Phi Meson Production in Au+Au Collisions at the Relativistic Heavy Ion Collider PDF Download
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Author: Eugene Toyonari Yamamoto
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Languages : en
Pages : 266
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Author: Eugene Toyonari Yamamoto
Publisher:
ISBN:
Category :
Languages : en
Pages : 266
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Author:
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Category :
Languages : en
Pages :
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Author: Dmitri Vladimirovitch Kotchetkov
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Category : Collisions (Nuclear physics)
Languages : en
Pages : 522
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Author: Mohammed Muniruzzaman
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Category : Collisions (Nuclear physics)
Languages : en
Pages : 544
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![Production of [phi] Mesons in Au+Au Collisions at 11.7 A. GeV/c PDF](https://books.google.com/books/content/images/frontcover/I67XpYkFfpwC?fife=w80-h100)
Author: Hong Xiang
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Category : Heavy ion collisions
Languages : en
Pages : 322
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![Measurement of [phi] Meson Production in Cu+Cu Collisions at 200 GeV Using the PHOBOS Detector at RHIC PDF](https://books.google.com/books/content/images/frontcover/Dh1HmAEACAAJ?fife=w80-h100)
Author: Siarhei S. Vaurynovich
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Category :
Languages : en
Pages : 275
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Strong enhancement of production of strange particles, and in particular of [phi] mesons, in heavy ion collisions of sufficiently high energies has been predicted to be an indication of a formation of a new state of matter, composed of deconfined quarks and gluons and having a property of chiral symmetry, called Quark Gluon Plasma (QGP). Studying production of [phi] mesons is of special interest due to their small cross-section of interaction with non-strange hadrons and due to their long lifetime, which should allow [phi] mesons to decouple from the strongly interacting medium produced in heavy ion collisions early in time and to escape the medium before decaying, thereby preserving information about the conditions in which the mesons were produced. In addition, the decay properties of [phi] mesons have been predicted to be modified in a hadronic gas medium. The [phi] -> K+K~ decay is of particular interest since the mass of a [phi] meson in vacuum is very close to the mass of two charged kaons, and consequently, even a small change in the mass or the width of [phi] mesons or in the mass of kaons would have a strong effect on the decay properties. Measurement of [phi] meson production using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC) has proven to be especially challenging due to a small acceptance of the PHOBOS spectrometer and due to a much lower than predicted yield of [phi] mesons in heavy ion collisions at the highest RHIC energy. The measurement required a development of a new tracking algorithm, specifically tailored to reconstruct charged kaons with a high efficiency in a high hit density environment, keeping at the same time the necessary computing time within feasible limits. Results of a measurement of [phi] meson invariant yield in the rapidity interval 0 y
Author: Yu Chen
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Category :
Languages : en
Pages : 312
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Author: Liwen Wen
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Category :
Languages : en
Pages : 147
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Ultra-relativistic heavy-ion collision produces an extremely hot and dense medium of de-confined quarks and gluons, which is called Quark-Gluon Plasma (QGP). The STAR detector at Relativistic Heavy Ion Collider (RHIC) provides powerful experimental capabilities to probe the properties of this new form of matter, as well as novel quantum effects induced by the restoration of fundamental symmetry in qauntum-chromdynamics (QCD). Towards these goals, two research projects have been carried out at STAR/RHIC and will be presented in this thesis: 1) Measurement of mid-rapidity ($|y|0.5$) multi-strangenss particle ($\Omega$ and $\phi$) production in Au+Au collisions at $\sqrt{s_{NN}}=14.5$ GeV; 2) A systematic search for chiral effects using identified particle correlation. Production mechanism for strange hadrons could be dramatically different in the presence of QGP compared to regular $pp$ collisions. Thus strangeness signal is used extensively in Beam Energy Scan I (BES-I) program at RHIC to map out the phase diagram of QCD matter. As a part of BES-I, gold nuclei are collided at $\sqrt{s_{NN}} = 14.5$ GeV and the productions of mid-rapidity $\Omega(sss)$ and $\phi(\bar{s}s)$ are measured for the collisions. The ratio of anti-omega ($\bar{\Omega}$) over omega ($\Omega^-$) is calculated and used to extract thermodynamics parameters ($\mu_B/T$ and $\mu_S/T$) of collision system via statistical model. Additionally, the transverse momentum ($p_T$) dependence of nuclear modification factor ($R_{cp}$) is measured for $\phi$ meson and the result shows similar feature to energies lower than 19.6 GeV. As a test of coalescence formation mechanism for strange hadrons, $\textrm{N}(\Omega^-+\bar{\Omega}^+)/2(\textrm{N}(\phi))$ as a function of $p_T$ is studied and the data from central collision is found to deviate from model calculation and higher energy ($\sqrt{s_{NN}}19.6$ GeV) results in $p_T$ range from $2.0-3.0$ GeV/c, which may imply a transition of created medium whose underlying