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1
Gomshi, Nobary M. A. "Heavy quark fragmentation models." Thesis, Durham University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328988.
Testo completo
2
Wambach, Achim. "Consistent application of quark models to heavy flavour physics." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386750.
Testo completo
3
Potter, Christopher Thomas. "A search for the rare decay B⁰ (arrow tau⁺ tau⁻) at the Babar experiment /." view abstract or download file of text, 2005. http://wwwlib.umi.com/cr/uoregon/fullcit?p3181121.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Oregon, 2005.<br>Typescript. Includes vita and abstract. Includes bibliographical references (leaves 219-223). Also available for download via the World Wide Web; free to University of Oregon users.
4
Murphy, Philip. "Nonrelativistic quark model calculation of the K-P --> [Lambda gamma] and K-P --> [Sigma]0[gamma] branching ratios." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30167.
Testo completoAbstract (sommario):
The radiative annihilation of K⁻p atoms to Λγ and ∑°γ is investigated using a non-relativistic harmonic oscillator quark model. A nonrelativistic reduction of the first order Feynman diagrams is performed to yield a gauge invariant interaction, which is sandwiched between three quark wave functions. Pseudoscalar and pseudovector coupling schemes are used for the strong vertex and the effects of SU(3)flavour breaking is explored. We obtain results which are in agreement with experiment for the ∑°γ but are somewhat high for the Λγ calculation.<br>Science, Faculty of<br>Physics and Astronomy, Department of<br>Graduate
5
Smith, Jason. "Quarks and antiquarks in nuclei /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9750.
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6
Detmold, William. "Nonperturbative approaches to quantum chromodynamics." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phd4817.pdf.
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7
Makke, Nour. "Measurement of the polarization of strange quark in the nucleon and determination of quark fragmentation functions into hadrons." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00673486.
Testo completoAbstract (sommario):
Understanding the nucleon structure is currently one of the main challenges encountered in nuclear physics. The present work represents a contribution to the study of the nucleon structure and deals, in particular, with the study of the role of strange quarks in the nucleon. The latter can be investigated by determing the strange quark distribution in the nucleon as well as the contribution of the spins of strange quarks to the nucleon spin ($\Delta s$). This work first presents a measurement of $\Delta s$ performed via Deeply Inelastic Scattering of a muon beam off polarized proton and deuterium targets. The result is found to be strongly dependent on the quark fragmentation functions into hadrons (FFs), which define the probability that a quark of a given flavour fragments into a final state hadron. The FFs are poorly known, in particular, the FF of strange quark into kaons, which play an important role in the determination of $\Delta s$. In deep inelastic scattering process, the access to the FFs is provided by the hadron multiplicities which, in turn, define the average number of hadrons produced per DIS event. Pion and kaon multiplicities have been extracted versus different kinematic variables, using DIS data collected by deeply inelastic scattering of a $160$ GeV muons off a deuterium target. A first LO extraction of the fragmentation functions has then been performed using the measured pion and kaon multiplicities.
8
Signal, Anthony Ian. "Deep inelastic scattering and bag model." Title page, abstract and contents only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phs578.pdf.
Testo completo
9
Irwin, Blake A. "Calculation of the meson decays of vector Πvector + pseudoscalar using Q.C.D." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63992.
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10
Morales, Patrícia Soares [UNESP]. "Limite de acoplamento forte da QCD e a interação méson-méson." Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/91868.
Testo completoAbstract (sommario):
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morales_ps_me_ift.pdf: 900348 bytes, checksum: 11b8ab9b4c422ec3a42face91d5074e6 (MD5)<br>O mecanismo de rearranjo de tubos de fluxo predito no limite de acoplamento forte da formulação Hamiltoniana da QCD na rede foi implementado num modelo de quarks constituintes e suas consequências investigadas para o espalhamento méson-méson. O rearranjo de tubos de fluxo leva a efeitos similares aos tradicionais efeitos de troca de quarks com troca de um glúon em interações hádron-hádron. Contudo, enquanto o primeiro está relacionado ao regime de confinamento da QCD, o último está relacionado ao regime de liberdade assintótica desta teoria. Mostra-se aqui que ambos mecanismos levam a resultados qualitativamente similares quando o potencial de rearranjo pode ser escrito como a soma de interações locais quark-quark, antiquark-antiquark e quark-antiquark. Para interações gerais, não locais e de longo alcance, o rearranjo de tubos de fluxo leva a resultados qualitativa e quantitativamente diferentes dos resultados de troca de quarks com troca de um glúon. As consequências disso para a fenomenologia das interações hádron-hádron são discutidas.<br>The mechanism of link rearrangement predicted in the strong coupling limit of Hamiltonian lattice QCD is implemented in a constituent quark model and its consequences for meson-meson scattering are investigated. Link rearrangement leads to effects similar to the traditional quark exchange with one gluon exchange in hadron-hadron interactions. However while the first is related to the confinement regime of QCD, the latter is related to the asymptotic freedom regime of this theory. It is shown here that both mechanisms lead to identical qualitative results when the rearrangement potential can be written as a sum of local quark-quark, antiqurk-antiquark e quark-antiquark. For general, long-range nonlocal interactions, link rearrangement leads to results qualitative and quantitatively different from those of quark exchange with one gluon exchange. The consequences of this for the phenomenology of hadron-hadron interactions are discussed.
11
Rasmussen, Rasmus Westphal. "Implications of physics beyond the Standard Model in the quark and lepton sectors." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19174.
Testo completoAbstract (sommario):
Das Standardmodell (SM) der Teilchenphysik hat sich in der Praxis als vielseitige Theorie bewährt, dennoch deuten nichtverschwindende Neutrinomassen, dunkle Materie und Baryonenasymmetrie auf Physik jenseits des SM (BSM) hin. Um also ein mit den Beobachtungen konsistentes Modell zu entwickeln, ist eine umfassendere Theorie nötig. Experimentell kann entweder in Abweichungen von den Vorhersagen des SM nach neuer Physik gesucht werden. So kann jedes BSM-Szenario getestet werden.
In dieser Arbeit werden BSM-Szenarien im Quark- sowie im Leptonen-Sektor und deren phänomenologische Konsequenzen auf messbare Observablen betrachtet. Ein konkretes Beispiel in dieser Dissertation sind Neutrino massen modellierung mit der Einführung von sterilen Neutrinos. Wir untersuchen die phänomenologische Konsequenz ihrer Einführung auf verschiedenen Massenskalen im Zusammenhang mit symmetriegenerierten oder strukturlosen Neutrinomassenmodellen. Unter den geschmacksabhängigen aktivsterilen Mischungen in den durch Symmetrie erzeugten Massenmodellen finden wir deutliche Hierarchien, die als Modelldiskriminator für zukünftige Experimente dienen.
