Dissertations / Theses on the topic 'Plasma de quarks (QGP)'
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Weitz, Eamonn. "Theoretical developments for jets in heavy-ion collisions." Electronic Thesis or Diss., Nantes Université, 2023. http://www.theses.fr/2023NANU4063.
The quark-gluon plasma (QGP) is an exotic phase of matter, composed of deconfined quarks and gluons and is briefly created in heavy-ion collisions (HIC) at the LHC and at the RHIC. High-energy, self-collimated structures of final-state particles also created in HIC, called jets, probe the QGP, piercing through it on their way to the particle detector. In particular, as the jet propagates, it is quenched, shedding its energy through its interaction with the QGP. Quantum field theory at finite temperature – thermal field theory, is then an extremely powerful tool, capable of analytically quantifying how such a high-energy object interacts with a weakly coupled thermal bath. In this thesis, we work towards the computation of corrections (in the expansion of the strong coupling constant) to two quantities, which dictate how jets are quenched by the QGP. The first being the transverse momentum broadening coefficient, which describes how the jet diffuses in transverse momentum space through its interaction with the medium. We focus on the computation of logarithmically enhanced corrections, carefully showing how the thermal scale affects the logarithmic phase space. The second is the asymptotic mass, which can be thought of as a shift in the jet’s dispersion relation as it undergoes forward scattering with the medium’s constituents. We complete a matching calculation, which rids the mass’ classical corrections of any unphysical divergences, while also beginning the completion of its full two-loop, quantum corrections
Roy, Christelle. "L'Etrangeté du Plasma de Quarks et de Gluons." Habilitation à diriger des recherches, Université de Nantes, 2005. http://tel.archives-ouvertes.fr/tel-00011076.
Après quasiment 20 ans de recherche auprès des différents accélérateurs de particules américains et européens, le CERN annonce le 10 février 2000 au cours d'une conférence de presse, la mise en évidence expérimentale d'un état particulier de la matière nucléaire, compatible avec la formation d'un QGP, sans pouvoir toutefois le caractériser pleinement. Les expériences du RHIC ont alors pris le relais. Aujourd'hui, au travers une pléthore de résultats nouveaux et parfois bien surprenants, il apparaît de façon de plus en plus certaine, qu'effectivement un état atypique de matière nucléaire a été créé à RHIC et notre vision du QGP comme un gaz parfait de partons n'interagissant que très faiblement, a depuis changé. Un nouvel acronyme a été défini : sQGP pour Strongly Interacting QGP.
Pour parvenir à cette observation, il a fallu passer par la caractérisation même de l'évolution des collisions d'ions lourds, du point de vue chimique et dynamique, en comparant les phénomènes des collisions d'ions lourds pour lesquelles les conditions devraient être réunies pour former un QGP à des collisions d'énergies moindres ou de systèmes plus légers qui ne peuvent permettre cette formation. Le QGP est en effet produit de manière beaucoup trop furtive pour pouvoir le sonder directement. Mon mémoire d'Habilitation à Diriger des Recherches présente les résultats des analyses que j'ai menées et qui ont contribué à la mise en évidence de la formation d'un état nouveau au RHIC et à cette nouvelle vision du plasma. Les stigmates du QGP ont été recherchés avec les particules contenant des quarks étranges : les résonances de particules simplement étranges et les baryons doublement étranges.
La production des résonances étranges Lambda(1520) apporte en effet des informations sur la phase d'hadronisation du plasma (lorsque les partons se recomposent en hadrons) : selon leur observation ou non, il pourrait être possible de caractériser le freeze-out chimique (instant où les interactions inélastiques cessent et la composition chimique du système est figée), le freeze-out cinétique (instant où les interactions élastiques cessent et les particules n'interagissent plus), si ces deux freeze-out coïncident ou si, au contraire ils sont séparés dans le temps et de combien. L'idée est la suivante : les Lambdas(1520) se désintègrent quasiment instantanément en un proton et un kaon. Par conséquent, si le temps entre les freeze-out chimique et cinétique est long, les produits de désintégration de ces particules peuvent être absorbés dans le milieu dense qui a été créé. En revanche, si les deux freeze-out coïncident ou sont très proches, les produits de désintégration ne sont pas affectés et la particule mère, c'est-à-dire la résonance, peut être identifiée. Ainsi, en mesurant les taux de production de ces particules dans les collisions proton–proton pour lesquelles les deux freeze-out coïncident, et en comparant les taux obtenus dans les collisions Au–Au, à l'énergie nominale du RHIC, il est apparu qu'effectivement, au moins 4 fm/c séparent les deux freeze-out dans les collisions Au–Au. Cette conclusion constitue une étape importante dans la compréhension des collisions d'ions lourds ultra-relativistes et du comportement de la matière dans des conditions extrêmes. Cette analyse est apparue comme originale au sein de la collaboration STAR, étant la première étude sur les résonances étranges. Des algorithmes spécifiques ont dû être mis au point et sont largement utilisés au sein de la collaboration qui depuis étudie de nombreuses autres résonances ou recherche des objets plus exotiques.
