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Дисертації з теми "Light quark"

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Автор: Grafiati

Опубліковано: 7 липня 2024

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1

Fariborz, A. H. "Investigations in light-quark low-energy quantum chromodynamics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq28486.pdf.

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2

Souchlas, Nicholas. "Quark Dynamics and Constituent Masses in Heavy Quark Systems." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1248013809.

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3

Mes, Alexes K. "Light Quark Masses from QCD Finite Energy Sum Rules." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/30901.

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Due to quark-gluon confinement in QCD, the quark masses entering the QCD Lagrangian cannot be measured with the same techniques one would use to determine the mass of non-confined particles. They must be determined either numerically from Lattice QCD, or analytically using QCD sum rules. The latter makes use of the complex squared energy plane, and Cauchy’s theorem for the correlator of axial-vector divergences. This procedure relates a QCD expression containing the quark masses, with an hadronic expression in terms of known hadron masses, couplings, and lifetimes/widths. Thus, the quark masses become a function of known hadronic information. In this dissertation, the light quark masses are determined from a QCD finite energy sum rule, using the pseudoscalar correlator to six-loop order in perturbative QCD, with the leading vacuum condensates and higher order quark mass corrections included. The systematic uncertainties stemming from the hadronic resonance sector are reduced, by introducing an integration kernel in the Cauchy integral in the complex squared energy plane. Additionally, the issue of convergence of the perturbative QCD expression for the pseudoscalar correlator is examined. Both the fixed order perturbation theory (FOPT) method and contour improved perturbation theory (CIPT) method are explored. Our results from the latter exhibit good convergence and stability in the window s0 = 3.0 − 5.0 GeV2 for the strange quark and s0 = 1.5 − 4.0 GeV2 for the up and down quarks; where s0 is the radius of the integration contour in the complex s-plane. The results are: ms(2 GeV) = 91.8 ± 9.9 MeV, mu(2 GeV) = 2.6 ± 0.4 MeV, md(2 GeV) = 5.3 ± 0.4 MeV, and the sum mud ≡ (mu + md)/2, is mud(2 GeV) = 3.9 ± 0.3 MeV. They compare favourably to the PDG and FLAG world averages. Further in this dissertation the updated series expansion of the quark mass renormalization group equation (RGE) to five-loop order is derived. The series provides the relation between a light quark mass in the modified minimal subtraction (MS) scheme defined at some given scale, e.g. at the tau-lepton mass scale, and another chosen energy scale, s. This relation explicitly depicts the renormalization scheme dependence of the running quark mass on the scale parameter, s, and is important in accurately determining a light quark mass at a chosen scale. The five-loop QCD β(as) and γ(as) functions are used in this determination.

4

Nelson, Daniel Richard. "Partially Quenched Chiral Perturbation Theory and a Massless Up Quark: A Lattice Calculation of the Light-Quark-Mass Ratio." Connect to this title online, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1038343149.

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Thesis (Ph. D.)--Ohio State University, 2002.
Title from first page of PDF file. Document formatted into pages; contains xxiii, 296 p.; also includes graphics (some col.) Includes bibliographical references (p. 293-296). Available online via OhioLINK's ETD Center

5

Samways, Benjamin. "A lattice measurement of the B*Bπ coupling using DWF light quarks and the relativistic heavy quark action". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/361526/.

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I describe a calculation of the B*Bπ coupling in lattice QCD. The B*Bπ coupling is directly related to gb, the leading order low-energy interaction constant of heavy meson chiral perturbation theory. Knowledge of the coupling will help decrease systematic uncertainties in lattice QCD B-physics studies, which are important to constrain the CKM matrix and probe the Standard Model. This calculation is performed with 2+1 flavours of dynamic quarks using the domain wall fermion action. To simulate the heavy b-quark I use a non-perturbatively tuned relativistic heavy quark action which keeps discretisation effects under good control. This allows me to make the first calculation of the B*Bπ coupling directly at the physical b-quark mass. I conduct a chiral and continuum extrapolation to the physical point and consider all sources of systematic error. The final result including both statistical and sytematic errors is gb = 0.567(52)stat(58)sys.

