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Dissertations / Theses on the topic 'Electrons and muons'

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Published: 18 May 2024

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1

Chhetri, Rabin Kumar. "Study of the structures of electrons and muons in cosmic ray extensive air showers." Thesis, University of North Bengal, 1999. http://hdl.handle.net/123456789/685.

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2

Hughes, Gareth James. "A search for scalar electrons and muons using the DELPHI detector at LEP2." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344006.

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3

Keoshkerian, Houry. "Mesure de la production de di-bosons WZ auprès du LHC avec l'expérience ATLAS." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY030/document.

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Ce travail de thèse se situe dans le cadre de l'experience ATLAS au LHC. Une première partie du travail présenté dans ce document porte sur l'étalonnage temporel du calorimètre à argon liquide d'ATLAS (LAr). Le control de l'alignement temporel du calorimètre est important pour la bonne qualité de l'énergie reconstruite dans le calorimètre. Les résultats présentésdans cette thèse ont permis une amélioration de 30% de la résolution temporelle globale du calorimètre LAr.Le Modèle Standard de la physique des particules prédit, lors des collisions de protons, la production de bosons faibles W et Z par paire via l'interaction d'un quark et d'un anti-quark. La production de dibosons peut être sensible aux couplages des bosons vecteurs entre eux. Une déviation anomale de ces couplages par rapport aux valeurs prédites par le MS pourrait signer la présence de nouvelle physique. L'exploitation de toute la statistique des données 2012 d'ATLAS nous a permis d'accroitre la précision de la mesure de ces couplages par rapport aux précédents résultats basés sur des lots de données moindres. Cette thèse présente donc la mesure de la section efficace de production des dibosons WZ utilisant l'ensemble de données collectées par ATLAS en 2012 lors de collisions p-p au LHC à une énergie de 8 TeV au centre de masse. Avecla statistique disponible, le rapport des sections efficaces de production des événements W^+Z et W^-Z a pu être aussi mesuré. Cette dernière mesure n'avait pu être effectuée jusqu'alors en utilisant les données 2011 en raison du manque de statistique. Enfin, des mesures de section efficaces différentielles normalisées en fonction de quatre variables cinématiques ont aussi étéeffectuées. La précision sur la section efficace integrée mesurée est de 5.5%, ce qui est atteint en réduisant l'incertitude statistique par 55% par rapport aux précédents résultats d'ATLAS. Ainsi, les incertitudes expérimentales des mesures ont commencé à se rapprocher des incertitudes des prédictions théoriques. Ceci est prometteur pour les futures mesures au LHC avec beaucoup plus de statistique où l'on s'attend alors à une augmentation significative de la précision expérimentale
This thesis is performed in the frame of the ATLAS experiment at the LHC.A first part of the work presented in this document consists on the time calibration of the ATLAS Liquid Argon (LAr) calorimeter. The control of the time alignment of the calorimeter is important for the goodness of the quality of the energy reconstructed in the calorimeter. The results presented in this thesis have allowed an improvement of 30% of the global time resolution of the LAr calorimeter.The Standard model of particle physics predicts, during proton collisions, the production of the W and Z weak bosons as a pair due to the interaction of a quark with an anti-quark. The diboson production can be sensitive to the couplings between vector bosons.An anomalous deviation of these couplings from the prediction of the SM would point to the presence of new physics.The use of the full statistics of the 2012 ATLAS data allowed us to increase the precision of the measurement of these couplings compared to previous results based on smaller datasets.This thesis presents therefore the measurement of the WZ dibosons production cross section using the full 2012 data collected by the ATLAS experiment from the p-p collisions at the LHC at a center-of-mass energy of 8~TeV. Also, with the available statistics the ratio of the production cross sections of W^+Z and W^-Z events were measured. This measurement was not performed previously using the 2011 data due to a lack of statistics. Finally, measurements of the normalized differential cross section as a function of four kinematic variables were also performed.The precision on the measured integrated cross section is 5.5% which is reached mainly by the reduction of the statistical uncertainty by 55% with respect to the previous ATLAS results. Therefore, the order of magnitude of the experimental uncertainties on the measurement started to approach that of the theoretical predictions. This is promising for future measurements at the LHC as with higher statistics the experimental precision is expected to overcome the theoretical one
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4

Brüggemann, Marc. "Determination of an arrival time cut for the separation of electrons and muons in extensive air showers." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983413223.

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5

Reis, Thomas. "Search for new massive resonances decaying to dielectrons or electron-muon pairs with the CMS detector." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209131.

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Le sujet de cette thèse porte sur la recherche de nouvelles résonances massives se désintégrant en une paire d’électrons ou une paire électron-muon avec le détecteur CMS, installé auprès du Grand Collisionneur du Hadrons (LHC) au CERN. Les données analysées correspondent à l’ensemble des collisions proton-proton enregistrées par le détecteur en 2012 à une énergie dans le centre de masse de 8 TeV. Après une brève introduction au modèle standard des particules élémentaires et à quelques unes des théories allant au-delà, le LHC et le détecteur CMS sont présentés. La reconstruction des différentes particules créées lors des collisions, en particulier des électrons et muons de haute énergie, est ensuite discutée. Deux analyses séparées sont menées.

La première consiste en la recherche d’une nouvelle résonance étroite, plus massive que le boson Z, dans le spectre de masse invariante des paires d’électrons, dont la principale contribution, dans le modèle standard, provient du processus de Drell–Yan. De telles résonances sont notamment prédites par des modèles dits de grande unification ou à dimensions spatiales supplémentaires. Le bruit de fond provenant des processus du modèle standard étant réduit dans la région étudiée, quelques événements localisés peuvent suffire pour mener à une découverte, et la sélection des électrons est optimisée afin de ne perdre aussi peu d’événements que possible. Les différentes contributions des bruits de fond sont partiellement estimées à partir de simulations. Une méthode basée sur le spectre de masse invariante des paires électron-muon mesuré dans les données est développée pour valider la contribution du second bruit de fond en terme d’importance. Aucun excès n’est observé par rapport aux prédictions du modèle standard et des limites supérieures à 95% de niveau de confiance sont placées sur le rapport entre la section efficace de production multipliée par le rapport de branchement d’une nouvelle résonance et celle au pic du boson Z. Ces limites sont ensuite converties en limites inférieures sur la masse de différentes particules hypothétiques de spin 1 ou de spin 2.

La seconde analyse consiste en une recherche de résonances massives et étroites dans le spectre de masse invariante des paires électron-muon. De telles résonances briseraient la conservation du nombre leptonique tel que prédit par le modèle standard. Cette possibilité existe cependant dans certains modèles de nouvelle physique. C’est notamment le cas pour un modèle à dimensions supplémentaires où apparaissent des nouveaux bosons neutres lourds. La sélection des événements demande un électron de haute énergie comme dans l’analyse précédente, et un muon de grande impulsion transverse. La stratégie de recherche est similaire au cas des paires d’électrons :le fait de rechercher un signal étroit rend l’analyse statistique très peu sensible aux erreurs systématiques affectant la normalisation absolue du spectre de masse électron-muon. Comme aucune déviation significative n’est observée par rapport aux prévisions du modèle standard, des limites supérieures sur la section efficace multipliée par le rapport de branchement sont établies pour le modèle à dimensions spatiales supplémentaires. Étant données les faibles valeurs théoriques de la section efficace de production des résonances violant la conservation de la saveur dans ce modèle, la quantité de données analysées ne permet pas d’en déduire une limite inférieure sur leur masse. Cette analyse représente néanmoins la première recherche directe avec l’expérience CMS, de bosons massifs, se désintégrant avec violation du nombre leptonique, en une paire électron-muon.


Doctorat en Sciences
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6

Durand, J. D. "Mesures du melange effectif et des asymetries des quarks b et c dans les desintegrations semileptoniques en electrons et en muons." Phd thesis, Université Claude Bernard - Lyon I, 1996. http://tel.archives-ouvertes.fr/in2p3-00002742.

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7

Abraham, Nicola Louise. "Search for Electroweak Supersymmetry in final states with three electrons or muons plus missing transverse momentum in 13 TeV proton-proton collisions at the Large Hadron Collider with the ATLAS Detector." Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/79859/.

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A search for the electroweak production of charginos and neutralinos decaying into final states involving three electrons or muons is presented. The analysis is based on 36.1 fb^-1 of √s = 13TeV proton–proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Scenarios considered are based on simplified models with the associated production of the next-to-lightest neutralino and the lightest chargino, followed by their decays into final states with leptons and the lightest neutralino via either sleptons or Standard Model gauge bosons. No significant deviations from Standard Model expectations are observed and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles. For a massless lightest neutralino, masses up to 1.13TeV are excluded for the associated production of the next-to-lightest neutralino and the lightest chargino, assuming slepton mediated decays, whereas for gauge-boson-mediated decays, masses up to 380 GeV are excluded.
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8

Sheridan, Alexandra Ellen. "A search for the standard model Higgs boson using the DELPHI detector at LEP2." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367146.

