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1
FIORENDI, SARA. « Measurement of the ratio B(Bc± → J/ψπ±π±π∓ )/B(Bc± → J/ψπ± ) and the production cross sections times branching fractions of Bc± → J/ψπ± and B± → J/ψK± in CMS ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/55490.
Texte intégralRésumé :
Il mesone pseudoscalare Bc, stato fondamentale del sistema ( ̄bc), è la particella più leggera formata da due quark pesanti di diverso sapore, e rappresenta perciò un laboratorio ideale per lo studio della dinamica dei decadimenti degli Heavy Flavor.
Lo studio delle proprietà del mesone Bc è di particolare interesse se paragonato agli stati ̄bb e ̄cc, che non portano sapore, e offre un nuovo terreno per verificare le predizioni dei modelli effettivi ispirati dalla cromodinamica quantistica.
Ciascuno dei due quark costituenti la Bc può decadere attraverso l’interazione debole. In particolare, la transizione b → c, che copre circa il 20% del rate di decadimento, ha un’alta probabilità di produrre un mesone J/ψ nello stato finale, che costituisce una segnatura sperimentale facilmente identificabile. Infatti, la prima osservazione del mesone Bc è stata effettuata nel canale di decadi- mento semileptonico Bc+ → J/ψl+ν(l = e,μ) dalla Collaborazione CDF.
Lo studio sperimentale del mesone Bc è entrato in una nuova fase con l’avvento del Large Hadron Collider (LHC) al CERN. Grazie alle alte energie e luminosità istantanee mai raggiunte prima, la statistica di eventi di Bc disponibile è molto più alta che negli esperimenti precedenti. Le caratteristiche dell’esperimento CMS (Compact Muon Solenoid) consentono di perseguire un ampio programma di misure nell’ambito della fisica del quark beauty. Accanto a ricerche indirette di nuova fisica attraverso lo studio di decadimenti rari, come Bs → μ+μ− e B0 → K0∗μ+μ−, lo studio del mesone Bc rappresenta un settore importante nel programma di fisica dell’esperimento. Inoltre, poichè la Bc rappresenta un potenziale background proprio nei decadimenti rari, una misura della sua sezione d’urto e la caratterizzazione dei suoi stati finali sono cruciali per poter ottenere un’accurata stima dei fondi.
In questa tesi presento l’analisi dei canali di decadimento Bc+ → J/ψπ+π+π− e Bc+ → J/ψπ+, e una misura del rapporto delle loro Branching Fraction, RBc ≡ B(Bc+ → J/ψπ+π+π−)/B(Bc+ → J/ψπ+). La misura è stata ottenuta presso l’esperimento CMS a LHC. L’esperimento CMS, infatti, è particolarmente adatto allo studio degli stati finali contenenti mesoni J/ψ, dove J/ψ → μ+μ−, grazie alle eccellenti prestazioni dei sistemi di rivelazione di muoni e di tracciamento.
La misura del rapporto RB è 2.55 ± 0.80(stat.) ± 0.33(syst.)+0.04-0.01(τBc ). Questo rapporto è indipendente dalla sezione d’urto della Bc, la cui misura non è ancora disponibile.
Il canale Bc+ → J/ψπ+ è anche confrontato con il decadimento B+ → J/ψK+, che ha le stesse caratteristiche topologiche. Il rapporto delle sezioni d’urto moltiplicato per le rispettive Branching Fractions è misurato essere [0.48± 0.05(stat.)±0.03(syst.)±0.05(τBc)]%. Nello spazio cinematico esplorato, il momento traverso del mesone Bc+ è maggiore di 15 GeV e la regione di rapidità è |y| < 1.6, complementare a quella accessibile all’esperimento LHCb. Questa misura contribuisce a una comprensione più completa della produzione di Bc+ in collisioni protone-protone.
L’analisi è stata condotta sui dati raccolti da CMS a sqrt(s) = 7 TeV, che corrispondono a una luminosità integrata di 5.1 fb−1. Il trigger utilizzato per la selezione degli eventi si basa sull’identificazione dei due muoni provenienti dal decadimento del mesone J/ψ. L’abbondante fondo combinatorio è stato ridotto sfruttando selezioni topologiche e cinematiche. L’efficienza di ricostruzione è stata accuratamente parametrizzata e misurata su appositi campioni Monte Carlo, che ben riproducono le condizioni della presa dati. Sono state valutate diverse fonti di incertezza sistematica, descritte accuratamente nel testo.
2
TARONI, SILVIA. « Performance of the cms forward pixel detector and analysis of the Bc to J/psi pi decay channel ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/7780.
Texte intégralRésumé :
The performance of the irradiate CMS forward pixel detector are discussed in the first part of the thesis. The analysed data are collected in a testbeam of a detector module irradiated up to 45 Mrad. The high absorbed dose has not compromised the detector response. In the second part, the feasibility of the analysis of the B_c decaying into J/psi + pion at CMS is expounded. The results are obtained for 1fb-1 and 200pb-1 of integrated luminosity.
3
Lyon, James David. « Rare semi-leptonic B meson decays ». Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/8904.
Texte intégralRésumé :
In this thesis, novel corrections to B → X˦ and B → Xl+l- decays, where X is a pseudoscalar or vector meson, are presented. These are the chromomagnetic matrix element, weak annihilation in a general four-quark operator basis and a long-distance charm loop contribution. The calculation of the chromomagnetic matrix element completes the calculation of matrix elements for all relevant effective weak operators in B → V decays, removing an infrared divergence which previous computations had treated in a very approximate way. It also encounters an interesting technical obstacle not previously seen in sum rule calculations, which is likely to be encountered regularly in future once higher order loop diagrams are calculated. The potential for this term to contribute to the CP asymmetry in D → V˦ in the presence of new physics is discussed. The improved computation of weak annihilation diagrams is applied to the analysis of isospin asymmetries in radiative and semi-leptonic B → (p;K(*)) decays, and the computation of long distance charm bubble terms is applied to produce an improved prediction for time-dependent CP asymmetries in various B → V decays.
4
Zhang, Hongshan (Kevin). « First measurements of the exclusive decays of the upsilon(5S) to B* meson B* bar meson pion pion final states and improved B*(s) meson mass measurements ». Related electronic resource : Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
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Rieger, Jason. « First measurement of the neutral B(S) meson semileptonic branching ratio to an orbitally excited D meson state (neutral B(S) meson decaying to D meson(2536)-muon(+)-neutrino-X meson) ». [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3331275.
Texte intégralRésumé :
Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2007.Title from PDF t.p. (viewed on Jul 27, 2009). Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6877. Adviser: Rick Van Kooten.
6
Anikeev, Konstantin. « Measurement of the lifetimes of B meson mass eigenstates ». Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32421.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 201-209).
In this dissertation, we present the results of the average lifetime measurements in ..., ..., and ... decays, as well as the results of a time-dependent angular analysis of ... and ... decays. The time-dependent angular analysis of ... allows the extraction of separate lifetimes for the mass eigenstates, ... and ..., in the ... system. The two lifetimes are combined to extract the width difference, ..., between the two eigenstates. This quantity is extremely useful for over-constraining the Unitarity Triangle and thereby inferring if CP violation in the quark sector is entirely explained within the Standard Model. From ... of data collected by CDF up to February 13, 2004, we obtain a wealth of results, most importantly: ... Several of the results obtained here are currently the best of their kind, and in some cases they are unique measurements. We devote special attention to these, in particular ...
by Konstantin Anikeev.