6

Williams, Jimmy. "Two-loop renormalization of the quark propagator in the light-cone gauge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0002/NQ43279.pdf.

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7

Holtmann, Sven. "Goldstone mode effects and critical behaviour of QCD with 2 light quark flavours." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971814430.

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8

DeWitt, Martin Alan. "The Spectrum and Decays of Scalar Mesons in the Light-Front Quark Model." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-03282008-142316/.

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We use the light-front quark model to investigate the structure of the scalar mesons, mainly focusing on the three heavy isoscalar states f0(1370), f0(1500), and f0(1710). We comput the spectrum of scalar mesons by diagonalizing a relativized, QCD-inspired model Hamiltonian written in a basis of 25 simple harmonic oscillator states. The masses are then used to perform a mixing analysis which assumes that the heavy isoscalars are mixtures of quarkonia and the scalar glueball. The resulting quark-glue content is used along with the meson wave functions determined from the spectrum to compute the decay rates to pairs of pseudoscalar mesons (two pions, two kaons, two eta mesons). We find that when the glueball contributions to the decays are ignored, the results are in poor agreement with the available data. However, when we estimate the effect of including the glueball contributions in the decays, a solution can be found that matches the data quite well. In this solution, the f0(1710) is mostly glueball (78%) while the f0(1500) and f0(1370) are mostly mixtures of quarkonia. Additionally, in this solution the glueball contributions to kaon and eta final states are significant, while the contributions to the pion final state is negligible. This finding is in agreement with Chanowitz who uses chiral perturbation theory to show that the amplitude for a scalar glueball to decay to a quark-antiquark pair is proportional to the quark mass. This results in a suppression of the pion decay channel compared to the kaon and eta decay channels.

9

Arndt, Daniel. "Light-Cone Quark Model Analysis ofPseudoscalar and Vector Mesons for Radially Excited States." NCSU, 1999. http://www.lib.ncsu.edu/theses/available/etd-19990518-132243.

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We present a relativistic constituent quark model to analyze the mass spectrum and hadronic properties of radially excited u and d quark sector mesons.Using a simple Gaussian function as a trial wave function for the variational principle togetherwith a QCD motivated Hamiltonian, including not only the Coulomb and confiningpotential but also a relativistic corrected hyperfine interaction term, we obtain the mass spectrum consistent with the experimental data. To do the same for several observables such as decay constants and form factors it seems necessary to include bothDirac and Pauli form factors on the level of constituentquarks. Taking into account these quark form factorswe thus present the generalized formulas for the rho mesondecay constant and the rho meson form factors as well asthe $\pi\gamma$ transition form factor.We alsopredict several hadronic properties for the radiallyexcited states.

10

Arndt, Daniel. "Light-cone quark model analysis of pseudoscalar and vector mesons for radially excited states." Raleigh, NC : North Carolina State University, 1999. http://www.lib.ncsu.edu/etd/public/etd-3522131849921371/etd.pdf.

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11

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.