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9

Santos, George De Conto. "Electron and muon anomalous magnetic dipole moment in the 3-3-1 model with heavy leptons /." São Paulo, 2018. http://hdl.handle.net/11449/153288.

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Orientador: Vicente Pleitez
Banca: Juan Carlos Montero Garcia
Banca: Ricardo D'Elia Matheus
Banca: João Pacheco Bicudo Cabral de Melo
Banca: Marcelo Moraes Guzzo
Resumo: Nós calculamos, no contexto do modelo 3-3-1 com léptons pesados carregados, vínculos sobre alguns dos parâmetros das partículas extras do modelo ao impor que suas contribuições aos fatores (g-2) do elétron e do múon estejam de acordo com os dados experimentais dentro de 1 sigma - 3 sigma. Para obter resultados realistas nós consideramos algumas das possíveis soluções das matrizes unitárias esquerda e direita que diagonalizam as matrizes de massa leptônicas, dando as massas leptônicas observadas e ao mesmo tempo acomodando a matriz de mistura de Pontecorvo-Maki-Nakagawa-Sakata (PMNS). Nós mostramos que, ao menos até a ordem de 1-loop, na faixa de parâmetros explorada, não é possível acomodar simultaneamente os fatores (g-2) do elétron e do múon a não ser que um dos léptons extras tenha massa da ordem de 20-40 GeVs e a escala de energia da simetria 331 esteja em torno de 60-80 TeVs.
Abstract: We calculate, in the context of the 3-3-1 model with heavy charged leptons, constraints on some parameters of the extra particles in the model by imposing that their contributions to both the electron and muon (g ���� 2) factors are in agreement with experimental data up to 1 -3 . In order to obtain realistic results we use some of the possible solutions of the left- and right- unitary matrices that diagonalize the lepton mass matrices, giving the observed lepton masses and at the same time allowing to accommodate the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. We show that, at least up to 1-loop order, in the particular range of the space parameter that we have explored, it is not possible to t the observed electron and muon (g ���� 2) factors at the same time unless one of the extra leptons has a mass of the order of 20-40 GeVs and the energy scale of the 331 symmetry to be of around 60-80 TeVs
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10

Yokoyama, Koji. "Muon probes of spin-polarized electrons in GaAs." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=104&did=1907186881&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270484411&clientId=48051.

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Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Includes bibliographical references (leaves 121-123). Issued in print and online. Available via ProQuest Digital Dissertations.
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11

Hubbard, Penny Louise. "Molecular and electron dynamics with muon spectroscopy." Thesis, University of East Anglia, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268573.

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12

Odier, Jérôme. "Première physique auprès du détecteur Atlas et recherche du boson de Higgs dans le canal H --> ZZ (*) --> 4 l." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22138.

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Après une description du LHC, de l'expérience Atlas et des systèmes calorimétriques à argon liquide, cette thèse montrera une étude qui vise à valider la simulation des gerbes électromagnétiques en utilisant des muons cosmiques. Nous discuterons ensuite de la reconstruction des pions neutres et de la cartographie de la matière dans le trajectographe interne en utilisant des photons convertis avec les premières données. Pour finir, nous présenterons les résultats obtenus concernant la recherche du boson de Higgs dans le canal H->ZZ->4l avec les données 2011 et une énergie √s=7TeV dans le centre de masse
After a description of the LHC, the ATLAS experiment and the liquid argon calorimeter system, this thesis will show a study to validate the simulation of electromagnetic showers using cosmic muons. Then, we will discuss about neutral pion reconstruction and about the material mapping of the inner tracker using converted photons with the first data. Finally, we will present the results concerning the search for the Higgs boson in the H-> ZZ-> 4l channel with the 2011 data and a energy √s = 7TeV
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13

Libby, James Frederick. "The study of e'+e'-#->##mu#'+#mu#'-(#gamma#) and the measurement of trilinear gauge couplings at LEP2 using the DELPHI detector." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301903.

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14

Casadei, Matteo. "Muon Spin Rotation (uSR) investigation of electron-doped iron-oxypnictide superconductors." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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In the last ten years, the Fe-based superconductors have been extensively investigated both from the experimental and theoretical point of view, and many studies have been devoted to investigate the intimate interplay between the magnetic and superconducting phases. However, many aspects of their phenomenology are still unclear. In this thesis work we focused onto a specific material family, namely the LaFeAsO1−xFx (1111), to perform a systematic experimental investigation of the superconducting and magnetic microscopic properties as a function of the Fluorine doping. We considered the doping range 0.04 < x < 0.15, namely from the emergence of superconductivity to the so-called overdoped regime. We used Muon Spin Rotation (µSR) spectroscopy, which is a very powerful local probe to study the microscopic superconducting and magnetic properties of materials. In particular, we systematically studied the doping dependence of i) the superconducting gap and the London penetration depth, related to the superconducting density ns, via the analysis of the muon depolarization rate, and of ii) the local magnetic susceptibility, through the local field probed at the muon site. The results suggest a possible change from s-wave to d-wave character when the superconducting critical temperature Tc is reduced. The normalized Tc as a function of the superfluid density for different Ln-1111 families collapses onto a single phenomenological universal curve that indicates a crossover from the so called-Uemura (Tc∝ns) to the BCS (Tc∿const) regime. This is a phenomenological original outcome of this work. Another important result of this thesis is the observation of a rehentrant paramagnetic behavior in all the samples, more evident for compositions with high Tc. We argued that it may arise from residual magnetic correlations which survive up the to optimally doped regime and beyond. The interplay between this anomalous rehentrant behavior and superconductivity deserves further investigation.
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15

Ginkel, John Fred. "A search for the rare decay kaon(L) going to muon/electron." W&M ScholarWorks, 1989. https://scholarworks.wm.edu/etd/1539623782.

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A sensitive search has been carried out for the rare decay $\rm K\sb{L}\to\mu e$. This decay violates conservation of separate lepton-number and thus is forbidden in the Standard Model of electro-weak interactions. Many new models have been proposed which could permit this process. The data were collected in the B5 beamline of the Alternating Gradient Synchrotron facility at the Brookhaven National Laboratory during the Spring, 1988 slow-extracted beam running period. The experiment was sensitive to approximately fifty million $\rm K\sb{L}\to\pi\pi$ decays. No $\rm K\sb{L}\to\mu e$ candidate events were detected. The 90% confidence level upper limit for the branching ratio is $\rm B(K\sb{L}\to\mu e) < 2.2 \times 10\sp{-10}$. This limit places a constraint on the mass of exotic particles proposed in many new theories.
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16

Tenti, Matteo <1982&gt. "Electron identification and reconstruction with the OPERA ECC bricks and search for muon neutrino to electron neutrino oscillations." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4294/1/TESI.pdf.

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The procedure for event location in OPERA ECC has been optimazed for penetrating particles while is less efficient for electrons. For this reason new procedure has been defined in order to recover event with an electromagnetic shower in its final state not located with the standard one. The new procedure include the standard procedure during which several electromagnetic shower hint has been defined by means of the available data. In case the event is not located, the presence of an electromagnetic shower hint trigger a dedicated procedure. The old and new location procedure has been then simulated in order to obtain the standard location efficiency and the possible gain due to the new one for the events with electromagnetic shower. Finally a Data-MC comparison has been performed for the 2008 and 2009 runs for what concern the NC in order to validate the Monte Carlo. Then the expected electron neutrino interactions for the 2008 and 2009 runs has been evaluated and compared with the available data.
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17

Tenti, Matteo <1982&gt. "Electron identification and reconstruction with the OPERA ECC bricks and search for muon neutrino to electron neutrino oscillations." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4294/.

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The procedure for event location in OPERA ECC has been optimazed for penetrating particles while is less efficient for electrons. For this reason new procedure has been defined in order to recover event with an electromagnetic shower in its final state not located with the standard one. The new procedure include the standard procedure during which several electromagnetic shower hint has been defined by means of the available data. In case the event is not located, the presence of an electromagnetic shower hint trigger a dedicated procedure. The old and new location procedure has been then simulated in order to obtain the standard location efficiency and the possible gain due to the new one for the events with electromagnetic shower. Finally a Data-MC comparison has been performed for the 2008 and 2009 runs for what concern the NC in order to validate the Monte Carlo. Then the expected electron neutrino interactions for the 2008 and 2009 runs has been evaluated and compared with the available data.
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18

Toner, Ruth Bushnell. "Measuring θ₁₃ via muon neutrino to electron neutrino oscillations in the MINOS experiment." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/265528.

