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1
Zhang, Ruiqi. « Search for the W ± W ± W ∓ production and the doubly charged higgs with the Atlas detector ». Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0434/document.
Texte intégralRésumé :
L’expérience ATLAS (A Toroidal LHC Apparatus), collaboration de plus de 3000 scientifiques dans le monde, mène des recherches auprès du grand collisionneur de hadron (LHC). Celui-ci a produit des collisions de faisceaux de protons à une énergie dans le centre de masse de 7 TeV en 2011 et 8 TeV en 2012, période appelée Run1 et représentant 20.3 fb−1 de luminosité intégrée, puis en 2015 et 2016 à 13 TeV pour le Run 2 avec 36.1 fb−1. Le détecteur généraliste ATLAS a un riche potentiel de mesures précises du Modèle Standard (SM) et de recherche de phénomènes de nouvel physique. Deux analyses de physiques sont ici présentées. La première consiste à rechercher dans les données Run 1 la production de tri-bosons, W±W±W∓, se désintégrant totalement ou partiellement en leptons et à étudier le couplage de jauge quartique anormal (aQGC). Le nombre d’événements observés est en accord avec les prédictions du SM. La limite supérieure observée à 95% CL sur la section efficace W±W±W∓ SM est de 730 fb avec une limite attendue de 560 fb en l’absence de production W±W±W∓. La deuxième analyse présentée est la recherche du boson de Higgs doublement chargé effectuée sur les données du Run 2. Ce boson est prédit par un modèle qui prolonge le SM pour permettre des neutrinos massif. Ce modèle introduit plusieurs bosons de Higgs dont l'un est le H±±. Le cas où ce dernier se désintègre en bosons W avec un état final à deux leptons de même charge est plus particulièrement étudié. Le bruit de fond total estimé est en accord avec les données et aucun excès significatif n’est observé. Des limites supérieures sont déduites et le modèle considéré est exclus à 95% CL pour MH±± < 220 GeVThe ATLAS (A Toroidal LHC Apparatus) experiment, a collaboration of more than 3,000 scientists worldwide, is conducting research at the Large Hadron Collider (LHC). It produced proton beam collisions at an energy in the center of mass of 7 TeV in 2011 and 8 TeV in 2012, period called Run1 and representing 20.3 fb-1 of integrated luminosity, then in 2015 and 2016 at 13 TeV for Run 2 with 36.1 fb-1. The ATLAS general purpose detector has a rich potential for accurate Standard Model (SM) measurements and the search for new physics phenomena. Two physics analyzes are presented here. The first is to search the Run 1 data for tri-bosons production, W ± W ± W∓, totally or partially decayed into leptons and to study abnormal quartic gauge coupling (aQGC). The number of observed events is consistent with the SM predictions. The observed upper limit at 95% CL on the W ± W ± W∓ SM cross section is 730 fb with an expected limit of 560 fb in the absence of W ± W ± W∓ production. The second analysis presented is the search for the doubly charged Higgs boson carried out on the Run 2 data. This boson is predicted by a model that extends the SM to allow massive neutrinos. This model introduces several Higgs bosons, one of which is the H ±±. The case where this latter decays in bosons W with a final state with two leptons of the same charge is more particularly studied. The estimated total background is in agreement with the data and no significant excess is observed. Upper limits are deduced and the model considered is excluded at 95% CL for MH ±± <220 GeV
2
Peter, Denise. « W.B. Yeats' Four Plays for Dancers : the search for unity ». Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23732.
Texte intégralRésumé :
This thesis proposes that Yeats found in certain conventions of the Noh drama a realization and defense of his idea of unity of culture, which his Noh-like Four Plays for Dancers illustrates. Yeats' use of recurrent imagery in the dance plays expresses his belief in a unity of culture defined and evoked by an image and stems in part from the pattern of images he discovered in the Pound-Fenollosa translations of the Noh. The imagery of the poetic text reappears in symbolic visual designs or is coordinated with music and dance in the production of the plays. The importance of the spoken word above all determined the basis of the association of arts with which Yeats characterized unity of culture and shaped his adaptation and occasional misconception of the staging techniques of the Noh. A common love of vivid, allusive words joined the audience for whom the dance plays were written. When Yeats stated that they were modelled on the audience of the Noh, his perception was colored, as usual, by his own priorities and experience.
3
Dahlberg, Erik. « Search for VBF Standard Model Higgs boson production in the H → W W (∗) decay channelusing boosted decision trees ». Thesis, KTH, Fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123591.
Texte intégral
4
BRIANZA, LUCA. « Search for heavy resonances decaying to VW in the semi-leptonic final state with the CMS detector ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2017. http://hdl.handle.net/10281/158141.
Texte intégralRésumé :
Il lavoro si concentra sulla ricerca di risonanze pesanti che decadono in uno stato finale VW, dove V denota un bosone W o Z, usando i dati raccolti dall'esperimento CMS situato al Large Hadron Collider (LHC). Lo stato finale analizzato è il canale semi-leptonico, dove il bosone W decade in una coppia leptone-neutrino mentre il bosone V decade in una coppia di quark.This work focuses on the search for heavy resonances decaying into a VW final state, where V denotes either a W or a Z boson, using the data collected by the CMS experiment located at the Large Hadron Collider (LHC). The investigated final state is the semi-leptonic channel, where the W boson decays into a lepton-neutrino pair while the V boson decays into a pair of quarks.
5
Hardy, Kenderick. « K-nowhere to run, no w-here to Hide : A Search for Innocence ». The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1391686650.
Texte intégral
6
Volken, Werner. « Strangelet search in S - W collisions at 200 · A GeV/c per nucleon / ». [S.l.] : [s.n.], 1994. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Texte intégral
7
Ruan, Xifeng. « Search for Higgs boson in the WW* channel in ATLAS and drift time measurement in the liquid argon calorimeter in ATLAS ». Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112236/document.