Ähnlich wie beim Ausnutzen von Symmetrien im Neutrinosektor, kann man Symmetrien auch in Modellen für Quarkmassen nutzen. In dieser Arbeit werden Symmetrien behandelt, die den Cabibbo-Winkel für Quarkmischung in führender Ordnung quantisieren können. Dies führt zu einer Vielzahl möglicher Symmetrien, welche genutzt werden können um spezifische Modelle für Quarkmassen zu entwickeln.
BSM-Physik indirekt mit Hilfe astrophysikalischer Neutrinos zu testen stellt eine Alternative zur direkten Detektion dar, und führt bei Betrachtung der Zusammensetzung des NeutrinoFlavours zu klaren Abweichungen von den Erwartungen. Neben der Behandlung verschiedenster BSM-Szenarien wird auch das Potenzial zukünftiger Experimente betrachtet, vor Allem im Hinblick auf deren Effektivität Physik jense.<br>The Standard Model (SM) of particle physics is a well-tested and predictive theory, however non-zero neutrino masses, the existence of dark matter, and the baryon asymmetry suggest physics beyond the SM. Thus, in order to have a model consistent with observations, a more complete theory is needed. Experimentally, one can search for new physics, thereby differentiate different BSM scenarios.
We consider BSM scenarios in the quark and lepton sectors, and study their phenomenological consequence on measurable observables. A specific example is neutrino mass modeling with the introduction of sterile neutrinos. We study the phenomenological consequence of introducing them at different mass scales in the context of symmetry-generated or structureless neutrino mass models. We find distinct hierarchies among the flavor-dependent active-sterile mixings in the symmetry-generated mass models, which acts as a model discriminator for future experiments.
Similarly as using symmetries in the neutrino sector, one can also use symmetries in quark mass models. This thesis consider symmetries capable of quantizing the Cabibbo quark mixing angle to leading order. As a result, a variety of possible symmetries are obtained, which can be used to build specific quark mass models.
Probing BSM physics indirectly via astrophysical neutrinos, acts as an alternative to direct detection, and using the neutrino flavor composition as observable, BSM physics leads to clear deviations from expectation. Additional information comes from other effects, and it helps in constraining the parameter space further. Beside discussing different BSM scenarios, we illustrate the potential of future experiments, emphasizing their effectiveness to test and discriminate BSM physics.
12
Ashley, Jonathan D. "Investigations in non-perturbative QCD." Title page, abstract and table of contents only, 2004. http://hdl.handle.net/2440/37959.
Testo completoAbstract (sommario):
In this thesis we review two methods for studying the non-pertubative region of QCD: the effective field theory, chiral perturbation theory (χPT), and the cloudy bag model, a successful chiral quark model of hadron structure. We use information from both of these sources to construct a simple extrapolation formula in the pion mass, mπ, for the nucleon electromagnetic form factors, which combines the correct non-analytic chiral behaviour predicted by (χPT), with the correct large mπ behaviour. This formula is applied to recent quenched lattice QCD results to extrapolate to the physical regime. Given the simple nature of the extrapolation scheme, our results compare surprisingly well with experiment. We also employ a simple chiral quark model (the hedgehog) to examine the volume and pion mass dependence of the axial coupling constant, ga, along with the hedgehog baryon mass. Our results for ga reveal large volume dependence at low pion masses.<br>Thesis (M.Sc.)--School of Chemistry and Physics, 2004.
13
Uzzo, Michael. "Stability of quark-antiquark models of mesons: A study on the validity of the spectator, Dirac, and Salpeter equations." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539623942.
Testo completoAbstract (sommario):
Mesons are made of quark-antiquark pairs held together by the strong force. The one channel spectator, Dirac, and Salpeter equations can each be used to model this pairing. We look at cases where the relativistic kernel of these equations corresponds to a linear combination of scalar exchange and vector exchange. The vector exchange will be either the time-like component or the full four vector. The systems covered here are referred to as quasirelativistic, which means retardation, regularization, and form factors are not included. Since the model used in this paper describes mesons which cannot decay physically, the equations must describe stable states. We find that this requirement is not always satisfied, and give a complete discussion of the conditions under which the various equations give unphysical, unstable solutions.
14
Jezo, Tomas. "Z' and W' gauge bosons in SU(2)xSU(2)xU(1) models : Collider phenomenology at LO and NLO QCD." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY071/document.
Testo completoAbstract (sommario):
Les modèles SU(2)xSU(2)xU(1) représentent une étape intermédiaire motivée par l'unification des groupes de jauge du Modèle Standard (MS). Un groupe de jauge étendu, par rapport a celui du MS, implique l'existence de nouveaux bosons de jauge, neutres et charges. Ces bosons dénotés Z' et W' sont recherches activement au Large Hadron Collider (LHC). Sur la base d'une analyse globale récente des contraintes sur ces modèles, provenant des expériences a basse énergie et du LEP, nous effectuons une analyse numérique au Leading Order (LO) des différentes signatures au LHC. Nous montrons que les sections efficaces totales pour les leptons et les paires de quarks de troisième génération, expérimentalement facilement accessibles, fournissent individuellement qu'uneinformation partielles sur le modèle réalise dans la nature. En revanche, les corrélations de ces mêmes sections efficaces pourraient bien conduire a une identification unique. Par la suite, nous étudions la production électrofaible d'une paire de quarks top au Next-to-Leading Order dans les extensions du MS prédisant un boson Z' supplémentaire et en supposant des couplages génériqueset diagonaux dans la base des saveurs. Nous calculons les corrections virtuelles et réelles a l'ordre de O(alS*alW^2) et les implémentons dans le générateur d'événements Monte Carlo POWHEG BOX qui permet de réaliser de manière cohérente la fusion du calcul QCD NLO avec les parton showers. Nousconstatons que les corrections QCD NLO peuvent être très importantes, mais que les K-facteurs restent modestes dans la région de masse invariante centrée autour de la masse de la résonance<br>General SU(2)x SU(2)x U(1) models represent a well-motivated intermediate step towards the unication of the Standard Model (SM) gauge groups. Extended gauge group sector, as compared to that of the SM, leads to additional neutral and charged gauge bosons. These so-called Z' and W' bosons are actively searched for at the Large Hadron Collider (LHC). Based on a recent global analysis of low-energy and LEP constraints of these models, we perform numerical scans of their various signals at the LHC at Leading Order accuracy. We show that total cross sections for lepton and third-generation quark pairs, while experimentally easily accessible, provide individually only partial information about the model realized in Nature. In contrast, correlations of these cross sections in the neutral and charged current channels may well lead to a unique identification. Subsequently we study the electroweak top-pair production at Next-to-leading Order (NLO) accuracy in the SM extensions with an additional Z' boson assuming general flavour-diagonal couplings. We calculate the virtual and real corrections at order O(alS*alW^2) and implement them in the POWHEG BOX framework which allows for consistent matching of NLO QCD calculations with parton showers. We find that the NLO corrections can be very important but the K-factors in the invariant mass region around the resonance mass are modest
15
Moch, Paul [Verfasser], Martin [Akademischer Betreuer] Beneke, and Andreas [Akademischer Betreuer] Weiler. "Loop-induced lepton and quark dipole transitions in Randall-Sundrum models / Paul Moch. Betreuer: Martin Beneke. Gutachter: Andreas Weiler ; Martin Beneke." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1081768010/34.