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One of the primary goals in neutrino physics at the present moment is to make a measurement of the neutrino oscillation parameter B13 . This parameter, in addition to being unknown, could potentially allow for the introduction of CP violation into the lepton sector. The MINOS long-baseline neutrino oscillation experiment has the ability to make a measurement of this parameter, by looking for the oscillation of muon neutrinos to electron neutrinos between a Near and Far Detector over a distance of 735 km. This thesis discusses the development of an analysis framework to search for this oscillation mode. Two major improvements to pre-existing analysis techniques have been implemented by the author. First, a novel particle ID technique based on strip topology, known as the Library Event Matching (LEM) method, is optimized for use in MINOS. Second, a multiple bin likelihood method is developed to fit the data. These two improvements, when combined, increase MINOS' sensitivity to sin2(W13 ) by 27% over previous analyses. This thesis sees a small excess over background in the Far Detector. A Frequentist interpretation of the data rules out B13 = 0 at 91 %. A Bayesian interpretation of the data is also presented, placing the most stringent upper boundary on the oscillation parameter to date, at sin2 (2B13 ) < 0.09(0.015) for the Normal (Inverted) Hierarchy and 6cp = 0.
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19

Willis, Maureen. "Muon spin relaxation as a probe of electron spin relaxation in organic semiconductors." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/5392.

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The purpose of this thesis is to study the electron spin relaxation (eSR) in small organic molecular semiconductors using the muon spin relaxation (MuSR) technique. One of the inherent problems in utilising the spin degree of freedom is the lack of understanding of the fundamental mechanisms behind spin relaxation. Two interactions have been proposed as the dominant mechanisms behind the spin relaxation, the Hyper ne interaction (HFI) and the Spin Orbit (SO) interaction. There remains much debate over the models for these interactions and their exact role, a contention that drives the work carried out in this thesis. The MuSR technique is utilised providing a novel molecular scale probe sensitive to relaxation rates in the range of 0.01-10 MHz. The Avoided Level crossing (ALC) MuSR application is useful in accessing the spin relaxation information. Temperature dependent ALC-MuSR measurements are performed for a selection of functionalised acenes and Quinolate molecules. Transverse eld MuSR measurements are also taken to determine the Hyper ne coupling constants present. DFT and semi-empirical computational methods are employed to determine theoretical values for the isotropic and anisotropic terms and the suitability of these methods was discussed. It is concluded that an intra-molecular eSR is present in all small organic molecular semiconductors. The mechanism behind this eSR was found not to be the HFI but in fact the SO interaction. It is also determined that the eSR is coupling to the vibrations in the molecule and a possible theory based on the curvature of the molecule from the vibrational modes inducing an enhanced SO coupling is proposed, which results in the eSR. The nal part of this thesis looks at the future experiments that have been initiated or can be conducted to further the understanding of spin relaxation and determine the role of a vibrationally enhanced SO coupling.
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20

Yang, Tingjun. "A study of muon neutrino to electron neutrino oscillations in the MINOS experiment /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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21

Gao, Xuyang. "Search for high mass resonances in electron-electron and electron-muon final states with CMS data and study of exotic states with BESIII data." Doctoral thesis, Universite Libre de Bruxelles, 2019. https://dipot.ulb.ac.be/dspace/bitstream/2013/288251/3/contents.pdf.

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We present a search for lepton flavor violation processes at eμ final states with the data collected by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV in 2016 corresponding to the integrated luminosity of 35.9 fb^(-1). No evidence for physics beyond the Standard Model is observed in the eμ invariant mass spectrum, the results are interpreted in terms of three different models, an R-parity violating SUSY model (RPV), a heavy Z’ gauge boson model, and a quantum black hole model (QBH). The lower mass limits at 95\% confidence level (C.L.) are found.We also present a search for new high-mass resonances decaying into electron pair with CMS 2016 data. No evidence of signature beyond the Standard Model prediction in the ee invariant mass spectrum observed, therefore the lower mass limits at 95\% C.L. are found for predictions of sequential standard model, grand unify theory, Randall-Sundrum model.Then we update the results of lower mass limits with the combination of 2016 data in ee and μμ channels and 2017 data in ee channel.Further to these, a study of the vector charmonium-like state Y(4220) is performed by using a combined fit on the cross sections of e^+ e^-→ωχ_c0, e^+ e^-→π^+ π^- h_c, e^+ e^-→π^+ π^- J/ψ and e^+ e^-→D^0 D^(*-) π^++c.c. measured by the BESIII experiment. The mass and width of the Y(4220) are obtained, We find the lower limit of its leptonic decay width to be 30 eV. We also estimate its partial decay width to π^+ π^- J/ψ in different scenarios. These results can be compared with the theoretical expectations of different models, and help the understanding of the nature of the Y(4220) state.
Doctorat en Sciences
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22

Smith, Bryan R. (Bryan Richard) 1971. "High energy pair production of muons in electron-positron annihilation at center of mass energies ranging from 130 to 183Gev." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50011.

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23

Norman, andrew J. "Measurement of the branching fraction for neutral kaon(long) decaying to muon-electron-positron." W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539623447.

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This dissertation describes the measurement of the decay of the long lived neutral kaon into two muons and two electrons. The measurement was performed using the data taken during experiment E871 which was performed on the B5 beamline at the Alternating Gradient Synchrotron (AGS) of the Brookhaven National Laboratory (BNL). The branching ratio B( K0L → mu+mu-e +e-) is sensitive to the absorptive portion of the long distance amplitude for decays of the form K0L → ℓ+ℓ- and can be used to properly extract the short distance weak interaction amplitudes from the dileptonic events.;Measurement of K0L → mu+mu-e +e- additionally allows for the exploration of the form factor for the K0L → gamma*gamma* vertex. Measurement of the K0L → mu+mu-e +e- branching fraction from the E871 data set provides a sensitive probe to distinguish between form factors arising from a chiral theory near the kaon mass, a low energy quark/QCD theory, a vector meson dominance model, models with CP violation and models which exhibit a uniform phase space.;The analysis of the data from the E871 mumu data stream observed 119 K0L → mu+mu-e +e- events on a measured background of 52 events. The K0L → mu+mu-e +e- event sample was normalized using simultaneously measured sample of 5685 K0L → mu+mu- events. The resulting branching fraction for K0L → mu+mu-e +e- was calculated to be 2.78 +/- 0.41 +/- 0.09 x 10-9 under the assumption of a chiPT form factor. The results are consistent with the world average for B( K0L → mu+mu-e +e-) and increase the total number of K0L → mu+mu-e +e- events observed world wide from 152 to 271.
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24

Versari, Federico <1992&gt. "Measurement of the atmospheric electron and muon neutrino flux with the ANTARES neutrino telescope." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9664/1/PhD_Thesis____.pdf.

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This thesis presents a combined measurement of the energy spectra of atmospheric electron and muon neutrinos in the energy range between around 100 GeV and 50 TeV with the ANTARES neutrino telescope. The analysis uses 3012 days of detector livetime in the period from 2007 to 2017, and selects 1016 neutrino interacting in (or close to) the instrumented volume of the detector, yielding shower-like events and starting track events. The contamination by atmospheric muons is suppressed at the level of a few per mill by different steps in the selection analysis, including a Boosted Decision Tree classifier. The distribution of reconstructed events is unfolded in terms of electron and muon neutrino fluxes and the derived energy spectra are compared with previous measurements.
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25

Starling, Elizabeth Rose. "Detection and Mitigation of Propagating Electrical Discharges Within the Gas Electron Multiplier Detectors of the CMS Muon System for the CERN HL-LHC." Doctoral thesis, Universite Libre de Bruxelles, 2020. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/315833.