Ph.D.
7
Capdevila, Soler Bernat. « Searching for new physics in semileptonic B meson decays ». Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/669491.
Texte intégralRésumé :
Al llarg dels últims anys, s'han observat nombroses senyals que suggereixen l'existència de Física més enllà del Model Estàndard en desintegracions semi-leptòniques de mesons B, mediades per transicions del tipus b --> sll. Més concretament, l'experiment LHCb, juntament amb altres experiments al LHC i col·laboracions externes com Belle, han trobat desviacions en les mesures experimentals de diferents observables d'important rellevància respecte les seves prediccions teòriques en el Model Estàndard. Parcialment, aquesta situació no es sorprenent, ja que en un conjunt gran de dades un sempre espera tenir un subconjunt en tensió amb les seves prediccions. No obstant, la importància de les observacions actuals és que totes aquestes tensions formen un patró coherent apuntant cap a "una direcció privilegiada". Per aquesta raó, els anàlisis globals d'aquestes dades mostren una discrepància general de més de 5sigmes respecte el Model Estàndard
Per estudiar aquestes tensions de manera consistent, treballem des del marc del Hamiltonià efectiu que descriu la dinàmica de les transicions b --> sll. Aquesta descripció, conceptualment senzilla, ens permet descriure qualsevol desintegració d'un mesó B, que procedeixi a través de l'anterior transició, en base a un conjunt reduït de paràmetres. Precisament, aquest fet és el fa possible analitzar la totalitat dels observables on s'observen tensions de manera eficient per mitjà de fits globals.
En aquesta Tesi, presentem la última versió dels anàlisis globals esmentats. Primer, descrivim el context teòric general que ens serveix de base per tots els nostres càlculs, fent especial èmfasi en l'estimació dels errors corresponents. I després, exposem els nostres resultats amb tota profunditat de detalls, així com comentem també les seves possibles implicacions.Recientemente, el campo de las desintegraciones electro-débiles de mesones B ha observado la aparición de numerosas señales que indican la existencia de Física más allá del Modelo Estándar, siendo los procesos mediados por transiciones b --> sll el contexto habitual de dichas señales. Más en detalle, el experimento LHCb, junto con otros de los experimentos en el LHC y otras colaboraciones como Belle, han encontrado desviaciones en los valores experimentales de distintos observables, relevantes en la caracterización de las transiciones b --> sll, con respecto sus predicciones teóricas en el marco del Modelo Estándar. En parte, esta situación no es sorprendente, puesto que uno se espera encontrar varias medidas en tensión con sus predicciones en un conjunto grande de datos. No obstante, lo que es muy destacable es que estas tensiones forman un patrón de desviaciones con coherencia interna y parece que apuntan todas "en la misma dirección". Por esta razón, al evaluar la importancia global del conjunto de tensiones mediante un análisis global, el resultado indica una discrepancia general de los datos con respecto del Modelo Estándar de más de 5sigmas. Para estudiar dichas tensiones de forma consistente utilizamos un Hamiltoniano efectivo, dónde se codifica la dinámica de las transiciones b --> sll. Esta simple herramienta nos permite describir cualquier desintegración de un mesón B, que opere a través de dicha transición, a través de un conjunto reducido de parámetros, hecho que posibilita poder analizar un conjunto numeroso de datos por medio de fits globales. En esta Tesis presentamos la última versión de los citados análisis globales. Primero, describimos el contexto teórico general que sirve de base para todos nuestros cálculos, prestando especial atención a los métodos utilizados para estimar la incertidumbre asociada a nuestras predicciones, para después mostrar todos los detalles de nuestro análisis así como sus implicaciones.
In the recent years, intriguing hints of New Physics (NP) have been accumulated in semileptonic B-meson decays, mostly involving neutral-current transitions b --> sll. The LHCb collaboration, other collaborations at the LHC and the Belle experiment have reported deviations from the Standard Model expectations in several observables measuring the aforementioned transition. These are commonly referred to in the literature as B-anomalies. Not surprisingly, some of these measurements show deviations from the SM predictions by a few standard deviations. More interesting is the fact that several of these deviations from the SM appear to be "in the same direction", in such a way that when quantified by a global fit the discrepancy with the SM is over the 5sigma level. In order to assess the significance of these anomalies and to treat them consistently, we propose a model-independent analysis based on an Effective Hamiltonian encoding the dynamics of the underlying quark level transition. This has the advantage of providing a simple systematic framework where all possible processes, mediated by the same transition, can be described with the same set of parameters, allowing for global fits of large numbers of observables defined in several channels. This Thesis presents our most updated global analyses of b --> sll data. First, we describe the general framework used to compute the different types of observables, paying special attention to the treatment of the uncertainties involved. And then, we discuss both our analytical approach and the implications of the most significant results obtained from our fits.
8
Gratrex, James. « Rare radiative and semileptonic B meson decays ». Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33173.
Texte intégralRésumé :
Recent results at the LHCb and B-factory experiments have suggested that rare processes in B →Vγ and B → V ℓ¯ℓ decays, where V is a vector meson, show some deviation from Standard Model predictions. Although these anomalies are not yet at the level to constitute a formal discovery, they are certainly suggestive of potential New Physics effects in flavour-changing neutral currents. However, explanations within the Standard Model cannot yet be ruled out. This thesis contributes to the understanding of such anomalies in two ways. Firstly, the angular distribution of the B → KJ (→ Kπ)ℓ1¯ℓ2 decay is derived, for the full dimension-six effective weak Hamiltonian, using a generalisation of the helicity formalism to effective theories mediating b → sℓ1¯ℓ2 transitions. This approach sheds light on the origin of the underlying structure, and in the process extends the general angular distribution to decays in which the two leptons in the final state, ℓ1¯ℓ2, are not necessarily identical. An additional benefit of the derivation of the angular distribution presented in this manner is that it lends itself to a moments analysis of the decay. It is shown how the angular distribution changes in the presence of new operators, predicted to be vanishingly small in the Standard Model. Such operators could be sizeable in the presence of New Physics, but using a moments analysis enables the contribution of such operators to be assessed. Secondly, an analysis is presented of the three-particle vector and axial meson distribution amplitudes. It is shown that the distribution amplitudes of both particles are, up to QCD corrections, nearly identical. These results are applied to a new calculation of the long-distance charm loop contribution to radiative B → Vγ decays, and it is shown that the approximate symmetry can be exploited to provide an improved theoretical control in the search for New Physics contributions to right-handed currents in radiative decays.
9
Wallace, Charlotte. « Studies of excited D mesons in B meson decays ». Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/85415/.