Testo completo
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Carlucci, Maria Valentina Verfasser], Andrzej [Akademischer Betreuer] [Buras, and Wolfgang F. L. [Akademischer Betreuer] Hollik. "Quark-Flavour Phenomenology of Models with Extended Gauge Symmetries / Maria Valentina Carlucci. Gutachter: Andrzej Jerzy Buras ; Wolfgang F. L. Hollik. Betreuer: Andrzej Jerzy Buras." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1037198530/34.
Testo completo
17
Hazelton, William Donald. "Configuration mixing of quark states in nucleons and other baryons in the MIT bag model /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9770.
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Michaud, Yonnel. "Etude phénoménologique de la réaction d'échange de charge (pi)-p -> (pi)[n à haute énergie]." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10097.
Testo completoAbstract (sommario):
La presente these est consacree a l'etude de la reaction d'echange de charge pion negatif proton donne pion nul neutron. Cette reaction fait partie des processus quasi-elastiques, caracterises par de petits moments transferes, et donc non interpretables par la chromodynamique quantique. Le modele de glauber, utilise avec succes dans le cadre de la diffusion elastique, est exploite ici pour l'etude de la reaction d'echange de charge. Une interaction effective entre quarks, incluant un terme central et un terme spinorbite, est employee afin de rendre compte de l'echange du meson rho. Les resultats obtenus permettent de conclure a la nature diffractive de la reaction etudiee, mais ne permettent pas de determiner avec precision les rayons moyens des densites de quarks interagissants
19
Mebarki, Noureddine. "Large [transverse momentum] direct photon production by [pion minus, pion plus], [proton and anti-proton] beams in perturbative quantum chromodynamics." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65946.
Testo completo
20
Dagdeviren, Nuri Ruhi. "A quark model for nuclear matter." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/32565.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1985.<br>MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.<br>Vita.<br>Includes bibliographical references.<br>by Nuri Ruhi Dagdeviren.<br>Ph.D.
21
Mehrban, Hossein. "Matter-antimatter asymmetry of b-quark and B-meson decays." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324379.
Testo completo
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Schweitzer, Peter. "Polarized quark and antiquark distribution functions of the nucleon in the chiral quark soliton model." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=96147923X.
Testo completo
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Traxler, Christoph. "Hadronisierung des Quark-Gluon-Plasmas im chromodielektrischen Modell." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=956793452.
Testo completo
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Nguyen, Khang D. "Systematic approach to optimizing free parameters in the Goldstone-boson-exchange model of quark-quark interactions." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1566292.
Testo completoAbstract (sommario):
<p> The set of parameters used in the Goldstone-boson-exchange (GBE) model of quark-quark interactions by a group from the University of Graz to calculate baryon energy spectra is not optimal. A systematic approach to optimize these free parameters for a greater collection of baryons than previously treated is presented here. The baryons considered possess a physical symmetry where their constituent quarks are either made of all identical quarks or just two identical quarks. In order to calculate the various energy states of these baryons, the Faddeev method is used under the premise that three-quark interactions are modeled by an infinitely rising confinement potential. The new parameters and resulting energy calculations obtained yield better agreement with experimental data than previously achieved. In addition to providing a stronger case for the GBE model, these newfound parameters have the potential to give further insight into how quarks interact and pave the way for more advanced work in the field of three-quark problems.</p>
25
Ohlsson, Tommy. "Properties of baryons in the chiral quark model." Licentiate thesis, KTH, Fysik, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-756.
Testo completoAbstract (sommario):
In this thesis, several properties of baryons are studied using the chiral quark model. The chiral quark model is a theory which can be used to describe low energy phenomena of baryons. In Paper 1, the chiral quark model is studied using wave functions with configuration mixing. This study is motivated by the fact that the chiral quark model cannot otherwise break the Coleman–Glashow sum-rule for the magnetic moments of the octet baryons, which is xperimentally broken by about ten standard deviations. Configuration mixing with quark-diquark components is also able to reproduce the octet baryon magnetic moments very accurately. In Paper 2, the chiral quark model is used to calculate the decuplet baryon magnetic moments. The values for the magnetic moments of the ++and− are in good agreement with the experimental results. The total quark spin polarizations are also calculated and are found to be significantly smaller than the non-relativistic quark model results. In Paper 3, the weak form factors for semileptonic octet baryon decays are studied in the chiral quark model. The “weak magnetism” form factors are found to be consistent with the conserved vector current (CVC) results and the induced pseudotensor form factors, which seem to be model independent, are small. The results obtained are in general agreement with experiments and are also compared with other model calculations.<br>QC 20100618
26
McGovern, J. A. "Strange baryons in a chiral quark-meson model." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233064.
Testo completo
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Helminen, Christina. "Aspects of the quark model for the baryons." Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/mat/fysii/vk/helminen/.
Testo completo
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Geng, Chaqiang. "Composite models of quarks and leptons." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/76097.
Testo completoAbstract (sommario):
We review the various constraints on composite models of quarks and leptons. Some dynamical mechanisms for chiral symmetry breaking in chiral preon models are discussed. We have constructed several "realistic candidate" chiral preon models satisfying complementarity between the Higgs and confining phases. The models predict three to four generations of ordinary quarks and leptons.<br>Ph. D.
29
Veiga, J. S. "Propriedades da matéria nuclear em modelos de quarks constituintes /." São Paulo, 1996. http://hdl.handle.net/11449/132865.
Testo completo
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Milstead, David Anthony. "The production of neutral kaons and lambdas in deep inelastic scattering at H1 and an upper limit on the production cross-section of instantons." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309902.
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Takan, Taylan. "Study Of The Heavy Quarkonia Spectra In The Quark Model." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614102/index.pdf.