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In preparation for the High-Luminosity Large Hadron Collider (HL-LHC) at CERN, the Compact Muon Solenoid (CMS) Detector is undergoing a series of upgrades to its existing infrastructure, and is adding in several completely new subdetector systems. The first of these new systems, called GE1/1, is a series of 144 gas electron multiplier (GEM) detectors, arranged as 36 two-detector "superchambers" in each of the muon endcaps of CMS. These detectors are a subtype of micropattern gas detectors, and consist of three layers of "GEM foils", thin sheets of polyimide coated with 5 um of copper on each side and chemically etched with holes of 50 - 70 um diameter at a pitch of 140 um. These layers are stacked on top of a printed circuit board (PCB) readout and sealed within a gastight volume that is filled with Ar:CO2 70:30, and a high voltage is applied to the foils to create electric fields within the GEM detectors. When a muon enters the detector and ionizes the gas within, the ionized electrons encounter these fields and multiply in Townsend avalanches at each successive foil layer, until they are read out at the readout PCB at a gain of ~10^4. In early 2017, a demonstrator system known as the "slice test" was installed into the negative endcap. Consisting of 10 GEM detectors, the two-year-long slice test served as both a proof of concept for the GE1/1 system and an invaluable learning experience that would permanently impact not only the GE1/1 project, but future GEM systems GE2/1 and ME0 as well. During the slice test, it was observed that readout channels were being lost in the course of operation to such a degree that the operational lifetime of the system was in serious jeopardy. These losses were attributed to damage to the front-end readout ASIC (VFAT) inputs, caused propagating electrical discharges within the detectors, and a dedicated campaign to study the discharges was launched. The results of this study will be presented in this dissertation. A campaign to mitigate these discharges and their resulting damage was launched. In order to protect the sensitive VFAT from damage, several external protection circuits were proposed and thoroughly tested. The results of these tests, which are presented herein, determined that a series of resistors totaling 470 Ohms would be installed on the VFAT hybrid. When coupled with an additional 200 kOhm resistor on the HV filter, this reduced the probability of damage following a discharge from 93% to 3% As GE2/1 and ME0 are not due to be installed for another few years, more complex discharge-prevention measures can be put into place. As such, the following measures have been examined, and results will be discussed herein: A new, larger VFAT hybrid is being manufactured, whose larger surface area can accommodate more robust protection circuits than those considered and used for GE1/1. As well, double-segmented GEM foils, in which both the top and bottom of each foil is segmented into < 100 cm^2 sectors that are separated by resistors, were examined for use in the detectors. These double-segmented foils were found to introduce a cross-talk signal in the detectors that results in false signals being treated as true signals, which causes a saturation of the GEM bandwidth and results in unwanted dead time. These cross-talk signals, as well as the compromises made to reduce the cross-talk while maintaining robust discharge prevention, will be discussed.
Doctorat en Sciences
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26

Materne, Philipp. "Local probe investigations of the electronic phase diagrams of iron pnictides and chalcogenides." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-186656.

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In this work, the electronic phase diagrams of Ca1−xNaxFe2As2 and Fe1+yTe were investigated using muon spin relaxation and Mössbauer spectroscopy. Single crystals of Ca1−xNaxFe2As2 with x = 0.00, 0.35, 0.50, and 0.67 were examined. The undoped 122 parent compound CaFe2As2 is a semi metal and shows antiferromagnetic commensurate spin density wave order below 167 K. By hole doping via Na substitution, the magnetic order is suppressed and superconductivity emerges including a Na-substitution level region, where both phases coexist. Upon Na substitution, a tilting of the magnetic moments out of the ab-plane is found. The interaction of the magnetic and superconducting order parameter in this coexistence region was studied and a nanoscopic coexistence of both order parameters is found. This is proven by a reduction of the magnetic order parameter of 7 % in x = 0.50 below the superconducting transition temperature. This reduction was analysed using Landau theory and a systematic correlation between the reduction of the magnetic order parameter and the ratio of the transition temperatures, Tc/TN, for the 122 family of the iron pnictides is presented. The magnetic phase transition is accompanied by a tetragonal-to-orthorhombic phase transition. The lattice dynamics at temperatures above and below this magneto-structural phase transition were studied and no change in the lattice dynamics were found. However, the lattice for finite x is softer than for the undoped compound. For x = 0.67, diluted magnetic order is found. Therefore, the magnetism in Ca1−xNaxFe2As2 is persistent even at optimal doping. The superconducting state is investigated by measuring the temperature dependence of the magnetic penetration depth, where two superconducting gaps with a weighting of nearly 50:50 are obtained. A temperature independent anisotropy of the magnetic penetration depth γ_λ = 1.5(4) is obtained, which is much smaller compared to other 122 compounds indicating a more three-dimensional behaviour of Ca1−xNaxFe2As2. Powder samples of Fe1+yTe with y = 0.06, 0.12, 0.13, and 0.15 were examined. Fluctuating paramagnetic moments at room temperature were found, which are independent of the excess iron level y. Below 100 K, a magnetic precursor phase is observed, which is independent of y. Fe1.06Te shows a commensurate spin density wave phase below TN, while for y ≥ 0.13 an incommensurate spin density wave phase below TN is found. However, a slowing down of the magnetic fluctuations with decreasing temperature and static magnetic order at lowest temperature are observed
In dieser Arbeit wurden die elektronischen Phasendiagramme von Ca1−xNaxFe2As2 and Fe1+yTe mit Hilfe der Myonspinrelaxations- und Mössbauerspektroskopie untersucht. Einkristalle von Ca1−xNaxFe2As2 mit x = 0.00, 0.35, 0.50 und 0.67 wurden untersucht. Das undorierte 122-System CaFe2As2 ist ein Halbmetal und zeigt eine antiferromagnetische Spindichtewelle unterhalb von 167 K. Substituiert man Ca durch Na, werden Löcher in das System eingebracht. Die magnetische Ordnung wird mit steigendem Na-Anteil unterdrückt und Supraleitung tritt auf. Dabei existiert ein Na-Substitutionslevelbereich, in welchem Magnetismus und Supraleitung koexistieren. Desweiteren wurde ein herausdrehen der magnetischen Momente aus der ab-Ebene als Funktion von x beobachtet. Die Wechselwirkung des magnetischen mit dem supraleitenden Ordnungsparameter in der Koexistenzregion wurde untersucht und nanoskopische Koexistenz der beiden Ordnungsparameter wurde gefunden. Dies konnte durch eine Reduktion des magnetischen Ordnungsparameteres um 7 % in x = 0.50 unterhalb der supraleitenden Ordnungstemperatur gezeigt werden. Diese Reduktion wurde mit Hilfe der Landautheorie untersucht und es wurden systematische Korrelationen zwischen der Reduktion des magnetischen Ordnungsparamteres und dem Verhältnis der Übergangstemperaturen, Tc/TN, in der 122-Familie der Eisenpniktide gefunden. Der magnetische Phasenübergang wird von einem strukturellen Phasenübergang begleitet. Die Gitterdynamik wurde bei Temperaturen oberhalb und unterhalb dieses magneto-elastischen Phasenübergangs untersucht. Es wurden keine Änderungen in der Gitterdynamik festgestellt. Jedoch konnte festgestellt werden, dass das Gitter für endliche x weicher ist als für das undotierte System. Für x = 0.67 wurde festgestellt, dass der Magnetismus im Ca1−xNaxFe2As2-System auch noch bei optimaler Dotierung zu finden ist. In der supraleitenden Phase wurde die Temperaturabghängigkeit der magnetischen Eindringtiefe untersucht und es wurden zwei supraleitende Bandlücken gefunden. Die Anisotropie der magnetischen Eindringtiefe ist temperaturunabhängig und mit γ_λ = 1.5(4) wesentlich kleiner als in anderen 122- Verbindungen, was für eine erhöhte Dreidimensionalität in Ca1−xNaxFe2As2 spricht. Pulverproben von Fe1+yTe mit y = 0.06, 0.12, 0.13 und 0.15 wurden untersucht. Es wurden fluktuierende paramagnetische Momente bei Raumtemperatur gefunden, welche unabhängig vom Überschusseisenlevel y sind. Unterhalb von 100 K wurde eine magnetische Vorgängerphase gefunden, welche unabhängig von y ist. Mit fallender Temperatur wurde eine Verlangsamung der magnetischen Fluktuationen festgestellt, welche in einer statischen magnetischen Ordnung bei tiefen Temperaturen münden
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27

Wenner, Sigurd. "Transmission electron microscopy and muon spin relaxation studies of precipitation in Al–Mg–Si alloys." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23701.