Texte intégralRésumé :
This thesis documents the studies of several three-body B+ meson decays, each with a charged charmed meson in the final state. All analyses presented use a data sample recorded by the LHCb detector in 2011 and 2012, corresponding to an integrated luminosity of 3:0 fb‾1 of pp collision data. The B+ →D‾ K+π + and B+ →D+ K+π.+ decay modes are observed for the first time. The branching fraction of the favoured B+ → D‾ K+π + decay mode is measured relative to the topologically similar B+ →D‾ π+ π+ decay and the B+ ‾ D‾ K+π+ final state is used as a normalisation channel for the suppressed B+ → D+ K+ π‾.decay branching fraction measurement. Searches are performed for the quasi-two-body decays B+→ D+ K* (892) 0 and B+ → D*2(2460) 0 K+ , using the sample of B+ → D+ K+π‾ candidate decays. No significant signals are observed for either decay mode and upper limits are set on their branching fractions. Excited charmed mesons decaying to D‾π+ are studied by performing fits to the Dalitz plots of B+ →D‾ K+π+ and B+ → D.‾π+π + candidates. A structure at m(D‾π.+) 2:78 GeV=c2 in the D‾ K+π+ data sample is determined to have spin-1 for the first time. Evidence from the B+ → D‾π+π + Dalitz plot suggests that the states at m(D‾π+ ) 2:76 GeV=c2 and 3:00 GeV=c2 , have spin-3 and spin-2, respectively. The mass and width parameters of these states are measured precisely, as are those of the well known D‾*2 (2460) 0 resonance. Fit fractions and product branching fractions are calculated for all contributions in the B+ ! D. K+ + and B+ → D‾π+ π+ amplitude models.
10
Corwin, Luke Andrew. « Leptonic Decays of the Charged B Meson ». The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228320450.
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11
Yasin, Zafar. « Search for the decay of a charged B meson to a charged rho meson and a f₀(980) meson ». Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=138&did=1907183711&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270493424&clientId=48051.
Texte intégralRésumé :
Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Includes bibliographical references (leaves 104-105). Issued in print and online. Available via ProQuest Digital Dissertations.
12
Saab, Tarek. « Study of charmonium final states in B meson decays ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/MQ44266.pdf.
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13
Rasheed, Reem. « Search for new physics using radiative B meson decays and lifetime measurment of the B meson with the Belle II experiment ». Thesis, Strasbourg, 2020. https://publication-theses.unistra.fr/public/theses_doctorat/2020/RASHEED_reem_2020_ED182.pdf.
Texte intégralRésumé :
Juste après le Big Bang, matière et antimatière étaient présentes en quantités égales. Mais l’univers que nous observons aujourd’hui est presque entièrement constitué de matière. Une différence de comportement des particules et anti-particules constitue un ingrédient fondamental pour expliquer cette disparition. La violation de la symétrie quantique CP (Charge et Parité) introduit une telle asymétrie, cependant le niveau observé actuellement pour cette violation ne suffit quantitativement pas. L’expérience Belle II vient de démarrer au Japon, elle permet d’étudier avec une très grande précision des systèmes particules/anti-particules produits par le collisionneur électron-positron SuperKEKB , qui sera bientôt le plus lumineux au monde. Dans mon doctorant, J'ai travaillé sur la mesure de la violation de CP dans les désintégrations radiatives du méson B (désintégrations avec des photons à l'état final) particulièrement prometteuses grâce à leur haute sensibilité aux possibles nouveaux processus. Suite à cette analyse, j'ai commencé une nouvelle mesure de la durée de vie des mésons B, pour vérifier la robustesse des outils utilisés pour mesurer la violation de CPAfter the Big Bang matter and antimatter were present in equal amounts. Today, however, everything we see, is made almost entirely of matter. A fundamental ingredient to explain this asymmetry between matter and antimatter is the violation of the CP (Charge Parity) symmetry. CP violation has been observed but quantitatively not enough to explain the huge asymmetry. The Belle II experiment in Japan studies the particles produced in electron-positron collisions at the SuperKEKB collider, the highest intensity collider in the World, allowing a high precision measurements of the known sources of CP violation and looking for new ones. In my PhD, I worked on measuring the CP violation in B meson radiative decays (decays with photon in final state) particularly promising thanks to their high sensitivity to possible new processes. Following this analysis, I started a new measurement of the B mesons lifetime where I could verify the robustness of the tools used in the CP violation measurement
14
Eriksson, David. « Phenomenology of Charged Higgs Bosons and B-meson Decays ». Doctoral thesis, Uppsala universitet, Kärn- och partikelfysik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9564.
Texte intégralRésumé :
For more than 30 years the Standard Model has been the theoretical foundation for particle physics. The theory has been verified successfully by experimental tests. Its biggest shortcoming is the non-discovery of the Higgs boson,responsible for giving the other particles masses. Despite its success there are hints that the Standard Model is not the complete theory and many extensions of it, such as supersymmetry, have been proposed. Extended theories often predict the existence of a charged Higgs boson and its detection will be a clear sign of physics beyond the Standard Model. The main focus in this thesis is on various phenomenological aspects of the charged Higgs boson. For favorable mass and couplings direct detection is shown to be possible at the Large Hadron Collider in production with an associated W boson. It is also shown how a light charged Higgs can have measurable effects on spin correlations in decays of pair-produced top quarks. The charged Higgs boson can also be seen indirectly, in for example B-meson decays, which can be used to put constraints on its mass and fermion couplings. Exclusion limits in two supersymmetric models are given together with a comparison with the discovery potentials for the LHC experiments. A tool for calculating properties, such as masses and decays, of both charged and neutral Higgs bosons in the Two-Higgs-Doublet Model is also presented. B-meson decays can also be used to test aspects of the strong interaction. Part of this thesis deals with improving and applying phenomenological models to B-meson decays. Although these models are not derived from first principles, their success shows that they capture important features of non-perturbative strong interactions.
15
Welty-Rieger, Leah. « The lifetime of a beautiful and charming meson B(c) meson lifetime measured using the D0 detector / ». [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337257.
Texte intégralRésumé :
Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2008.Title from PDF t.p. (viewed on Jul 28, 2009). Source: Dissertation Abstracts International, Volume: 69-12, Section: B, page: 7581. Adviser: Rick Van Kooten.
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Morda, Alessandro. « Rare dileptonic B meson decays at LHCb ». Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4042/document.