La production des baryons étranges a été largement investiguée les années passées car une augmentation « anormale » des taux de production est attendue si un QGP est formé. Les expériences du CERN ont observé effectivement une surproduction de l'étrangeté dans les collisions Pb–Pb mais n'ont pu conclure de manière décisive quant à une formation éventuelle d'un plasma car ces résultats pouvaient être également reproduits par des modèles de gaz de hadrons. Nous avons mené une analyse similaire avec les données de STAR en comparant les taux de production des Xi, baryons doublement étranges, dans les collisions proton–proton et Au–Au à sqrt(s_NN) = 200 GeV. Là aussi, les résultats sont demeurés ambigus. Ainsi, ces résultats ont conduit un certain nombre de physiciens à ne plus considérer les taux de production de particules étranges comme une signature robuste de la formation d'un QGP. En revanche, l'étrangeté est revenue sur le devant de la scène, de façon plus indirecte donnant des informations très diverses et sur les différentes étapes de la collision.
Les Xi ont révélé tout d'abord que le système créé à l'énergie nominale du RHIC serait en équilibre thermique et chimique et que les températures de freeze-out chimique sont proches de la température de déconfinement prédite par QCD. Nous avons également étudié les phénomènes dynamiques collectifs, appelés flot, qui naissent des interactions entre constituants et se traduisent par une émission de matière dans des directions privilégiées de l'espace de phase. En accord avec leurs faibles sections efficaces d'interaction, les Xi semblent émis bien plus tôt que les particules plus légères. Toutefois, le fait que ces baryons subissent un flot important, laisse supposer qu'elles auraient développé un flot, donc qu'elles auraient été soumises à des interactions, avant la phase d'hadronisation, autrement dit, dans une phase partonique. Les partons subiraient donc des interactions résiduelles, contrairement à ce que préconisaient les théoriciens du milieu des années soixante-dix.
Par ailleurs, en 2003, les quatre expériences du RHIC ont révélé conjointement la mise en évidence du phénomène de jet-quenching dans les collisions d'ions lourds : il traduit une diminution de la production de particules chargées de très haute impulsion transverse s'expliquant par la perte d'énergie des partons dans un milieu très dense. Nous avons réalisé cette analyse en considérant les X et montré que non seulement ces baryons subissent un jet-quenching mais aussi qu'ils ont un comportement différent de celui des mésons. Une dépendance des phénomènes dynamiques au type de particules a ainsi été mise en évidence en accord avec les modèles de coalescence préconisant que les hadrons se forment à partir de la recombinaison des quarks. Là aussi, émergence des partons comme degrés de liberté pertinents.
A partir de ces résultats entre autres, certains théoriciens affirment la découverte du QGP à RHIC mais les expérimentateurs sont plus prudents et désirent auparavant confirmer et enrichir leurs résultats par l'étude d'autres observables qui viendraient corroborer ces observations. Ces années ont été particulièrement stimulantes par l'évolution de nos connaissances grâce aux formidables résultats produits par les quatre expériences du RHIC. Les « vielles » signatures ont fait peau neuve se transformant en sondes nouvelles et riches en informations originales. La conception du QGP a évolué : il ne s'agit plus d'un gaz parfait constitué de partons évoluant librement mais d'un sQGP.
Vauthier, Astrid. "Mesure des corrélations photon-hadron auprès de l'expérience ALICE au LHC pour l'étude du plasma de quarks et de gluons." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY062/document.
The quantum chromodynamics (QCD), the theory used at present to describe the strong interaction, predicts the existence of a phase transition, at very high temperature and/or density, towards a state of nuclear matter where quarks and gluons are deconfined : the Quark-Gluon Plasma (QGP). Such a medium can be produced in laboratory, and the measurement of its properties allows to give a new perspective on the mechanisms of interactions between the constituents as well as to test the QCD in unexplored domains.Ultra-relativistic heavy ion collisions delivered by the accelerator LHC at CERN allow to obtain the thermodynamical conditions necessary for the QGP to be formed. By means of a diversified instrumentation, the ALICE experiment allows to reach a large number of observables allowing to characterize the QGP. Among these, the measurement of the fragmentation of the partons (quarks and gluons) allows to study in detail the mechanisms of energy loss in the medium and its redistribution in the final state, and can also be compared with theoretical calculations, based on QCD, that model the interaction of an energetic parton with the QGP which is passing through.The work presented in this manuscript is articulated around the study of the fragmentation function via the measurement of the photon-hadron correlations in proton-proton and proton-Lead collisions. At first, a work on energy calibration of the ALICE experiment’s electromagnetic calorimeter was realized, along with the characterization of the uncertainties of this calibration. Secondly, the photon-hadron correlations, whose main difficulty is the identification of the direct photons, were studied. The results obtained in both systems of collisions demonstrate the feasibility of the analysis which can be easily widened to the peripheral Lead-Lead collisions. Finally, this work shows that the dominant uncertainties of the measurement will be reducible with the new data delivered by the LHC
Sansavini, Francesca. "Misura della risoluzione temporale del sistema a Tempo di Volo (TOF) di ALICE a $\sqrt(s_NN)=5.02$ TeV." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/12401/.
LaHurd, Danielle V. "Searching for Quark Gluon Plasma Signatures in Ultra High Energy Cosmic Rays." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1479298851843212.
Castillo, Javier. "Production de particules doublement étranges dans les collisions d'ions lourds ultra-relativistes à √SNN = 130 GeV." Paris 7, 2002. http://www.theses.fr/2002PA077043.
Puglisi, Armando. "Transport coefficients and early time dynamics of the Quark-Gluon Plasma created in ultra-relativistic heavy ion collisions." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/4016.
Rosnet, P. "Les saveurs lourdes dans les collisions d'ions lourds ultra-relativistes." Habilitation à diriger des recherches, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00262436.
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.
