Littérature scientifique sur le sujet « Quark léger »
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Articles de revues sur le sujet "Quark léger"
Darles, Christian, Alain Badie et Jean-Jacques Malmary. « Le couronnement du rempart de Saint-Lézer (Castrum Bigorra) en Novempopulanie ». Journal of Roman Archaeology 15 (2002) : 317–24. http://dx.doi.org/10.1017/s1047759400014008.
Texte intégralChauvel, Louis, Henri Mendras, Marco Oberti et Pascal Vennesson. « Chronique des tendances de la société française ». Revue de l'OFCE 48, no 1 (1 janvier 1994) : 151–75. http://dx.doi.org/10.3917/reof.p1994.48n1.0151.
Texte intégralThèses sur le sujet "Quark léger"
Okugawa, Yuichi. « Analysis of test beam data using a technological prototype of a highly granular calorimeter and study of light quark production at a future linear collider ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP008.
Texte intégralThis thesis presents two main studies regarding the International Linear Collider (ILC), the future electron-positron linear collider operating at center of mass energy of √s = 250GeV, with the potential extension to √s = 1TeV. The first study is the analysis of data recorded with the silicon-tungsten electromagnetic calorimeter (SiW-ECAL) prototype. Highly granular calorimeters are part of all detector concepts of current and future particle physics projects, to precisely reconstruct the jet energy with high resolution using Particle Flow Algorithm. To verify the feasibility of a SiW-ECAL, 15 layers of a technological prototypes, comprising 15,360 silicon pixels, were assembled. After the full chain of commissioning, the prototypes were tested in beam at the SPS at CERN. The study analyzes one of the √s = 10GeV. Electron beam runs, and compare the result with the GEANT4 simulation using the same setup. The electromagnetic energy resolution for the 10 GeV run was measured to be 12.5±0.2% and found to be compatible with simulated result of 13.6±0.3%. The second study is the measurement of the differential cross sections of light quark production in the process in e⁺e⁻ → qqbar at √s = 250GeV with qqbar being u, d or s. The differential cross section is measured with respect to the cosine of the polar angle of the scattered quark. The precise measurement may allow for the extraction of electroweak coupling constants to the Standard Model photon or Z. These electroweak couplings depend on the fermion helicity. Therefore, this measurement is greatly supported by the polarization of electron and positron beams. In order to extract the underlying hard process, we select the charged Particle Flow Object (PFO) with the largest momentum within a jet. To accomplish this, a precise particle identification method is required. We use the dE/dx information provided by the Time Projection Chamber (TPC) of ILD. The obtained precision for the forward-backward asymmetry, A_{FB}, for the uubar and ddbar channels including the systematic error ranges between 3.1% and 9.5% at the time of the submission of thesis. For ssbar, A_{FB} can be measured with systematic uncertainty as small as 0.2% and 1.5%
Lagae, Jean-François D. « Etude théorique de la spectroscopie des mésons constitués de quarks légers ». Doctoral thesis, Universite Libre de Bruxelles, 1991. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213019.
Texte intégralVulvert, Gregory. « Masse des hadrons et des quarks légers en chromodynamique quantique sur réseau ». Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22021/document.
Texte intégralThe main topic of this thesis is the computation ab initio of masses from lattice QCD.In the first part, the light hadron spectrum is computed. Thanks to a Lüscher-Weisz gauge action and a clover Wilson action describing with the quarks with six levels of stout-smearing, light hadron masses are extracted from simulations with $N_f=2+1$ flavors. These masses agree with experiment with a few percent accuracy and all the systematic errors are under control.In the second part, the light quark masses are determined. We use the same action as previously but with two levels of hex smearing. The simulations are done at the physical point mass and five lattice spacings are used to take a safe conitnuum limit, thus eliminating a higher source of systematice incertitude. Renormalization is perfo,rmed non perturbatively à la Rome-Southampton, thereby suppressing perturbative errors. We obtain in this work the first full non perturbative resultats at the physical point with a high accuracy since we obtain an error of about 5%
Chang, Emmanuel. « QCD sur réseaux et les propriétés des mésons lourd-légers : les distributions radiales dans les mésons lourd-légers et le mélange Bº-B̄º dans la limite statique ». Paris 7, 2009. http://www.theses.fr/2009PA077204.