Texte intégralRésumé :
Une recherche du boson de Higgs est effectuée dans le canal WW → lνlν en utilisant l’ensemble des données de 2011 à une énergie dans le centre de masse de √s = 7 TeV et une partie des données de 2012 à 8 TeV prises par l’expérience ATLAS auprès du LHC. Les luminosités intégrées correspondantes sont 4.7 fb−1 et 5.8 fb−1, respectivement. L’analyse est effectuée avec des coupures. Plusieurs méthodes sont introduites pour estimer à partir des données la contribution de bruits de fond des différents processus afin de minimiser l’utilisation de simulation. Pour la contribution du bruit de fond top dans le canal dominant avec zéro jet, elle est estimée avec une méthode que nous avons proposée. Une autre méthode pour corriger la forme de la distribution de l’énergie transverse manquante dans les événements Drell-Yan à partir des événements W +jets est également présentée. En 2011, le boson de Higgs du modèle standard avec la masse du Higgs de 133 à 261 GeV est exclue à 95% de niveau de confiance, tandis que la plage d’exclusion prévue est de 127 à 234 GeV. En 2012, un excès d’événements au-dessus du bruit de fond attendu est observé dans une plage de masse autour de 125GeV. En combinant les deux échantillons, la probabilité minimale (“p-value”) pour que l’hypothèse bruit de fond seul fournisse autant ou plus d’événements qu’observé dans les données est de 3 × 10−3, ce qui correspond à une signifiance statistique de 2,8 écarts types. Le taux de production mesuré du signal par rapport au taux prédit pour le boson de Higgs du modèle standard à mH = 125GeV est de 1,4 ± 0,5. La probabilité attendue pour un Higgs avec mH = 125GeV est de 0,01, soit de 2,3 écarts types. La limite d’exclusion d’un Higgs dans un modèle avec une quatrième génération est également présentée en utilisant une partie de l’échantillon de données 2011, la gamme de masse entre 120 GeV et 600 GeV a été exclue à 95% de niveau de confiance. Enfin, l’étude sur le temps de dérive dans le calorimètre à argon liquide du détecteur ATLAS est effectuée en utilisant tous les échantillons de données du rayonnement cosmique, du faisceau splash et de collision. Les résultats ne montrent aucune non-uniformité significative sur la largeur de l’espace cellulaire mis à part un effet de “sagging” dans les régions de transition dû au poids du calorimètreA Higgs search is performed in the WW → lνlν channel using the full 2011 data at a center-of-mass energy of √s = 7 TeV and part of 2012 data at 8 TeV taken by the ATLAS experiment at the LHC. The corresponding integrated luminosity values are 4.7fb−1 and 5.8fb−1, respectively. The cut based analysis is performed and several data-driven methods for background estimation are introduced. The jet veto survival probability method for top background estimation in 0-jet bin is proposed and used in the Higgs search. Another data-driven method to correct the shape of the missing transverse energy distribution in the Drell-Yan process is also presented. In 2011, the standard model Higgs boson with the Higgs mass from 133 to 261 GeV is excluded at 95% CL, while the expected exclusion range is 127 − 234 GeV. In 2012, an excess of events over expected background is observed at mH = 125GeV. Combining the both samples, the minimum observed p0 value is 3 × 10−3, corresponding to 2.8 standard deviations. The fitted signal strength at mH = 125 GeV is μ = 1.4 ± 0.5. The expected p0 for a Higgs with mH = 125 GeV is 0.01, or 2.3 standard deviations. The exclusion limit for a Higgs in a fourth generation model is shown using part of the 2011 data sample, the mass range between 120GeV and 600GeV has been excluded at 95%CL. The study on the drift time in the liquid argon calorimeter in ALTAS is performed using all special data samples from cosmic muon, beam splash and beam collision data. The results show no significant non-uniformity on the cell gap width and a sagging effect due to gravity is observed
8
Tannenwald, Benjamin. « Measurement of W-Helicity Fractions in tt¯ decays and Search for Exotic Dihiggs Production in the bb¯W W * Decay Channel Using the ATLAS Detector ». The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500547038919569.
Texte intégral
9
Ruckert, Benjamin. « Search for a Higgs Boson Produced in Association with a W Boson at ATLAS ». Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-108382.
Texte intégral
10
Xie, Si Ph D. Massachusetts Institute of Technology. « Search for the Standard Model Higgs boson decaying to two W bosons at CMS ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77499.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 255-264).
In this thesis, we search for the production of the Standard Model Higgs boson at the Large Hadron Collider, through its decay mode to two W bosons, which each in turn decay into a charged lepton and a neutrino. The Higgs boson is the only elementary particle predicted by the Standard Model of particle physics which has not yet been experimentally observed. The question of its existence has been the subject of a wide body of experimental and theoretical work for the past half-century. Using 4.9 fb-1 of integrated luminosity, this search is expected, on average, to exclude the Standard Model predicted Higgs boson production cross section for masses between 126 GeV/c 2 and 260 GeV/c 2 under the background-only hypothesis. We observe no statistically significant excesses in the data, and we exclude the Standard Model Higgs boson production for masses between 129 GeV/c 2 and 260 GeV/c 2 . This result represents a significant reduction of the mass region in which the Standard Model Higgs boson is allowed to exist.
by Si Xie.
Ph.D.
11
Bernard, Jürgen Verfasser], Dieter W. [Akademischer Betreuer] [Fellner et Tobias [Akademischer Betreuer] Schreck. « Exploratory search in time-oriented primary data / Jürgen Bernard. Betreuer : Dieter W. Fellner ; Tobias Schreck ». Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://d-nb.info/1112268898/34.
Texte intégral
12
Bernard, Jürgen [Verfasser], Dieter W. [Akademischer Betreuer] Fellner et Tobias [Akademischer Betreuer] Schreck. « Exploratory search in time-oriented primary data / Jürgen Bernard. Betreuer : Dieter W. Fellner ; Tobias Schreck ». Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-51739.
Texte intégral
13
Slaunwhite, Jason M. « Search for the Higgs Boson Produced in Association with a W Boson at CDF Run II ». The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1232121462.
Texte intégral
14
Schwoebel, Michelle. « In Search of Real Fathers : Plenzdorf's Die neuen Leiden des jungen W. and Vater, Mutter, Mörderkind ». BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3544.
Texte intégralRésumé :
Plenzdorf's works, one written before the fall of socialism in the German Democratic Republic (hereafter referred to as the DDR), and one after, portray relationships between fathers and sons, which act as a metaphor to express a personal perspective of the state, revealing that the DDR was neither as repressive or as omnipresent for the average citizen as outsiders are often given to believe. The father, or Übervater, a figure deeply rooted in the German consciousness, is represented by the state and proves itself as an entity which gives the protagonists in both works little notice, despite their best efforts to seek out a paternalistic presence.
15
Biebel, Jochen. « Predictions for the Search for AnomalousCouplings of Gauge Bosons and Leptons ine^+e^- - scattering ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2001. http://dx.doi.org/10.18452/14588.
Texte intégralRésumé :
Die Auswirkungen von anomalen Kopplungen bei den Prozessen der W-Paar- und der ZZ-Erzeugung werden untersucht. Analytische Ausdruecke fuer die differentiellen Wirkungsquerschnitte werden fuer beide Prozesse abgeleitet und numerische Ergebnisse werden praesentiert. Die analytischen Ergebnisse zur W-Paarerzeugung wurden in das Fortranprogramm GENTLE eingebaut, waehrend die Ergebnisse zur ZZ-Erzeugung in einem separaten Program ZAC zur Verfuegung stehen. Die numerischen Resultate werden mit den Vorhersagen des Standardmodells verglichen. Bei der W-Paarerzeugung sind Strahlungskorrekturen durch den Strukturfunktionszugang im Rahmen der Anfangszustandsabstrahlung beruecksichtig worden. Die Auswirkungen eines anomalen magnetischen Momentes a_tau des tau-Leptons auf die Endzustandsabstrahlung im Prozess der tau-Paarproduktion bei LEP1 wurden untersucht. Dieser Prozess erlaubt die Bestimmung des experimentellen Limits fuer das anomale magnetische Moment a_tau. Als ein Ergebnis erhalten wir, dass Beitraege, die linear in a_tau sind und als klein angesehen wurden, bei den heutigen Limits nicht mehr vernachlaessigt werden koennen.Predictions are made for the effects of anomalous couplings in the processes of W-pair and ZZ production. Analytical expressions for the differential cross-sections are derived in both cases and numerical results are presented. The analytical results for W-pair production were implemented into the Fortran program GENTLE, while the ZZ production results are available in the stand-alone program ZAC. The numerical results are compared with the Standard Model predictions. For W-pair production radiative corrections are considered by using the structure function approach for the description of initial state radiation. Effects of an anomalous magnetic moment a_tau of the tau-lepton to the final state radiation in the process of tau-pair production at LEP1 are examined. This process allows to determine experimental limits for the anomalous magnetic moment of the tau. As a result we find that contributions linear in a_tau, which were believed to be small, cannot be neglegted at the present limits.
16
Olofsson, Kristin. « Pa(w)ticipatory design – Designing mediated wearable interaction between an air-scent search dog and a human ». Thesis, Södertörns högskola, Medieteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-38186.