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The Al–Mg–Si system is a heat-treatable class of aluminium alloys that gain their mechanical strength via precipitation hardening. The main hardening phases are precipitated as needle-shaped nano-sized particles from a solid solution of Mg, Si and other added elements. Transmission electron microscopy and muon spin relaxation was used to study precipitation and clustering in Al–Mg–Si alloys, varying the heat treatment and chemical composition in order to understand the kinetics of precipitation and the morphology, distribution, and atomic structure of hardening precipitates. Muons were found to form bonds with vacancies, atoms in solid solution, and clusters of solute atoms, which are the defects we can gain information from by applying muon spin relaxation to Al alloys. In binary Al–Mg and Al–Si alloys, we discovered very different vacancy behaviours after cooling from high temperatures: Si–vacancy clusters are quickly formed at room temperature in Al–Si, while Al–Mg keeps a much higher vacancy content than pure Al and Al–Si despite a lack of solute clustering. A high muon trapping in a specific temperature range was found in a 1.6% Mg2Si alloy annealed for 16 hours at 70–150 °C. These conditions contain clusters and Guinier–Preston-zones preceding the main hardening phase beta'' in the precipitation sequence. Density functional theory calculations support that the relevant muon trapping site is vacancies inside these structures, suggesting that the structures are stabilised by absorbing vacancies during annealing. The roles of the elements Cu and Ca on precipitation during artificial ageing were investigated. Room temperature storage gives a negative effect on the strength of aged high-solute Al–Mg–Si alloys, in particular when the Mg/Si ratio is high. The negative effect was found to be diminished and delayed by adding 0.14 at.% Cu to alloys with Mg+Si = 1.3 at.%, in addition to giving an overall strength increase. Transmission electron microscopy investigations revealed that the fraction of Cu-containing precipitates increased with room temperature storage before ageing. The Cu addition is believed to help the formation of clusters that can act as nucleation sites for hardening precipitates and/or prevent the formation of clusters that can not. Various amounts of Ca was added to an alloy with 0.53% Mg and 0.40% Si. The Ca accumulated in large particles with composition CaAl2Si2, as determined by X-ray energy dispersive spectroscopy. The presence of Si in the particles causes a reduction of the available Si for precipitation and an increase in the effective Mg/Si ratio. The result is a coarser microstructure with a higher fraction of over-aged precipitates and a lower mechanical strength. Aberration-corrected scanning transmission electron microscopy coupled with electron energy loss spectroscopy was conducted on an over-aged Al–Mg–Si–Cu–Ag alloy. The microstructure consisted of mostly disordered L and Q' precipitates. After applying principal component analysis to the acquired spectrum images, atomic columns containing Cu and Ag could be clearly distinguished. Cu and Ag were seen to prefer different atomic configurations, and were not observed occupying the same columns. While Cu columns mostly resided in ordered parts of precipitates and along precipitate–matrix interfaces, Ag was diluted in several nearby columns in disordered parts, and at precipitate–matrix interfaces of high misfit.
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28

MORESCALCHI, LUCA. "Study of the calorimetric detection of the muon to electron conversion in the Mu2e experiment." Doctoral thesis, Università di Siena, 2017. http://hdl.handle.net/11365/1030437.

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The Mu2e experiment will search for Charged Lepton Flavor Violation (CLFV), looking at the coherent conversion of a muon into an electron in the field of an aluminum nucleus. The knowledge of such a CLFV reaction allows to indirectly probe new physics at energy scales up to thousands of TeV, inaccessible with direct searches at either present or planned high energy colliders. For this reason, Mu2e will measure the muon-to-electron conversion rate R_{\mu e} with an unprecedented accuracy, so to improve of a factor 10^4 the best current measurement and, in case of no observation, to constrain its value below 6 x 10^-17 at 90% of CL. To reach this ambitious sensitivity, about 10^18 muonic atom decays have to be observed: Mu2e is expected to use an intense pulsed muon beam, and rely on a detector system composed of a straw tube tracker and an electromagnetic calorimeter. The calorimeter is composed of 1348 un-doped CsI crystals, each coupled to two large area Silicon Photomultipliers (SiPMs). It plays a central role in the Mu2e measurement, providing particle identification capabilities that are necessary to reject the cosmic muons and antiprotons induced background. Moreover, the calorimeter has to help the tracker providing a seed for the pattern recognition and to provide a fast independ trigger. Having these experimental requests as pivotal reference, a set of Quality Assurance (QA) criteria for the calorimeter active components have been defined. Following the corresponding QA procedures, a first batch of crystals and photosensors has been characterized and used to assemble a medium scale prototype of the calorimeter (Module-0). The Module-0 has been studied by means of a 100 MeV electron beam, confirming that expected calorimeter performances well satisfy the Mu2e requirements.
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29

Hollnagel, Annika [Verfasser], and Caren [Akademischer Betreuer] Hagner. "Energy reconstruction of electron neutrino events and muon neutrino-to-electron neutrino appearance search in the OPERA detector / Annika Hollnagel ; Betreuer: Caren Hagner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2018. http://d-nb.info/1164158724/34.

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30

Santos, George de Conto. "Electron and muon anomalous magnetic dipole moment in the 3-3-1 model with heavy leptons." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153288.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Nós calculamos, no contexto do modelo 3-3-1 com léptons pesados carregados, vínculos sobre alguns dos parâmetros das partículas extras do modelo ao impor que suas contribuições aos fatores (g-2) do elétron e do múon estejam de acordo com os dados experimentais dentro de 1 sigma - 3 sigma. Para obter resultados realistas nós consideramos algumas das possíveis soluções das matrizes unitárias esquerda e direita que diagonalizam as matrizes de massa leptônicas, dando as massas leptônicas observadas e ao mesmo tempo acomodando a matriz de mistura de Pontecorvo-Maki-Nakagawa-Sakata (PMNS). Nós mostramos que, ao menos até a ordem de 1-loop, na faixa de parâmetros explorada, não é possível acomodar simultaneamente os fatores (g-2) do elétron e do múon a não ser que um dos léptons extras tenha massa da ordem de 20-40 GeVs e a escala de energia da simetria 331 esteja em torno de 60-80 TeVs.
We calculate, in the context of the 3-3-1 model with heavy charged leptons, constraints on some parameters of the extra particles in the model by imposing that their contributions to both the electron and muon (g-2) factors are in agreement with experimental data up to 1 sigma - 3 sigma. In order to obtain realistic results we use some of the possible solutions of the left- and right- unitary matrices that diagonalize the lepton mass matrices, giving the observed lepton masses and at the same time allowing to accommodate the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. We show that, at least up to 1-loop order, in the particular range of the space parameter that we have explored, it is not possible to fit the observed electron and muon (g-2) factors at the same time unless one of the extra leptons has a mass of the order of 20-40 GeVs and the energy scale of the 331 symmetry to be of around 60-80 TeVs.
152740/2014-7
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31

Dhen, Mikaël. "Muon to electron conversion, flavored leptogenesis and asymmetric dark matter in minimal extensions of the Standard Model." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/217745.

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Il est clair que le Modèle Standard des particules élémentaires n'est pas complet. Parmi tous les indices d'une physique au-delà du Modèle Standard, la masse des neutrinos, l'asymétrie matière-antimatière de notre Univers et la matière noire constituent les trois contextes généraux de cette thèse.Le fait que les neutrinos soient massifs constitue la plus claire évidence d'une physique au-delà du Modèle Standard. La masse des neutrinos peut trouver une explication notamment dans le cadre des modèles favoris dits "modèles Seesaw". Ces modèles, en plus de générer une petite masse pour les neutrinos, génèrent aussi des processus dans lesquels la saveur d'un lepton chargé est changée, comme la désintégration d'un muon en un électron et un photon, ou la conversion d'un muon en un électron au sein d'un atome sans émission de neutrino. Ces processus sont importants car les expériences futures devraient atteindre des sensibilités impressionnantes sur leurs taux, mais aussi parce que leur observation confirmerait l'existence d'une physique nouvelle et pourrait peut-être discriminé parmi les différents modèles. Il est donc important d'avoir une expression analytique fiable du taux de ces processus dans le cadre de ces modèles Seesaw favoris. Dans la première partie de cette thèse, nous calculons l'expression du taux de conversion d'un muon en un électron au sein d'un atome dans le cadre des modèles Seesaw de type 1, et analysons la phénoménologie s'y rapportant. Ces modèles Seesaw, en plus de générer une petite masse pour les neutrinos et des processus changeant la saveur leptonique, permettent aussi la création de l'asymétrie matière-antimatière dans l'Univers, à travers le mécanisme dit de "leptogenèse". Selon ce mécanisme, une asymétrie leptonique aurait d'abord été créée, avant d'être partiellement transférée en une asymétrie baryonique. Dans la seconde partie de cette thèse, nous calculons et analysons la leptogenèse dans le cadre des modèles Seesaw de type 2 avec, pour la première fois, la prise en compte des effets de saveurs.Finalement, la troisième et dernière partie de cette thèse se concentre sur la possibilité de générer non seulement la matière baryonique à partir d'une asymétrie, mais aussi la matière noire. A cette fin, nous considérons le modèle dit "doublet inerte'', car il contient une interaction qui pourrait à priori générer de la matière noire à partir d'une asymétrie. Nous adressons dès lors la question suivante et y répondons: est-il possible de générer toute la matière noire à partir d'une asymétrie de matière noire dans le contexte du modèle doublet inerte ?
Option Physique du Doctorat en Sciences
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32

Astier, Pierre. "Recherche d'oscillations de neutrinos dans le canal neutrino-muon vers neutrino-electron aupres de l'accelerateur de brookhaven." Paris 7, 1987. http://www.theses.fr/1987PA077268.