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
Estienne, Magali. "Propriétés chimiques et dynamiques des collisions d'ions lourds aux énergies du RHIC par la mesure de la production des baryons doublement étranges dans l'expérience STAR." Phd thesis, Université de Nantes, 2005. http://tel.archives-ouvertes.fr/tel-00011024.
Wu, Tao. "Production de phi et omega dans les collisions PbPb a 158 GeV par nucléon." Phd thesis, Université Paris Sud - Paris XI, 2003. http://tel.archives-ouvertes.fr/tel-00004516.
La multiplicité du J/Psi observée dans ces résultats ne confirme pas une brutale décroissance pour les collisions très centrales. Inversement, il n'y a pas non plus d'évidence pour une saturation de la suppression, comme prédit par plusieurs modèles théoriques ne postulant pas l'existence d'une phase plasma.
Les sections efficaces de production et les multiplicités des dimuons issus des mésons phi et omega sont similaires aux précédents travaux. Néanmoins l'évolution depuis 2002 de la valeur du PPDB du BR_(phi->mu mu) induit un rapprochement entre les multiplicités de phi observées ici et celles obtenues par NA49, ce qui résoud en partie le «phi puzzle ». Toutefois les pentes apparentes restent différentes.
Cette étude débouche aussi sur des perspectives pour la détermination du taux d'étrangeté dans le milieu grâce à l'utilisation directe du rapport phi/omega qui correspond au carré du facteur de saturation de l'étrangeté chi_s utilisé dans de nombreux modèles thermiques.
Gaudichet, Ludovic. "Production de Lambda(1520) dans les collisions p+p et Au+Au à sqrt(s_NN) = 200 GeV dans l'expérience STAR au RHIC." Phd thesis, Université de Nantes, 2003. http://tel.archives-ouvertes.fr/tel-00003775.
Ragoni, Simone. "Hadron spectra measurement in Xe--Xe collisions at $\sqrt{s_{\rm{NN}}}=5.44 \text{ TeV}$ with the ALICE experiment at the LHC." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16383/.
Masson, Erwann. "Mesure de la production de photons isolés dans les collisions proton-proton et proton-plomb au LHC avec l’expérience ALICE." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2019. http://www.theses.fr/2019IMTA0148/document.
In the Standard Model of particle physics, elementary constituents of matter identified to date are quarks and gluons, generically called partons and obeying the strong interaction described by quantum chromodynamics (QCD). While partons are confined in hadrons under standard temperature and density conditions, the existence of a deconfined state, quark-gluon plasma (QGP), has been predicted by QCD for extreme thermodynamic conditions. This state of matter can be reached in ultrarelativistic heavy-ion collisions such as produced at the CERN Large Hadron Collider (LHC) and can be probed with many observables accessible to the ALICE experiment in particular. Prompt photons, emitted by high-energy partonic processes, constitute a key probe of hadronic matter. Insensitive to the strong interaction they can traverse the deconfined medium preserving primary information about a collision, and thus represent a valuable reference not affected by QGP a priori. These photons can be identified with electromagnetic calorimetry and isolation techniques. Within this doctoral thesis, the isolated photon production has been measured in proton-proton and proton-lead collisions with the ALICE experiment. The results are in agreement with QCD predictions, including in a kinematic range unexplored by this observable thus far
Fanì, Mattia. "Proposal of a Continuous Read-out Implementation in the ALICE-TOF detector." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9569/.
Lima, Lucas Mafia. "Estudo da produção de quarks pesados no experimento STAR@RHIC." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-02052012-201236/.
The quark and gluon plasma is a prediction of QCD, and high energy experiments have studied evidences of its creation in relativistic heavy ion collisions. One of these evidences was proposed by Matsui and Satz [1] that provides a experimental signature of the creation of the plasma, observing an anomalous supression on the heavy quarkonium production. This project aims to get production cross section in the STAR experiment in collisions p+p and d+Au with energy in the center of mass of 200GeV and calculate the nuclear modification factor Rab. To this end, it was necessary to reconstruct the from his leptonic decay. The subsystems used in this analysis were the TPC, BEMC and the heavy quarkonia trigger system. The values for the cross sections were 3i=1 (nS)e-e+(nS)p+p= 84 ±9(stat)+18-19(sist)pb and 3i=1 (nS)e-e+(nS)d + Au = 41 ± 4(stat) +7-8(sist)nb for pp2009 and dAu2008 productions, respectively. These values are compatible with the theoretical calculated by the color evaporation model. The determined value for the factor Rab was 1.24 ± 0.18(stat)+0.35 0.38(sist).
Zhu, Jianhui. "W boson measurement in the muonic decay channel at forward rapidity with ALICE." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0014/document.
The high collision energies available at the LHC allow for an abundant production of hard probes, such as quarkonia, high-pT jets and vector bosons (W, Z), which are produced in initial hard parton scattering processes. The latter decay before the formation of the Quark-Gluon Plasma (QGP), which is a deconfined phase of QCD matter produced in high-energy heavy-ion collisions. Their leptonic decay products do not interact strongly with the QGP. Thus electroweak bosons introduce a way for benchmarking in-medium modifications to coloured probes. The production of W-boson in pp collisions at √s=8 TeV and p-Pb collisions at √sNN=5.02 TeV are measured via the muonic decay channel at the LHC with the ALICE detector. In pp collisions the rapidity covered by the measurement is -4cms<-2.5. In p-Pb collisions, on the other hand, the different energies of the proton and lead ion give rise to a rapidity shift. By exchanging the direction of the beams, it is possible to cover the rapidity ranges -4.46cms<-2.96 and 2.03cms<3.53. The production cross section and charge asymmetry of muons from W-boson decays with pμT>10 GeV/c are determined. The results are compared to theoretical calculations both with and without including the nPDFs. The W-boson production is also studied as a function of the collision centrality: the cross section of muons from W-boson decays is found to scale with the average number of binary nucleon-nucleon collisions with uncertainties
Wu, Yang. "Azimuthal anisotropy in gold-gold collisions at 4.5 GeV center-of-mass energy per nucleon pair using fixed-target mode at the Relativistic Heavy-Ion Collider." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1562355001935965.