Texte intégralRésumé :
Designing for and with animals is common within Animal-Computer Interaction (ACI). However, studies involving animals within the design process has challenges due to verbal barriers, and an unclear methodology on how to both understand, and analyse animals in ACI. This paper explores how an air-scent search dog can participate in the design process from the beginning to end involved in various design methods with a Participatory design (PD) approach, to empower the relationship between human and dog with the help of wearable technology. The study explores the benefits and challenges of the involvement of other species than humans in the process of making a prototype. Furthermore, two types of tools with biting and pulling interactions attached to a vest were developed and tested on an air-scent search dog in two different environments. Due to the verbal barrier between dogs and humans, it was necessary to let the dog participate by testing physical prototypes. This study aims to empower this relationship between an air-scent search dog and its handler with the help of wearable technology. The results suggest that direct contact with the other species is crucial in the creation and iteration of prototypes regarding; weight, placement, and wearable technology. The results also showed that in the context of search training, or situated based action, it is crucial to test the prototypes in an environment that reflects a real scenario in a forest, which is a typical place for search training.
17
Chow, Bonnie Kar Bo. « Search for Higgs boson decays in the H-> ; W+W- ->lvlv channel via vector boson fusion with the ATLAS detector at the LHC ». Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-177305.
Texte intégral
18
Rich, Philip. « Search for the Standard Model Higgs Boson in the W H -> ; tvbb channel with the D0 Detector ». Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508548.
Texte intégral
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Terpstra, Wesley W. [Verfasser], Alejandro [Akademischer Betreuer] Buchmann, Jussi [Akademischer Betreuer] Kangasharju et Ken [Akademischer Betreuer] Moody. « BubbleStorm : Rendezvous Theory in Unstructured Peer-to-Peer Search / Wesley W. Terpstra. Betreuer : Alejandro Buchmann ; Jussi Kangasharju ; Ken Moody ». Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://d-nb.info/1111910472/34.
Texte intégral
20
Andrean, Stefio Yosse. « Search for Stop Using the ATLAS Detector and Performance Analysis of the Tile Calorimeter with Muons from W Decays ». Licentiate thesis, Stockholms universitet, Fysikum, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-191555.
Texte intégralRésumé :
This thesis presents a search for the supersymmetric partner of the top quark in the final state with one lepton. The search focuses especially in the region of the parameter space where the 2-body decay dominates. The analysis is performed using LHC full Run 2 data at √s = 13 TeV as recorded by the ATLAS detector. No significant excess above the backgrounds is observed, and 95% confidence level exclusion limits are calculated in the stop-neutralino mass plane. Stops are excluded up to 1200 GeV in the low neutralino mass scenario of below 400 GeV. The Tile Calorimeter is part of the ATLAS calorimeter system whose main task is to measure the energy of hadrons. A performance study is conducted on the Tile Calorimeter using muons from W boson decay originating from proton-proton collisions. Each calorimeter cell response is measure in data and compared with detector simulation. The azimuthal cell response uniformity is also investigated using a likelihood method. Overall, a good data to detector simulation agreement and azimuthal uniformity is observed which shows well-calibrated cells and uniform responses among the calorimeter modules.
21
Kövesárki, Peter [Verfasser]. « Multivariate methods and the search for single top-quark production in association with a W boson in ATLAS / Peter Kövesárki ». Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1044970855/34.
Texte intégral
22
Zeißler, Stefan [Verfasser], et W. de [Akademischer Betreuer] Boer. « Search for anisotropies in the arrival directions of charged cosmic rays with AMS-02 / Stefan Zeißler ; Betreuer : W. de Boer ». Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1156327792/34.
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23
Bristow, Timothy Michael. « Search for the Higgs boson decaying to bottom quarks and W boson tagging techniques at the ATLAS experiment at the LHC ». Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25393.
Texte intégralRésumé :
The Standard Model of particle physics is currently the most complete theory of subatomic particles. The discovery of the Higgs boson with a mass of 125 GeV in 2012 further validated the Standard Model, providing evidence for the theory that vector bosons obtain non-zero masses through the Higgs mechanism. Studies are ongoing to determine the exact nature and properties of the Higgs boson. A Higgs boson of this mass is predicted to decay to a pair of b-b quarks with a branching ratio of 58%, however this decay mode has not yet been observed. This thesis presents a search for the associated production of a Higgs boson with a leptonically decaying W boson, WH → ℓvb-b, using 20.3 fb-1 of Run 1 data collected by ATLAS at the LHC from pp collisions at a centre-of-mass energy of ps = 8 TeV. The observed (expected) significance of a Higgs boson with a mass of 125 GeV for the WH → ℓvb-b process is found to be 2:7σ (1:3σ). The measured cross section in units of the expected Standard Model cross section has a best-fit value of μ = μ/μSM = 2:2+0:67-0:64(stat:)+0:7-0:59(syst:) = 2:2+0:97-0:87. The results are combined with the search for ZH → v-vb-b and ZH → ℓ+ℓ-b-b to provide a best-fit value of μ = μ/μSM = 1:1+0:61-0:56. The start of Run 2 of the LHC in 2015 saw the collision energy being raised to √s = 13 TeV, increasing the probability of particles being produced with a large momentum boost. At these high energies there is also a possibility to discover new particles and interactions. An extension of the Standard Model, the Heavy Vector Triplet (HVT) model, describes new heavy vector bosons W¹ and Z¹, which can decay to pairs of heavy bosons (W, Z or Higgs bosons). If the W0 and Z0 bosons are sufficiently heavy, the hadronic decays of the diboson final states produce boosted jets. In this thesis, methods for identifying hadronically decaying boosted bosons are developed, based on techniques that examine the internal substructure of the jet. Multiple substructure variables are combined into a single discriminant using two machine learning techniques: boosted decision trees and deep neural networks. Simulated events of W¹→WZ → q-qq-q are used to develop these boosted W boson taggers. An improvement in the background rejection power, whilst keeping 50% of the signal, over previous boosted W boson taggers of up to 13%-when using deep neural networks-and 36%-when using boosted decision trees-is obtained. The performance of the new boosted W boson taggers are evaluated in a search for a narrow WW resonances from the decay of a Z¹ with boson-tagged jets in 3.2 fb-1 of pp collisions at √s = 13 TeV collected with the ATLAS detector.
24
Chow, Bonnie Kar Bo [Verfasser], et Johannes [Akademischer Betreuer] Elmsheuser. « Search for Higgs boson decays in the H→ W+W- →lvlv channel via vector boson fusion with the ATLAS detector at the LHC / Bonnie Kar Bo Chow. Betreuer : Johannes Elmsheuser ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1063875366/34.
Texte intégral
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Javůrek, Tomáš [Verfasser], et Gregor [Akademischer Betreuer] Herten. « Search for squarks and gluinos in final state with jets, missing transverse momentum and boosted W bosons with the ATLAS experiment ». Freiburg : Universität, 2016. http://d-nb.info/1122743084/34.
Texte intégral
26
Boddy, Christopher. « A search for the Standard Model Higgs boson via its decay to tau leptons and W bosons at the ATLAS detector ». Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:abba39e7-4de1-46c5-a533-7b677ae254f2.
Texte intégralRésumé :
Understanding the origin or Electroweak symmetry breaking within the Standard Model was a key motivation for the construction of the Large Hadron Collider (LHC) experiment at CERN. This thesis presents a search for evidence of Higgs boson production in the 4.7 fb−1 of collision data recorded at a centre-of-mass energy of 7 TeV at the ATLAS detector during 2011. This search is focused on signal events in which a Higgs boson is produced in the mass range 100 < mH < 180 GeV/c2 and subsequently decays to a pair of W bosons or a pair of tau leptons to final states with one hadronically decaying tau lepton and one light lepton. After an event selection criteria has been applied, the number of events in this data sample is consistent with the total background estimate and an upper limit is placed on the SM Higgs boson production rate at 95% confidence level. In addition, the prospects for measuring the SM Higgs coupling strength to tau leptons with the associated Higgs production channels and the full LHC dataset are also presented.