Texte intégralRésumé :
Les désintégrations rares B0(s)→ll sont générées par des courants neutres avec changement de la saveur. Pour cette raison, ainsi qu'à cause de la suppression d'hélicité, leurs taux de désintégration sont très petits dans le Modèle Standard (MS), mais la présence de particules virtuelles de Nouvelle Physique peut radicalement modifier cette prédiction. Une partie du travail original présenté dans cette thèse est dédié à l'optimisation de l'algorithme d'Analyse Multi Varié (MVA) pour la recherche de la désintégration B0(s)→μμ avec l'échantillon collecté par l'expérience LHCb. Cet échantillon a été combiné avec celui collecté par l'expérience CMS et pour la première fois la désintégration B0(s)→μμ a été observée. En vue d'améliorer la sensibilité au mode B0(s)→μμ de nouvelles études ont également été menées pour augmenter la performance des analyses multivariées. Une autre partie du travail original présenté dans cette thèse concerne la définition d'une chaine de sélection pour la recherche des désintégrations B0(s)→τ τ dans l'état final où les deux τ vont en trois π chargées et un τ est étudié. La présence des deux ν dans l'état final de la désintégration rend difficile une reconstruction des impulsions des deux τ. Cependant, la possibilité de mesurer les deux vertex de désintégration des τ ainsi que le vertex d'origine du candidat B, permet d'imposer des contraintes géométriques qui peuvent être utilisées dans la reconstruction des impulsions des deux τ. En particulier, un nouvel algorithme pour la reconstruction complété, événement par événement, de ces impulsions et de leurs variables associées est présenté et discutéThe B0(s)→ll decays are generated by Flavor Changing Neutral Currents, hence they can proceed only through loop processes. For this reason, and because of an additional helicity suppression, their branching ratios are predicted to be very small in the Standard Model (SM). A part of the original work presented in this thesis has been devoted to the optimization of the Multi Variate Analysis classifier for the search of the B0(s)→μμ with the full dataset collected at LHCb. This dataset has also been combined with the one collected from CMS to obtain the first observation of B0(s)→μμ has been obtained. In view of the update of the analysis aiming to improve the sensitivity for the B0(s)→μμ mode, a new isolation variable, exploiting a topological vertexing algorithm, has been developed and additional studies for a further optimization of the MVA classifier performances have been done. The presence of two ν in the final state of the decay makes the reconstruction of the τ momenta of the two τ. Nevertheless the possibility of measuring the two decay vertexes of the τ, as well as the B candidate production vertex, allows to impose geometrical constraints that can be used in the reconstruction of the τ momenta. In particular, a new algorithm for the full reconstruction of each event of these momenta and of related variables has been presented and discussed
17
Damet, Jerome. « Physics and Detector Simulation Studies of B-Meson Decays in ATLAS ». Doctoral thesis, Uppsala University, Department of Nuclear and Particle Physics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1284.
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Damet, Jérôme. « Physics and detector simulation studies of B-meson decays in ATLAS / ». Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-4942-5/.
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Bertholet, Émilie. « Search for new physics in charmless three-body B-meson decays ». Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS178.
Texte intégralRésumé :
Cette thèse traite de différents aspects de l'analyse des désintégrations de mésons B en trois particules non charmées. Une étude d'une méthode d'extraction de la phase faible gamma de la matrice CKM utilisant cinq modes de désintégration sous l'hypothèse de symétrie SU(3) de saveur est effectuée. Le résultat est obtenu en utilisant les résultats d'analyses de BABAR et inclut une propagation complète des incertitudes. Six solutions sont obtenues avec une incertitude inférieure à 11 degrés. Il est aussi montré que l'effet de la brisure de SU(3) sur l'analyse, moyenné sur le plan de Dalitz, est de l'ordre de quelques pourcents. Une seconde analyse décrite dans ce manuscrit concerne la mesure des rapports de branchements des modes B0(s)->KShh', où h(') représente un pion ou un kaon. Le résultat est obtenu en utilisant les données collectées par le détecteur LHCb pendant le run I et une partie du run II, correspondant à une luminosité intégrée de 5/fb. Le mode B0s->KSKK est observé pour la première fois, avec une significance de presque 7 déviations standard. Le rapport de branchement de B0s->KSKK normalisé par B0->KSpipi est extrait. Cette analyse constitue une étape vers la mesure des rapports de branchements des six modes B0(s)->KShh' avec la totalité des données des runs I et IIThis thesis discusses different aspects of the analysis of charmless three-body B-meson decays. A study of a method of extracting the weak phase gamma using five decay modes under the assumption of flavour-SU(3) symmetry is performed. This study is carried out using BABAR-analysis results and consists in a complete proof of principle, including fully propagated uncertainties. Six possible solutions are obtained with an uncertainty below 11 degrees. It is also found that, when averaged over the entire Dalitz plane, the effect of SU(3) breaking on the analysis is only at the percent level. A second analysis presented in the manuscipt consists in the measurement of the branching fractions of the B0(s)->KShh' modes, where h(') represents a pion or a kaon. It uses data collected by the LHCb detector during run I and a part of run II, corresponding to an integrated luminosity of almost 5/fb. The B0s->KSKK decay mode is observed for the first time, with a significance of almost 7 standard deviations; the B0s->KSKK branching fraction with respect to B0->KSpipi is extracted. This analysis paves the road to the measurements of the branching fractions of the six B0(s)->KShh' decay modes with the whole run I and run II LHCb dataset
20
Maksimović, Petar 1968. « Observation of [pi]-B meson charge-flavor correlations and measurement of time dependent B⁰⁰ mixing in pp collisions ». Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47407.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1998.On t.p. "[pi]" appears as the lower case Greek letter, and the second "B" and "p" are each surmounted by a stroke.
Includes bibliographical references (p. 238-243).
by Petar Maksimović.
Ph.D.
21
King, James Edward. « A study of charm meson production in semileptonic B decays at LEP ». Thesis, Queen Mary, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339003.
Texte intégral
22
Bellerive, Alain. « Investigation of semileptonic B meson decays to p-wave charm mesons ». Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34913.
Texte intégralRésumé :
This thesis presents an investigation of semileptonic B meson decays with a narrow P-wave charm meson in the final state. The data sample consists of 3.29 x 106 BB¯ events collected with the CLEO II detector at the Cornell Electron-positron Storage Ring. The P-wave charm mesons are reconstructed in the chain of decays: D0J→D*+p- ,D*+→D0p+,D 0→K-p+ or D0→K-p+p 0 . Study of the decay B-→D*+p0ℓ -nℓ&d1; reveals useful information about the deficit observed in inclusive charm semileptonic B decays and the effective couplings of the W boson to heavy quark mesons. The results obtained for the exclusive semileptonic product branching fractions are BB-→D0 1ℓ-nℓ &d1;B D01→D*+p - = (0.373 +/- 0.085 +/- 0.052 +/- 0.024)% and BB-→D*0 2ℓ-nℓ&d1; BD*0 2→D*+p- < 0.16% (90% C.L.). The assumption BD01→D* +p- = 67% and BD*02→D *+p- = 20% implies BB-→D01 ℓ-nℓ&d1; (0.56 0.13 +/- 0.08 +/- 0.04)% and BB-→D*0 2ℓnℓ&d1; < 0.8% (90% C.L.). These results indicate that at least 18% of the total B semileptonic rate is still unaccounted for by the observed exclusive decays, B&d1;→D0ℓ- n&d1;ℓ, B&d1;→D*ℓn &d1;ℓ,B&d1; →D1ℓn&d1; ℓ, and B&d1;→D*2 ℓn&d1;ℓ . Furthermore, the first measurement of the q 2 spectrum for B-→D01ℓn &d1;ℓ is presented. The present analysis also suggests that the Λ QCD/mQ corrections beyond the HQS prescriptions might be significant in the theoretical treatment of the dynamics of B semileptonic decays to excited charm mesons.
23
Kanik, Inanc. « Light Cone Qcd Sum Rules And Meson Physics ». Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610082/index.pdf.