Alalawi, Huda. "INVESTIGATION OF NUCLEAR COMPRESSION IN THE AMPT MODELOF NUCLEUS-NUCLEUS COLLISIONS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1543405727739039.
Wong, Stephen Man Hoe. "Finite temperature field theory - hard thermal loops and the quark-gluon plasma." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309328.
Jahnke, Viktor. "A correspondência AdS/CFT e o plasma de quarks e glúons." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-30102016-225555/.
The aim of this work is to study applications of the AdS/CFT correspondence to strongly coupled plasmas similar to the quark-gluon plasma (QGP) produced in heavy ion collisions at RHIC and LHC. The project is articulated in two parts. Initially, we will study how some observables, such as photon and dilepton production rates, are affected by spatial anisotropies present in the plasma. This is important, since the QGP produced in real world experiments generically starts in highly anisotropic configurations, which later evolve towards isotropy. To model anisotropy at strong coupling we will make use of an anisotropic black hole solution of type IIB supergravity which has been recently obtained in arXiv:1105.3472/ hep-th. As a second direction of research and again focusing on applications of the AdS/CFT correspondence to the QGP, we will investigate Lovelock theories of gravity, which are natural generalizations of Einsteins general relativity. These theories contain higher derivative terms, while maintaining the equations of motion of second order, and constitute an ideal arena where to start understanding how higher derivative corrections affect various physical observables of the plasma.
Jacobsen, Rafael Bán. "Plasma de quarks e glúons no interior de estrelas de nêutrons." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/15328.
The purpose of this work is the study of nuclear matter at high densities considering the hadronic and quark phases at zero temperature, with the perspective of applying the developed formalism to the analysis of global static properties of neutron stars. in this work, after presenting important aspects of stellar evolution and neutron star theory, we study the properties and models of nuclear matter. In the nuclear matter studies for the hadronic phase, we have considered the relativistic nuclear quantum eld theory developed by J. D. Walecka, J. Zimanyi and S. A. Moszkowski, and by J. Boguta and A. R. Bodmer, also known, respectively, as Sigma-omega, ZM and Non-linear models. In these models the nuclear matter is described by a relativistic and strong interaction lagrangian many-body formulation with baryon e ective elds coupled to scalar, vector and iso-vector mesons. In this study we consider initially the description of global static properties of manybody nuclear systems at zero temperature as, for instance, the nucleon e ective mass for symmetric nuclear and neutron matter. Knowledge of the neutron matter equation of state makes it possible the description of global static properties of a neutron star, such as its mass and radius, through the Tolman, Oppenheimer and Volko equations. The results we have obtained in this work are in agreement with the corresponding ones presented by other authors. We have further included into the formalism the chemical equilibrium equations, lepton degrees of freedom for electrons and muons, the fundamental octet of baryons and the charge neutrality condition. Our choice for the hyperonic coupling constants is based on the SU(6) symmetry and on the counting rules for quarks. The consideration of generalized beta equilibrium among the particles in our formalism generates a strongly coupled system of eleven equations to be numerically solved to nd the di erent fermionic populations. At last we study a phenomenological lagrangian model of nuclear matter with adjustable derivative coupling, which exhibits a parametrization, through mathematical expressions with adjustable coe cients, of the intensity of the meson-nucleon coupling. We study the in uence of these couplings in the determination of the main nuclear properties and global static properties of neutron stars. This model is the one we use to develop our study of the hadronic matter to quark matter phase transition in the last part of our work, using the Gibbs criteria. In the quark matter study, we have considered the bag model developed ih the Massachusetts Institute of Technology (MIT) by A. Chodos, R. L. Ja e, K. Johnson, C. B. Thorn and V. F. Weisskopf. As a main result, we have determined a general equation of state for hadronic and quark matter, and we have analyzed the equilibrium conditions for hybrid stars. We have then focused the in uence of the adjustable model couplings in the determination of the phase transition baryon density. We have also analyzed how the existence of the quarkgluon plasma core in the star repercutes in its global static properties (such as radius and maximum mass) and in the thermodynamical property known as the adiabatic index. The predictions of our work, even though based on new results, are in complete agreement with the corresponding ones obtained by other authors.
Caron, Huot Simon 1984. "Heavy quark energy losses in the quark-gluon plasma : beyond leading order." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112385.
Junior, Samuel Mendes Sanches. "Equações de estado do plasma de quarks e glúons e suas aplicações." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-07122018-135435/.
The quark gluon plama is a subject that has been actively studied in recent years, due to the advent of modern particle colliders and advances in research related to compact stars. Thus, in this thesis we had as main goal the study of this plasma. For this, we improved an equation of state developed by our group, where an interaction with a constant magnetic field was added. With this new equation of state, which is formulated from the mean field approximation technique, we made several applications. As in the study of propagation of linear and non-linear waves, with the goal of verifying whether the causality and stability are respected. We solved the Tolman-Oppenheimer-Volkoff equation to obtain the mass-radius diagram for a compact quark star. We study how the temporal evolution of the primordial Universe by solving Friedmanns equations and the temporal evolution of bubbles of quark gluon plasma in a hadrons gas (and also of bubbles of hadrons gas in a quark gluon plasma) using the relativistic Rayleigh-Plesset equation.