27
Venturi, Manuela [Verfasser], et Karl [Akademischer Betreuer] Jakobs. « Search for the Standard Model Higgs boson in the H → W^+ W^− → ℓ^+ ν ℓ^− ν̄ final state with the ATLAS experiment and study of its spin and parity quantum numbers ». Freiburg : Universität, 2016. http://d-nb.info/1119806003/34.
Texte intégral
28
González, Parra Garoé. « Search for the SM Higgs boson in the (W/Z)H channel with H → bb using the ATLAS detector at the LHC ». Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/288276.
Texte intégralRésumé :
Esta tesis presenta los últimos resultados de ATLAS en la búsqueda del bosón de
Higgs del Modelo Estándar (SM) en su decaimiento a un par de quarks-b. La
búsqueda del bosón de Higgs se realiza en los canales de producción asociados
con un bosón vectorial W o Z en el estado final. Ésta incluye el decaimiento
leptónico (electrón y muón) del bosón vectorial además del canal en el que el
bosón Z decae a un par de neutrinos. En particular, este documento se centra en
el canal ZH (Z → νν and H → bb). El análisis utiliza todos los datos generados por
colisiones de protones en el experimento ATLAS a √s = 7TeV y √s = 8 TeV.
El análisis se basa en una compleja caracterización de eventos en función del
modo de decaimiento del bosón vectorial, el número de jets y de b-jets en el
estado final, y el momento transverso del bosón vectorial. Esto permite hacer un
estudio detallado de los principales procesos de fondo. Dos enfoques diferentes se
consideran para el análisis: la utilización de la distribución de mbb como variable
principal de discriminación o el uso de una técnica multivariante de redes
neuronales.
El análisis utiliza una compleja estrategia de ajuste de datos y predicciones de
fondo en regiones de control y señal que posibilita constreñir los procesos de
fondo, reducir las incertidumbres sistemáticas e incrementar la sensibilidad a la
señal del Higgs. El proceso se valida con la búsqueda del proceso conocido de
dos bosones (diboson) (W/Z)Z (Z →bb) de estado final similar. La señal de
diboson se observa claramente con una significación estadística de 4.9σ. La
fuerza de la señal observada (comparada con la del SM) es de μVZ=
0.74±0.09(stat)±0.14(sys), compatible con la predicción del SM.
La distribución de la variable resultante del algoritmo multivariante para cada
categoría del análisis se compara con las distribuciones de la señal y el fondo
esperados, observándose un exceso de eventos para una masa del bosón de
Higgs mH de 125GeV. La significación estadística observada (esperada) de este
exceso es de 1.4σ (2.6σ) y la proporción de la cantidad de señal medida
comparada con la esperada por el SM es de μ = 0.51 ± 0.31(stat) ± 0.24(syst).
Este resultado es consistente entre todos los canales y compatible con los
obtenidos por el análisis que usa la distribución mbb como principal variable
discriminante. Aunque se haya observado un exceso de eventos, su significación
estadística no es suficientemente alta como confirmar una observación o un
descubrimiento del proceso.This thesis presents the latest ATLAS results on the search for the Standard Model (SM) Higgs boson decaying into a pair of b-quarks. The Higgs boson is searched for in the production channel for which the Higgs is produced in association with a W or Z boson in the final state. This includes the leptonic (electron and muon) decay channels for the vector bosons in addition to the channel with Z decaying into a pair of neutrinos. In particular, this document is mostly focused on the ZH (Z → νν and H → bb) channel. The analysis has considered all the proton-proton collision data collected by the ATLAS experiment at √s = 7 TeV and √s = 8 TeV. The analysis is based on a characterization of the events according to the vector boson decay, the number of jets and b-jets in the final state, and the vector boson transverse momentum. This permits a detail study of the main background processes. Two different approaches are considered for the analysis: using the mbb distribution as main discriminating variable or using a neural-net multivariate technique. The analysis involves a complex fitting strategy of data and background predictions in control and signal regions that contributes to constrain the background processes, to reduce the systematic uncertainties, and to increase the sensitivity to the Higgs signal. The whole procedure is validated by searching for the known diboson (W/Z)Z (Z →bb) process with similar final state. The diboson signal is clearly observed with a significance of 4.9σ. Its observed strength (compared to that of the SM) is μVZ= 0.74±0.09(stat.)±0.14(syst.), in agreement with the SM prediction. The measured output distributions of the multivariate algorithm in each event category are compared with the expected signal and background distributions and an excess of events above the expected background is observed at a Higgs mass mH of 125GeV. The observed (expected) significance of this excess is 1.4σ (2.6σ) and the ratio of the measured signal yield to the Standard Model expectation is found to be μ = 0.51 ± 0.31(stat) ± 0.24(syst). These results are consistent among channels and in agreement with those obtained with the analysis that uses mbb distributions as the main discriminating variable. Although an excess is observed, its statistical significance is not large enough to claim neither evidence nor discovery of the process.
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DE, GUIO FEDERICO. « Search for a heavy gauge boson w' in the final state with electron and large missing energy in p-p collisions at sqrt(s) = 7 TeV ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/29499.
Texte intégralRésumé :
In this thesis work the search for a new heavy charged gauge boson, with 1.13 inverse femtobarn of data collected in 2011 with the CMS detector at the LHC, is performed accordingly to the Reference Model by Altarelli.
The Model is a generalization of the Left-Right-Symmetric Model where the gauge group of the Standard Model of elementary particles is enlarged in order to restore the Lagrangian left-right symmetry. As a consequence new heavy gauge bosons, W′ and Z′, come out as heavy partners of the Standard Model W and Z bosons. The W′ particle is searched for in the decay channel W′ → eν.
The electromagnetic calorimeter of CMS plays a central role in the analysis and its performances are discussed in detail together with methods to calibrate and monitor its response.
Since no excess with respect to the Standard Model background prediction were observed in the analyzed dataset, an upper limit on the W′ production cross section times branching fraction is set. The analysis result can be translated into a lower limit on the mass of the potential W′ of 2.15 TeV/c² at 95% CL.
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Schmidt, Evelyn [Verfasser], et Karl [Akademischer Betreuer] Jakobs. « Search for the Standard Model Higgs boson in the H → W+W- → l+νl-ν̄+decay mode in proton-proton collisions at √s=7 TeV and √s=8 TeV with the ATLAS experiment ». Freiburg : Universität, 2013. http://d-nb.info/1123475873/34.
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Fischer, Julia [Verfasser]. « Measurement of electroweak W + Jets Production and Search for anomalous Triple Gauge Boson Couplings with the ATLAS Experiment at √ s = 8TeV / Julia Fischer ». Wuppertal : Universitätsbibliothek Wuppertal, 2016. http://d-nb.info/112033781X/34.
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Stillings, Jan André [Verfasser]. « Search for the associated production of a W boson and a top quark with the ATLAS detector at 7 TeV / Jan André Stillings ». Bonn : Universitäts- und Landesbibliothek Bonn, 2015. http://d-nb.info/107728988X/34.
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Proissl, Manuel Daniel. « Dijet invariant mass studies in the Higgs boson H→bb- resonance search in association with a W/Z boson using the ATLAS detector ». Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10516.