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Cette thèse présente deux études principales concernant le collisionneur linéaire international (ILC), le futur collisionneur linéaire électron-positron fonctionnant à une énergie de centre de masse de √s = 250GeV, avec une extension potentielle à √s = 1TeV.La première étude porte sur l'analyse des données enregistrées avec un prototype d’un calorimètre électromagnétique silicium-tungstène (SiW-ECAL). Les calorimètres à haute granularité font partie de tous les concepts de détecteurs des projets actuels et futurs de la physique des particules. Ce type de calorimètre permet de reconstruire précisément l'énergie du jet avec une haute résolution à l'aide des algorithmes dits “Particle Flow Algorithms (PFA)”. Pour vérifier la faisabilité de SiW-ECAL, 15 couches comprenant en total 15,360 pixels de silicium, ont été assemblées. Après la chaîne complète de mise en service et leur étalonnage, le prototype fut testé en faisceau de test au SPS du CERN. L'étude analyse des données enregistrées avec un faisceau d'électrons d'une énergie de 10GeV. Les données sont comparées avec une simulation du prototype basé sur le logiciel de simulation GEANT4. La résolution de l'énergie électromagnétique à 10GeV a été mesurée à 12.5±0.2% et s'est avérée compatible avec le résultat simulé de 13.6±0.3%. La seconde étude porte sur la mesure des sections efficaces différentielles de la production de quarks légers dans le processus en e⁺e⁻ → qqbar à √s = 250GeV avec qqbar étant u, d ou s. La section efficace différentielle est mesurée par rapport au cosinus de l'angle polaire du quark diffusé. La mesure précise peut permettre d'extraire les constantes de couplage électrofaible avec le photon ou Z du modèle standard. Ces couplages électrofaibles dépendent de l'hélicité du fermion. Par conséquent, cette mesure profite grandement de la polarisation des faisceaux d'électrons et de positrons. Afin d'extraire le processus dur original, nous sélectionnons l'objet chargé avec la plus grande impulsion d'un jet, qui représente l'empreinte du processus dur. Pour ce faire, une méthode précise d'identification des particules est nécessaire, ce qui est réalisé par l'utilisation des informations dE/dx fournies par la chambre à projection temporelle (TPC) de l'ILD. La précision obtenue sur l'asymétrie avant-arrière A_{FB} pour les états finaux uubar et ddbar se situe entre 3.1% et 9.5% y compris l'erreur systématique. Pour l'état final ssbar la précision sur A_{FB} est entre 0.2% et 1.5%
This 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%

12

Hepburn, Derek John. "Light hadron spectrum, quark masses and meson decay constants from lattice QCD with O(a)-improved dynamical Wilson fermions." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/15009.

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In this thesis I present results for the light hadron spectrum, light quark masses and meson decay constants from numerical simulations of lattice QCD. The simulations were performed on a 16³ x 32 space-time lattice using the standard Wilson gauge field action and a fully O(a)-improved Sheikholeslami-Wohlert fermion action with N_j = 2 degenerate flavours of dynamical fermions. A subset of these simulations were performed at fixed lattice spacing, as determined through the Sommer scale parameter, r_o, in order to investigate the effects associated with a finite sea quark mass whilst keeping cutoff and finite size effects fixed. A quenched simulation was also performed at this lattice spacing for comparative purposes. No clear evidence of unquenching was found in the light hadron spectrum at the quark masses used in the matched simulations studied here. Light quark masses were determined from chiral extrapolations of pseudoscalar and vector meson masses to both the standard and PCAC definitions of the quark mass. The bare strange quark mass was fixed through the K, K* and ø meson masses for comparison. Renormalised quark masses have been determined in the ? scheme at a reference scale of 2GeV with matching performed at two values of the scale parameter, m = 1/a and m = p/a, in order to study the systematic effects.

13

Radloff, Peter. "Search for new light scalar bosons produced in association with a bottom-quark and decaying to two tau leptons." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20536.

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A search for new neutral scalar bosons produced in association with a bottom-quark is performed. The analysis uses data acquired with proton-proton collisions at a center-of-mass energy of 8 TeV and observed with the ATLAS detector at the LHC, corresponding to 20.3 $fb^{-1}$ of integrated luminosity. The search focuses on scalar boson decays into tau lepton pairs, where each decays leptonically ($\tau \rightarrow l \nu_{\tau} \bar{\nu_{l}}$) resulting in one muon, one electron and four neutrinos. No significant excess is observed and upper limits on the signal strength are determined as a function of scalar boson mass.

14

Caldeira, Balkeståhl Li. "Measurement of the Dalitz Plot Distribution for η→π+π−π0 with KLOE". Doctoral thesis, Uppsala universitet, Kärnfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-266871.