Jackson, Greg. "The Runny Gauge Plasma: shear viscosity to entropy for quarks and gluons." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/23061.
Boyer, Bruno. "Etude des J/psi dans le canal dimuon du spectromètre de l'expérience ALICE auprès du LHC dans les collisions proton+proton à sqrt(s) = 7 TeV." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00662272.
Marty, Rudy. "Simulation de l'expansion et la transition de phase d'un plasma de quarks et d'antiquarks." Nantes, 2012. http://archive.bu.univ-nantes.fr/pollux/show.action?id=1e717997-f289-455a-ad6b-f9721bd98a45.
The study of the phase diagram of nuclear matter is often not trivial. This thesis attempts to describe the phase transition created in accelerators of particles, at hightemperature and low baryonic density. If accelerators of particles can be seen as the microscopes of the matter, nevertheless we can not directly observe the phase transition. So we will use a theoretical model to reproduce this phenomenon. The processes involved in the transition are of low energy, where the standard theory Quantum Chromodynamics (QCD)- can not be applied in a perturbative way. I will therefore present and use a more simplified model of this theory : the model of Nambu and Jona-Lasinio (NLJ). This model can describe the fundamental particles of matter and their subsequent hadronization via cross sections and the construction of the mass of hadrons. Finally we use the masses and cross sections of this model in a new simulation code based on relativistic molecular dynamics. The presentation of this model begins with the justification of its relativistic aspect, then the explanation of its algorithms. The results of these simulations are finally analyzed and compared with data from RHIC. The phenomenology of non-observable results is also discussed
Denke, Robson Zacarelli. "Transições de fase na matéria de quarks magnetizada com repulsão vetorial." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/157418.
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Neste trabalho investigamos as transições de fase na matéria de quarks magnetizada usando o modelo de NJL com dois sabores na presença de acoplamento vetorial repulsivo (GV). Verificamos que a contribuição vetorial produz o encolhimento da linha de transição de primeira ordem e pode favorecer o mecanismo de back-bending no regime de acoplamento forte. Este fato permite conciliar alguns resultados da rede com as previsões teóricas sobre a existência de um ponto crítico no diagrama de fases da QCD. Analisamos como a ação de um campo magnético (B) intenso na matéria de quarks tende a fortalecer a região de primeira ordem e que também determina um padrão oscilatório na densidade. Concluímos que os efeitos opostos do acoplamento vetorial e do campo magnético na restauração da simetria quiral levam a um desdobramento de múltiplas fases magnetizadas. A ação combinada de B e GV pode originar linhas de coexistência no diagrama de fases que apresentam um comportamento exótico similar ao observado para a transição sólido-líquido da água. Mostramos como a influência da repulsão vetorial deve estabilizar fases magnéticas de densidade intermediária e que certas combinações dos parâmetros B e GV determinam pontos triplos no diagrama de fases. Exploramos as propriedades magnéticas anisotrópicas sobre os quarks e como a contribuição vetorial deve afetar a magnetização induzida determinando um comportamento diamagnético para o sistema.
Abstract : In this work we investigate the phase diagram of dense magnetizedquark matter in the framework of the two-flavor Nambu-Jona-Lasiniomodel when a repulsive vector coupling (GV ) is present. We verifythat the vector contribution could shrink the first order transition lineand can support the back-bending mechanism under a strong couplingregime. This result allows one to conciliate some lattice results withtheoretical predictions about the existence of a critical point in theQCD phase diagram. Our analysis shows how an intense magnetic field(B) acts in the quark matter, strengthening the coexistence region inthe phase diagram and setting an oscillatory pattern in density values.The opposite effect of the vector coupling and magnetic field in thechiral symmetry restoration leads to a splitting of multiple magneticphases. The combined action of B and GV gives rise to coexistencelines which can render an exotic behavior resembling the solid-liquidtransition observed in the water phase diagram. We show how thevector repulsion stabilizes the intermediary magnetic phases and thatcertain B and GV parametric combinations can cause a triple point toappear in the phase diagram. We also study the anisotropic propertiesof magnetized quark matter and how the vector-like contribution affectsthe induced magnetization leading to a diamagnetic behavior.
Coci, Gabriele. "Probing the Quark-Gluon Plasma properties through Heavy Quarks' dynamics: transport coefficients and elliptic flow." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/4190.
Espagnon, Bruno. "Aperçu sur l'étude du Plasma de Quarks et de Gluons à l'aide du spectromètre dimuons d'ALICE." Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00260365.
Hamieh, Salah. "Hydrodynamique du plasma de quarks et de gluons dans les collisions d'ions lourds : évolution de l'étrangeté." Paris 11, 2000. http://www.theses.fr/2000PA112225.
Socolowski, Jr O. (Otávio). "RPA relativística para ressonâncias gigantes isovetoriais /." São Paulo, 1994. http://hdl.handle.net/11449/132707.
