A novel synthetic methodology has been developed for attaching fluorene derivatives, containing different types of electron donating and accepting groups at the 2 and 7 positions, to gold nanoparticles of different sizes by exploiting the affinity of the thiol functional group for gold. The distance between the dye and nanoparticles was varied by introducing two alkyl chains containing different number of carbon atoms at the 9 position on the fluorene ring system. The methodology that was developed gave enough scope for performing Radiative Decay Engineering (RDE) studies, in order to investigate the impact of gold nanoparticles on the singlet oxygen quantum yields of fluorene dyes that already exhibit high singlet oxygen quantum yields as well as high two photon absorption (2PA) cross-sections. The dialkylation of the fluorene derivatives was accomplished by reacting the dye with [alpha], [omega]-dibromoalkanes containing different number of carbon atoms in a biphasic reaction mixture containing toluene and aqueous sodium hydroxide solution in the presence of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The bromine atom on the alkyl chains was converted to thioester by reaction with potassium thioacetate. This was followed by the hydrolysis of the thioester to form the thiol moiety. The compounds synthesized were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Functionalization of gold nanoparticles was attempted by bringing into contact a solution of the thiol compound in toluene and an aqueous gold nanoparticles solution. UV-vis absorbance spectroscopy was used to monitor the progress of the attachment. Surface Enhanced Raman Scattering (SERS) spectroscopy was used to probe the enhancement of Raman signal by the metallic nanoparticles.

Nessa tese procuramos o decaimento radioativo raro - -. É um dos resultados da experiência E761 realizada no Proton Center do Fermilab, usando o feixe de híperons carregados com momento de 377 GeV/c. Medimos a fração deste feixe que é constituída de -, sendo esta (3,9 ±0,3)X10-5. Não encontramos sinal do decaimento radiativo - - e determinamos um novo limite superior de 7,5X 10-4 (90% CL). / In this thesis we have searched for the rare hyperon radiative decay - -. It is one of the results of E761 experiment which was realized at Fermilab Proton Center using a 377 GevIc charged hyperon beam. We measure the - beam fraction, which is (3.9 ± 0.3)x10-5 at the start of the decay region. No signal for the radiative decay was found and we determine a new upper limit of 7.5 x 10-4 at 90% CL for the - - branching ratio.

Nessa tese procuramos o decaimento radioativo raro - -. É um dos resultados da experiência E761 realizada no Proton Center do Fermilab, usando o feixe de híperons carregados com momento de 377 GeV/c. Medimos a fração deste feixe que é constituída de -, sendo esta (3,9 ±0,3)X10-5. Não encontramos sinal do decaimento radiativo - - e determinamos um novo limite superior de 7,5X 10-4 (90% CL). / In this thesis we have searched for the rare hyperon radiative decay - -. It is one of the results of E761 experiment which was realized at Fermilab Proton Center using a 377 GevIc charged hyperon beam. We measure the - beam fraction, which is (3.9 ± 0.3)x10-5 at the start of the decay region. No signal for the radiative decay was found and we determine a new upper limit of 7.5 x 10-4 at 90% CL for the - - branching ratio.

