O advento dos colisores modernos tem proporcionado novas possibilidades de estudo em física de partículas como, por exemplo, a busca por nova física e o estudo de novos estados da matéria hadrônica. Em particular, em colisões de íons pesados em altas energias, acredita-se que um novo estado da matéria seja formado antes da colisão, o chamado condensado de vidros de cor. Tal estado seria a condição inicial de um plasma de quarks e glúons e é caracterizado por altas densidades de pártons (quarks e glúons). De fato, as equações de evolução da Cromodinâmica Quântica predizem que, para virtualidades moderadas e altas energias, os hádrons se tornam sistemas extremamente densos devido ao crescimento das distribuições de glúons nessas condições. Um crescimento indefinido das distribuições de glúons poderia levar à violação do vínculo de unitariedade. Para evitar essa violação, existe um mecanismo chamado de saturação de pártons o qual contém o crescimento das distribuições de quarks e glúons de forma a respeitar o vínculo de unitariedade. Teoricamente, no limite de altas energias, observa-se que os hádrons são populados especialmente por glúons. Experimentalmente, existem indícios da saturação em colisões ep, pp, pA e AA, contudo, isso ainda é uma questão em aberto. Portanto, no limite de altas densidades, espera- se que a física não linear, a qual leva em conta efeitos de recombinações de glúon, passe a se manifestar. Uma alternativa para o estudo da saturação em colisores hadrônicos são os processos foto-induzidos, os quais ocorrem em interações ultraperiféricas. Em uma colisão ultraperiférica entre dois hádrons, o parâmetro de impacto é maior do que a soma dos raios dos hádrons, de forma que interações fortes são suprimidas. Dessa forma os hádrons atuam como fontes de fótons (quase reais) podendo ocorrer interações fóton-hádron e fóton-fóton. Nesse trabalho estudamos a fotoprodução difrativa de mésons vetoriais em energias do LHC para colisões ultraperiféricas próton-próton, próton-núcleo e núcleo-núcleo e a produção dupla de mésons vetoriais em colisões fóton-fóton e devido ao mecanismo de duplo espalhamento fóton-p(A). Mostramos como esses processos podem ser usados para estudar a física de altas energias e os efeitos de saturação. Os efeitos de saturação em nossos cálculos são levados em conta através do formalismo de dipolo de cor, que é uma das ferramentas básicas usadas nessa tese. O tratamento de colisões ultraperiféricas hádron-hádron foi feito com a aproximação de fótons equivalentes que assim como o formalismo de dipolo, foi extensamente usada. Nossos resultados apontam que o estudo fenomenológico e experimental dos tipos de processos citados acima são factíveis e podem ser usados para vincular a dinâmica da QCD em altas energias. / The advent of the modern colliders has provided new possibilities of study in particle physics as, for example, the search for new physics and the study of new states of the hadronic matter. In particular, in high energy heavy ion collisions is expected that a new state can be formed before the collision, the so called Color Glass Condensate. This state would be the initial condition of the Quark Gluon Plasma and is characterized by high parton (quarks and gluons) densities. Indeed, the Quantum Chromodynamics evolution equations predict that, for moderate virtualities and high energies, the hadrons become extremely dense systems due to the growth of the parton distribution in these conditions. An indefinite growth of the parton distributions could lead to the violation of the unitarity bound. To avoid this violation, there is a mechanism called parton saturation which tames the growth of the parton distributions to satisfy the unitarity bound. Theoretically, in the high energy limit, one can see that the hadrons are populated mainly by gluons. Experimentally, there are indications of the saturation in ep, pp, pA and AA collisions, however, this is an open question. So, in the high density limit, we expect that the nonlinear physics, which takes into account gluon recombination effects start to manifest itself. An alternative for the study of the saturation at hadronic colliders are the photon-induced processes, which occurs in ultra-peripheral collisions. In a ultra-peripheral collision between two hadrons the impact parameter is greater than the sum of the radii of the hadrons, so the strong interaction is suppressed. Thus, the hadrons act as sources of (almost real) photons and may occur photon-hadron and photon-photon interactions. In this work we study the diffractive photoproduction of vector mesons at LHC and future colliders energies in ultra-peripheral proton-proton, proton-nucleus and nucleus-nucleus collisions and the double vector meson production in photon-photon collisions and due to the double photon-p(A) scattering mechanism. We show how these processes can be used to study the high energy physics and the saturation effects. These effects are considered in our calculations through the color dipole formalism, which is one of the basic tools used in this thesis. The treatment of the ultra-peripheral hadron-hadron collisions was done through the equivalent photon approximation that just as in the dipole formalism, was widely used. Our results point that the phenomenological and experimental studies of the processes cited above are feasible and can be used to constraint the QCD dynamics in high energies.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23002号 / 理博第4679号 / 新制||理||1671(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 大西 明, 准教授 菅沼 秀夫, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Title: Study of transverse flow of kaons in Au + Au collisions at 1.23A GeV Author: Lukáš Chlad Abstract: The production and propagation of strange hadrons at the threshold energy are important probes of the in-medium hadron's properties and stiffness of the equation of state of nuclear matter. In this thesis, the transverse kaon flow at Au + Au collisions with kinetic beam energy 1.23A GeV measured with the HADES spectrometer is discussed. The motivation for such an analysis and the theoretical introduction are described first, followed by the characterization of the the individual parts of HADES spectrometer. The procedure to identify detected particles from the measured signals is introduced. Finally, the flow analysis and its results are presented. The differential directed and elliptic flow of kaons in measured gold on gold collisions is compared with published data and with kinetic transport model predictions. Keywords: relativistic heavy-ion collisions, transverse flow, kaon flow 1