Testo completoAbstract (sommario):
Conventional Heavy Quarkonium systems, Charmonium and Bottomonium, are believed to
be composed of a heavy quark and anti-quark pair. These systems are investigated by dierent
methods resulting from dierent approaches to Quantum Chromodynamics (QCD), such as
Lattice QCD, Eective Theories and Sum Rules. In this thesis we study the spectrum of
Charmonium and Bottomonium using a non-relativistic Quark Model. Assuming one gluon
exchange for the short distances and a linear confining potential for long distances we derive
Breit-Fermi interaction Hamiltonian and calculate the spectra arising from this Hamiltonian.
Also we calculate the partial widths of E1 and M1 radiative decays.
32
Elliott, Louie C. "Regular and Hybrid Mesons in a Non-RelativisticConstituent Quark Model." NCSU, 1998. http://www.lib.ncsu.edu/theses/available/etd-19980807-164043.
Testo completoAbstract (sommario):
<p>We investigate q-qbar and q-qbar-g mesons with regularand exotic quantum numbers in a non-relativisticconstituent quark model. Simple harmonic oscillator statesare used as radial wave functions, which allows for analyticmatrix elements. Employing a diagonalization withvariational approach, the resulting generalizedeigenvalue problem is solved for the meson bound states.With a minimal number of parameters, we are able to describe the non-exotic meson spectrum within a few percent.Predictions are also made for the masses of hybrid mesons,with the lowest lying 1-+ u-ubar-g mass of 1.26 MeV.<P>
33
Moore, Liam Ronald. "Top quark physics in the Standard Model Effective Field Theory." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7841/.
Testo completoAbstract (sommario):
We explore some applications of the Standard Model (SM) Effective Field Theory (EFT) as a tool with which to describe generic nonresonant new physics (NP) at hadron colliders. A global fit of the dimension-six Wilson Coefficients relevant to top quark production is presented, utilizing diverse experimental datasets from both the Large Hadron Collider (LHC) Runs I and II and the TeVatron, with current results in good agreement with the SM. Machinery is developed to systematically treat redundancies between higher-dimensional operators in the automated model-building and phenomenology toolkit FeynRules, and a general SMEFT model implementation for event generators detailed. We then investigate the importance of high momentum transfer final states in top pair production to the EFT fit, taking advantage of boosted reconstruction techniques. We find sensitivity is typically driven by fully resolved analyses in several benchmark scenarios for total integrated luminosity and experimental systematic uncertainties.
34
Folador, Bruna Cesira. "Correções relativísticas ao modelo de quarks no espalhamento J/ψ-nucleon". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/117765.
Testo completoAbstract (sommario):
O Método do Grupo Ressonante (RGM) é um método utilizado no estudo da interação hádron-hádron, na qual não são desprezados os graus de liberdade internos destas partículas. Nesta dissertação estudaremos os efeitos associados `a interação entre um quark pesado Q com outro leve q no potencial de troca de um gluón chamado de One Gluon Exchange Potencial (OGEP), tradicionalmente obtido a partir de um potencial relativístico de interação do modelos de quarks, fazendo uma expansão em potências de momentos nos espinores constituintes (potencial de Fermi-Breit). Faremos uma aproximação semi-relativística para o quark leve q, enquanto que o quark pesado Q será considerado não-relativístico. Este potencial semi-relativístico será usado no RGM para estudar a interação entre charmônios e nucleons como no caso da interação J/ψ-nucleon.<br>The Resonating Group Method (RGM) is used in hadron-hadron interactions, when internal degrees of freedom of composite particles can’t be neglected. In this dissertation we shall study the effects associated with the interaction between a heavy quark Q with a light quark q, using the the One Gluon Exchange Potential (OGEP) traditionally obtained from a relativistic interaction potential in the quark model, by an expansion in powers of momentum of the constituent spinors (potential Fermi-Breit). We will make a semi-relativistic approach for light quark q, while the heavy quark Q will be considered non-relativistic. This semi-relativistic potential will be used in the RGM to study the interaction between charmonia and nucleons as the case J/ψ-nucleon interaction.
35
Schulze, Robert. "From hot lattice QCD to cold quark stars." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65426.
Testo completoAbstract (sommario):
A thermodynamic model of the quark-gluon plasma using quasiparticle degrees of freedom based on the hard thermal loop self-energies is introduced. It provides a connection between an established phenomenological quasiparticle model – following from the former using a series of approximations – and QCD – from which the former is derived using the Cornwall-Jackiw-Tomboulis formalism and a special parametrization of the running coupling.
Both models allow for an extrapolation of first-principle QCD results available at small chemical potentials using Monte-Carlo methods on the lattice to large net baryon densities with remarkably similar results. They are used to construct equations of state for heavy-ion collider experiments at SPS and FAIR as well as quark and neutron star interiors. A mixed-phase construction allows for a connection of the SPS equation of state to the hadron resonance gas.
An extension to the weak sector is presented as well as general stability and binding arguments for compact stellar objects are developed. From the extrapolation of the most recent lattice results [Baz09, Bor10b] the existence of bound pure quark stars is not suggested. However, quark matter might exist in a hybrid phase in cores of neutron stars.
36
Faustino, Sara Raquel Ferreira. "Gestão de talento no setor da saúde : proposta do modelo Quark." Master's thesis, Instituto Superior de Economia e Gestão, 2019. http://hdl.handle.net/10400.5/19039.
Testo completoAbstract (sommario):
Mestrado em Gestão de Recursos Humanos<br>O presente projeto tem como objetivo a criação de um modelo de Gestão de Talento (GT) numa empresa de outsourcing que desenvolve a sua atividade no setor da saúde. A elaboração deste projeto surge como resposta à necessidade estratégica da organização identificar e mapear talento, criar políticas de desenvolvimento e elaborar um plano de ação (PA) para os colaboradores. Em termos metodológicos, recorreu-se a uma abordagem qualitativa que consistiu em observação participante e entrevistas semi-diretivas e focus group. Para a identificação do talento foi construída uma matriz através do cruzamento dos resultados da avaliação de desempenho e de um questionário de avaliação de potencial. O PA foi elaborado tendo em consideração os quadrantes definidos na matriz de talento e as necessidades identificadas nas entrevistas realizadas aos colaboradores da empresa, de diferentes categorias profissionais. Desta forma, este plano surge não só enquanto proposta das medidas formativas a serem aplicadas na organização, mas também como ferramenta essencial para a retenção de talento, uma vez que vai de encontro às expectativas e motivações dos colaboradores. A implementação do presente modelo de GT pretende criar, a longo prazo, condições que permitam o desenvolvimento de talento e retenção dos colaboradores.<br>This project purposes to create a Talent Management Model in an outsourcing company that develops its activity in the health sector. This project arises in response to the company's strategic need of identify/map talent, create human resources development policies and develop an action plan for its employees. Regarding the methodology used, it was used a qualitative approach that consisted of participant observation and semi-directive and focus group interviews. In order to identify talent, it was designed a matrix by cross-checking the performance evaluation results and a potential assessment questionnaire. The action plan was prepared according the quadrants defined in the talent matrix and the needs identified in the multiple interviews conducted with the different company's employees. Thus, this action plan emerges not only as a proposal of the training measures to be applied in the organization, but also as an essential tool for retaining talent, as it meets the employee's expectations and motivations. The implementation of this Talent Management Model aims to create, in the long run, conditions that allow the talent development and employees retention.<br>info:eu-repo/semantics/publishedVersion
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Veiga, J. S. [UNESP]. "Propriedades da matéria nuclear em modelos de quarks constituintes." Universidade Estadual Paulista (UNESP), 1996. http://hdl.handle.net/11449/132865.