Le LHC a commencé, dès le mois de Novembre 2009, à prendre des données. Cela initie une nouvelle ère de découverte pour la physique des particules. Le détecteur CMS est une des expériences principales de physique présente au LHC. Un des buts de cette expérience est la recherche du boson de Higgs, pouvant être à l'origine de la brisure de symétrie électrofaible. Après un replacement de la place du LHC et de CMS au sein de la physique des particules d'aujourd'hui, je présenterai alors l'ensemble de la chaîne permettant de passer de l'évènement physique aux analyses finales permettant d'extraire, des particules reconstruites, les informations permettant, à terme, la découverte de nouvelles particules telles que le boson de Higgs. Une première partie de mes travaux a porté sur la mesure et le suivi des rapports de gains de l'électronique d'acquisition, permettant de mesurer de manière précise l'énergie des photons sur toute la gamme d'énergie accessible (35 MeV  1.7 TeV). Mes travaux ont alors concernés la vérification de la validité des méthodes de calibration des cartes d'acquisition VFE au sein du détecteur. Une seconde partie de mes travaux à porté sur la manière dont doivent êtres générés les évènements de physique pour ne pas avoir de double-comptage entre les photons provenant de générateurs à éléments de matrices et ceux provenant de générateur à gerbe partonique. En collaboration avec des physiciens phénoménologues une méthode de véto anti double-comptage a été élaborée. Enfin, la dernière partie de mes résultats concerne la manière dont les désintégrations radiatives du boson de jauge électrofaible neutre Z° permettent, par la sélection d'une population de photons certifiés et isotopiques, d'extraire l'échelle d'énergie des photons au sein du calorimètre électromagnétique de CMS / The LHC has started, since november 2009 taking data. This started a new era of discovery in particle physics. The CMS detector is one of the main experiment at the LHC (CERN). One goal of this experiment is the Higgs's boson discovery, that can be related to the electroweak symmetry breaking. After a contextual replacement of the LHC and CMS within the nowdays's particle physics, I will explain the whole chain allowing to go from the physical event to the nal analysis, in order to extract the reconstructed particles and the informations allowing, at the end, the discovery of new particles like the Higgs's boson. A rst part of my works was about the measurement and the study of the acquisition electronics's gains-ratios. This work aimed to have a precise measurement of the photons energy on the whole available energy band (35 MeV -> 1.7 TeV). In particular, my works were upon the validation of the dierent calibration methods for the VFE acquisition cards within the detector. A second part of my work was about the way that one have to generate the physics events avoiding double-counting between photons coming from matrix-element generators and those coming from parton-shower algorithms. In collaboration with phenomenologists physicists, an anti-double-counting veto have been created. At last, the nal part of my results was about the way the radiative decay of the Z° neutral electroweak gauge boson allow, by the selection of certied photons, the extraction of the photons energy scale inside the electromagnetical calorimeter of CMS.

No description available.

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.

A general analysis of the photon and lepton polarizations in the rare Bs &amp / #8594 / &amp / #61543 / l+l- decay by using the most general model independent form of the effective Hamiltonian is presented. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are studied. The sensitivity of &quot / photon polarization asymmetry&quot / and the longitudinal, transverse and normal polarization asymmetries of final state leptons, as well as lepton-antilepton combined asymmetries in Bs &amp / #8594 / &amp / #61543 / l+l- decay to the new Wilson coefficients are also investigated. It is shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.

The radiative &amp / #969 / &amp / #8594 / &amp / #960 / 0&amp / #960 / 0&amp / #947 / , &amp / #961 / &amp / #8594 / &amp / #960 / 0&amp / #960 / 0&amp / #947 / , &amp / #969 / &amp / #8594 / &amp / #960 / +&amp / #960 / &amp / #8722 / &amp / #947 / and &amp / #961 / &amp / #8594 / &amp / #960 / +&amp / #960 / &amp / #8722 / &amp / #947 / decays are studied by adding the effect of vector meson mixing to the amplitude of these decays. For the above decays we consider only &amp / #961 / &amp / #8722 / &amp / #969 / mixing. In addition to the &amp / #961 / &amp / #8722 / &amp / #969 / mixing, we also analyse the contributions coming from different intermediate states to examine the decay mechanism of these decays in a phenomenological framework. For &amp / #969 / &amp / #8594 / &amp / #960 / 0&amp / #960 / 0&amp / #947 / decay, we consider the contributions of the &amp / #961 / -meson and &amp / #963 / -meson intermediate states and of the kaon-loop, and for the &amp / #961 / &amp / #8594 / &amp / #960 / 0&amp / #960 / 0&amp / #947 / decay we calculate the amplitude using the contributions of the &amp / #969 / -meson and &amp / #963 / -meson intermediate states and pion-loop. Moreover, the radiative &amp / #969 / &amp / #8594 / &amp / #960 / +&amp / #960 / &amp / #8722 / &amp / #947 / decay is studied by considering the contributions of &amp / #963 / -meson and &amp / #961 / -meson intermediate states and the decay &amp / #961 / &amp / #8594 / &amp / #960 / +&amp / #960 / &amp / #8722 / &amp / #947 / is investigated by taking into account the contributions of bremmsstrahlung, pion-loop and &amp / #963 / - meson intermediate state amplitude. We also estimate the coupling constant g&amp / #969 / &amp / #963 / &amp / #947 / utilizing the latest experimental value of the branching ratio &amp / #969 / &amp / #8594 / &amp / #960 / 0&amp / #960 / 0&amp / #947 / .

No description available.