Texte intégralRésumé :
The Standard Model of Particle Physics describes the fundamental building blocks of matter and phenomena up to the highest particle interaction energies. The theory demands the existence of a scalar particle: the Higgs boson. The Higgs boson was discovered by the ATLAS and CMS collaborations at CERN using bosonic final states and is measured to have a mass of around 125 GeV. This particle is predicted to decay predominantly into pairs of b-quarks at this mass, but suffers from overwhelming backgrounds from the multijet production expected from QCD interactions. Therefore, H→bb- production in association with a leptonically decaying W or Z boson is considered, with Z → vv-, W → lv and Z → ll, where ` denotes electrons and muons. This thesis presents a search for the Higgs boson decaying into bb- pairs in association with a W or Z boson using the ATLAS detector at the Large Hadron Collider (LHC) at CERN. The analysis uses the full dataset recorded during pp collisions at the LHC in Run-1, corresponding to 4.7 fb-1 at √s = 7 TeV and 20.3 fb-1 at √s = 8 TeV. A multivariate technique and a kinematic cut-based approach have been used to maximize the signal over background ratio, where a particular emphasis on the latter approach is made in this thesis. Final state radiation and reconstruction effects may decrease the bb- resonance resolution significantly, while comparably decreasing the probability of observing the decay over the background. The b quark pairs from the Higgs boson are reconstructed as topological clusters formed to jets in the ATLAS calorimeter. Thus, the reconstruction and calibration of these jets are crucial for the final Higgs mass resolution and paramount for the search and for future precision measurements of V H, H→bb- production. This thesis presents the development and evaluation of advanced techniques to improve the invariant dijet mass reconstruction of the H→bb- candidate. Sequential jet calibrations, semileptonic corrections and pT corrections to account for the interplay between jet resolution/scale and the underlying signal pT spectrum obtained from Monte Carlo simulations have been studied. A major focus has been made on the development and evaluation of an event-level kinematic likelihood fitting framework to exploit the full kinematic potential of V H topologies within the detector uncertainties of the reconstructed final state signatures in order to improve the measurement of the b-tagged jet kinematics. The jet energy calibrations of the H→bb- signal candidates yield an overall improvement of the dijet invariant mass resolution of up to ~30%, and of the expected statistical significance of ~12%. The analysis procedure is validated using the resonant V Z(bb-) production in the same final states as for the Higgs boson search, and is observed, compatible with the Standard Model expectation, with a significance of 4.9 standard deviations and a signal strength of μ^V Z = 0:74+0:17 -0:16. For a Higgs boson mass of 125.36 GeV, the observed (expected) deviation from the background-only hypothesis is found with a significance of 1.4 (2.6) standard deviations and a signal strength is determined to be μ^V H = 0:52±0:32(stat.)±0:24(syst.).
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Duphil, Dominique. « Synthèse et caractérisation de nanoparticules de fullerènes de dichalcogénures de métaux de transition MX2 (où M=Mo, W ; X=S, Se) ». Paris 12, 2003. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990002113970204611&vid=upec.
Texte intégralRésumé :
Trois méthodes de synthèses chimiques de nanoparticules de MX2 (M=Mo, W; X= S, Se) ont été mises au point. La première méthode est basée sur la réaction de M(CO)6 et X dans le p- xylène au reflux. Une poudre de nanoparticules amorphes est obtenue et cristallise après recuit à 550°C : les sulfures ont une morphologie appelée «spaghetti», avec des feuillets de van der Waals courbés et enchevêtrés ; les séléniures sont sous la forme de nanoplaquettes, avec des feuillets droits et alignés. Une 2ème méthode utilise un système de solvants immiscibles : le DMSO et le nonanethiol. Après recuit, des fullerènes de MoS2 sont observés au MET. La 3ème méthode développée est la pyrolyse d’aérosol liquide. Des solutions de MS4(NH4)2 dans l’eau ou l’éthanol sont pulvérisées dans un four à 750 ou 900°C. Les particules obtenues dans l’eau sont sphériques et cristallisées. Des fullerènes de MoS2 sont obtenus dans l’éthanol, tandis que WS2 forme un nouveau type de fullerène rectangulaire (« nanoboîte»)Three synthetic methods for the formation of MX2 (M=Mo, W ; X=S, Se) nanoparticles have been developed. The first is based on the reaction of M(CO)6 and X in p-xylene under refluxing conditions. A powder of amorphous nanoparticles is obtained, and crystallises after annealing at 550°C. The sulphides have a spaghetti-like morphology, with van der Waals planes curved and in every direction; selenides crystallise as nanoplatelets with straight. Aligned sheets. The second method uses a system consisting of two non-miscible solvents : DMSO and nonanethiol. After annealing, MoS2 fullerene-like nanoparticles are obtained. The third method is spray pyrolysis. MS4(NH4)2 bas been dissolved in water or ethanol, and then sprayed at 750 or 900°C in a furnace. Particles obtained from water solutions are spherical and crystallised. Fullerene-like MoS2 is obtained from ethanol, whereas the WS2 forms a new type of rectangular fullerene-like particles (‘bucky boxes”)
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Tröndle, Daniel Cedric [Verfasser], et W. de [Akademischer Betreuer] Boer. « Search for Supersymmetry using Multileptonic Signatures in Proton-Proton Collisions with the CMS Detector at the LHC / Daniel Cedric Tröndle. Betreuer : W. de Boer ». Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1022626833/34.
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Frensch, Felix [Verfasser], et W. de [Akademischer Betreuer] Boer. « Search for Higgs Bosons beyond the Standard Model in Proton-Proton Collisions with the CMS Detector at the LHC / Felix Frensch. Betreuer : W. de Boer ». Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1073204863/34.
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Negro, Giulia. « Search for heavy neutrinos with the CMS experiment and studies for the upgrade of its electromagnetic calorimeter ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS308/document.
Texte intégralRésumé :
Dans cette thèse, la recherche de neutrinos lourds droitiers à travers la désintégration d'un boson W droitier (Wʀ) en deux leptons et deux jets avec l'expérience CMS au Grand Collisionneur de Hadrons (LHC) est présentée.Le boson Wʀ se désintègre en un lepton et un neutrino massif (Nʀ), et le neutrino se désintègre en un autre lepton de la même saveur et en une paire de jets. Les données recueillies par l'expérience CMS dans les collisions proton-proton à 13 TeV en 2016 correspondant à une luminosité totale intégrée de 35.9 fb ⁻¹ ont été utilisés pour cette analyse.Ces neutrinos lourds manquent dans le Modèle Standard (SM) de la physique des particules et ils sont donc importants pour faire la lumière sur la physique au-delà du SM. Mes principales contributions ont été la simulation et la validation des échantillons de signaux, l'estimation de l'un des principaux bruit de fonds, la production des limites 1D et 2D sur la section transversale du Wʀ (en fonction de la masse du Wʀ et de la masse du Wʀ par rapport à la masse du Nʀ, et l'analyse statistique et systématique. Les résultats obtenus avec cette analyse donnent les limites les plus strictes à ce jour.Des études pour l'amélioration du calorimètre électromagnétique de CMS pour la Phase II du LHC, qui prévoit un remplacement partiel de l'électronique dans le tonneau, sont également présentés. Mes principales contributions ont été dans la préparation de l'installation et dans la prise de données des test beams réalisée à la ligne de faisceau H4 dans la zone SPS Nord du CERN,dont le but était d'étudier la performance du prototype pour les nouvelles Very-Front-End cartes (CATIA chips avec un ADC de 160 MHz), et dans l'étude des formes et bruit des signaux recueillis par une matrice de 5 x 5 cristaux pour calculer leur timing et leur résolution énergétique.Le document commence par une introduction théorique sur le Modèle Standard et sur la physique au delà du Modèle Standard, en particulier sur les neutrinos lourds, suivi d'une description du détecteur CMS et de son calorimètre électromagnétique. Les études pour l'amélioration du calorimètre électromagnétique sont présentées dans un chapitre dédié, puis l'analyse sur la recherche de neutrinos lourds et un aperçu de la physique des neutrinos au LHC et autres expériences sont décritsIn this thesis, the search for heavy right-handed neutrinos through the decay of a right-handed W (Wʀ) boson into two leptons and two jets with the CMS experiment at the Large Hadron Collider is presented. The Wʀ boson decays into a lepton and a massive neutrino (Nʀ), and the neutrino decays into another lepton of the same flavor and into a pair of jets. The data collected by the CMS experiment in proton-proton collisions at 13 TeV during 2016 and corresponding to a total integrated luminosity of 35.9 fb ⁻¹ were used for this analysis. These heavy neutrinos are missing in the Standard Model (SM) of particle physics and thus they are important to shed light on physics beyond the SM. My main contributions were the simulation and validation of the signal samples, the estimation of one of the main backgrounds, the production of the 1D and 2D limits on the Wʀ cross section (as a function of the Wʀ mass and of the Wʀ mass versus Nʀ mass), and the systematics and statistical analysis. The results obtained with this analysis give the most stringent limits to date.Studies on the upgrade of the CMS electromagnetic calorimeter for the LHC Phase II, that foresees a partial replacement of the electronics in the barrel, are also presented. My main contributions were in the preparation of the setup and in the data taking of test beams performed at the H4 beam line in the SPS North Area of CERN, whose goal was to study the performance of the prototype for the new Very-Front-End boards (CATIA chips with 160 MHz ADC), and in studying the shapes and noise of the signals collected by a matrix of 5 x 5 crystals calculating their timing and energy resolution.The document starts with a theoretical introduction about the Standard Model and the physics beyond the Standard Model, in particular on heavy neutrinos, followed by a description of the CMS detector and its electromagnetic calorimeter. The upgrade studies on the electromagnetic calorimeter are presented in a dedicated chapter, then the analysis on the search for heavy neutrinos and an overview on the overall neutrino physics at the LHC and other experiments are described
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Allbrooke, Benedict Marc Miller. « Search for the Higgs Boson decaying to a b quark pair produced in association with a W Boson using missing transverse energy triggered events at ATLAS ». Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5681/.