Testo completoAbstract (sommario):
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Fukukawa, Kenji. "Nucleon-Deuteron Scattering Described by a Quark-Model Nonlocal Gaussian Potential." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157771.
Testo completo
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Wunderlich, Falk. "Photoemissivity near a chiral critical point within the quark-meson model." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233657.
Testo completoAbstract (sommario):
The interplay of thermodynamic properties of strongly interacting matter and its emission of photons is investigated. For this purpose the Lagrangian of the quark meson model (in the literature also dubbed "linear sigma model" or "linear sigma model with quarks") is extended by an electromagnetic sector. Based on this extended Lagrangian both the grand-canonical potential and the generating functional of correlation functions are calculated in a consistent manner. From the former, the phase structure and various thermodynamical properties are determined. Especially, the dependence of certain landmarks (critical point, intersections of the phase boundary with the coordinate axes, etc.) of the phase diagram with respect to the model parameters is investigated in detail. With the help of the generating functional in turn, the photon propagator can be computed whose imaginary part is connected to the emission rate of photons. The leading order of the result with respect to the number of participating particles and the power of the quark-meson coupling is expressed in terms of tree level diagrams, which are calculated likewise. On this basis, the photon emissivity with respect to temperature, chemical potential and photon frequency is calculated and analyzed addressing various questions. The dependence of the particle masses with respect to temperature and chemical potential leaves notable imprints on the emissivities of the individual production processes. Especially a first-order phase transition can easily be identified, since, there, the emissivity may jump - depending on the temperature - by a factor of about ten. Contrarily, within our analysis, we do not find signatures in the photon emissivities that specifically mark a critical end point. Moreover, it is investigated on which parameters the photon emission rate depends in the low- and high-frequency regions. With these results the behavior of the emissivity with respect to temperature and chemical potential can be understood and many peculiarities of the emissivities can be explained<br>Das Zusammenspiel der thermodynamischen Eigenschaften von stark wechselwirkender Materie und deren Emission von Photonen wird untersucht. Dazu wird die Lagrangedichte des Quark-Meson-Modells (auch: Linear-Sigma-Modell oder Linear-Sigma-Modell mit Quarks) um einen elektromagnetischen Sektor erweitert. Aus der so erweiterten Lagrangedichte werden auf konsistente Weise sowohl das großkanonische Potential als auch das erzeugende Funktional der Korrelationsfunktionen ermittelt. Aus ersterem werden die Phasenstruktur des Modells sowie zahlreiche thermodynamische Eigenschaften berechnet. Insbesondere wird die Abhänigkeit einiger Orientierungspunkte (kritischer Punkt, Schnittpunkte der Phasengrenze mit den Koordinatenachsen usw.) des Phasendiagramms von den Modellparametern detailiert untersucht. Mit Hilfe des erzeugenden Funktionals wiederum kann der Photonenpropagator bestimmt werden, dessen Imaginärteil mit der Emissionsrate von Photonen zusammenhängt. Die führende Ordnung in einer Entwicklung nach der Anzahl der beteiligten Teilchen und der Potenz der Quark-Meson-Kopplung lässt sich durch Baumgraphen-Diagramme darstellen, die ebenfalls berechnet werden. Auf dieser Basis wird die Photon-Emissivität in Abhängigkeit von Temperatur, chemischem Potential und Photon-Frequenz berechnet und unter verschiedenen Gesichtspunkten analysiert. Die Abhängigkeit der Teilchenmassen von Temperatur und chemischem Potential hinterlässt teilweise ausgeprägte Signaturen in den Emissivitäten der einzelnen sub-Prozesse. Insbesondere ein Phasenübergang erster Ordnung zeigt sich deutlich, da an diesem die Emissivität - abhänging von der Temperatur - um einen Faktor der Größenordnung zehn springen kann. Jedoch finden wir im Rahmen dieser Analyse keine spezifischen Signaturen in den Photonen-Emissivitäten, die einen kritischen Punkt auszeichnen. Des weiteren wird untersucht von welchen Parametern die Photonen-Emissionsrate in den Bereichen niedriger oder hoher Photonen-Frequenzen abhängt. Mit diesen Ergebnissen kann das Verhalten der Emissivität in Abhängigkeit von Temperatur und chemischem Potential gut verstanden und zahlreiche Auffälligkeiten in den Emissivitäten erklärt werden
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Downum, Clark R. "Low Energy Nucleon-Nucleon Interactions from the Quark Model with Applications." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526559.
Testo completo
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Algarín, Fernando Enrique Serna [UNESP]. "Symmetry-preserving contact interaction model for hadron structure and quark matter." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152474.