Banca: Diógenes Galetti
Banca: Brett V. Carlson
Resumo: Utilizamos o modelo hidrodinâmico de emissão contínua de partículas para estudar vários dados experimentais do SPS/CERN. Dados sobre razões de partículas estranhas das colaborações WA85 e WA97 são usados para determinar um conjunto de condições iniciais para o fluxo hidrodinâmico. Testamos a autoconsistência do modelo estudando outros dados experimentais com as mesmas condições iniciais que reproduziram as razões de partículas estranhas. Mostramos que os espectros em massa transversal de NA35, WA85, NA49 e WA97 podem ser bem reproduzidas. A grande vantagem dessa abordagem (além de ser corroborada pelos modelos microscópicos) é que ela pode resolver, de um modo natural, alguns dos problemas enfrentados pelo modelo usual de freeze-out: possíveis altas densidades de partículas, pequena abundância de píons e temperatura incorreta do 'ômega'
Abstract: We use the hydrodynamical model of continuous particle emission to study several ex- perimental data from SPS/CERN. Data on strange particle ratios from WA85 and WA97 Collaborations are used to determine a set of initial conditions for the hydrodynamical flow. We test the self-consistency of the model by studying several other experimental data by using the same initial conditions that reproduce strange particle ratios. We show that the transverse mass spectra from WA35, WA85, NA49 and WA97 can be well repro- duced. We also reproduce particle abundances, including the tt one. The big advantage of this approach (in addition to being corroborated by microscopical models) is that it may solve, in a natural way, some of the problems met by the standard hydrodynamical approach with sudden freeze-out: possible too high densities, too small pion abundance and wrong 'ômega' temperature
Mestre
Guiot, Benjamin. "Production de charms et de photons prompts avec le générateur d'évènements EPOS." Thesis, Nantes, Ecole des Mines, 2014. http://www.theses.fr/2014EMNA0192/document.
At the LHC, strong interaction is studied by doing collisions of high energy particles. In the case of nucleus-nucleus collision (lead at the LHC), a new state of matter, called Quarks Gluons Plasma (QGP), is created. The study of this QGP is currently a lively research field. Hard probes, like heavy quarks and prompt photons, are produced during early times of collisions done at the LHC. This is why they are ideal probes for the study of the QGP. They will go through and interact with the medium produced by the collision. A comparison with a case without QGP (proton-proton- collision) will allow us to see how hard probes properties are modified by themedium. Then, medium properties like temperature and density can be extracted. This study requires a good understanding of hard probes production in proton-proton collisions. The aim of my thesis is the implementation of heavy quarks and prompt photons in the event generator EPOS (computer code for colliders), for p-p collisions. Our final aim is the study of the QGP in Pb-Pb collisions
Pillot, Philippe. "Les résonances de quarks lourds comme sonde du plasma de quarks et de gluons : optimisation du spectromètre à muons de l'expérience ALICE et étude de la production du J/$\psi$ dans l'expérience NA60." Phd thesis, Université Claude Bernard - Lyon I, 2005. http://tel.archives-ouvertes.fr/tel-00010685.
Guerin, F. "Sonde muonique et instrumentation associée pour l'étude du plasma de quarks et de gluons dans l'expérience ALICE." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00132781.
Guérin, Fabien. "Sonde muonique et instrumentation associée pour l'étude du plasma de quarks et de gluons dans l'expérience ALICE." Clermont-Ferrand 2, 2006. http://195.221.120.247/simclient/consultation/binaries/stream.asp?INSTANCE=UCFRSIM&eidmpa=DOCUMENTS_THESES_215.
Jahnke, Cristiane. "Measurement of electrons from heavy-flavour hadron decays in p-Pb collisions at $\\sqrt{s_{NN}} = 5.02$ TeV using TPC and EMCal detectors with ALICE at LHC." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17062016-153829/.
Colisões de íons pesados relativísticos é uma ferramenta poderosa para se estudar o plasma de quarks e glúons (QGP). Quarks pesados ({\\it charm} e {\\it beauty}) são produzidos nos estágios iniciais da colisão e participam da evolução completa do sistema. Medidas de elétrons provenientes de quarks pesados é uma das possíveis formas de se estudar a interação destas partículas com o QGP. Utilizando o detetor ALICE do LHC, elétrons podem ser identificados com alta eficiência e boa pureza. Uma forte supressão de elétrons provenientes de quarks pesados foi observada em alto $p_$ em colisões de Pb-Pb a 2.76 TeV. Medidas do mesmo observável em colisões p-Pb são cruciais para se entender os efeitos da matéria nuclear fria na produção de tais partículas. O espectro de elétrons provenientes de hádrons que contêm {\\it charm} ou {\\it beauty} foi medido em colisões p-Pb a $\\sqrt = 5.02$ TeV. Os elétrons foram identificados utilizando o {\\it Time Projection Chamber} (TPC) e o {\\it Electromagnetic Calorimeter} (EMCal) do detetor ALICE, no intervalo de momento transversal de $2 < p_ < 20$ GeV/c. As medidas foram realizadas utilizando dois diferentes conjunto de dados: colisões de mínima tendenciosidade ({\\it minimum bias (MB)}) e colisões tomadas utilizando o trigger do EMCal. Os elétrons de fundo foram removidos utilizando um método de massa invariante. Os resultados são compatíveis com a unidade ($R_ \\approx$ 1) e os efeitos da matéria nuclear fria são pequenos para elétrons provenientes de quarks pesados.
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.
Coorientador: Bruno El-Bennich
Banca: Lauro Tomio
Banca: Juan Pablo Carlomagno
Banca: Sidney dos Santos Avancini
Banca: Kazuo Tsushima
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)
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)
Doutor
Guernane, Rachid. "Optimisation du spectromètre à muons du détecteur ALICE pour l'étude du plasma de quarks et de gluons au LHC." Phd thesis, Université Claude Bernard - Lyon I, 2001. http://tel.archives-ouvertes.fr/tel-00001419.