Texte intégralRésumé :
In this thesis, we applied Light Cone QCD sum rules
(LCSR) to several problems in meson physics. Semileptonic B->eta l v decays are important to get information on Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. We calculated form factors of this decay in LCSR frame. Our results are confirmed by later studies and these similar studies had been used for enhancing result on b to u quark transition matrix element of CKM matrix by BaBar collaboration. We used LCSR method also for calculating coupling constant of radiative rho ->
eta photon decay since the analysis of the vector particle to pseudoscalar particle radiative decay with eta and eta'
mesons in final state can provide insights to the long standing issue of the eta and eta'
mixing. Our result g_{rho eta photon}=(1.4 ±
0.2) is very close to experimental value g_{ rho eta photon} = (1.42 ±
0.12). We also calculated magnetic moment of the rho meson in LCSR frame which is an important parameter since it is strongly related to internal structure of hadron. Our result 2.3 ±
0.5 in units of (e/2m_rho), is in better agreement with lattice QCD results than traditional QCD sum rules. Quark contents of light scalar mesons are still under debate and we analyzed phi ->
K K decays which is important for understanding the quark content of the f0 meson. Our final result is g_{phi KK} = 4.9 ±
0.8 which is in well agreement with existing experimental result g_{phi KK} = 4.8.
24
Cakmak, Kerim Mehmet. « Model Independent Analysis Of Rare Exlusive B-meson Decays ». Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604763/index.pdf.
Texte intégralRésumé :
Using the general, model indepenent form of the effective Hamiltonian, the general expressions of the longitudinal, normal and transversal polarization asymmetries for l+ and l- for the effective B ->K(K*)l+l- decays has been calculated. Existence of regions of Wilson coefficients for which the branching ratio coincides with the Standard Model result, while the lepton polarizations differ from the standard model prediction is expected. Hence, studying lepton polarizations in these regions of Wilson coefficients may be helpful in establishing new physics beyond standard model.
25
Krop, Dan. « A search for neutral B meson oscillations at the Tevatron collider experiment DO ». [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3264318.
Texte intégralRésumé :
Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2007.Source: Dissertation Abstracts International, Volume: 68-05, Section: B, page: 3121. Adviser: Rick Van Kooten. "Title from dissertation home page (viewed Jan. 24, 2008)."
26
Gerardin, Antoine. « Heavy-light meson properties from latice QCD ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112185/document.
Texte intégralRésumé :
Les mésons lourd-légers jouent un rôle majeur dans la recherche de nouvelle physique au delà du modèle standard. En particulier, les propriétés du méson B sont utilisées pour contraindre la matrice Cabibbo-Kobayashi-Maskawa (CKM) qui décrit les changements de saveur d’un quark lors d’une interaction faible.Les interactions entre quarks et gluons sont décrites par la théorie de l'interaction forte (QCD). Cette dernière prédit, qu'à faible énergie, le couplage de la théorie croît rendant tout traitement perturbatif impossible. La QCD sur réseau est une régularisation non-perturbative de la QCD adaptée aux simulations numériques. Néanmoins, l'étude des mésons lourd-légers est particulièrement délicate puisqu'elle nécessite la prise en compte de nombreuses échelles d'énergies. La théorie effective des quarks lourds (HQET) peut alors être utilisée : elle consiste en une expansion systématique du Lagrangien QCD et des fonctions de corrélation en puissance de 1/m où m est la masse du quark lourd.Après avoir présenté les outils de la QCD sur réseaux, un calcul de la masse du quark b avec nf=2 quarks dynamiques est présentée. Toutes les étapes sont réalisées de manière non-perturbative et le résultat est une importante vérification de la valeur actuellement citée par le PDG et qui repose essentiellement sur des calculs perturbatifs.Dans la seconde partie de la thèse, après avoir présenté les Lagrangiens décrivant les mésons lourd-légers dans la limite chirale, je présente le calcul de deux couplages. Le premier couplage est associé à la transition hadronique B* '→Bπ où B* 'est la première excitation radiale du méson B vecteur. Il est obtenue en étudiant le rapport de fonctions de corrélation à trois et deux points et le problème aux valeurs propres généralisées (GEVP) est utilisé pour isoler la contribution de l'état excité. Dans un second temps, le couplage h décrivant la transition entre des mésons B scalaire et pseudoscalaire est calculé. Ce couplage intervient dans les extrapolations chirales de différentes quantités, comme la constante de désintégration du méson B scalaire. Nous verrons que le couplage h est important et qu'il ne peux pas être négligé.Finalement, je présenterai nos résultats concernant le calcul de la masse et de la constant d'annihilation de la première excitation radiale du méson D. Je comparerai la masse obtenue avec celle du nouvel état récemment découvert par la Collaboration BaBar et j'expliquerai comment le calcul de la constante d'annihilation peut aider dans la résolution du problème "1/2 vs. 3/2''. Tout au long de ce travail, le GEVP est utilisé pour réduire la contribution des états excités. De plus les extrapolations chirales et la limite du continue sont étudiées afin de tenir compte des différentes sources d'erreurs statistiquesHeavy-light mesons play an important role in the search of new physics beyond the Standard Model. In particular B-mesons properties can be used to put constraints on the matrix elements of the Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix governing flavour-changing weak decays.The dynamics of quarks and gluons are described by Quantum Chromodynamic (QCD). This theory predicts that, at low energies, the associated coupling constant increases, making the use of perturbative methods ineffective. Lattice QCD is a non-perturbative regularization scheme of QCD, suitable for numerical simulations. However, studying heavy-light mesons remains a challenging task due to the many different energy scales that must be considered simultaneously on the lattice. In this work, I use the Heavy Quark Effective Theory (HQET), which consists in a systematic expansion of the QCD Lagrangian and correlation functions in 1/m where m is the mass of the heavy quark.After a presentation of the main techniques used in lattice simulations, a computation of the b-quark mass with nf=2 dynamical quarks is presented. All the steps are performed non-perturbatively, offering an important cross-check of the value cited in the PDG which mainly relies on perturbation theory. A computation of the B-meson decay constant at static and first orders in HQET will be also presented and phenomenological implication are discussed.In the second part of this thesis, after introducing the Heavy Meson Chiral Lagrangians and its different couplings, I present the lattice computation of two such couplings. The first one is associated to the hadronic transitionB* '→Bπ where B* 'is the radial excitation of the vector B meson. The Generalized Eigenvalue Problem (GEVP) will be used to extract information about the excited state from the ratio of three-point to two-point correlation functions and I will discuss the phenomenological implications of our results. Then, I will present the computation of the coupling h between the scalar and the pseudoscalar B mesons using two-point correlation functions. This coupling enters the formulae used to guide the chiral extrapolations when positive parity states are taken into account. We will see that h is large compared to the other couplings and that B meson orbital excitation degrees of freedom cannot be missed in chiral loops.Finally, I will present the lattice computation of the mass and decay constant of the first radial excitation of the D meson. The mass will be compared with the recently observed state by the BaBar Collaboration and I show how the decay constant can help to solve the so-called "1/2 vs. 3/2'' puzzle. In this work, the GEVP is used to control the contribution from higher excited states and continuum and chiral extrapolations are performed to take intro account systematic errors
27
Williams, Kimberly Marie. « Search the decay of the B meson to two leptons at the Belle Experiment ». Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73753.
Texte intégralRésumé :
The set of decays known as B⁰ → l⁺l⁻ are exceedingly rare. This thesis details procedures developed to optimize signal extraction and improve the upper limit on the measured branching fraction. When applied to 85 million BB events collected at the Belle experiment in Tsukuba, Japan, the resulting upper limits on branching fractions were 8.8×10⁻⁸ for B⁰ → e⁺e⁻, 1.0×10⁻⁷ for B⁰ → μ⁺μ⁻, and 8.5×10⁻⁸ for B⁰ → e±μ∓" at the 90% confidence level.Ph. D.
