Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xviii, 126 p.; also includes graphics (some col.) Includes bibliographical references (p. 121-126). Available online via OhioLINK's ETD Center

Thesis (M.Sc.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2009/13/07). Includes bibliographical references.

University, Diss., 2004--Bielefeld.

Techn. University, Diss., 2006--Darmstadt.

Orientador: Alfredo Pio Noronha Rodrigues Galeão / 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

Please read the abstract in the section 00front of this document / Dissertation (MSc (Physics))--University of Pretoria, 2007. / Physics / unrestricted

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19486号 / 理博第4146号 / 新制||理||1596(附属図書館) / 32522 / 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 永江 知文, 教授 谷森 達講師村上 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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The Quark-Gluon Plasma (QGP) produced in heavy-ion collisions has been shown to behave like a nearly perfect fluid, characterized by a very low ratio of shear viscosity to entropy density. Significant measurements in large collision systems have improved the constraints on the value of 𝜂/𝑠. However, the precise temperature dependence of 𝜂/𝑠 still remains unknown. The interplay between viscous effects and initial geometry fluctuations is important that requires further investigation. Another key open question in the study of multi-particle production is the relationship between the “ridge” – observed azimuthal correlations between particles in the underlying event that extend over all rapidities – and hard or semi-hard scattering processes in small collision systems. In particular, it is not known whether jets or their soft fragments are correlated with particles in the underlying event. This dissertation presents two analyses. The first analysis measures flow harmonics 𝜈2–𝜈6 in 3 𝜇b^-1 of Xe+Xe collisions at √𝑠𝖭𝖭 = 5.44 TeV using the ATLAS detector at the LHC. The centrality, multiplicity, and 𝑝_T dependence of the 𝜈n values obtained using two-particle correlations and template-fit procedure are presented, and the measurements are compared with those in Pb+Pb collisions and 𝑝+Pb collisions at 5.02 TeV. The 𝜈n values in Xe+Xe collisions are observed to be larger than those in Pb+Pb collisions for n = 2, 3, and 4 in the most central events. However, the 𝜈n values in Xe+Xe collisions become smaller than those in Pb+Pb collisions with decreasing centrality or increasing harmonic order n. The 𝜈n in Xe+Xe and Pb+Pb collisions are also compared as a function of the mean number of participating nucleons and the measured charged-particle multiplicity in the detector. The 𝜈3 values in Xe+Xe and Pb+Pb collisions are observed to be similar at the same ⟨𝑁_part⟩ or multiplicity, but the other harmonics are significantly different. The second analysis studies two-particle correlations in pp collisions at 13 TeV using data collected by the ATLAS experiment at the LHC, with an integrated luminosity of 15.8 pb⁻¹, in two different configurations. In the first case, charged particles associated with jets are excluded from the correlation analysis, while in the second case, correlations are measured between particles within jets and charged particles from the underlying event. Second-order flow coefficients, 𝜈2, are presented as a function of event multiplicity and transverse momentum. These measurements show that excluding particles associated with jets does not affect the measured correlations. Moreover, particles associated with jets do not exhibit any significant azimuthal correlations with the underlying event, ruling out hard processes contributing to the ridge.

Understanding what contributes to the intrinsic angular momentum (spin) of the proton has been a major goal of the nuclear physics community. In the 1980s, it was discovered that quarks contribute 30% to the spin of the proton. This information led to a search to find other contributions to the spin of the proton. At STAR, the double spin asymmetry (ALL) is measured as it is sensitive to the polarized gluon distribution (Dg(x)). The STAR 2009 inclusive jet ALL at sqrt(s) = 200 GeV has been incorporated into two independent global fits. These fits show for the first time a statistically significant non-zero gluon contribution to the spin of the proton in the parton momentum fraction range x > 0.05. Dijet ALL is also measured at STAR. Dijets are advantageous since the parton momentum fraction (x) of the initial partons may be reconstructed to first order from final state measurements. In 2013 STAR collected an estimated 250 pb-1 of data at sqrt(s) = 510 GeV. The higher center of mass energy will allow STAR to probe Dg(x) at x values as low as 0.02. The large statistics will allow a reduction in the uncertainties. Once the data is incorporated into future global fits, it will allow for a more precise determination of Dg(x). The 2013 dijet ALL results will be presented. The results show good agreement with both global fits and previous STAR results dijet measurements. / Physics