Zarake, Haitham. "Production de photons et de dileptons dans un plasma de quarks et de gluons : structure infrarouge et effets cohérents." Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10078.
Filho, Elienos Pereira de Oliveira. "Study of the angular correlation between heavy-flavour decay electrons and charged unidentified particles in pp and p-Pb collisions with ALICE." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-18012015-125411/.
O próposito de colisões entre íons pesados relativísticos é investigar as propriedades do plasma de quarks e gluons (QGP, do inglês Quark-Gluon Plasma). A transição de fase, de um estado hadrônico para o QGP, ocorre em regimes onde a temperatura e/ou densidade atingem um valor suficientemente alto. Neste contexto, colisões entre íons pesados e leves (por exemplo, p-Pb) permitem acessar efeitos devido à matéria nuclear fria (CNM, do inglês Cold Nuclear Matter) e colisões elementares (por exemplo, próton-próton) são usadas como referência para estudos com íons pesados, além de proporcionarem testes para cálculos de QCD perturbativa. Quarks pesados, isto é charm e bottom, são ferramentes muito convenientes no estudo e caracterização do QGP. Essas partículas são produzidas através de espalhamento duro nos instantes iniciais da colisão e, portanto, elas atuam como uma sonda externa para o sistema criado na reação. Esse trabalho consiste no estudo da correlação angular entre elétrons oriundos de quarks pesados e partículas carregadas, em colisões pp (2.76 e 7 TeV) e p-Pb (5.02 TeV), no acelerador LHC (do inglês Large Hadron Collider) do CERN, usando o detector ALICE (do inglês A Large Ion Collider Experiment). A distribuição angular mencionada foi medida em função da multiplicidade do evento, no caso de colisões p-Pb. Em colisões pp, a contribuição relativa de quarks charm e bottom para o total de elétrons provenientes de quarks pesados foi estimada usando a função de correlação obtida.
Martinez, Gines. "Introduction à l'étude expérimentale de la matière hadronique dans les collisions entre ions lourds. Le Plasma de Quarks et de Gluons." Habilitation à diriger des recherches, Université de Nantes, 2006. http://tel.archives-ouvertes.fr/tel-00370481.
Gelis, François. "Fonctions de corrélation en théorie des champs à température finie : Aspects formels et applications au plasma de quarks et de gluons." Phd thesis, Chambéry, 1998. http://www.theses.fr/1998CHAMS028.
Gardim, Fernando Gonçalves. "Termodinâmica de quase-partículas /." São Paulo, 2009. http://hdl.handle.net/11449/132792.
Banca: Sandra dos Santos Padula
Banca: Jun Takahashi
Banca: Eduardo Souza Fraga
Banca: Manuel Máximo Bastos Malheiro de Oliveira
Resumo: O problema da inconsistência termodinâmica do modelo de quase-partículas foi parcialmente resolvido por Gorenstein e Yang há quase duas décadas. Entretanto sua solução mostra-se como uma solução particular para o problema da inconsistência termodinâmica. Este trabalho apresenta a solução geral para o modelo de quase-partículas a partir da generalização da solução de Gorenstein-Yang, estudando-se assim o modelo de quase-partículas em dois cenários diferentes: para o caso onde este é formado apenas por bósons, e quando é formado por bósons mais férmions e anti-férmions. Para o caso bosônico assume-se os bósons não-massivos, em um sistema à temperatura finita e potencial químico nulo, obtendo então sua solução termodinâmica geral. A partir desta utiliza-se uma solução particular para descrever a matéria desconfinada, o Plasma de Glúons, e compara-se esta solução com os dados provenientes de QCD na rede para pressão, entropia e energia interna. Estuda-se também a solução geral para um sistema à temperatura e potencial químico finitos formado por férmions, anti-férmions e bósons. O limite assintótico destas soluções também é analisado. Uma solução particular, análoga à utilizada no caso apenas de bósons, é utilizada para descrever os resultados de QCD na rede, para um Plasma de Quarks e Glúons. Este formalismo permite descrever o Plasma de Quarks e Glúons em toda região de desconfinamento. Seja no caso bosônico, ou no caso de bósons e férmions, encontra-se uma solução mais simples que a de Gorenstein-Yang para descrever o QGP
Abstract: The thermodynamics quasi-particle problem was partially solved by Gorenstein and Yang. Nevertheless, its solution is a particular solution of the thermodynamic inconsistency problem. In this work the thermodynamics of the quasi-particle model is studied from a generalization of the Gorenstein-Yang solution. This work is split in two parts: For the case of finite temperature and vanishing chemical potential for non-massive bosons, and for finite temperature and Chemical potential of anti-fermions, fermions plus bosons. For the boson case is computed the thermodynamical general solution and from it, a particular solution it is used to describe the deconfined matter, Gluon Plasma. This solution is compared to QCD lattice data, thus the pressure, entropy and internal energy can be fitted. Also is developed the solution for a system composed by fermions, antifermions and gluons. An analogue solution to boson case it is used to describe the real case, the Quark Gluon Plasma. It is shown that solution is able to describe the lattice data. This general formalism allows study the QGP in all deconfined region. Whether in the bosonic case, or in bosonic plus fermionic case, it is found a simpler solution than the Gorenstein-Yang
Doutor
Silva, Cesar Luiz da. "Estudos de mésons vetoriais pesados no detector Phenix." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17042009-150222/.