dominant degrees of freedom change from quarks/gluons to hadrons as collision energy goes below 19.6 GeV. %whose underlying dominant degrees of freedom change from quarks/gluons to hadrons as... With excellent particle identification capability of STAR, a systematic search for the Chiral Magnetic Effect (CME) via measurements of $\gamma_{112}$ correlation and $\kappa_K$ parameter for identified particle pairs ($\pi\pi$, $pK$, $\pi K$, $pp$, $p\pi$) in Au+Au collisions has been conducted. The $\kappa_K$ results are compared to expectations from the \textit{A Multi-Phase Transport Model} (AMPT) simulations. Except $\pi\pi$ and $pp$ correlations, the CME signals from other particle pairs are consistent with background model. $\kappa_K$ from $\pi\pi$ shows higher values than background expectation, while the result for $pp$ is even lower than the background, which requires further investigation. %A study of $\gamma_{112}$ and $\delta$ correlations for $\Lambda p$ in Au+Au 27 GeV shows that in mid-central and mid-peripheral collisions, baryon numbers are separated across reaction plane, which is consistent with the Chiral Vortical Effect (CVE) expectation. To search for Chiral Vortical Effect (CVE), a measurement of $\gamma_{112}$ and $\delta$ correlations for $\Lambda p$ pairs in Au+Au collisions at $\sqrt{s_{NN}}=27$ GeV was carried out and the results show that the CVE induced baryon number separation may exist in mid-central and mid-peripheral collisions with little contamination from flowing resonance decay background. Future development of searches for the chirality effect in heavy ion collisions will also be discussed.
Author: Curtis Patrick Leon Lansdell
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ISBN:
Category : Colliders (Nuclear physics)
Languages : en
Pages :
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Author: Ayman I.A. Hamad
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Category :
Languages : en
Pages : 0
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Quantum Chromodynamics (QCD), the theory of the strong interaction between quarks and gluons, predicts that at extreme conditions of high temperature and/or density, quarks and gluons are no longer confined within individual hadrons. This new deconfined state of quarks and gluons is called Quark-Gluon Plasma (QGP). The Universe was in this QGP state a few microseconds after the Big Bang. The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) on Long Island, NY was built to create and study the properties of QGP.Due to their heavy masses, quarks with heavy flavor (charm and bottom) are mainly created during the early, energetic stages of the collisions. Heavy flavor is considered to be a unique probe for QGP studies, since it propagates through all phases of a collision, and is affected by the hot and dense medium throughout its evolution. Initial studies, via indirect reconstruction of heavy flavor using their decay electrons, indicated a much higher energy loss by these quarks compared to model predictions, with a magnitude comparable to that of light quarks. Mesons such as D0 could provide information about the interaction of heavy quarks with the surrounding medium through measurements such as elliptic flow. Such data help constrain the transport parameters of the QGP medium and reveal its degree of thermalization.Because heavy hadrons have a low production yield and short lifetime (e.g. ct = 120μm for D0), it is very challenging to obtain accurate measurements of open heavy flavor in heavy-ion collisions, especially since the collisions also produce large quantities of light-flavor particles. Also due to their short lifetime, it is difficult to distinguish heavy-flavor decay vertices from the primary collision vertex; one needs a very high precision vertex detector in order to separate and reconstruct the decay of the heavy flavor particles in the presence of thousands of other particles produced in each collision.The STAR collaboration built a new micro-vertex detector and installed it in the experiment in 2014. This state-of-the-art silicon pixel technology is named the Heavy Flavor Tracker (HFT). The HFT was designed in order to perform direct topological reconstruction of the weak decay products from hadrons that include a heavy quark. The HFT consists of four layers of silicon, and it improves the track pointing resolution of the STAR experiment from a few mm to around 30 ℗æm for charged pions at a momentum of 1 GeV/c.In this dissertation, I focus on one of the main goals of the HFT detector, which is to study the elliptic flow v2 (a type of azimuthal anisotropy) for D0 mesons in Au+Au collisions at vsNN = 200 GeV. My analysis is based on the 2014 data set (about 1.2 billion collisions covering all impact parameters) that include data from the HFT detector. There are two new and unique analysis elements used in this dissertation. First, I performed the analysis using a Kalman filter algorithm to reconstruct the charmed-meson candidates. The standard reconstruction is via a simple helix-swim method. The advantage of using the Kalman algorithm is in the use of the full error matrix of each track in the vertex estimation and reconstruction of the properties of the heavy-flavor parent particle. Second, I also used the Tool for Multivariate Analysis (TMVA), a ROOT-environment tool, to its full potential for signal significance optimization, instead of the previous approach based on a set of fixed cuts for separating signal from background.This dissertation presents the elliptic component (v2) of azimuthal anisotropy of D0 mesons as a function of transverse momentum, pT . The centrality (impact parameter) dependence of D0 v2(pT) is also studied. Results are compared with similar studies involving light quarks, and with the predictions of several theoretical models.