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33

Campagne, Jean-Eric. "Etude du canal electron + positron muons + (photons) dans le cadre de l'experience delphi : corrections radiatives et performances du systeme de declenchement et de reconstruction." Paris 6, 1989. http://www.theses.fr/1989PA066084.

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34

Ashby, Shaun Francis. "A study of the process e'+e'-#->##mu#'+#mu#'-(#gamma#) at #square root#." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368452.

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35

Short, Daniel R. "A search for supersymmetry with the ATLAS detector using kinematic shape constraints in events containing one electron or muon." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:0c427106-4595-42d7-aa65-37f03fae7db7.

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The ATLAS experiment is used to observe the √s=7 TeV proton-proton collisions produced by the LHC at CERN. This gives an unprecedented opportunity to search for physics beyond the Standard Model at hitherto unexplored kinematic regimes. Supersymmetry (SUSY) provides interesting solutions to a variety of theoretical problems that may be encountered in the Standard Model at high energy scales, while providing signatures that may be observed at the LHC. However, in order to produce a search that is sensitive to SUSY it is vital to understand how the physics that has been discovered to date may produce signatures that mimic those expected from SUSY. Statistical models are constructed using both Monte Carlo and data-driven predictions of various background processes. The expectations are compared to the observed data for selections containing one electron or muon, each in association with jets and missing transverse momentum. Kinematic variable shapes, in the form of histograms, are used to enhance the sensitivity of the search. Squark and gluino masses in a MSUGRA SUSY model are excluded up to 1200 GeV, while gluino masses up to 900 GeV are excluded in a simplified SUSY model. Model-independent limits are also set, excluding theoretical models with efficiency times cross section above 1 fb.
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36

Curatolo, C. "High brilliance photon pulses interacting with relativistic electron and proton beams." Doctoral thesis, Università degli Studi di Milano, 2016. http://hdl.handle.net/2434/358227.

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We present a detailed study of the interaction between relativistic electron beams and high intensity laser pulses aimed at the production, through Inverse Compton scattering, of high brilliance gamma rays. In particular, we focus on the simulations of the emitted photon beams for the Extreme Light Infrastructure Nuclear Physics Gamma Beam System. The machine, presently under construction, is designed to deliver gamma ray photon beams in the 0.2-19.5 MeV energy range characterized by unprecedented performances in terms of monochromaticity, brilliance, spectral density, tunability and polarization. The possibility to generate low emittance TeV-class energy pion and muon beams via photo-production in a highly relativistic Lorentz boosted frame is discussed in the second part of the dissertation. The kinematics of all the events given by the proton-photon beams interaction has been considered: pion photo-production and further decay into muon and neutrino, lepton pair photo-production (electron/positron and muon pairs) and Inverse Compton scattering. We analyze the brightness of the secondary beams achievable by the coupling of advanced high efficiency high repetition rate Free Electron Laser pulses and Large Hadron Collider or Future Circular Collider proton beams.
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37

Aad, G., Richard Brenner, Claus P. Buszello, Tord Ekelöf, Mattias Ellert, Arnaud Ferrari, and L. Zwalinski. "Search for a heavy neutral particle decaying into an electron and a muon using 1 fb(-1) of ATLAS data." Uppsala universitet, Högenergifysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171766.

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A search is presented for a high mass neutral particle that decays directly to the e(+/-) mu(-/+) final state. The data sample was recorded by the ATLAS detector in root s = 7 TeV pp collisions at the LHC from March to June 2011 and corresponds to an integrated luminosity of 1.07 fb(-1). The data are found to be consistent with the Standard Model background. The high e(+/-) mu(-/+) mass region is used to set 95% confidence level upper limits on the production of two possible new physics processes: tau sneutrinos in an R-parity violating supersymmetric model and Z'-like vector bosons in a lepton flavor violating model.

ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-011-1809-9

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Wardrope, David Robert. "Preparations for measurement of electroweak vector boson production cross-sections using the electron decay modes, with the Compact Muon Solenoid detector." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5517.

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The Compact Muon Solenoid was designed to make discoveries at the TeV scale : to elucidate the nature of electroweak symmetry breaking and to search for physics beyond the Standard Model. For any such discovery to be credible, it must first be demonstrated that the CMS detector is understood. One mechanism to make this demonstration is to measure "standard candle" processes, such as W and Z production. This thesis describes preparations undertaken to make these measurements using the electron decay modes, with [derivative]Ldt = 10 pb-1 of collision data. The energy resolution of the electromagnetic calorimeter was measured in test beam data. An improved method of deriving the optimised weights necessary for amplitude reconstruction is described. The measurement of electron charge using tracks is impaired by the electron showering in the tracker material. A novel charge measurement technique that is complementary to the existing method was assessed. Missing transverse energy is a powerful discriminating variable for the selection of W+/ -> e+/ [upsilon]e events, however it is difficult to simulate accurately due to its global nature. The Ersatz Missing Energy method was developed to provide reliable and accurate descriptions of missing energy from data using readily reconstructible [gamma]*/Z -> e+e- events. The method is described and evaluated. Finally, the measurement strategy for W and Z boson production cross-sections in early data is outlined and analysed using simulated data. Significant results can be obtained with only [derivative] Ldt = 10 pb-1.
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BRUNDU, DAVIDE. "Radiation hardness of the upgraded LHCb muon detector electronics and prospects for a full angular analysis in multi-body rare charm decays." Doctoral thesis, Università degli Studi di Cagliari, 2020. http://hdl.handle.net/11584/284134.

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In this dissertation the results of the studies on the new readout electronics for the muon system of the LHCb experiment, and the perspectives for carrying out a full angular analysis in the rare decays D0 -> pi+ pi- mu+ mu- and D0 -> K+ K- mu+ mu- will be described. The LHCb experiment studies the heavy hadron physics, containing charm or bottom quarks, in particular searching for new Charge-Parity (CP ) symmetry violation sources, searching for rare decays and studying their properties. LHCb produced leading results in these fields so far. In order to obtain more precise measurements or be able to study new observables, many analyses need a considerable increase in statistics, thus the experiment is now being upgraded to run with an higher instantaneous luminosity of proton-proton collisions. For this reason the readout electronics has been completely replaced by a new optimised version. Several tests have been performed on the new readout electronics that will be here discussed, and that have allowed a comprehensive radiation hardness characterization of the UMC 130 nm technology, used to develop the main electronics device of the muon system readout electronics, the nSYNC chip. On the other hand, in the last two years of data taking, 2017 and 2018, an excellent performance of the LHCb experiment has been obtained and the significant increase in statistics allowed access to new observables, especially in the field of rare decays. In particular, it has been possible to increase the statistics of rare four-body charm decays, like D0 -> pi+ pi- mu+ mu- and D0 -> K+ K- mu+ mu- , of which LHCb already carried out the branching fractions measurement, as well as of angular and CP asymmetries. Since interesting results and flavour anomalies have already been obtained from angular analyses of rare B decays, it is important to study the possibility of these analyses in the complementary sector of rare charm decays. In this work the perspectives for performing a full angular analysis with D0 -> pi+ pi- mu+ mu- and D0 -> K+ K- mu+ mu- decays will be discussed. An angular analysis will allow to carry out several Standard Model tests in the field of rare D decays, allowing also to measure theoretically clean observables for probing effects of physics beyond Standard Model, that can occur at high energy scale.
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Hourlier, Adrien. "Background studies for electron anti-neutrino oscillations measurement at the Double Chooz experiment." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC192/document.