Texte intégralRésumé :
The WH → \(lv\)bb production and decay mode of the standard model Higgs Boson is searched for using the 2012 LHC proton-proton data recorded by the ATLAS detector at a centre-of-mass energy √s=8 TeV. Events containing W → μ\(v\) that fail muon triggers are recovered using a novel technique of recording these events with missing transverse energy based triggers. Two analyses are employed, one based on simple selection criteria to enhance the signal-to-background ratio and one that uses more complex multivariate techniques to separate signal from background. Both analyses exploit the different signal-to-background ratios in regions of the reconstructed W transverse momentum and b-jet tagging categorisation. The events recorded using the missing transverse energy triggers are analysed exclusively as well as merged with the events recorded using lepton triggers to improve the sensitivity of the final analyses. The multivariate merged analysis is found to be the more sensitive of the two analyses, gaining 18.5% compared to the equivalent cut-based analysis. The observed (expected) 95% CL limit for the WH → \(lv\)bb mode is found to be 2.507 (1.369) and the observed (expected) significance is 1.905 (1.534). The final value of the signal strength for WH → \(lv\)bb is μ=1.231± \[^{0.733}_{0.665}\] which is consistent with the Standard Model expectation.
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Camp, Joe Harden. « Birch rod to arsenal : a study of the Naval Ordnance Plant at South Charleston, West Virginia and the search for a government industrial policy / ». VIEW WEB VERSION, 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2359.
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Templeton, Alan. « Studies of bismuth vanadate (Biâ†4Vâ†2Oâ†1â†1) and BiMeVOX (Me=W'6'+, Ta'5'+, Nb'5'+, Zr'4'+ and Ti'4'+) materials ». Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU528242.
Texte intégralRésumé :
The oxide ion conductor bismuth vanadate (Bi4V2O11) can be doped with various metal cations, Me2+ to Me6+; Me partially substitutes for vanadium to produce a new family of solid electrolytes known as BiMeVOX (Bismuth Metal Vanadium Oxides. Bi4V2O11 is polymorphic having three forms α, β and γ; the high temperature form (γ) has high oxygen ion conductivity of comparable magnitude to existing solid electrolytes such as YSZ; however, this occurs at high temperatures (> 560°C). Doping Bi4V2O11 with Me ions, leads to stabilisation of the γ-phase to room temperature, thus producing a material with promising practical applications. The parent material, Bi4V2O11, is a non-stoichiometric phase forming a limited solid solution given by Bi4+yV2-yO11-y; by virtue of the variable Bi:B ratio this leads to a range of compositions for the BiMeVOX materials and hence the overall formula Bi4-yV2-x-yMexO11-y-σ. Thus, there is scope for a range of γ-phase compositions. The aims of this study were to - (1) investigate the Bi4+yV2-yO11-y solid solution and formation of stoichiometric Bi4V2O11 (i.e. y = 0); (2) optimise synthesis conditions of Me-doped Bi4V2O11 (Me = W6+, Ta5+, Nb5+, Zr4+ and Ti4+); (3) determine the compositional extent of each solid solution formed by using a variety of diffraction, thermal and microscopic techniques; (4) investigate stabilisation, to room temperature, of the high temperature gamma (γ) phase, formed on doping Bi4V2O11; (5) elucidate possible substitution mechanisms and initiate a crystallographic study of gamma phase materials. Bi4V2O11 : It is shown that stoichiometric Bi4B2O11 does not form, via solid state reaction, without precipitation of BiVoO4 (scheelite) as secondary phase; a slight excess of Bi (y ≈ 0.02) is required to form single phase material in this system.
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Buzatu, Adrian. « Search for the standard model Higgs Boson produced in association with a W Boson in the isolated-track charged-lepton channel using the collider detector at Fermilab ». Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104593.