28
Chai, Xuedong. « Exclusive B decays into final states with two charmed baryons ». Diss., University of Iowa, 2007. http://ir.uiowa.edu/etd/126.
Texte intégral
29
Shears, Tara Georgina. « A measurement of the B'+ and B'0 meson lifetimes and lifetime ratio using the OPAL detector at LEP ». Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390212.
Texte intégral
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Janicek, René. « Search for charmed meson-pion continuum production in semileptonic B decays at CLEO II ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ64583.pdf.
Texte intégral
31
Grant, Fraser Cameron. « A study of B'0â†S meson production in Z'0 decays at LEP ». Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360596.
Texte intégral
32
Sigamani, Michael. « Determination of |Vub| using the lepton energy spectrum in events tagged with a fully reconstructed B meson ». Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/585.
Texte intégralRésumé :
We present measurements of partial branching fractions for the inclusive semileptonic decay of B ! Xu` (` = e or ) leading to the determination of the CKM matrix element jVubj. This analysis is based on a sample of 460 million BB events recorded at the (4S) resonance at the BABAR detector. We select B ! Xu` events using the energy spectrum of the lepton (E`) in an event where one of the B-mesons is fully reconstructed. We measure partial branching fractions in restricted regions of the E` spectrum, which are translated into values of jVubj using four theoretical approaches. We calculate the arithmetic mean, using the results from the four theoretical approaches at E` > 1:5 GeV resulting in: jVubj = (4:68+0:31 0:32) 10 3. The analysis presented in this thesis is the rst time a measurement of jVubj has been performed using the E` spectrum in events tagged with a fully reconstructed B meson.
33
Goldenzweig, Pablo D. « A Study of Neutral B Meson Decays to ωK*0 at Belle ». University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227110694.
Texte intégral
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Nolte, Detlef Reinhard. « Topics in high energy physics : from supersymmetric gauge field theories to rare B meson decays / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9974117.
Texte intégral
35
Bird, Thomas. « Flavour studies with LHCb : b-meson mixing, lepton-flavour violation and the velo upgrade ». Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/flavour-studies-with-lhcb-bmeson-mixing-leptonflavour-violation-and-the-velo-upgrade(7a8a7cf6-4885-4bc3-80b7-8208d606cf9f).html.
Texte intégralRésumé :
Semileptonic B decays of the type Bq⁰→Dq⁻μ⁺ν (where Dq⁻→K⁻K⁺pie⁻) are selected and their lifetimes are corrected using a statistical simulation-based correction called the k-factor. Using 1 fb⁻¹ of LHCb data the B⁰ and Bs⁰ mixing frequencies are measured to be Deltamd = ( 0.503 ± 0.011 (stat) ± 0.013 (syst) ) ps⁻¹ and Deltams = ( 17.93 ± 0.22 (stat) ± 0.15 (syst) ) ps⁻¹. We exclude the null hypothesis of no mixing for the B⁰ and Bs⁰ by 5.8 and 13.0 standard deviations respectively. This is the first observation of Bs Bsbar mixing using only semileptonic B decays. The lepton flavour violating decay D⁰→eμ is searched for, using tagged D⁰ decays from D*→D⁰pie, and the measurement is normalised using D⁰→K⁻pie⁺ decays. No evidence is seen of an excess over the expected background and so a limit is placed B(D⁰→eμ) < 1.3×10⁻⁸ at a 90% confidence level using 3 fb⁻¹ of LHCb data. This improves the previous measurement by a factor of 20 and is the world's best measurement. Possible upgrades to the LHCb VELO detector are simulated and aspects of the upgraded detector are optimised to ensure that all tracks within the angular acceptance can be detected with high precision. Finally the simulated performance of the current and upgraded VELO detectors are compared.
36
Webber, Adam Dane. « Radiation damage studies in the LHCb VELO detector and measurement of the flavour-specific asymmetry in semileptonic B-decays ». Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/radiation-damage-studies-in-the-lhcb-velo-detector-and-measurement-of-the-flavourspecific-asymmetry-in-semileptonic-bdecays(6a41db51-8d4e-4b43-914b-80a1c73d5271).html.
Texte intégralRésumé :
This thesis presents several studies of data collected at the LHCb detector during its first two years of operation. A detector upgrade study is first presented, using simulated events at an increased luminosity. A second study involves radiation damage to the silicon sensors of the LHCb Vertex Locator. During 2010 and 2011the silicon sensors were exposed to a range of fluences, with sensors in the mostactive regions exposed to fluences of up to approximately 45x10^12 1MeV neutron equivalent (1MeV neq). The first observation of n+-on-n sensor type inversion at the Large Hadron Collider is reported, occurring at a fluence of around (10-15)x10^12 of 1MeV neq. The effective depletion voltages of the only n+-on-p sensors in use at the Large Hadron Collider have also been studied, with decreases of around 25V observed after initial irradiation. Following this, the effective depletion voltage inn+-on-p type sensors is observed to increase at a comparable rate to type inverted n+-on-n type sensors. A reduction in the charge collection efficiency due to an unexpected effect involving the sensor readout lines is also observed. A third study relates to CP violation in neutral B-meson mixing, by the measurement of the flavour-specific asymmetry. In the Standard Model, CP violation from this source is expected to be of order 10^-4. Any measured enhancement of this would be a strong indication of new physics. The DØ collaboration has measured the flavour specific asymmetry from B0 and B0s mixing, and found it to be inconsistent with the Standard Model at a confidence level of 3.9 standard deviations, thus motivating an independent measurement from the LHCb experiment. Using the full 2011 LHCb dataset, corresponding to 1.0 fb^-1 of recorded luminosity, the B0s-meson component of the flavour-specific asymmetry is measured to be afs_s = (-0.12 +/- 0.48 +/- 0.34)%, where the first uncertainty is statistical and the second is systematic. This is the single most accurate measurement of afs_s, and is consistent with both the DØ measurement and the Standard Model prediction.
37
Lindemann, Dana. « The search for rare non-hadronic B-meson decays with final-state Neutrinos using the BaBar detector ». Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110563.