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L’expérience Double Chooz étudie les anti-neutrinos électroniques provenant de réacteurs nucléaires pour mesurer le paramètre de mélange θ13 dans le phénomène d’oscillation des neutrinos. Deux détecteurs souterrains identiques sont placés à différentes distances des réacteurs de la centrale de Chooz dans les Ardennes. Le Détecteur Lointain est entré en service en avril 2011, et le Détecteur Proche en janvier 2015. Cette thèse présente une analyse des phases simple et double détecteurs de l’expérience. Les neutrinos sont détectés par désintégration β inverse dans Double Chooz, où un positron et un neutron sont émis, créant deux signaux coïncidents. Différentes analyses ont été menées sur des échantillons dans lesquels le neutron capture sur un atome de gadolinium ou d’hydrogène. Une analyse jointe des deux captures est également présentée. Les bruits de fond proviennent de la radioactivité ambiante et des muons atmosphériques (émetteurs (β-n), neutrons rapides et muons s’arrêtant et se désintégrant dans le détecteur). Cette thèse se focalise sur le développement de techniques pour réduire le bruit de fond lié aux muons se désintégrant dans le détecteur. Avec l’aide de collègues de l’APC et du MIT, un TPC à neutrons a été installé dans les deux laboratoires souterrains à Chooz. Cette chambre à projection temporelle, appelée DCTPC, remplie d’un mélange hélium/CF4 mesure le flux, le spectre en énergie, et la direction des neutrons rapides dans les deux laboratoires avec des blindages différents (respectivement 150 et 300 mètres équivalents d’eau pour le Laboratoire Proche et Lointain)
Double Chooz is a reactor anti-neutrino experiment which measures the θ13 mixing parameter in the neutrino oscillation phenomenon thanks to two identical underground detectors located at different distances from the two reactors of the Chooz nuclear power plant in the French Ardennes. The Far Detector started data taking in April 2011 and the Near Detector began operations in January 2015. This thesis presents an analysis of both the single- and twodetector phases. Neutrinos interact in Double Chooz through inverse β decay on protons, where positron and a neutron are emitted, creating two coincident signals. Analyses were performed for each detector on independent samples using the neutron capture on Gadolinium or on Hydrogen. A combined analysis, using both neutron captures is also presented. Backgrounds to the neutrino sample originate from the ambient radioactivity and the abundance of atmospheric muons (cosmogenic (β-n) emitters, fast neutron showers, and muons stopping and decaying inside the detector). This thesis focuses on developing techniques for measuring and reducing the Stopping Muon background. With colleagues from APC and MIT, a 60 litre neutron TPC was installed in both underground laboratories at Chooz. This low pressure He/CF4-based time projection chamber, called DCTPC, measures the flux, energy spectrum and direction of fast neutrons in both locations, with different overburdens (150 and 300 meters water equivalent for the Near and Far Laboratories respectively)
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41

Zenoni, Florian. "Study of Triple-GEM detectors for the CMS muon spectrometer upgrade at LHC and study of the forward-backward charge asymmetry for the search of extra neutral gauge bosons." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/229354.

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Cette thèse de doctorat a pour cadre l’expérience CMS auprès du grand collisionneur de protons du CERN, le LHC. Le LHC, qui a permis la découverte en 2012 du boson de Brout-Englert-Higgs, est destiné à fonctionner pour encore 20 ans, avec une luminosité qui croîtra progressivement pour atteindre d’ici 2025 la valeur de 7.5 x 10^34 cm^-2 s^-1, c'est à dire environ cinq fois la valeur initialement prévue. Ceci a pour conséquence que les expériences doivent s’adapter et mettre à niveau une série de leurs composants et détecteurs. Une des prochaines mises à niveau de l’expérience CMS concerne les détecteurs Triple Gas Electron Multiplier (GEM) qui sont actuellement en développement pour la partie avant du spectromètre à muons de l’expérience. Ces détecteurs seront installés dans CMS durant le deuxième long arrêt du LHC, en 2018-2019, appelé LS2. Cette mise à niveau a pour but de contrôler les taux de déclenchement d’événements pour la détection de muons, grâce à la haute performance de ces détecteurs Triple GEM en présence de taux de particules extrêmement élevés (>1 kHz/cm^2). De plus, grâce à sa très bonne résolution spatiale (~250 um), la technologie GEM peut améliorer la reconstruction des traces de muons et la capacité d’identification du détecteur avant.Le but de mon travail de recherche est d’estimer la sensitivité des Triple GEMs à l’environnement de radiation hostile dans CMS, essentiellement composé de neutrons et de photons produits lors des interactions entre les particules et les détecteurs constituant l’expérience CMS. L’estimation précise de cette sensitivité est très importante, car une sous-estimation pourrait avoir des effets désastreux pour l’efficacité des Triple GEMs une fois installés dans CMS. Pour valider mes simulations, j’ai également reproduit des résultats expérimentaux obtenus avec d’autres détecteurs similaires déjà installés dans CMS, tels que les Resistive Plate Chambers (RPC).La deuxième partie de mon travail concerne l’étude de la capacité de l’expérience CMS à discerner différents modèles de nouvelle physique prédisant l’existence de bosons vecteurs, appelés Z'. Ces modèles font partie des extensions plausibles du Modèle Standard. En particulier, l’analyse se concentre sur des simulations dans lesquelles le Z' se désintègre en deux muons, et sur l’impact que les mises à niveau avec les détecteurs Triple GEM apporteront à ces mesures tout le long de la phase de haute intensité du LHC. Mes simulations montrent que plus de 20% des événements simulés comptent au moins un muon dans la région en pseudo-rapidité (eta) de CMS couverte par les détecteurs Triple GEM. Les résultats préliminaires démontrent que, dans le case de modèles à 3 TeV/c^2, il sera possible dès la fin de la Phase I de distinguer un Z'I d'un Z'SSM avec un niveau de signification alpha > 3 sigma.
This PhD thesis takes place in the CMS experiment at CERN's Large Hadron Collider (LHC). The LHC allowed the discovery of the Brout-Englert-Higgs boson in 2012, and is designed to run for at least 20 years, with an increasing luminosity that will reach by 2025 a value of 7.5 x 10^34 cm^-2 s^-1, that is a yield five times greater than the one initially intended. As a consequence, the experiments must adapt and upgrade many of their components and particle detectors. One of the foreseen upgrades of the CMS experiment concerns the Triple Gas Electron Multiplier (GEM) detectors, currently in development for the forward muon spectrometer. These detectors will be installed in CMS during the second long LHC shutdown (LS2), in 2018-2019. The aim of this upgrade is to better control the event trigger rate at Level 1 for muon detection, thanks to the high performance of these Triple GEM detectors, in presence of very high particle rates (>1 kHz/cm^2). Moreover, thanks to its excellent spatial resolution (~250 um), the GEM technology can improve the muon track reconstruction and the identification capability of the forward detector.The goal of my research is to estimate the sensitivity of Triple GEMs to the hostile background radiation in CMS, essentially made of neutron and photons generated by the interaction between the particles and CMS detectors. The accurate evaluation of this sensitivity is very important, as an underestimation could have ruinous effects of the Triple GEMs efficiency, once they are installed in CMS. To validate my simulations, I have reproduced experimental results obtained with similar detectors already installed in CMS, such as the Resistive Plate Chambers (RPC).The second part of my work regards the study of the CMS experiment capability to discriminate between different models of new physics predicting the existence of neutral vector bosons called Z'. These models belong to plausible extensions of the Standard Model. In particular, the analysis is focused on simulated samples in which the Z' decays in two muons, and on the impact that the Triple GEM detectors upgrades will bring to these measurements during the high luminosity phase of the LHC, called Phase II. My simulations prove that more than 20% of the simulated events see at least one muon in the CMS pseudo-rapidity (eta) region covered by Triple GEM detectors. Preliminary results show that, in the case of 3 TeV/c^2 models, it will be possible already at the end of Phase I to discriminate a Z'I from a Z'SSM with a significance level alpha > 3 sigma.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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42

Güth, Andreas [Verfasser], Thomas [Akademischer Betreuer] Hebbeker, and Michael [Akademischer Betreuer] Krämer. "Searches for charged lepton flavour violation involving final states with an electron / muon pair in pp collisions at the CMS detector / Andreas Güth ; Thomas Hebbeker, Michael Krämer." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/116965763X/34.

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43

UROS, CORRALES VICTOR. "Experience nomad de recherche d'oscillations neutrino muon a neutrino tau : etude de la radiation de photons reels durs dans la diffusion par courant charge neutrino electron-nucleon." Paris 6, 1995. http://www.theses.fr/1995PA066223.

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Nomad est une experience de recherche d'oscillation entre le neutrino muon et le neutrino tau aupres d'un accelerateur (sps au cern). Pour l'identification des interactions par courant charge du neutrino tau on utilise des criteres purement cinematiques. Parmi les canaux de desintegration du tau le canal en electron est l'un des plus sensibles. Dans cette these on etudie en detail l'une des sources de bruit de fond potentielles dans ce canal, a savoir, la diffusion par courant charge des neutrinos electron avec emission d'un photon dur. Notre travail nous a amenes, d'abord, a calculer la section efficace radiative, et ensuite, a developper un generateur d'evenements radiatifs. Cela nous a permis d'etudier la cinematique de ces evenements, de montrer leur specificite par rapport au bremsstrahlung de l'electron dans la cible, et, finalement, d'estimer le bruit de fond recherche. Les resultats de notre analyse montrent que cette nouvelle source de bruit de fond est peu importante par rapport aux sources deja etudiees (elle contribue dans une proportion de l'ordre de 10% du fond total). Nous avons remarque que le bruit de fond du a la production directe d'electrons par la diffusion par courant charge des neutrino electron est produit a un transfert d'impulsion inferieur a 4 gev#2. Notre generateur, qui utilise le modele des partrons, n'est pas l'outil adequat pour simuler cette physique a des valeurs si faibles du transfert. Un generateur specifique se revele necessaire et est a l'etude dans le cadre de la collaboration
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44

Nowak, Sebastian [Verfasser], Hubert [Akademischer Betreuer] Kroha, and Lothar [Akademischer Betreuer] Oberauer. "Studies of Read-Out Electronics and Trigger for Muon Drift Tube Detectors at High Luminosities / Sebastian Nowak. Gutachter: Lothar Oberauer ; Hubert Kroha. Betreuer: Hubert Kroha." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/107499955X/34.