Highly energetic jets are considered to be a direct probe of hot and dense QCD medium created in heavy ion collisions. Jet measurements performed both at the LHC and RHIC indicate a presence of the jet quenching phenomenon. This thesis summarizes ATLAS jet heavy ion measurements and it reports the first exploratory study of properties of the multi-jet production in heavy ion collisions presented in terms of yield of neighbouring jets. The work is expected to shed a light on the process of the parton energy loss. The measurement is performed using the Pb+Pb collision data collected by ATLAS detector during the 2011 LHC runs at the nucleon-nucleon center of mass energy of 2.76 TeV. 1

In this thesis a production of J/ψ meson in pp and heavy-ion collisions was investigated. A comparison between Monte Carlo generator and data by ATLAS experiment at CERN was done. PYTHIA version 8.2 was chosen for the Monte Carlo generator. In the first part, comparisons of several configurations of PYTHIA were used to establish the best matching of the Monte Carlo to the data using collisions with centre-of-mass energy of 7 TeV. Choice of parton distribution functions was found not to be important, while presence or absence of initial and final state radiation were proven to have an important impact on the result. In the second part, correlation of J/ψ meson and the jet production was quantified. Anti-kt algorithm with R = 0.4 was used to reconstruct jets. Pairs of muons were used to identify J/ψ meson candidates. Only less than 10% of J/ψ mesons were found to be associated with jets. 1

Les collisions d’ions lourds à haute énergieproduisentunnouvelétatdelamatièreappelé le plasma de quarks et de gluons. Un parton traversant le plasma perds de l’énergie, en atténuant les gerbeshadroniques:c’estl’effetde"jetquenching". La dépendance du jet quenching dans la saveur du parton fournit des contraintes sur les modèles de perte d’énergie. Le déséquilibre d’une paire de jets issus de quarks b est une observable appropriée pour étudier ce phénomène. Cette thèse présente lamesure du déséquilibre en impulsion transverse des jets de b et des jets inclusifs (non-identifiés), dans des collisions PbPb a √sNN = 5.02 TeV, réalisée avecledétecteurCMSauLHCpouruneluminosité intégrée de 404 µb−1. Aucune différence n’est observée dans le jet quenching entre les jets issus de partons légers et lourds. Une analyse des résultats à l’aide d’un modèle simple de perte d’énergie est présentée. / The collisions of heavy ions at high energy produce the new state of matter called the quark gluon plasma. A parton traversing the plasma loses its energy which results in the jet quenching phenomenon. The dependence of the jet quenchingonthepartonflavorprovidesconstraints the models describing energy loss. The imbalance of b-jets is a very suitable observable to study this phenomena. This dissertation presents the measurement of the transverse momentum imbalance of b-jets and inclusive (non-identified) jets in PbPb collisions at √sNN = 5.02 TeV which is performed with the CMS detector at the LHC with total integral luminosity of 404 µb−1. No significant difference in jet quenching between light and heavy flavor jets is observed. The interpretation of results with a simple model of energy loss is performed.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20173号 / 理博第4258号 / 新制||理||1612(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 大西 明, 教授 國廣 悌二, 教授 川合 光 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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<h4>Exotic hadrons are hadrons with constituent quark content different from the normal meson and baryon. The f₀(980) hadron is one of the exotic hadron candidates, which was first discovered in $\pi\pi$ scattering experiments in the 1970's. It could be a ordinary quarnk-antiquark meson, a tetraquark exotic state, a kaon-antikaon molecule, or a quark-antiquark-gluon hybrid state.</h4><p dir="ltr">Anisotropic flow (v_n) is a powerful tool to probe the dynamics of relativistic heavy ion collisions. The observed approximate scaling of v_n by the number of constituent quarks (NCQ) suggests the importance of partonic degree of freedom in these collisions. Large v_n and NCQ-scaling have also been observed in high-multiplicity proton-lead (pPb) collisions at the LHC, suggesting similar dynamics in pPb collisions. The empirically established NCQ-scaling can be exploited to probe the constituent quark content of the f₀(980) hadron.</p><p dir="ltr">We measure the elliptic flow (v₂) of f₀(980) in high-multiplicity pPb collisions at 8 TeV with the Compact Muon Solenoid (CMS) detector at the LHC, through its main pion-pion ($\pi^+\pi^-$) decay channel. The invariant mass spectrum is obtained from opposite sign pion pairs, and the combinatorial background is estimated by same-sign pion pairs and subtracted. The f₀(980) signal and the remaining residual background are modeled by relativistic Breit-Wigner and polynomial functions, respectively. The yield of f₀(980) is extracted as a function of azimuthal angle relative to the event plane, and the f₀(980) v₂ is measured as function of $p_T$, corrected for the event-plane resolution. The non-flow component in f₀(980) v₂ has been estimated by that of K_s⁰. By comparing the measured v₂ of the f₀(980) to those of other hadrons, we infer the number of constituent quarks for the f₀(980) assuming NCQ scaling. The f₀(980) is found to be a 2-quark state in this work. We discuss the systematic uncertainties involved in our study, implications of our result, and possible future works in this endeavor.</p>