Texte intégralRésumé :
This thesis presents the searches for two rare B meson decays: the radiative leptonic decay B+ -> l+ nu gamma (l = e, mu) and the flavor-changing neutral current B -> K(*) nu nubar. These searches use the full dataset collected by the BaBar experiment, which corresponds to almost 500 million BB pairs. After fully reconstructing the hadronic decay of one of the B mesons in Upsilon(4S) -> BB decays, evidence of B+ -> l+ nu gamma or B -> K(*) nu nubar is looked for in the rest of the event. No significant evidence of either signal decay is observed. Model-independent branching-fraction upper limits are set at BR(B ->e nu gamma)<17 x10^{-6}, BR(B ->mu nu gamma)<24 x10^{-6}, and BR(B ->l nu gamma)<15.6 x10^{-6}, all at the 90% confidence level. These are currently the most stringent published upper limits for B+ -> l+ nu gamma. In addition, branching-fraction upper limits are set at BR(B -> K+ nu nubar)<3.7 x10^{-5}, BR(B -> K0 nu nubar)<8.0 x10^{-5}, BR(B -> K*+ nu nubar)<11.5 x10^{-5}, and BR(B -> K*0 nu nubar)<9.2 x10^{-5}, all at the 90% confidence level. For additional sensitivity to New Physics contributions, partial B -> K(*) nu nubar branching-fraction upper limits are also determined over the full kinematic range.Cette thèse présente l'étude de deux désintégrations rares de mésons B: la désintégration radiative leptonique B+ -> l+ nu gamma (l = e, mu) et le courant neutre qui change la saveur B -> K(*) nu nubar. Ces études utilisent l'ensemble des données recueuillies par l'expérience BaBar, ce qui correspond à près de 500 millions paires BB. Après la reconstruction totale de la désintégration hadronique de l'un des mésons B dans la désintégration Upsilon(4S) -> BB, la manifestation de B+ -> l+ nu gamma ou B -> K(*) nu nubar est recherché dans le reste de l'événement. Aucune preuve significative de la désintégration du signal n'a été observée. Les limites supérieures du rapport d'embranchement indépendantes du modèle sont évaluées à BR(B -> e nu gamma)<17 x10^{-6}, BR(B -> mu nu gamma)<24 x10^{-6}, et BR(B -> l nu gamma)<15,6 x10^{-6}, à un niveau de confiance de 90%. Ce sont actuellement les limites supérieures les plus strictes publiés pour B+ -> l+ nu gamma. De plus, les limites supérieure du rapport d'embranchement sont évaluées à BR(B -> K+ nu nubar)<3,7 x10^{-5}, BR(B -> K0 nu nubar)<8,0 x10^{-5}, BR(B -> K*+ nu nubar)<11,5 x10^{-5}, et BR(B -> K*0 nu nubar)<9,2 x10^{-5}, à un niveau de confiance de 90%. Pour demeurer réceptives aux contributions de la nouvelle physique, les limites supérieures du rapport d'embranchement partiel de B -> K(*) nu nubar sont déterminés dans le spectre cinématique complet.
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Rogers, Gareth James. « A study of direct CP-violation in charged B-meson decays with the LHCb experiment ». Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610176.
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Davis, Adam C. « Search for Mixing and Charge Parity Violation in Neutral Charm Mesons through Semileptonic B Meson Decay ». University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470671480.
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Trincaz-Duvoid, Sophie. « Etude du bruit de fond engendré par la machine PEP-II à l'aide d'une mini-TPC. Etude de la désintégration doublement charmée du meson B avec le détecteur BaBar ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2001. http://tel.archives-ouvertes.fr/tel-00006496.
Texte intégral
41
Hill, Donal Patrick. « Studies using B± → Dh± decays in the LHCb Run I data ». Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:4e2457b4-f947-4cae-a4eb-0ea44ffd9421.
Texte intégralRésumé :
Using data equivalent to an integrated luminosity of 3 fb−1 collected by the LHCb experiment during Run I (2011-2012), studies of beauty mesons decaying to a final state containing open charm are performed, concluding with a number of new results. Direct CP-violation is explored in B± → Dh± decays through several measurements of CP violating observables, where the charmed meson D is reconstructed in both 2-track and 4-track final states. A measurement of the B± production asymmetry at LHCb is reported using B± → Dπ± decays, and a complementary measurement of the CP asymmetry in B± → J/ψK± decays made. A search for the rare Bc− → D(*)π− and Bc− → D (*)K− decays concludes this work.
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Eygi, Zeynep Deniz. « The Standard Model Analyasis Of The Cp Violation In The Inclusive Semileptonic B-meson Decays ». Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12604712/index.pdf.
Texte intégralRésumé :
Being a flavor changing neutral current process, inclusive semileptonic B- meson decays provide reliable testing grounds for the Standard Model at the loop level. They are also importanat in the CKM phenomology and investing the CP violation due to the existence of sizable interference terms in the decay amplitude. In this work , the rare inclusive semileptonic B- meson decays for (lepton is electron ,muon , tau) are investigated in the context of the Standard Model.The differential branching ratio, forward-backward asymmetry ,CP &ndashviolating asymmetry and CP &ndash
violating asymmetry in the forward-backward asymmetry in these processes are examined.The dependencies of these physical parameters on the Standard Model parametres are analyzed by paying a special attention to the long distance effects. Although the branching ratios predicted for the inclusive semileptonic B- meson decays are relatively small because of CKM suppression , it has been found that there is a significant ACP and ACP(AFB) for these processes.
43
Yilmaz, Umit Oktay. « The Polarization Properties Of The Final State Particles In The Rare Radiative B-meson Decay ». Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606100/index.pdf.
Texte intégralRésumé :
A general analysis of the photon and lepton polarizations in the rare Bs →
&
#61543
l+l- decay by using the most general model independent form of the effective Hamiltonian is presented. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are studied. The sensitivity of "
photon polarization asymmetry"
and the longitudinal, transverse and normal polarization asymmetries of final state leptons, as well as lepton-antilepton combined asymmetries in Bs &
#8594
&
#61543
l+l- decay to the new Wilson coefficients are also investigated. It is shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.
44
Williams, Michael D. Jr. « Searching for Clean Observables in $B -> ; D* /tau- \bar{\nu}_{\tau}$ Decays ». VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5885.
Texte intégralRésumé :
In this thesis, the clean angular observables in the $\bar{B} \to D^{*+} \ell^- \bar{\nu}_{\ell}$ angular distribution is studied. Similar angular observables are widely studied in $B \to K^* \mu^+ \mu^-$ decays. We believed that these angular observables may have different sensitivities to different new physics structures.
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Duraisamy, Murugeswaran. « Power Corrections in e+e- →M1M2 and in Charmless Two Body B meson Decays ». University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258470956.
Texte intégral
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Acar, Hilal. « The Inclusive Semileptonic Decays Of The B-meson In A Cp Softly Broken Two Higgs Doublet Model ». Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604766/index.pdf.
Texte intégralRésumé :
In this work, the B->X_dell ell decays are examined in the context of a CP softly broken two Higgs doublet model. The differential branching ratio, forward-backward asymmetry, CP-violating asymmetry, CP-violating asymmetry in the forward-backward asymmetry and polarization asymmetries of the final lepton in this decay are studied. The dependencies of these physical parameters on the model parameters are analyzed by paying a special attention to the effects of neutral Higgs boson (NHB) exchanges and possible CP violating effects. It has been found that NHB effects are quite significant for the tau mode and the above-mentioned observables seems to be promising as a testing ground for new physics beyond the SM, especially for the existence of the CP-violating phase in the theory.
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Blount, Nicholas L. 1979. « A search for direct and radiative decays of the neutral B meson to invisible final states using a hadronic tagging method at the BABAR detector ». Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/9171.