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The mechanism of the isospin violating η→π+π−π0 decay is studied in a high precision experiment using a Dalitz plot analysis. The process is sensitive to the difference between up and down quark masses. The measurement provides an important input for the determination of the light quark masses and for the theoretical description of the low energy strong interactions. The measurement was carried out between 2004 and 2005 using the KLOE detector at the DAΦNE e+e− collider located in Frascati, Italy. The data was collected at a center of mass energy corresponding to the φ-meson peak (1019.5 MeV) with an integrated luminosity of 1.6 fb−1. The source of the η-mesons is the radiative decay of the φ-meson: e+e−→φ→ηγ, resulting in the world’s largest data sample of about 4.7·106 η→π+π−π0 decay events. In this thesis, the KLOE Monte Carlo simulation and reconstruction programs are used to optimize the background rejection cuts and to evaluate the signal efficiency. The background contamination in the final data sample is below 1%. The data sample is used to construct the Dalitz plot distribution in the normalized dimensionless variables X and Y. The distribution is parametrized by determining the coefficients of the third order polynomial in the X and Y variables (so called Dalitz plot parameters). The statistical accuracy of the extracted parameters is two times better than any of the previous measurements. In particular the contribution of the X2Y term is found to be different from zero with a significance of approximately 3σ. The systematic effects are studied and found to be of the same size as the statistical uncertainty. The contribution of the terms related to charge conjugation violation (odd powers of the X variable) and the measured charge asymmetries are consistent with zero. The background subtracted and acceptance corrected bin contents of the Dalitz plot distribution are provided to facilitate direct comparison with other experiments and with theoretical calculations.

15

Wallbott, Paul C. [Verfasser]. "Heavy-light four-quark states in the charmonium region in a Bethe-Salpeter and Dyson-Schwinger approach / Paul C. Wallbott." Gießen : Universitätsbibliothek, 2020. http://d-nb.info/1209135248/34.

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16

Peters, Antje Katharine [Verfasser], Marc [Gutachter] Wagner, Pedro [Gutachter] Bicudo, and Christian [Gutachter] Fischer. "Investigation of heavy-light four-quark systems by means of Lattice QCD / Antje Katharine Peters ; Gutachter: Marc Wagner, Pedro Bicudo, Christian Fischer." Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2017. http://d-nb.info/1141230682/34.

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17

Prausa, Mario Verfasser], Robert V. [Akademischer Betreuer] [Harlander, and Michal [Akademischer Betreuer] Czakon. "Towards light quark mass effects in Higgs production and decay at next-to-next-to-leading order / Mario Prausa ; Robert Valentin Harlander, Michal Wiktor Czakon." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171818564/34.

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18

Prausa, Mario [Verfasser], Robert V. [Akademischer Betreuer] Harlander, and Michal [Akademischer Betreuer] Czakon. "Towards light quark mass effects in Higgs production and decay at next-to-next-to-leading order / Mario Prausa ; Robert Valentin Harlander, Michal Wiktor Czakon." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171818564/34.

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19

Gallorini, Stefano. "Study of the K+ → e+νeγ decay with the NA62 experiment". Doctoral thesis, Scuola Normale Superiore, 2013. http://hdl.handle.net/11384/85872.

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The present thesis is focused on the measurement of the form factors of the K+ → e+νeγ decay (Ke2γ) with data collected by the NA62 experiment in 2007 during a preliminary phase of data taking, dedicated to a precision test of lepton flavour universality. For this phase, the NA62 collaboration used the pre-existing apparatus of the NA48/2 experiment. The measurement of the form factors is a test for the effective theories of strong interaction at low energies as the Chiral Perturbation Theory (ChPT) and the Light Front Quark Model (LFQM). The only kinematic configuration accessible to the analysis is the structure-dependent configuration in which the photon is emitted preferentially with positive helicity (SD+ term). The measurement of the Ke2γ form factors is obtained by analysing 11170 reconstructed Ke2γ(SD+) candidates with 4% background contamination, about ten times the statistics collected by earlier experiments. The final result of the analysis, assuming ChPT at O(p6), is: FV (0) + FA(0) = 0.127 ± 0.002stat ± 0.010syst λ = 0.60 ± 0.05stat ± 0.39syst The LFQMprediction of the form factors was also tested but it was found to be completely inconsistent with data.