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Previous issue date: 2017-10-02<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Nesta tese empregamos um modelo de interação de contato que preserva simetrias para estudar estrututura hadrônica e matéria de quarks. A interação de contato é uma representação de kernels não perturbativos usados em equações de Dyson-Schwinger e Bethe-Salpeter da Cromodinâmica Quântica (QCD). A ideia básica do modelo está baseada num esquema de subtração que evita passos tradicionais no cálculo de de integrais divergentes que invariavelmente levam a violações de simetrias. Em temperatura zero, as equações de Dyson-Schwinger equation para os propagadores dos quarks u; d; s and c são resolvidas e amplitudes de estado ligado de Bethe-Salpeter, que respeitam a invariância sob translações espaço-temporais e as identidades de Ward-Takahashi associadas com simetrias globais da QCD, são obtidas para calcular as massas e as constantes de decaimento eletrofracas dos mésons pseudoscalares π; K, D e Ds e dos mésons vetorias ρ, K*, D* e Ds*. As predições do modelo estão em bom acordo com dados experimentais e da QCD na rede. Em adição, estendemos o modelo para temperaturas diferentes de zero; neste caso, o problema de violação de simetrias está restrito apenas às partes puramente divergentes porque os termos que dependem das distribuições térmicas são finitas e não requerem regularização. Finalmente, investigamos a dependência com a temperatura das contribuições das flutuações quânticas quark-π e quark-σ aos coeficientes de transporte de viscosidade de cisalhamento η e volumétrica ζ e as suas razões com a densidade de entropia s. As larguras térmicas originárias dessas fluctuações são calculadas com o formalismo de teoria de campos a temperatura finita de tempo real. Para esse cálculo, empregamos os resultados obtidos com as equações de Dyson-Schwinger e Bethe-Salpeter para a dependência com a temperatura das massas dos mésons e as contantes de acoplamento quark-méson. Os resultados para as razões η/s and ζ/s estão em bom acordo com resultados com a literatura obtidos com modelos e técnicas diferentes. Em particular, nossos resultados para η/s possuem um mínimo muito próximo ao limite inferior da conjectura AdS/CFT, η/s = 1/4π.<br>In thesis, a symmetry-preserving contact interaction model is used to study hadron structure and quark matter. The contact interaction is a representation of nonperturbative kernels used in Dyson-Schwinger and Bethe-Salpeter equations of Quantum Chromodynamics (QCD). The basic idea of the model is based on a subtraction scheme that avoids standard steps in the evaluation of divergent integrals that invariably lead to symmetry violation. At zero temperature, the Dyson-Schwinger equation is solved for the u; d; s and c quark propagators and the boundstate Bethe-Salpeter amplitudes respecting spacetime-translation invariance and the Ward-Green-Takahashi identities associated with global symmetries of QCD are obtained to calculate masses and electroweak decay constants of the pseudoscalar π; K, D and Ds and vector ρ, K*, D*, and Ds* mesons. The predictions of the model are in good agreement with available experimental and lattice QCD data. In addition, we extend the model to nonzero temperature; here, the problem of symmetry violation is associated only with the purely divergent parts because the effects due to the termal distributions are finite and do not need regularization. We compute the temperature dependence of the masses and decay constants of the pseudoscalar mesons considered here. Finally, we have investigated the temperature dependence of the contributions of quark-π and quark-σ quantum fluctuations to the transport coefficients of shear η and bulk ζ viscosities and their ratios to the entropy density s. The quark thermal widths originating those fluctuations are calculated with the formalism of real-time thermal field theory. For these calculations, we have used the results obtained via Dyson-Schwinger and Bethe-Salpeter equations for the temperature dependence of constituent quark and meson masses and quark-meson couplings. The results for the ratios η/s and ζ/s are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for η/s has a minimum very close to the conjectured AdS/CFT lower bound, η/s = 1/4π.<br>CNPq:140041/2014-1
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Algarín, F. E. S. (Fernando Enrique Serna). "Symmetry-preserving contact interaction model for hadron structure and quark matter /." São Paulo, 2017. http://hdl.handle.net/11449/152474.
Testo completoAbstract (sommario):
Orientador: Gastão Inácio krein<br>Coorientador: Bruno El-Bennich<br>Banca: Lauro Tomio<br>Banca: Juan Pablo Carlomagno<br>Banca: Sidney dos Santos Avancini<br>Banca: Kazuo Tsushima<br>Resumo: Nesta tese empregamos um modelo de interação de contato que preserva simetrias para estudar estrututura hadrônica e matéria de quarks. A interação de contato é uma representação de kernels não perturbativos usados em equações de Dyson-Schwinger e Bethe-Salpeter da Cromodinâmica Quântica (QCD). A ideia básica do modelo está baseada num esquema de subtração que evita passos tradicionais no cálculo de de integrais divergentes que invariavelmente levam a violações de simetrias. Em temperatura zero, as equações de Dyson-Schwinger equation para os propagadores dos quarks u; d; s and c são resolvidas e amplitudes de estado ligado de Bethe-Salpeter, que respeitam a invariância sob translações espaço-temporais e as identidades de Ward-Takahashi associadas com simetrias globais da QCD, são obtidas para calcular as massas e as constantes de decaimento eletrofracas dos mésons pseudoscalares π; K, D e Ds e dos mésons vetorias ρ, K*, D* e Ds*. As predições do modelo estão em bom acordo com dados experimentais e da QCD na rede. Em adição, estendemos o modelo para temperaturas diferentes de zero; neste caso, o problema de violação de simetrias está restrito apenas às partes puramente divergentes porque os termos que dependem das distribuições térmicas são finitas e não requerem regularização. Finalmente, investigamos a dependência com a temperatura das contribuições das flutuações quânticas quark-π e quark-σ aos coeficientes de transporte de viscosidade de cisalhamento η e volumétrica ζ e as... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: In thesis, a symmetry-preserving contact interaction model is used to study hadron structure and quark matter. The contact interaction is a representation of nonperturbative kernels used in Dyson-Schwinger and Bethe-Salpeter equations of Quantum Chromodynamics (QCD). The basic idea of the model is based on a subtraction scheme that avoids standard steps in the evaluation of divergent integrals that invariably lead to symmetry violation. At zero temperature, the Dyson-Schwinger equation is solved for the u; d; s and c quark propagators and the boundstate Bethe-Salpeter amplitudes respecting spacetime-translation invariance and the Ward-Green-Takahashi identities associated with global symmetries of QCD are obtained to calculate masses and electroweak decay constants of the pseudoscalar π; K, D and Ds and vector ρ, K*, D*, and Ds* mesons. The predictions of the model are in good agreement with available experimental and lattice QCD data. In addition, we extend the model to nonzero temperature; here, the problem of symmetry violation is associated only with the purely divergent parts because the effects due to the termal distributions are finite and do not need regularization. We compute the temperature dependence of the masses and decay constants of the pseudoscalar mesons considered here. Finally, we have investigated the temperature dependence of the contributions of quark-π and quark-σ quantum fluctuations to the transport coefficients of shear η and bulk ζ viscosities and t... (Complete abstract click electronic access below)<br>Doutor
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Zhang, Zuman. "Open heavy-flavour measurements via muons in proton-proton and nucleus-nucleus collisions with the ALICE detector at the CERN-LHC." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC077/document.