Texte intégralPhenomenology of the heavy-light mesons is investigated by using QCD simulations on the lattice. The work is particularly focused on the light quark dynamics in the heavy-light Systems when the heavy quark is infinitely heavy. The mass splitting between the excited and the lowest lying states has been studied with the unquenched lattice data containing SN__f=2S dynamical light quarks. A very high accuracy of the lattice results for the coupling to the pions is achieved through several improvements over previous lattice computations of these couplings. Moreover, the present study provides a new method which allows for the first lattice determination of the pion emission in the transition between the first excited and the lowest lying heavy-light meson. These couplings are necessary ingredients for the description of heavy-light mesons by an effective theory known as the Heavy Meson Chiral Perturbation Theory. They are also essential in the chiral extrapolations of the lattice results for the quantities which are relevant to the SBS-physics phenomenology. Special attention is devoted to the improvement of the technique of Computing the static heavy quark propagator on the lattice by using the hyper-cubic blocking techniques (HYP). We then make a detailed study of the matrix elements of ail parity conserving four-quark S\Delta B=2S operators which enter the theoretical description of the SB~0S-S\bar B~0S mixing amplitude in the Standard Model, and in its supersymmetric extensions. This is the first such study with HYP-blocked Wilson lines, which provides us with an extra benefit: the spurious mixing of operators computed on the lattice is much smaller with respect to what has been done in the past. Renormalization and matching of Heavy Quark Effective Theory on the lattice to the continuum QCD is made by using boosted perturbation theory. A short discussion of impact of our results on the SBS-physics phenomenology is provided too
Levêque, Jessica. « Recherche d'un boson de Higgs léger produit en association avec une paire de quarks top dans l'expérience ATLAS ». Aix-Marseille 2, 2003. http://www.theses.fr/2003AIX22024.
Texte intégralCharles, Jérôme. « Désintégration des mésons B. Méthodes d'extraction des angles décrivant la violation de CP. Théorie effective des facteurs de forme lourd à léger ». Phd thesis, Université Paris Sud - Paris XI, 1999. http://tel.archives-ouvertes.fr/tel-00002502.
Texte intégralToucas, Guillaume. « Mécanisme de brisure de symétrie chirale pour trois saveurs de quarks légers et extrapolation de résultats de chromodynamique quantique sur réseau ». Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00754994.
Texte intégralCogneras, E. « Production de paires de Top et effet de Nouvelle Physique. Calibration des jets légers avec le processus W en jet-jet. Mesure de la masse du Top ». Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2007. http://tel.archives-ouvertes.fr/tel-00178221.
Texte intégralGerardin, Antoine. « Heavy-light meson properties from latice QCD ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112185/document.
Texte intégralHeavy-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
Blossier, Benoît. « Phénoménologie des mésons B et Chromodynamique sur réseau ». Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00116253.
Texte intégralsimulation numérique de la Chromodynamique Quantique sur réseau, qui est une approche non perturbative - basée sur les principes premiers de la Théorie Quantique des Champs - de calculer les fonctions de Green de la théorie.
Les couplages $\hat{g}$ et $\tilde{g}$ paramétrant le Lagrangien chiral effectif qui décrit les interactions entre mésons lourd-légers et pions mous ont été calculés au-delà de l'approximation quenched (à N_f=2). L'opérateur
$\bar{q}\gamma_\m \gc q$ a été renormalisé non perturbativement en utilisant les identités de Ward chirales. On trouve
$\hat{g}=0.4\div 0.6$ et $\tilde{g}=-0.1\div-0.3$.
La masse du quark étrange a été estimée par
une simulation unquenched (à N_f=2): elle a été renormalisée
dans le schéma non perturbatif RI-MOM. On obtient en faisant le raccordement avec le schéma MSbar m_s^{MSbar}(2 GeV)=101\pm 8^{+25}_{-0} MeV.
Une méthode a été proposée pour évaluer sur le réseau les facteurs de
forme associés aux transitions semileptoniques à recul nul
B \to D^{**} décrites dans le cadre de la Théorie Effective des Quarks Lourds. La constante de renormalisation de l'opérateur $\bar{h}\gamma_i \gc D_j h$ a été calculée à l'ordre d'une boucle de la théorie des perturbations.
On trouve \tau_1/2(1)=0.3\div 0.5 et \tau_3/2(1)=0.5\div 0.7.
Enfin le paramètre de sac associé à l'amplitude de mélange B_s-anti B_s a été évalué, en choisissant une action pour le quark étrange qui vérifie la symétrie chirale à maille a du réseau finie. De cette manière les erreurs systématiques, provenant des mélanges de chiralité, sont nettement réduites lors de la renormalisation de l'opérateur à 4 fermions $\bar{h}\gamma_{\m L}q\bar{h}\gamma_{\m L}q$. On obtient dans l'approximation quenched $B_{B_s}=0.92(3)$.