20

Volk, Alexei. "Measurement of the Partial Branching Fraction for Inclusive Semileptonic B Meson Decays to Light Hadrons B->Xu l nu and an Improved Determination of the Quark-Mixing Matrix Element |V_ub|." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-24169.

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This thesis presents an analysis of inclusive semileptonic $B \to X_u e \nu$ decays using approximately 454 million $\Upsilon(4S) \to B \bar{B}$ decays collected during the years 1999 to 2008 with the BABAR detector. The electron energy, $E_e$, and the invariant mass squared of the electron-neutrino pair,$ q^2$, are reconstructed, where the neutrino kinematics is deduced from the decay products of both B mesons. The final hadronic state,$ X_u$, consists of a sum of many hadronic channels, each of which contains at least one $u$ quark. The variables $q^2$ and $E_e$ are then combined to compute the maximum kinematically allowed invariant mass squared of the hadronic system, $s_h^{max}$. Using these kinematic quantities, the partial branching fraction, $\Delta BR(B \to X_u e \nu)$, unfolded for detector effects, is measured to be $\Delta BR(E_e>2.0 GeV, s_h^{max}<3.52 GeV^2) = (3.33 \pm 0.18 \pm 0.21) \times 10^{-4} in the $\Upsilon(4S)$ and \Delta \tilde{\BR}(\tilde E_e>1.9 GeV, \tilde {s}^{max}_{h} < 3.5 GeV^2) = (4.57 \pm 0.24 \pm 0.32) \times 10^{-4} in the $B$ meson rest frames. The quoted errors are statistical and systematic, respectively. The CKM matrix element $|V_{ub}|$ is determined from the measured $\Delta \tilde{\BR}$ using theoretical calculation based on Heavy Quark Expansion. The result is $|V_{ub}| = (4.19 \pm 0.18{}^{+0.26}_{-0.20} {}^{+0.26}_{-0.25}) \times 10^{-3}, where the errors represent experimental uncertainties, uncertainties from HQE parameters and theoretical uncertainties, respectively.

21

Moomaw, Peter. "Drooped Strings and Dressed Mesons: Implications of Gauge-Gravity Duality for the Properties of Heavy-Light Mesons at Finite Temperature." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250538856.

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22

CASULA, ESTER ANNA RITA. "Low mass dimuon production with the ALICE muon spectrometer." Doctoral thesis, Università degli Studi di Cagliari, 2014. http://hdl.handle.net/11584/266451.

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Low mass vector meson (ρ, ω,Φ ) production provides key information on the hot and dense state of strongly interacting matter produced in high-energy heavy ion collisions (called Quark Gluon Plasma). Strangeness enhancement is one of the possible signatures of the Quark Gluon Plasma formation and can be accessed through the measurement of Φ meson production with respect to ρ and Φ mesons, while the measurement of the Φ nuclear modification factor provides a powerful tool to probe the production dynamics and hadronization process in relativistic heavy ion collisions. Vector mesons can be detected through their decays into muon pairs with the ALICE muon spectrometer. This thesis presents the results on the measurement of the Φ differential cross section, as a function of the transverse momentum, in pp collisions at √s = 2.76 TeV; the measurement of the Φ fyield and of the nuclear modification factor RpA at forward and backward rapidity, as a function of the transverse momentum, in p-Pb collisions at √s = 5.02 TeV; the measurement of the Φ/ (ρ+ω) ratio, as well as of the Φ nuclear modification factors RAA and RCP , as a function of the number of participating nucleons, in Pb-Pb collisions at √sNN = 2.76 TeV.

23

Sandmeyer, Hauke [Verfasser]. "Hadronic correlators from heavy to very to very light quarks / Hauke Sandmeyer." Bielefeld : Universitätsbibliothek Bielefeld, 2019. http://d-nb.info/1189813165/34.

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24

Gavin, Elizabeth Jane Ogle. "Bound states of heavy and light quarks in the framework of quantum chromodynamics." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/14576.

