universe - questions that confirmation and then characterisation of particle dark matter will provide many answers to. This thesis presents some of the world's most sensitive searches to date for certain types of axion dark matter, axion-like particles, and two-neutrino double electron capture. These have been conducted using the Large Underground Xenon (LUX) experiment. Evidence for dark matter and physics beyond the Standard Model of particle physics is described in Chapter 1, while Chapter 2 gives an overview of proposed candidates for particle dark matter. The various experimental approaches being used to detect particle dark matter are presented in Chapter 3. Direct detection with time projection chambers plays a major role in this thesis, with particular interest in the LUX detector, that is described in its components and operations. Chapter 4 presents LUX direct searches for weakly interacting massive particles. Although I have contributed to these analyses, they are included for completeness only, as they are not part of my central work. The LUX collaboration's searches for axion dark matter and axion-like particle have delivered world-leading results on the axion-electron coupling constant. These results, that I personally led and which have been published in Physics Review Letters, are presented in Chapter 5, along with sensitivity studies, also led by me, made for the future LUX-ZEPLIN experiment. Finally, a search for two-neutrino double electron capture of 124Xe, that I performed using LUX data to extract a limit on the half life of the process, is presented in Chapter 6. Although being allowed by the Standard Model, two-neutrino double electron capture shares the matrix element calculation framework with the neutrinoless channel of the same process, becoming of great interest in the scope of neutrino physics. Conclusions follow and close the thesis.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho calculamos os fatores de forma e constantes de acoplamento para os vértices B*sBK, B*BsK e BsBK* usando as Regras de Soma da Cromodinâmica Quântica (QCD). Ainda estão incluídos os diagramas não perturbativos. Nós usamos a técnica de considerar dois mésons fora da camada de massa para obter dois fatores de forma diferentes a fim de diminuir as incertezas. Os cálculos das incertezas foram incluídos neste trabalho. / In this work, we calculate the Form Factors and the Coupling Constants for the vertices B*sBK, BsB*K and BsBK* using the QCD Sum Rules. We use the technique of considering two mesons of shell to obtaining two differents form factors in order to give less uncertainty to the obtaining of the coupling constant. The evaluation of the uncertaints were included in this work.

O presente trabalho descreve a investigação de funcionais de densidade para os cálculos das constantes escalares de acoplamento indireto spin-spin para diferentes tipos de átomos. 26 DFTs são inicialmente avaliados para um conjunto de calibração contendo constantes de acoplamento indireto spin-spin das moléculas HF, CO, H2O, NH3, PH3, PF3, BHF2, BF3, F2O, CH4, C2H2, C2H4 e C2H6. As estratégias utilizadas envolvem principalmente o ajuste da porcentagem de troca orbital Hartree-Fock (EXHF), a fim de melhorar a precisão. Estudos anteriores sugeriram que a utilização de uma certa porcentagem de troca exata contribui para obter resultados mais precisos para as constantes de acoplamento. Do total, BHandH, B1B95, a família B97 e a família ωB97 forneceram bons resultados para o conjunto de calibração. Em geral, DFTs híbridos contendo entre 30% e 50% de EXHF em sua composição apresentam valores mais precisos para as constantes de acoplamento. Os funcionais modificados B1B95 40% EXHF, BHandH 40% EXHF e B972B95 60% EXHF apresentam ótima precisão para rotinas de otimização de geometria e cálculo da constante de acoplamento. Para funcionais corrigidos no longo alcance, a porcentagem EXHF não é bem definida, mas pode ser ajustada em termos de três parâmetros. Uma versão de ωB97XD com γ incrementado para 0,35 tem ótima precisão, assim como umaversão de ωB97X com α incrementado para 0,2. Versões corrigidas no longo alcance de B1B95 e BHandH fornecem excelentes precisões com α =0,4, α + β =1,0 e γ ajustado ao funcional. Os funcionais de longo alcance e o B972B95 60% EXHF desafiam os níveis