Texte intégralRésumé :
xii, 118 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.This dissertation describes a search for the decays B 0 [arrow right] invisible and B 0 [arrow right] invisible+γ, where invisible refers to a final state consisting of long lived particles with a low cross-section for interaction with matter, leading to a low probability of detection in typical particle detectors. While the branching fractions for these decays predicted by the Standard Model are far below what could be feasably measured by current experiments, new physics such as right-handed neutrinos propagating in large extra space-time dimensions or light R-parity violating neutralinos in supersymmetry could greatly enhance the branching fractions. The decays are searched for in data corresponding to 423.5 fb -1 integrated luminosity produced at the Υ(4 S ) resonance collected with the BABAR detector at the PEP-II B factory, corresponding to 2.30 × 10 8 B 0 B¯ 0 pairs. Using those events that contain a hadronically reconstructed neutral B meson, evidence for the signal decays is sought in the remainder of the event. In (5.00 ± 0.02) × 10 5 events with a fully reconstructed neutral B meson, a total of 39 events consistent with the B 0 [arrow right] invisible decay mode are seen in data with an expected background of 28.5 ± 7.8(stat.)±9.2(syst.) events, and 8 events consistent with the B 0 [arrow right] invisible+γ decay mode are seen in data mode with an expected background of 14.1 ± 5.5(stat.)±8.1(syst.) events, from which upper limits of [Special characters omitted.] ( B 0 [arrow right] invisible) < 11.7 × 10 -5 and of [Special characters omitted.] ( B 0 [arrow right] invisible+γ) < 4.3 × 10 -5 at the 90% confidence level are obtained.
Adviser: David Strom
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Sumensari, Olcyr. « Search of new physics through flavor physics observables ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS315/document.
Texte intégralRésumé :
La recherche indirecte des effets de la physique au-delà du Modèle Standard à travers les processus de la saveur est complémentaire aux efforts au LHC pour observer directement la nouvelle physique. Dans cette thèse nous discutons plusieurs scénarios au-delà du Modèle Standard (a) en utilisant une approche basée sur les théories de champs effective et (b) en considérant des extensions explicites du Modèle Standard, à savoir les modèles à deux doublets de Higgs et les scénarios postulant l'existence des bosons leptoquarks scalaires à basse énergie. En particulier, nous discutons le phénomène de la brisure de l'universalité des couplages leptoniques dans les désintégrations basées sur les transitions b → sℓℓ et b → cτν, et la possibilité de chercher les signatures de la violation de la saveur leptonique à travers les modes de désintégration similaires. Une proposition pour tester la présence d'un boson pseudoscalaire léger à travers les désintégrations des quarkonia est aussi présentéeIndirect searches of physics beyond the Standard Model through flavor physics processes at low energies are complementary to the ongoing efforts at the LHC to observe the New Physic phenomena directly. In this thesis we discuss several scenarios of physics beyond the Standard Model by (a) reusing the effective field theory approach and (b) by considering explicit extensions of the Standard Model, namely the two-Higgs doublet models and the scenarios involving the low energy scalar leptoquark states. Particular emphasis is devoted to the issue of the lepton flavor universality violation in the exclusive decays based on b → sℓℓ and b → cτν, and to the possibility of searching for signs of lepton flavor violation through similar decay modes. A proposal for testing the presence of the light CP-odd Higgs through quarkonia decays is also made
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Tayduganov, Andrey. « Electroweak radiative B-decays as a test of the Standard Model and beyond ». Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00648217.
Texte intégralRésumé :
Recently the radiative B-decay to strange axial-vector mesons, B--> K1(1270) gamma, was observed with a rather large branching ratio. This process is particularly interesting as the subsequent K1-decay into its three-body final state allows us to determine the polarization of the photon, which is mostly left(right)-handed for Bbar(B) in the Standard Model while various new physics models predict additional right(left)-handed components. In this thesis, a new method is proposed to determine the polarization, exploiting the full Dalitz plot distribution, which seems to reduce significantly the statistical errors on the polarization parameter lambda_gamma measurement.This polarization measurement requires, however a detailed knowledge of the K1--> K pi pi strong interaction decays, namely, the complex pattern of the various partial wave amplitudes into several possible quasi-two-body channels as well as their relative phases. A number of experiments have been done to extract all these information while there remain various problems in the previous studies. In this thesis, we investigate the details of these problems. As a theoretical tool, we use the 3P0 quark-pair-creation model in order to improve our understanding of strong K1 decays.Finally we try to estimate some theoretical uncertainties: in particular, the one coming from the uncertainty on the K1 mixing angle, and the effect of a possible ''off-set'' phase in strong decay S-waves. According to our estimations, the systematic errors are found to be of the order of sigma(lambda_gamma)^th<20%. On the other hand, we discuss the sensitivity of the future experiments, namely the SuperB factories and LHCb, to lambda_gamma. Naively estimating the annual signal yields, we found the statistical error of the new method to be sigma(lambda_gamma)^stat<10% which turns out to be reduced by a factor 2 with respect to using the simple angular distribution.We also discuss a comparison to the other methods of the polarization measurement using processes, such as B--> K* e^+ e^-, Bd--> K* gamma and Bs--> phi gamma, for the determination of the ratio of the Wilson coefficients C7gamma^'eff/C7gamma^eff. We show an example of the potential constraints on C7gamma^'eff/C7gamma^eff. in several scenarios of supersymmetric models.
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Otto, Stephan. « Search for the Decay B0 -> ; eta phi at the BABAR Experiment ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1115583729110-72123.
Texte intégralRésumé :
Presented is a search for the rare hadronic B meson decay B0 -> eta phi. It is based on 86 x 10^6 BB pairs recorded by the BABAR experiment at the Stanford Linear Accelerator Center between 1999 and 2002. phi mesons are reconstructed in the channel phi -> K+ K-. eta mesons are reconstructed in the channels eta -> gamma gamma and eta -> pi+ pi- pi0. Signal events are identified by a candidate counting and a maximum-likelihood method. To ensure an unbiased measurement, the number of signal events is blinded throughout the analysis. Although no significant signal is found by either method, the maximum-likelihood method obtains a smaller statistical uncertainty. In this method, the branching fraction of the decay B0 -> eta phi is determined by the upper limit BR (B0 -> eta phi) < 3.28 x 10^-6 (90%). This value includes a systematic uncertainty of 6.2%. The cited upper limit is consistent with recent theoretical predictions. Therefore, this search gives no indication for particle interactions that are not described by the Standard Model of particle physicsVorgestellt wird eine Suche nach dem seltenen hadronischen B-Meson-Zerfall B0 -> eta phi. Sie basiert auf 86 x 10^6 BB-Paaren, die zwischen 1999 und 2002 vom BABAR-Experiment am Stanford Linear Accelerator Center aufgezeichnet wurden. phi-Mesonen werden im Kanal phi -> K+ K- rekonstruiert. eta-Mesonen werden in den Kanälen eta -> gamma gamma und eta -> pi+ pi- pi0 rekonstruiert. Zur Identifikation von Signalereignissen wird eine Abzählmethode und eine Maximum-Likelihood-Methode verwendet. Um eine unvoreingenommene Messung zu gewährleisten, bleibt die Anzahl der Signalereignisse während der gesamten Analyse blind. Durch keine der verwendeten Methoden wird ein signifikantes Signal nachgewiesen. Die Maximum-Likelihood-Methode liefert jedoch eine kleinere statistische Unsicherheit. In dieser Methode ist das Verzweigungsverhältnis des Zerfalls B0 -> eta phi durch die obere Grenze BR (B0 -> eta phi) < 3.28 x 10^-6 (90%) gegeben. Dieser Wert enthält eine systematische Unsicherheit von 6.2%. Die angegebene obere Grenze ist mit aktuellen theoretischen Vorhersagen konsistent. Damit gibt diese Untersuchung keine Hinweise auf Wechselwirkungen, die nicht durch das Standardmodell der Elementarteilchenphysik beschrieben werden