Testo completoAbstract (sommario):
Les collisions d'ions lourds ultra-relativistes ont pour objectif l'étude d'un état de matière en interaction forte dans des conditions extrêmes de densité d'énergie et température, le plasma de quarks et gluons (QGP). Les saveurs lourdes (charme et beauté) sont produites principalement lors de processus durs aux premiers instants de la collision et participent aux différentes étapes de la collision. Par conséquent, la mesure des saveurs lourdes ouvertes devrait permettre d'extraire des informations importantes concernant le système créé aux premiers instants de la collision. L'étude des collisions proton-proton (pp) fournit la référence indispensable pour la mesure des saveurs lourdes dans les systèmes lourds. Cette thèse est dédiée à l'étude de la production des muons de décroissance des hadrons charmés et beaux aux rapidités avant (2.5 < y < 4) dans les collisions pp sqrt (s) = 5.02 TeV, Pb-Pb à sqrt (sNN) = 2.76 et 5.02 TeV et Xe-Xe à sqrt (sNN) = 5.44 TeV enregistrées avec le détecteur ALICE au CERN-LHC. La mesure des sections efficaces différentielles de production des muons de décroissance des hadrons charmés et beaux dans les collisions pp à sqrt (s) = 5.02 TeV couvre un grand domaine en impulsion transverse de 2 à 20 GeV/c et ont une meilleure précision par rapport aux résultats publiés à sqrt (s) = 2.76 et 7 TeV. Les résultats sont en bon accord avec les calculs perturbatifs de QCD. Une importante suppression de la production des muons de décroissance des hadrons charmés et beaux est observée dans les collisions centrales (0-10%) Pb-Pb à sqrt (sNN) = 2.76 et 5.02 TeV. Cette suppression est attribuée au milieu dense et chaud formé dans ces collisions. L'influence de la taille du système est étudiée avec le système Xe-Xe à sqrt (sNN) = 5.44 TeV. La suppression est similaire à celle mesurée dans les collisions Pb-Pb. Les résultats obtenus dans les collisions Pb-Pb et Xe-Xe apportent des contraintes fortes aux paramètres des modèles<br>The study of ultra-relativistic heavy-ion collisions aims at investigating a state of strongly-interacting matter at high energy density and temperature, the Quark-Gluon Plasma (QGP). Heavy quarks (charm and beauty) are predominantly produced in initial hard scattering processes during the early stage of the collisions and experience the full evolution of the medium. Therefore, the measurement of open heavy flavours should provide essential information on the QGP properties. Similar measurements in small systems are also essential for a comprehensible understanding of the QGP properties. The study of open heavy flavours in proton-proton (pp) collisions provides the mandatory reference for measurements in heavy-ion collisions. This thesis presents measurements of the production of muons from heavy-flavour hadron decays at forward rapidity (2.5 < y < 4) in pp collisions at sqrt (s) = 5.02 TeV, Pb-Pb collisions at sqrt (sNN) = 2.76 and 5.02 TeV and Xe-Xe collisions at sqrt (sNN) = 5.44 TeV collected with the ALICE detector at the CERN-LHC. The differential production cross sections of muons from heavy-flavour hadron decays in pp collisions at sqrt (s) = 5.02 TeV are obtained in a wide transverse momentum interval, 2 < pT < 20 GeV/c, and with an improved precision compared to the previously published measurements at sqrt (s) = 2.76 and 7 TeV. The measurements are described within uncertainties by predictions based on perturbative QCD. A strong suppression of the yield of muons from heavy-flavour decays is observed in the 10% most central Pb-Pb collisions at both sqrt (sNN) = 2.76 and 5.02 TeV. This suppression is due to final-state effects induced by the hot and dense medium. The suppression in Xe-Xe collisions is similar to that observed with Pb-Pb collisions. The comparison in the two colliding systems provides insight in the path-length dependence of medium-induced parton energy loss. The results constrain model calculations
44
Gomes, Rosana de Oliveira. "Transições de fase hádron-quark em estrelas de nêutrons." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/55416.
Testo completoAbstract (sommario):
Os recentes avanços no campo da física de altas energias têm possibilitado cada vez mais o estudo da matéria sob condições extremas. Nesse contexto, novos estados da matéria vêm sendo descobertos e especulados. Dentre esses estados hipotéticos da matéria, encontra-se o de quarks desconfinados quando em ambientes de altíssimas densidades e/ou temperaturas. O cenário de densidades extremas e baixas temperaturas é encontrado no interior de estrelas de nêutrons, fazendo destas verdadeiros laboratórios para o estudo da matéria nuclear. A proposta desse trabalho é estudar a transição de fase de desconfinamento de quarks no interior de estrelas de nêutrons não-rotantes. Começamos o trabalho com urna introdução aos modelos da hadrodinâmica quântica que descreve a matéria nuclear através de um formalismo relativístico de interação de muitos corpos, no qual a troca de mésons escalares e vetoriais é a fonte de interação entre bárions. Neste trabalho, a matéria hadrônica é descrita pelo Modelo a — w Não-Linear e pelo Modelo Ajustável, que são extensões do Modelo de Walecka. O primeiro modelo considera um acoplamento mínimo entre bárions e mésons e o segundo, um acoplamento derivativo ajustável. O ajuste de valores dos parâmetros de ambos modelos é feito através das propriedades da matéria nuclear na saturação. Em particular, ao considerarmos a presença de híperons para densidades maiores, somos impelidos a utilizar modelos teóricos para descrever o acoplamento dos mesmos com os núcleons, uma vez que híperons não populam a matéria nuclear na saturação. O diagrama de fases da Cromodinâmica Quântica (Quantum Chromodynamics - Q.C.D.) apresenta uma série de novas fases quando tomamos extremos de temperatura e/ou densidades. Em particular, estamos interessados na transição de fase que ocorre para baixa temperatura e alta densidade, no qual os quarks sofrem um desconfinamento. A matéria de quarks desconfinados é comumente descrita na literatura através do modelo de sacola do M.I.T., no qual os quarks são considerados assintoticamente livres em uma região do espaço denominada sacola. A estabilidade da sacola é assegurada através de um parâmetro denominado constante de sacola, cujos valores serão relacionados à densidade de energia da matéria de quarks. Como consideramos duas fases distintas, compostas por diferentes tipos de partículas, teremos um sistema multicomponente composto por duas fases independentes. Assumimos que a transição de fase segue o critério de Gibbs e é de primeira ordem, apresentando, portanto, uma fase mista onde ocorrerá a coexistência de fases. Consideramos ainda a conservação global da carga elétrica e do número bariônico, fazendo com que a equação de estado cresça continuamente ao longo da fase mista e possibilitando a descrição de uma estrela. É verificada a influência de diferentes escolhas de parâmetros, esquemas de acoplamentos de híperons e modelos que descrevem a matéria hadrônica na transição de fase. Os reflexos dessas incertezas serão estudados na rigidez da equação de estado, no tamanho da fase mista e no início e final da transição. Urna vez obtida a equação de estado para a matéria no interior da estrela, determinamos suas propriedades observáveis estáticas, ou seja, sua relação massa-raio, através das equações de Tolman-Oppenheimer-Volkoff (TOV). Através da equação de estado para matéria de hádrons populada por híperons. obtemos as propriedades de estrelas de híperons e.Recent advances on the field of high energy physics have enabled the study of matter under extreme conditions and, in this context, new states of matter are being discovered and speculated upon. Among these hypothetical states of matter is the one of deconfined quarks in high densities and/or temperatures. An environment with extreme densities and low temperature is found in the