This work reports measurements done by the PHENIX detector at RHIC about J/Psi in p+p and Au+Au collisions at s^(1/2) = 200 GeV in the mid-rapidity range and Psi\' in p+p collisions in the same conditions. The measurements include the transverse momentum dependence of charmonium production and J/Psi nuclear modification factor in different centrality regimes.
Speltz, Jeff Coffin Jean-Pierre. "Caractérisation d'un état dense de quarks et de gluons grâce aux fonctions d'excitation des hypérons multi-étranges mesurées avec l'expérience STAR au RHIC." Strasbourg : Université Louis Pasteur, 2007. http://eprints-scd-ulp.u-strasbg.fr:8080/714/01/Speltz2006.pdf.
Nendaz, Fabien. "Préparation à l'étude du plasma de quarks et de gluons dans ALICE : le détecteur V0 et les résonances de masses dans le spectromètre à muons." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00452580.
Guimarães, Karin Silvia Franzoni Fornazier. "Estudo da produção de estranheza em colisões entre íons pesados relativísticos a &." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17122007-105539/.
The main goal of this work was to measure the production of the singly strange particles, such as K0, and in Au+Au collisions at ?sNN = 62.4 GeV, inserting these results in a systematic energy scan study. The data were obtained from the STAR detector, one of the RHIC experiments. In addition, we have used the particle production in these collision to study two specific stages of the fireball evolution: the chemical and kinetic freeze-outs. These two stages were studied comparing the ratio between different particles (strange or not) and also the transverse momentum distribution with thermal models fits in order to check possible effects of equilibrated Quark Gluon Plasma (QGP) in the hadron production. The chemical freeze-out was studied comparing the ratios between particles produced in the collision with two different thermal models: one which assumes a equilibrated hadron gas (THERMUS) and another one which assumes a possible non-equilibrated system (SHM). The experimental data were well described by the THERMUS model fit in a great range of energy collisions, mainly at 62.4 GeV. The thermodynamic parameters had been studied as function of the energy in order to verify if it has a smooth or abrupt behavior. The result indicated that this behavior is very smooth with energy. We also compared these results with SHM\'s predictions and, in this comparison, the ratio presented an interesting behavior, suggesting that at low energies the fireball consists of a non-equilibrated system, such as described by SHM model, whereas the model that considers the fireball as a equilibrated hadron gas. The kinetic freeze-out was studied with the transverse momentum spectra using a hydrodynamics inspired model. The results indicate that for the most central events there is a higher expanding velocity and a lower freeze-out temperature. It was also observed that for the particle, the freeze-out temperature is higher than the one for other particles (?, K, p) indicating an earlier decoupling of these particles from the fireball. Finally, we have studied the inclusion for the SVT in the V0 reconstruction analysis, trying to optimize this detector usage in the analysis. The results show that the inclusion of this detector in the analysis can improve the efficiency and purity of the V0 reconstruction in the STAR experiment.
Wu, Tao. "Production de phi et oméga dans les collisions Pb-Pb à 158 Gev par nucléon." Paris 11, 2003. https://tel.archives-ouvertes.fr/tel-00004516.
In the most central collisions of Pb-Pb nuclei at SPS CERN, sufficiently high values of energy density could be reached so that a transient new state of matter, the plasma of quarks and gluons (QGP) could be formed. The identification of the production of this state relies on consequences it could induceon final products of the collision, like J/psi suppression due to screening effect on the quark pair potential, or increase of the strangeness production in the plasma. Measuring muon pairs in coincidence with observables characterising the PbPb impact parameter, like the transverse energy E-T produced, the NASO experiment bas observed the anomalous suppression of the J/psi and the enhancement of the phi(grec) production. This thesis deals mainly with the phi production study in the data collected by NA50 in year 2000, with an improved experimental setup, in particular concerning the trigger used for measurement of the transverse energy distribution of the Pb-Pb collisions, and rejection of collisions not occurring in the target. These improvements have given a better access to peripheral and central collisions. The transverse energy spectrum obtained is nicely reproduced by a Glauber geometrical model of the collision, from a low E-T threshold. A cross check between various muon pairs multiplicities do not exhibit systematical bias for the most central collisions. Similarly a cross comparison between J/psi and minimum bias events as a function of E-T bas been used to determine the effect on the efficiency of signal determination, of rejections performed on the events. The behaviour of J/psi multiplicity with E-T which is obtained in this study does not confirm the additional drop that could have been suggested by previous results. Inversely the observed decrease of the J/psi multiplicity divided by the number of n-n collisions determined in the Glauber calculation does not seem to saturate for the most central collisions, as predicted by several models which does not suppose the formation of a QGP. The multiplicities and cross sections that we obtain with 2000 datas for phi and w(omega) are in agreement with the ones obtained with previous data sets. The change in the phi branching ratio into dimuons partly reconciles NA50 phi multiplicities with the one measured by NA49 experiment, but the slopes of the MT spectra remains very different. In summary this study confirms the results previously obtained, and brings additional information about most central collision, for J/psi and phi multiplicities. The interest of the phi/w(omega) ratio as a direct estimate of the square of the strangeness saturation factor γs is underlined
Fleuret, Frédéric. "Recherche du plasma de quarks et de gluons par l'étude des mésons Jpsi et Jpsi’ dans les collisions d'ions Pb et de protons ultrarelativistes sur divers noyaux." Palaiseau, Ecole polytechnique, 1997. http://www.theses.fr/1997EPXX0015.