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45

Schmidt-Sommerfeld, Korbinian Ralf [Verfasser], Hubert [Akademischer Betreuer] Kroha, Hubert [Gutachter] Kroha, and Lothar [Gutachter] Oberauer. "Study of Muon Drift Tube Detectors and Fast Readout Electronics for Very High Counting Rates / Korbinian Ralf Schmidt-Sommerfeld ; Gutachter: Hubert Kroha, Lothar Oberauer ; Betreuer: Hubert Kroha." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1206687541/34.

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46

Goltz, Til. "On the electronic phase diagram of Ba1-xKx(Fe1-yCoy)2As2 and EuFe2(As1-xPx)2 superconductors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-192059.

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In this thesis, I study the electronic and structural phase diagrams of the superconducting 122 iron pnictides systems Ba1-xKx(Fe1-yCoy)2As2 and EuFe2(As1-xPx)2 by means of the local probe techniques 57Fe Mössbauer spectroscopy (MS) and muon spin relaxation (muSR). For both isovalent substitution strategies - Co/K for Fe/Ba and P for As, respectively - the antiferromagnetic Fe ordering and orthorhombic distortion of the parent compounds BaFe2As2 and EuFe2As2 are subsequently suppressed with increasing chemical substitution and superconductivity arises, once long-range and coherent Fe magnetic order is sufficiently but not entirely suppressed. For Ba1-xKx(Fe1-yCoy)2As2 in the charge compensated state (x/2=y), a remarkably similar suppression of both, the orthorhombic distortion and Fe magnetic ordering, as a function of increasing substitution is observed and a linear relationship between the structural and the magnetic order parameter is found. Superconductivity is evidenced at intermediate substitution with a maximum Tsc of 15 K coexisting with static magnetic order on a microscopic length scale. The appearance of superconductivity within the antiferromagnetic state can by explained by the introduction of disorder due to nonmagnetic impurities to a system with a constant charge carrier density. Within this model, the experimental findings are compatible with the predicted s± pairing symmetry. For EuFe2(As1-xPx)2, the results from 57Fe MS and ZF-muSR reveal an intriguing interplay of the local Eu 2+ magnetic moments and the itinerant magnetic Fe moments due to the competing structures of the iron and europium magnetic subsystems. For the investigated single crystals with x=0.19 and 0.28, 57Fe MS evidences the interplay of Fe and Eu magnetism by the observation of a transferred hyperfine field below Tafm at which the Eu subsystem orders into a canted A-type AFM magnetic structure. Furthermore, an additional temperature dependent out-of-plane tilting of the static Fe hyperfine field is observed below the onset of static Eu ordering. ZF-muSR shows a strong increase of the local field at the muon site below Tafm=20 K and a crossover from isotropic to anisotropic Eu spin-dynamics between 30 and 10 K. The temperature dependence of the spin dynamics, as derived from the muSR dynamic relaxation rates, are related to a critical slowing down of Eu-spin fluctuations which extends to even much higher temperatures (~100 K). They also effect the experimental linewidth observed in the 57Fe MS experiments. The strong influence of the Eu magnetic order onto the primary observables in both methods prevents conclusive interpretation of the experimental data with respect to a putative interplay of Fe magnetism and superconductivity.
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47

Martschei, Daniel Michael [Verfasser], and M. [Akademischer Betreuer] Feindt. "Measurement of the t-channel single top quark production cross section in the electron and muon decay channel with the CMS detector at the LHC / Daniel Michael Martschei. Betreuer: M. Feindt." Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1024729516/34.

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48

Nibigira, Emery. "Recherche d'un nouveau boson massif W' se désintégrant en un quark top et un quark b avec le détecteur ATLAS au LHC." Thesis, Université Clermont Auvergne‎ (2017-2020), 2019. http://www.theses.fr/2019CLFAC070.

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Le principal sujet de cette thèse porte sur la recherche d'un boson d'interaction chargé, noté W', se désintégrant en un quark top et un quark b dans un état final avec un lepton chargé, un neutrino et deux quarks b. Cette recherche est effectuée avec les données de collision proton-proton, produites par le LHC à une énergie au centre de masse de √13=TeV collectées avec le détecteur ATLAS, correspondant à une luminosité intégrée de 36.1 fb⁻¹. L'analyse des données couvre une gamme de masse allant de 0.5 à 5.0 TeV pour des bosons W' se couplant à des fermions de chiralité droite, les bosons W'_R. Les résultats obtenus montrent un bon accord entre les données observées et les bruits de fond estimés et ne permettent donc pas de déceler l'existence d'un boson W'. Des limites d'exclusion sont placées sur la section efficace σ(pp→W') multipliée par le taux d'embranchement B(W'→t ̄b) et sur le couplage effectif du boson W' aux fermions en fonction de sa masse. Pour un couplage effectif égal à la constante de couplage du Modèle Standard, les bosons W'_R avec des masses inférieures à 3.15 TeV sont exclus à 95% de niveau de confiance. Cette recherche est également combinée avec un résultat précédemment publié par ATLAS pour un boson W'→t ̄b dans l'état final hadronique. En utilisant les recherches combinées, les bosons W'_R avec des masses inférieures à 3.25 TeV sont exclus. Cette thèse décrit également le travail effectué pour intégrer dans le code de simulation d'ATLAS le traitement de signal effectué par une carte électronique appelée FATALIC. FATALIC a été conçue et développée au Laboratoire de Physique de Clermont-Ferrand (LPC) pour la lecture des signaux du calorimètre hadronique (TileCal) pour la future phase d'exploitation du LHC à haute luminosité appelée HL-LHC. En tenant compte du bruit de l'électronique attendu, les performances obtenues sur la mesure de l'énergie sont présentées pour deux positions dans le calorimètre et pour différentes valeurs du bruit d'empilement. calorimètre lorsque l'empilement passe de 30 à 200
The main goal of this thesis is the search for new charged massive gauge bosons, W', that decay to a top quark and a bottom quark leading to a final state with a charged lepton, neutrino, and two b quarks. The search is performed with the ATLAS detector at the LHC using data collected in proton–proton collisions at a centre-of-mass energy of √13=TeV and corresponding to an integrated luminosity of 36.1 fb⁻¹. This analysis covers resonance masses between 0.5 and 5.0 TeV and considers right-handed W' bosons, W'_R. No significant deviation from the Standard Model expectation is observed and upper limits are set on the W′→t ̄b cross section times branching ratio and the W' boson effective couplings as a function of the W' boson mass. W'_R bosons with coupling equal to the Standard Model weak coupling constant. Masses below 3.15 TeV are excluded at the 95% confidence level. This search is also combined with that for W'→t ̄b in the fully hadronic final state. Using the combined searches, right-handed W' bosons with masses below 3.25 TeV are excluded at the 95% confidence level. This thesis includes also the work carried out to integrate into the ATLAS simulation code the signal processing of the hadronic Calorimeter (TileCal) front-end readout called FATALIC. FATALIC was developed at Laboratoire de Physique de Clermont-Ferrand (LPC) and proposed for the High Luminosity (HL) phase LHC upgrade. Taking into account the expected electronic noise, the performances obtained on the energy measurement are presented for two relevant cells and for different values of pileup noise
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Manfredini, Alessandro [Verfasser], Hubert [Akademischer Betreuer] Kroha, and Lothar [Akademischer Betreuer] Oberauer. "Search for Neutral MSSM Higgs Bosons in A/h/H → Tau+ Tau- → Electron and Muon + 4 Neutrino Decays with the ATLAS Detector / Alessandro Manfredini. Gutachter: Lothar Oberauer ; Hubert Kroha. Betreuer: Hubert Kroha." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1055039899/34.

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Kamusella, Sirko [Verfasser], Hans-Henning [Akademischer Betreuer] [Gutachter] Klauß, and Vadim [Gutachter] Ksenofontov. "Electronic phase diagrams and competing ground states of complex iron pnictides and chalcogenides : A Mössbauer spectroscopy and muon spin rotation/relaxation study / Sirko Kamusella ; Gutachter: Hans-Henning Klauß, Vadim Ksenofontov ; Betreuer: Hans-Henning Klauß." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/112910513X/34.

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