de teoria SOPPA(CCSD) e SOPPA(CC2), que apresentam boa precisão independente do tipo de núcleo envolvido no acoplamento. O termo do contato de Fermi está principalmente associado às diferenças nos resultados para as constantes de acoplamento calculadas entre os métodos. Segundo o teorema de Janak, os funcionais de longo alcance estão mais próximos do comportamento exato de um funcional; o aumento da troca exata em DFTs híbridos leva a um aumento da localização eletrônica, levando a concavidades menores. A utilização de um conjunto teste com mais tipos de acoplamento reforça a ótima precisão obtida com B1B95 40% EXHF, BHandH 40% EXHF e suas versões de longo alcance. / This work seeks to describe the investigation of density functionals for calculating indirect spin-spin scalar coupling constants for different types of atoms. 26 DFTs are initially evaluated for a calibration set containing HF, CO, H2O, NH3, PH3, PF3, BHF2, BF3, F2O, CH4, C2H2, C2H4 and C2H6 indirect spin-spin coupling constants. The strategies used mainly involve adjusting the percentage of Hartree-Fock orbital exchange (EXHF) in order to increase accuracy. Previous studies have suggested that the use of a certain percentage of exact exchange contributes to obtain more accurate results for coupling constants. Overall, BHandH, B1B95, B97 family and ωB97 family have provided good results for the calibration set. In general, hybrid DFTs containing between 30% and 50% EXHF in their composition show more accurate values for the coupling constants. The modified functionals B1B95 40% EXHF, BHandH 40% EXHF and B972B95 60% EXHF have optimal accuracy for geometry optimization and coupling constant calculation routines. For long-range corrected functionals, EXHF percentage is not well defined but can be adjusted in terms of three parameters. A version of ωB97XD with γ increased to 0.35 has great accuracy, as well as a version of ωB97X with α increased to 0.2. Long-range corrected versions of B1B95 and BHandH provided excellent accuracies with α =0.4, α + β =1.0 and γ adjusted to the functional. Long-range functionals and B972B95 60% EXHF challenge SOPPA(CCSD) and SOPPA(CC2) levels of theory, which have good accuracy regardless of the core type involved in the coupling. Fermi-contact term is mainly associated with the differences from results of calculated coupling constants between methods. According to Janaks theorem, long-range functionals are closest to the exact behavior of a functional; increasing exact exchange in hybrid DFTs leads to an increased electronic localization, leading to lower concavities. Using a test set with more coupling types reinforces the optimum accuracy obtained with B1B95 40% EXHF, BHandH 40% EXHF and their long-range versions.

The role of scalar mesons in radiative vector meson decays is investigated. The effects of scalar-isoscalar f_{0}(980) and scalar-isovector a_{0}(980) mesons are studied in the mechanism of the radiative Phi-&gt / pi{+}pi{-}gamma and phi-&gt / pi{0}eta gamma decays, respectively. A phenomenological approach is used to study the radiative phi-&gt / pi{+}p{-}gamma decay by considering the contributions of sigma-meson, rho-meson and f_{0}-meson. The interference effects between different contributions are analyzed and the branching ratio for this decay is calculated. The radiative phi-&gt / pi{0}eta gamma decay is studied within the framework of a phenomenological approach in which the contributions of rho-meson, chiral loop and a_{0}-meson are considered. The interference effects between different contributions are examined and the coupling constants g_{phi a_{0} gamma} and g_{a_{0}K{+}K{-}} are estimated using the experimental branching ratio for the phi-&gt / pi{0}eta gamma decay. Furthermore, the radiative rho{0}pi{+}pi{-}gamma$ and rho{0}-&gt / pi{0}pi{0}gamma decays are studied to investigate the role of scalar-isoscalar sigma-meson. The branching ratios of the rho{0}-&gt / pi{+}pi{-}gamma and rho{0}-&gt / pi{0}pi{0}gamma decays are calculated using a phenomenological approach by adding to the amplitude calculated within the framework of chiral perturbation theory and vector meson dominance the amplitude of sigma-meson intermediate state. In all the decays studied the scalar meson intermediate states make important contributions to the overall amplitude.