interior of neutron stars, making them laboratories for the study of nuclear matter. The aim of this work is to study the quark deconfinement phase transition in the interior of non-rotating neutron stars. We begin by introducing quantum hadrodynamics (QHD) models that describe nuclear matter in a relativistic many-body formalism, in which the exchange of scalar and vector mesons is responsible for the interaction among baryons. In this work the hadronic matter is described by the Non-Linear a — w Model and by the Adjustable Model, which are extentions of the Walecka Model. The former considers a minimal coupling between baryons and mesons, while the latter considers an adjustable derivative coupling. In both models, the parameters are tuned to reproduce the properties of nuclear matter at saturation dcom as equações de estado para as fases de hádrons, mista e de quarks, modelamos uma estrela híbrida, com um caroço de quarks livres em seu interior. Por fim, apontamos as incertezas teóricas inerentes à dependência dos parâmetros dos modelos que descrevem a matéria de hádrons e de quarks e também de diferentes modelos de acoplamentos de híperons para as propriedades de estrelas de híperons e híbridas. São ainda abordados tópicos em aberto no que se refere à transições de fase no contexto de estrelas compactas e novas perpectivas que podem levar a resultados mais realistas.<br>Recent advances on the field of high energy physics have enabled the study of matter under extreme conditions and, in this context, new states of matter are being discovered and speculated upon. Among these hypothetical states of matter is the one of deconfined quarks in high densities and/or temperatures. An environment with extreme densities and low temperature is found in the interior of neutron stars, making them laboratories for the study of nuclear matter. The aim of this work is to study the quark deconfinement phase transition in the interior of non-rotating neutron stars. We begin by introducing quantum hadrodynamics (QHD) models that describe nuclear matter in a relativistic many-body formalism, in which the exchange of scalar and vector mesons is responsible for the interaction among baryons. In this work the hadronic matter is described by the Non-Linear a — w Model and by the Adjustable Model, which are extentions of the Walecka Model. The former considers a minimal coupling between baryons and mesons, while the latter considers an adjustable derivative coupling. In both models, the parameters are tuned to reproduce the properties of nuclear matter at saturation density. In particular, when considering the presence of hyperons at higher densities, we need to use theoretical models to describe their coupling with the mesons, since hyperons do not populate nuclear matter at saturation. The quantum chromodynamics (QCD) phase diagram presents several new phases when we consider extreme temperatures and/or densities. In particular, we are interested on the transition that takes place in low temperature and high densities, in which the quarks suffer deconfinement. This kind of quark matter is usually described in the literature by means of the MIT bag model, in which the quarks are considered to be asymptotically free in a space region denominated bag. The stability of the bag is assured by means of a parameter, the bag constant, whose values are related to the energy density of quark matter. Since we consider two distinct phases, each formed of different kinds of particles, this multicomponent system is composed of two different independent phases. We assume the phase transition is first-order and follows the Gibbs' criteria, and therefore presents mixed phase. We consider a global electric and baryonic charge conservation, making the equation of state to grow continuously through the mixed phase and making it possible to describe a star. We investigate the influence of different choices of parameters, hyperon coupling schemes and QHD models on the phase transition. The influence of these uncertainties are studied in the stiffness of the equation of state. the size of the mixed phase and in the beginning and ending of the phase transition. Having determined the equation of state for the matter in the interior of the star, we obtain the star's static properties, i.e., the mass-radius relation, by use of the Tolman- Oppenheimer-Volkoff (TOV) equations. Using the equation of state for hadronic matter populated by hyperons we obtain the properties of hyperon stars and, also considering the equation of state for mixed and quark matter, we model a hybrid star, with a core made of free quarks. Finally, we point out the theoretical uncertainties, inherent to the parameters of the QHD models and of the MIT model, and also to the different hyperon scheme couplings, on the hyperon and hybrid stars' properties. In addition, open topics related to the context of phase transitions on compact stars, and new perspectives that may lead to more realistic results, are discussed.
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Serenone, Willian Matioli. "Potencial de quarks pesados com input de teorias de gauge na rede." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-24092014-163411/.
Testo completoAbstract (sommario):
Nesta dissertação nós revisamos aspectos gerais de teorias de gauge, os princípios da formulação de rede da cromodinâmica quântica (QCD) e algumas propriedades de quarkônios pesados, i.e. estados ligados de um quark pesado e seu antiquark. Como um exemplo de simulações de Monte Carlo de modelos de rede, apresentamos aplicações nos casos do oscilador harmônico e teorias de gauge SU(2). Nós estudamos o efeito de incorporar o propagador de gluon de simulações na rede em um modelo de potencial para a descrição do quarkônio, no caso do botômomio e do charmônio. Nós usamos em ambos os casos uma abordagem numérica para calcular as massas dos estados de quarkônio. O espectro resultante é comparado em ambos os casos com cálculos usando o potencial de Coulomb mais linear (ou potencial Cornell).<br>In this dissertation we review general aspects of gauge theories, the principles of the lattice formulation of quantum chromodynamics (QCD) and some properties of heavy quarkonia, i.e. bound states of a heavy quark and its antiquark. As an illustration of Monte Carlo simulations of lattice models, we present applications in the case of the harmonic oscillator and SU(2) gauge theory. We study the effect of incorporating the gluon propagator from lattice simulations into a potential model for the description of quarkonium, in the case of bottomonium and charmonium. We use a numerical approach to evaluate masses of quarkonium states. The resulting spectrum is compared in both cases to calculations using the Coulomb plus linear (or Cornell) potential.
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Silva, António. "Form factors of the baryon octet in the chiral quark soliton model." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972728074.
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Ossmann, Jens. "Angular momentum structure of the nucleon in the chiral quark soliton model." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973438827.
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González, Patrick José [Verfasser]. "Top quark and higgs physics in standard model extensions / Patrick José González." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1025882466/34.
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Clague, David Edward. "Dynamical symmetry breaking by a top quark condensate in the standard model." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293372.
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Blundell, Harry G. (Harry Grahame) Carleton University Dissertation Physics. "Meson properties in the quark model; a look at some outstanding problems." Ottawa, 1996.
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