Texte intégralRésumé :
The Higgs boson is the only elementary particle predicted by the Standard Model (SM) that has not yet been observed experimentally. If it exists, it explains the spontaneous electroweak symmetry breaking and the origin of mass for gauge bosons and fermions. We test the validity of the SM by performing a search for the associated production of a Higgs boson and a W boson in the channel where the Higgs boson decays to a bottom-antibottom quark pair and the W boson decays to a charged lepton and a neutrino (the WH channel). We study a dataset of proton-antiproton collisions at a centre-of-mass energy of 1.96 TeV provided by the Tevatron accelerator, corresponding to an integrated luminosity of 5.7 inverse femtobarns , and recorded using the Collider Detector at Fermilab (CDF). We select events consistent with the signature of exactly one charged lepton (electron or muon), missing transverse energy due to the undetected neutrino (MET) and two collimated streams of particles (jets), at least one of which is required to be identified as originating from a bottom quark. We improve the discrimination of Higgs signal from backgrounds through the use of an artificial neural network. Using a Bayesian statistical inference approach, we set for each hypothetical Higgs boson mass in the range 100 - 150 GeV/c^2 with 5 GeV/c^2 increments a 95% credibility level (CL) upper limit on the ratio between the Higgs production cross section times branching fraction and the SM prediction.Our main original contributions are the addition of a novel charged lepton reconstruction algorithm with looser requirements (ISOTRK) with respect the electron or muon tight criteria (TIGHT), as well as the introduction of a novel trigger-combination method that allows to maximize the event yield while avoiding trigger correlations and that is used for the ISOTRK category. The ISOTRK candidate is a high-transverse-momentum good-quality track isolated from other activity in the tracking system and not required to match a calorimeter cluster, as for a tight electron candidate, or an energy deposit in the muon detector, as for a tight muon candidate. The ISOTRK category recovers real charged leptons that otherwise would be lost in the non-instrumented regions of the detector. This allows the reconstruction of more W boson candidates, which in turn increases the number of reconstructed WH signal candidate events, and therefore improves the sensitivity of the WH search. Since there is no ISOTRK-dedicated trigger at CDF, for the ISOTRK charged lepton category we employ three MET-plus-jets-based triggers using a novel method, which allows the combination of any number of triggers in order to maximize the event yield while avoiding trigger correlations. On an event-by-event basis, only the trigger with the largest efficiency is used. By avoiding a logical "OR" between triggers, the loss in the yield of events accepted by the trigger combination is compensated by a smaller and easier-to-compute corresponding systematic uncertainty. The addition of the ISOTRK charged lepton category to the TIGHT category produces an increase of 33% in the WH signal yield and a decrease of 15.5 % to 19.0 % in the median expected 95 % CL cross-section upper limits across the entire studied Higgs mass interval. The observed (median expected) 95 % CL SM Higgs upper limits on cross section times branching ratio vary between 2.39 x SM (2.73 x SM) for a Higgs mass of 100 GeV/c^2 to 31.1 x SM (31.2 x SM) for a Higgs mass of 150 GeV/c^2, while the value for a 115 GeV/c^2 Higgs boson is that of 5.08 x SM (3.79 x SM).The novel trigger combination method is already in use by several CDF analyses. It is applicable to any analysis that uses triggers based on MET and jets, such as supersymmetry searches at the ATLAS and CMS experiments at the Large Hadron Collider. In its most general form, the method can be used by any analysis that combines any number of different triggers.Le boson de Higgs est la seule particule elementaire predite par le Modele Standard qui n'a jamais ete observee experimentalement. S'il existe, il explique la brisure spontanee de la symetrie electrofaible, ainsi que la masse des bosons W et Z et de tous les fermions. On verifie la validite du Modele standard en effectuant une recherche sur la production associee d'un boson de Higgs et d'un boson W dans le cas ou le boson de Higgs se desintegre en une paire de quarks bottom-antibottom et le boson W se desintegre en un lepton charge et un neutrino (le mode WH). Nos donnees furent accumulees en etudiant des collisions proton-antiproton a une energie au centre de masse de 1.96 Tev produites par l'accelerateur Tevatron, a une luminosite integree de 5.7 femtobarns inverses et collectees par le detecteur Collider Detector at Fermilab (CDF). On selectionne des evenements avec une signature correspondante a exactement un lepton charge (electron ou muon), de l'energie manquante transversale a cause du neutrino qui s'echappe du detecteur (MET) et deux jets de particules, dont au moins un doit provenir d'un quark bottom. On ameliore la discrimination entre le signal Higgs et le bruit de fond a l'aide d'un reseau de neurones artificiels. En utilisant une inference statistique bayesienne, on calcule pour chaque masse hypothetique du boson de Higgs dans l'intervalle 100-150 GeV/c^2, avec des increments de 5 GeV/c^2, une limite superieure de 95% d'intervalle de credibilite (CL), sur le rapport entre la section efficace multipliee par le rapport d'embranchement et celle predite par le Modele Standard. Notre contribution principale est l'introduction d'un nouvel algorithme de reconstruction d'un lepton charge avec des criteres plus laches (ISOTRK) par rapport aux criteres stricts de reconstruction des candidats d'electrons et de muons (TIGHT). La deuxieme contribution majeure consiste en l'introduction d'une nouvelle methode pour combiner des declencheurs differents permetant de maximiser le nombre d'evenements selectionnes et en meme temps que d'eviter les correlations entre les declencheurs.Un candidat de ISOTRK est une trajectoire qui correspond aux criteres de qualite, qui a une large quantite de mouvement transverse, qui est isolee d'autres activites dans le detecteur de trajectoires et qui ne doit pas se prolonger dans une zone active du calorimetre (detecteur de muons), comme pour un candidat d'electron (muon). Les candidats de ISOTRK recuperent de vrais leptons charges qui seraient autrement perdus dans les zones non instrumentees du detecteur. L'ajout de la categorie ISOTRK a la categorie TIGHT permet de reconstruire plusieurs bosons W reels et par la suite de recuperer plusieurs evenements WH, ce qui ameliore la sensitivite de la recherche de WH.Comme a CDF il n'y a pas de declencheurs dedies au leptons charges ISOTRK, on utilise pour la categorie ISOTRK trois declencheurs bases sur MET et jets avec une nouvelle methode qui permet de maximiser le nombre d'evenements accumules tout en evitant les correlations des declencheurs. Pour chaque evenement, ce n'est que le declencheur avec la plus grande efficacite qui est utilise. Le nombre d'evenements ramasses est legerement inferieur a celui d'un "OR" logique entre les declencheurs, mais cela est compense par une erreur systematique qui est a la fois moins importante et plus facile a evaluer. Dans sa forme la plus generale, la methode peut etre utilisee par toute analyse qui utilise un nombre variable de declencheurs differents. L'utilisation de la categorie ISOTRK en plus de la categorie TIGHT augmente de 33% le nombre d'evenements WH selectionnes et decroit de 15.5% a 19.0% la limite superieure mediane attendue. La limite superieure observee (attendue) varie entre 2.39 x SM(2.73 x SM) pour un boson de Higgs de 100 GeV/c^2 jusqu'a 31.1 x SM(31.2 x SM) pour un boson de Higgs de 150 GeV/c^2. En meme temps, pour un boson de Higgs de 115 GeV/c^2, la valeur est 5.08 x SM(3.79 x SM).
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Ellajosyula, Venugopal. « Search for a doubly charged Higgs boson decaying to same-sign W bosons in a triplet-doublet extension of the standard model with the Atlas detector at the LHC ». Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0477/document.
Texte intégralRésumé :
La recherche de bosons scalaires de charge électrique +2 se désintégrant en deux bosons W de même charge est effectuée en analysant un échantillon de données collectées en 2015 et 2016 à une énergie de centre de masse de 13 Tev au LHC auprès du détecteur ATLAS, correspondant à une luminosité intégrée de 36.1 fb$^{-1}$. Cette recherche est motivée par un modèle comprenant une extension du secteur scalaire grâce à l'ajout d'un triplet. Il propose une explication à la masse des neutrinos et prédit une riche phénoménologie autour des bosons scalaires de charge +1 et +2 ainsi que des deux nouveaux bosons neutres, en plus d'un aux propriétés identiques à celles du boson de Higgs du MS. Le boson doublement chargé est produit par paires dans les collisions proton-proton et se désintègre majoritairement en bosons W. L'intervalle de masse exploré est situé entre 200 et 700 GeV, en utilisant des signatures expérimentales qui incluent plusieurs leptons, de l'énergie transverse manquante et des jets. L'analyse avec trois leptons dans l'état final est décrite dans cette thèse. Une combinaison de l'analyse avec deux, trois et quatre leptons est réalisée pour augmenter la sensibilité. Une interprétation statistique des résultats donne une limite inférieure en masse de 220 GeV. Ceci constitue la première recherche expérimentale de ce modèle dans cet espace de paramètres auprès d'un collisionneurA search for doubly charged scalar bosons decaying to W boson pairs is performed using a data sample corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected by the ATLAS detector at the LHC at a centre-of-mass energy of 13 TeV in 2015 and 2016. The search is guided by a model including an extension of the scalar sector through a scalar triplet which provides an explanation of neutrino masses. Such a model predicts a rich phenomenology that includes singly- and doubly-charged bosons, and two new neutral bosons, besides a boson whose properties are identical to the SM Higgs boson. The doubly-charged bosons are produced by pairs in proton-proton collisions and decay predominantly into W bosons. The mass range from 200 to 700 GeV is explored using experimental signatures including several leptons, missing transverse energy and jets. The analysis in the final state of three leptons is described in this thesis. A combination of the analysis in two, three, and four leptons is used to enhance sensitivity. A statistical interpretation of the results gives an observed lower bound on the mass of 220 GeV. This is the first search of this model in this parameter space at the colliders
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Ravenscroft, Thomas Oliver. « Studies of possible improvements to the b-Jet energy resolution applied to the search for the Higgs boson produced in association with a W boson at the ATLAS detector ». Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6664/.