In the present work some hadronic properties of the scalar &kappa / meson are studied. Using the QCD sum rules approach, which is a nonperturbative method, the mass and the overlap amplitude of this meson are calculated. As well as the mass and the overlap amplitude, &kappa / &rarr / K^+&pi / ^&minus / decay is also studied. For this decay the coupling constant g_&kappa / K^+&pi / ^&minus / is obtained using light cone QCD sum rules which is an extension of the QCD sum rules method. Moreover, the coupling constant is calculated using the experimental decay width and it is compared with the value obtained in light cone QCD sum rules approach. The result of the calculation of g_&kappa / K^+&pi / ^&minus / , the one obtained from light cone QCD sum rules approach, is also applied to acquire the f_0 &minus / &sigma / scalar mixing angle, &theta / s, using the ratio g^2 (&kappa / &rarr / K^+&pi / ^&minus / )/g^2 (&sigma / &rarr / &pi / &pi / ) obtained from experimental decay width. The value of scalar mixing angle is also compared with its experimental results.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This dissertation first describes the collection of literature data among the years 2005 to 2011 for the subsequent data analysis of 1H NMR chemical shifts and coupling constants and 2JHH 3JHH with emphasis on the synthesis of 3,5-diaryl-4,5-dihydro-1H-pyrazoles. Initially, was analyzed the data from X-ray diffraction of compounds 4,5-dihydro-1H-pyrazoles with a focus on the molecular structure description. Posteriorly, the X-rays data was correlated with the 1H NMR chemical shifts observing the influence of different substituents on the pyrazole ring. The coupling constants 2JHH 3JHH were correlated with bond angles and dihedral angles observed respectively for the molecules of 3,5-diaryl-4,5-dihydro-1H-pyrazoles. / A presente dissertação descreve inicialmente a coleta de dados da literatura entre os anos de 2005 e 2011 para a posterior análise de dados de deslocamento químico de RMN 1H, e constantes de acoplamento 2JHH e 3JHH com ênfase à síntese de 3,5-diaril-4,5-diidro-pirazóis. Primeiramente, foram analisados os dados de difração de raios-X de compostos 4,5-diidro-1H-pirazóis com foco na estrutura molecular descrita. A seguir, correlacionou-se os dados de raios-X com os deslocamentos químicos de RMN 1H observando a influência dos diferentes substituintes sobre o anel pirazolínico. Foram correlacionadas as constantes de acoplamento 2JHH e 3JHH com os ângulos de ligação e ângulos diedros observados, respectivamente, para as moléculas de 3,5-diaril-4,5-diidro-1H-pirazóis.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A física de partículas vem atualmente estudando tópicos como o plasma de quarks e glúons (QGP), o bóson de Higgs e a matéria escura, que requerem experimentos de colisões entre partículas cada vez mais energéticas. Para isso, são necessários aceleradores capazes de gerar partículas projéteis a cada vez mais altas energias, o que pode levar a uma nova física. Quando novos dados surgem nos laboratórios, novos processos são necessários para explicar estes dados e algumas vezes a estrutura interna das partículas envolvidas é desconhecida. Nos modelos teóricos, usados para descrever estes processos de espalhamento, é comum introduzir o fator de forma. O fator de forma é simplesmente uma maneira de simular a sub-estrutura das partículas envolvidas nestes processos com função da energia ou momento. A obtenção dos atores de forma pode ser feita usando o método conhecido como Regras de Soma da QCD (RSQCD). Neste trabalho, será estudado o vértice D*Dp usando as RSQCD, de modo que seja possível obter os seus fatores de forma e sua constante de acoplamento. Para isso, foram estudados os casos em que o méson ρ e o méson D estão fora de suas camadas de massa. O vértice D*Dp é muito importante para entender melhor o ρπ Puzzle, onde o méson Ј/ψ decai ρπ em com um branching ratio maior do que o esperado (este é um processo suprimido pela regra de OZI). Estudando este processo com graus de liberdade mesnicos, é possível escapar da regra de OZI, uma vez que o processo Ј/ψ→ DD → ρπ não é suprimido por OZI. Ao se fazer isso, aparecerá, entre outros, o vértice D*Dp . Este é um vértice que também aparece em outros decaimentos, como por exemplo X(3872) →Ј/ψp e B→Ј/ψD. Ao final do desenvolvimento, os resultados obtidos neste trabalho para o vértice D*Dp foram comparados com outros encontrados na literatura, se mostrando compatíveis com estes outros trabalhos. / The particle physics have been studying topics like the Quark-Gluon Plasma (QGP), Higgs boson and dark matter, which require experiments in heavy-ion collisions. Therefore, accelerators capable of