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Bibliography: leaves 53-55.
The spectra of the D, F, B and E mesons have been calculated using the MIT bag model together with a static potential related to the Fourier transform of the "dressed" gluon propagator. The heavy quark has been assumed to coincide with the centre of the bag, while the Light antiquark was treated relativistically using the Dirac equation. The spectra obtained are compared with experimental data as well as with the results of other models of these Qq mesons. The ratio mb/mc obtained in the fit to experimentally known states is compared with the result expected from the hyperfine splitting of the D and B mesons. It appears that tris ratio is model dependent. More experimental data are required to further evaluate the validity of this model.

25

Wissel, Sönke. "Mesonic correlation functions from light quarks and their spectral representation in hot quenched lattice QCD." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982318332.

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26

Gerardin, Antoine. "Heavy-light meson properties from latice QCD." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112185/document.

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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 statistiques
Heavy-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

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ming-long, Hong, and 洪敏隆. "Some Topics of Hadrons within Light-Front Quark Model." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/84217206039344986497.

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碩士
國立高雄師範大學
物理學系
94
Recently, the pentaquarrk has been found in some experiments. The mass of is 1540MeV, but its magnetic moment is unknown.. If we want to identify the pentaquark, we need to know its magnetic moment like mass. Theorists have made several assumptions about the structure of the pentaquark. We choose one of them: the Jaffe- Wilczek model. In this work, we calculate its magnetic moment within the light front mode. In addition, for understanding more information inside mesons, we try to construct the D and D^smesons in S-wave and P-wave state including the hyperfine and fine splitting. Finally, the third topic is the mass and the two photon decay width of eta_b . It is known that decay widths depend on the form factor. We make use the form factors to predict the widths directly. On the other hand, we use our theory to predict the value of eta_c and fit the experimental data to enhance our persuasion.

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Nicmorus, Marinescu Diana [Verfasser]. "Electromagnetic properties of light and heavy baryons in the relativistic quark model / vorgelegt von Diana Nicmorus Marinescu." 2007. http://d-nb.info/985123788/34.

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Holtmann, Sven [Verfasser]. "Goldstone mode effects and critical behaviour of QCD with 2 light quark flavours / vorgelegt von Sven Holtmann." 2004. http://d-nb.info/971814430/34.

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Volk, Alexei [Verfasser]. "Measurement of the partial branching fraction for inclusive semileptonic B meson decays to light hadrons B→Xulv and an improved determination of the quark mixing matrix element Vub / von Alexei Volk." 2009. http://d-nb.info/100774944X/34.

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Jin, Luchang. "Lattice Calculation of Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment." Thesis, 2016. https://doi.org/10.7916/D8319W3T.

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The quark-connected part of the hadronic light-by-light scattering contribution to the muon’s anomalous magnetic moment is computed using lattice QCD with chiral fermions. We report several significant algorithmic improvements and demonstrate their effectiveness through specific calculations which show a reduction in statistical errors by more than an order of magnitude. The most realistic of these calculations is performed with a near-physical, 139 MeV pion mass on a (5.5 fm)³ spatial volume using the 48³ × 96 Iwasaki gauge ensemble of the RBC/UKQCD Collaboration.

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Li, Meng-Wei, and 李孟瑋. "Approaching Connement Structure for Light Quarks in a Holographic Soft Wall QCD Mode." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/hef2gs.

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碩士
國立交通大學
物理研究所
105
In this thesis, I study confinement-deconfinement phase transition of light quarks by holographic soft-wall QCD model. I obtain the phase structure of the black hole backgrounds by solving the Einstein-Maxwell-scalar system analytically. I impose probe open strings in such background to investigate the confinement-deconfinement phase transition from different open string configurations. Finally, I obtain the Cornell potential in confinement phase by the Wilson loop.

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Wissel, Sönke [Verfasser]. "Mesonic correlation functions from light quarks and their spectral representation in hot quenched lattice QCD / vorgelegt von Sönke Wissel." 2006. http://d-nb.info/982318332/34.

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