Texte intégralRésumé :
This thesis presents a measurement of the cross-section for the produc- tion of a Higgs boson in association with a W boson. Where the Higgs boson decays to a pair of b-quarks and the W boson decays leptonically to a electron-neutrino pair or muon-neutrino pair. The measurements have been taken using 20 fb−1 of data collected at a centre-of-mass energy √s = 8 TeV from the ATLAS detector; one of the four main experiments at the Large Hadron Collider (LHC). An expected upper limit is calculated in the background-only hypothesis at 1.51 times the Standard Model expectation. The signal strength is measured at a Higgs boson mass m = 125 GeV to be μ = 3.22+0.71(stat.)+1.03(syst.) H −0.69 −0.87 As part of the analysis performed, extensive studies have been carried out into the impact of the four jet calibrations used by the WH → lνb ̄b analysis for the Run I result. Jet calibrations are used to correct for detector effects and inefficiencies in the reconstruction of the jets. In addition to the studies on the current jet calibration methods, two additional jet calibrations are studied and their perfor- mance within the analysis are measured, with comparisons against the nominal expected upper limit. The first additional calibration replaces the current jet pT calibration with one which uses different calibrations depending upon whether the jet contains a muon or not. By applying this calibration the expected upper limit improves to 1.50 times the Standard Model expectation. The second calibration uses a regression to improve the b-jet resolu- tion. Using well modelled variables, there is no change in the expected upper limit, however by considering all variables, the expected upper limit improves to 1.47 times the Standard Model expectation, giving a 2.5% improvement to the nominal analysis.
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Kraus, Jana [Verfasser]. « W -> ; tau nu(tau) Cross Section Measurement and Search for the Standard Model Higgs Boson in the tau(lep) tau(had) Final State with the ATLAS Detector / Jana Kraus ». Bonn : Universitäts- und Landesbibliothek Bonn, 2015. http://d-nb.info/1077289677/34.
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DI, MATTEO LEONARDO. « CMS ECAL intercalibration with electrons from W and Z decays and Search for the Standard Model Higgs boson in the H > ; WW > ; lvqq channel with the CMS detector ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41813.
Texte intégralRésumé :
The usage of isolated electrons from W and Z leptonic decays for the intercalibration of the CMS ECAL single channel response is described. The statistics of 5 fb−1, collected at LHC in 2011 at sqrt(s)=7 TeV, allowed to reach a statistical precision of about 1% in the central part of the ECAL barrel and about 4% in the ECAL endcaps. The results obtained with this method are combined with others, and the impact on the Higgs to di-photon search is shown.
Subsequently, the thesis describes the search strategy for the Higgs boson in the H > WW > lvqq final state. The results are based on a data sample corresponding to an integrated luminosity of 17 fb−1 of proton-proton collisions accumulated during the 2011-2012 LHC run.
The standard model Higgs boson is excluded at 95% confidence level in the mass ranges [215 − 490] + [525 − 600] GeV.
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Napolitano, Fabrizio [Verfasser], et Oleg [Akademischer Betreuer] Brandt. « Search for Dark Matter produced in association with a hypothetical Dark Higgs Boson decaying to W ± W ∓ or ZZ boson pairs in the fully hadronic final state at √s = 13 TeV using 139 fb−1 of pp collisions recorded with the ATLAS Detector / Fabrizio Napolitano ; Betreuer : Oleg Brandt ». Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1217539727/34.
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Held, Hauke [Verfasser], et T. [Akademischer Betreuer] Müller. « Measurement of the Jet Momentum Resolution and Search for a light Standard Model Higgs Boson in the H(bb̄)W(lv) Channel with the CMS Detector at the LHC / Hauke Held. Betreuer : T. Müller ». Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1022123815/34.
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Jiggins, S. P. « Search for new resonances decaying to a Standard Model Vector boson (W/Z) and Higgs boson in the llbƃ, lνbƃ & ; vvbƃ channels, in proton-proton collisons at √s = 13 TeV with the ATLAS detector ». Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10044750/.
Texte intégralRésumé :
The following thesis presents the result of a Beyond the Standard Model search for heavy resonances (V'/A) decaying into a Standard Model W or Z boson, and a Higgs (h) boson with a final state signature llbb̄, lνbb̄, or ννbb̄, where l= e/μ , in proton-proton collisions at a center of mass energy of √s = 13 TeV. The data is collected using the ATLAS detector at the Large Hadron Collider, during the data periods of 2015+2016, amounting to 36.1 fb^{-1}. The search is conducted using the (transverse) invariant mass spectrum of the reconstructed Standard Model W/Z boson and Higgs boson system, W/Z + h, to search for excesses using the CL_{s} binned profile likelihood test statistic. No excess is observed, therefore the results are interpreted in terms of constraints on σ_{V/A} × BR(h→bb̄), for heavy vector bosons predicted by Heavy Vector Triplet models (HVT ), W'/Z', or the CP-odd scalar boson A predicted by Two-Higgs Doublet Models (2HDM ). The upper limits on the production cross-sections are then used to assign constraints to the model parameter space. For the HVT interpretation, limits on two benchmark models corresponding to fermiophobic and fermiophilic extensions, labelled A and B, of the heavy resonances are set: m_{V'} = 2800(2930) GeV. For 2HDMs, limits on the production cross-section for mediator masses ranging from 220-2000 GeV are set: 5.5 × 10^{−3} pb → 2.4 × 10^{−1} pb for gg→A production, and 3.4 × 10^{−3} → 7.3 × 10^{−1} pb for bbA associated production.
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Sparrow, Alexander. « Measurement of the polarisation of the W boson and application to supersymmetry searches at the Large Hadron Collider ». Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10212.
Texte intégralRésumé :
This thesis gives an account of two analyses performed using data from the Compact Muon Solenoid experiment at the Large Hadron Collider. The first analysis measures the polarisation of W bosons with large transverse momentum using 36 pb⁻¹ of data collected in 2010. The second applies similar techniques to a search for supersymmetry in events containing a single lepton, jets and missing transverse energy. This analysis utilises 1.14 fb⁻¹ of data collected up to 2011. Background material related to the Standard Model, supersymmetry and the experimental apparatus are reviewed in detail. The W polarisation measurement is performed in both the W->ev and W->μv channels. The expected effect, a large dominance of the left-handed over the right-handed helicity state, is observed with a significance of 7.8σ for the W⁺ and 5.1σ for the W⁻ in the muon channel. Similar results are found in the electron channel and for a combined fit to both lepton channels. The second analysis conducts a search for supersymmetry in events containing a single lepton, jets and missing transverse energy. The search employs techniques developed for the W polarisation measurement to separate supersymmetry from Standard Model backgrounds. No deviation from the Standard Model is observed. A detailed statistical interpretation is performed and used to set limits within the Constrained Minimal Supersymmetric Standard Model as well as two simplified models.
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Bogavac, Danijela [Verfasser], et Dorothee [Akademischer Betreuer] Schaile. « Searches for supersymmetric particles decaying to W and Higgs bosons in events with an isolated lepton with the ATLAS detector / Danijela Bogavac ; Betreuer : Dorothee Schaile ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1164376926/34.
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