generate high energy particle beams are necessary and may generate new physics. When new data arise in the laboratories, new processes are necessary to explain this data and sometimes, the internal structure of the involved particles is unknow or are virtual. In the theoretical models, used to describe this scattering processes, is common to introduce the form factors. The form factor is a way to simulate the sub-structure of the involved particles as function of energy or momentum. The form factor can be obtained using a method called QCD Sum Rules (QCDSR). In this work, the vertex D*Dp will be studied using the QCDSR, in order to obtain its form factors and coupling constant.The D*Dp vertex is very important to understand the ρπ Puzzle, where the Ј/ψ meson decays in ρπ with a branching ratio bigger than expected (this is a suppressed process by the OZI Rule). Studying this process with hadronic degrees of freedom, its possible to escape of the OZI rule, once the Ј/ψ→ DD → ρπ is not suppressed by the OZI rule. In this process, the D*Dp vertex is necessary. There are other processes where this vertex is necessary: X(3872)→Ј/ψp and B→Ј/ψD for example. In this work, was only possible to obtain results from the ρ off-shell diagram. This results were compared with others obtained in the literature.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A física de partículas vem atualmente estudando tópicos como o plasma de quarks e glúons (QGP), o bóson de Higgs e a matéria escura, que requerem experimentos de colisões entre partículas cada vez mais energéticas. Para isso, são necessários aceleradores capazes de gerar partículas projéteis a cada vez mais altas energias, o que pode levar a uma nova física. Quando novos dados surgem nos laboratórios, novos processos são necessários para explicar estes dados e algumas vezes a estrutura interna das partículas envolvidas é desconhecida. Nos modelos teóricos, usados para descrever estes processos de espalhamento, é comum introduzir o fator de forma. O fator de forma é simplesmente uma maneira de simular a sub-estrutura das partículas envolvidas nestes processos com função da energia ou momento. A obtenção dos atores de forma pode ser feita usando o método conhecido como Regras de Soma da QCD (RSQCD). Neste trabalho, será estudado o vértice D*Dp usando as RSQCD, de modo que seja possível obter os seus fatores de forma e sua constante de acoplamento. Para isso, foram estudados os casos em que o méson ρ e o méson D estão fora de suas camadas de massa. O vértice D*Dp é muito importante para entender melhor o ρπ Puzzle, onde o méson Ј/ψ decai ρπ em com um branching ratio maior do que o esperado (este é um processo suprimido pela regra de OZI). Estudando este processo com graus de liberdade mesnicos, é possível escapar da regra de OZI, uma vez que o processo Ј/ψ→ DD → ρπ não é suprimido por OZI. Ao se fazer isso, aparecerá, entre outros, o vértice D*Dp . Este é um vértice que também aparece em outros decaimentos, como por exemplo X(3872) →Ј/ψp e B→Ј/ψD. Ao final do desenvolvimento, os resultados obtidos neste trabalho para o vértice D*Dp foram comparados com outros encontrados na literatura, se mostrando compatíveis com estes outros trabalhos. / The particle physics have been studying topics like the Quark-Gluon Plasma (QGP), Higgs boson and dark matter, which require experiments in heavy-ion collisions. Therefore, accelerators capable of generate high energy particle beams are necessary and may generate new physics. When new data arise in the laboratories, new processes are necessary to explain this data and sometimes, the internal structure of the involved particles is unknow or are virtual. In the theoretical models, used to describe this scattering processes, is common to introduce the form factors. The form factor is a way to simulate the sub-structure of the involved particles as function of energy or momentum. The form factor can be obtained using a method called QCD Sum Rules (QCDSR). In this work, the vertex D*Dp will be studied using the QCDSR, in order to obtain its form factors and coupling constant.The D*Dp vertex is very important to understand the ρπ Puzzle, where the Ј/ψ meson decays in ρπ with a branching ratio bigger than expected (this is a suppressed process by the OZI Rule). Studying this process with hadronic degrees of freedom, its possible to escape of the OZI rule, once the Ј/ψ→ DD → ρπ is not suppressed by the OZI rule. In this process, the D*Dp vertex is necessary. There are other processes where this vertex is necessary: X(3872)→Ј/ψp and B→Ј/ψD for example. In this work, was only possible to obtain results from the ρ off-shell diagram. This results were compared with others obtained in the literature.