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Author: Andre Sungho Yoon
Publisher:
ISBN:
Category :
Languages : en
Pages : 284
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Book Description
The charged particle spectrum at large transverse momentum (PT), dominated by hadrons originating from parton fragmentation, is an important observable for studying the properties of the hot, dense medium produced in high-energy heavy-ion collisions. The study of the modifications of the PT spectrum in PbPb compared to pp collisions at the same collision energy can shed light on the detailed mechanism by which hard partons lose energy traversing the medium. In this thesis, the transverse momentum spectra of charged particles in pp and PbPb collisions at [square root of]Snn = 2.76 TeV measured up to PT = 100 GeV/c with the CMS experiment at the Large Hadron Collider (LHC) are presented. In the transverse momentum range PT = 5-10 GeV/c, the charged particle yield in the most central PbPb collisions is suppressed by up to a factor of 7 compared to the pp yield scaled by the number of incoherent nucleon-nucleon collisions. At higher PT, this suppression is significantly reduced, approaching roughly a factor of 2 for particles with PT in the range PT = 40-100 GeV/c. A simple modeling of the parton energy loss applied to the PYTHIA Monte-Carlo (MC) reveals that the charged particle spectrum with the pQCD-motivated fractional parton energy loss can describes the shape of the measured suppression well in the range PT = 5-100 GeV/c.
Author: Andre Sungho Yoon
Publisher:
ISBN:
Category :
Languages : en
Pages : 284
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Book Description
The charged particle spectrum at large transverse momentum (PT), dominated by hadrons originating from parton fragmentation, is an important observable for studying the properties of the hot, dense medium produced in high-energy heavy-ion collisions. The study of the modifications of the PT spectrum in PbPb compared to pp collisions at the same collision energy can shed light on the detailed mechanism by which hard partons lose energy traversing the medium. In this thesis, the transverse momentum spectra of charged particles in pp and PbPb collisions at [square root of]Snn = 2.76 TeV measured up to PT = 100 GeV/c with the CMS experiment at the Large Hadron Collider (LHC) are presented. In the transverse momentum range PT = 5-10 GeV/c, the charged particle yield in the most central PbPb collisions is suppressed by up to a factor of 7 compared to the pp yield scaled by the number of incoherent nucleon-nucleon collisions. At higher PT, this suppression is significantly reduced, approaching roughly a factor of 2 for particles with PT in the range PT = 40-100 GeV/c. A simple modeling of the parton energy loss applied to the PYTHIA Monte-Carlo (MC) reveals that the charged particle spectrum with the pQCD-motivated fractional parton energy loss can describes the shape of the measured suppression well in the range PT = 5-100 GeV/c.
Author: Edward Allen Wenger
Publisher:
ISBN:
Category :
Languages : en
Pages : 151
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Book Description
The use of high-pT particles as calibrated probes has proven to be an effective tool for understanding the properties of the system produced in relativistic heavy ion collisions. In this thesis, two such measurements are presented using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC): 1. The transverse momentum spectra of charged particles produced near mid rapidity in Cu+Cu collisions with center-of-mass energies of 62.4 and 200 GeV per nucleon pair 2. Two-particle correlations with a high transverse momentum trigger particle (pT> 2.5 GeV=c) in Au+Au collisions at ... 200 GeV over the broad longitudinal acceptance of the PHOBOS detector ... In central Au+Au collisions at 200 GeV, the single-particle yields are suppressed at high-pT by a factor of about five compared to p+p collisions scaled by the number of binary collisions. This is typically understood to be a consequence of energy loss by high-pT partons in the dense QCD medium, as such a suppression is absent in d+Au collisions. In Cu+Cu collisions, the nuclear modification factor, RAA, has been measured relative to p+p data as a function of collision centrality. For the same number of participating nucleons (Npart), RAA is essentially the same for the Cu+Cu and Au+Au systems over the measured range of pT, in spite of the significantly different geometries. At high-pT, the similarity between the two systems can be described by simple, geometric models of parton energy loss. Two-particle angular correlations are a more powerful tool for examining how highpT jets lose energy and how the medium is modified by the deposited energy. In central Au+Au collisions, particle production correlated with a high-pT trigger is strongly modified compared to p+p. Not only is the away-side yield much broader in, the nearside peak of jet fragments now sits atop an unmistakable 'ridge' of correlated partners extending continuously and undiminished all the way to = 4.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 36
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Book Description
The charged particle transverse momentum (pT) spectra are presented for pp collisions at sqrt(s)=0.9 and 7 TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 inverse microbarns and 2.96 inverse picobarns, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with both leading-order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT = 2 pT/sqrt(s) over the pT range up to 200 GeV/c. Using a combination of xT scaling and direct interpolation at fixed pT, a reference transverse momentum spectrum at sqrt(s)=2.76 TeV is constructed, which can be used for studying high-pT particle suppression in the dense QCD medium produced in heavy-ion collisions at that centre-of-mass energy.
Author: Jerzy Bartke
Publisher: World Scientific
ISBN: 9810212313
Category : Science
Languages : en
Pages : 239
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Book Description
This book attempts to cover the fascinating field of physics of relativistic heavy ions, mainly from the experimentalist's point of view. After the introductory chapter on quantum chromodynamics, basic properties of atomic nuclei, sources of relativistic nuclei, and typical detector set-ups are described in three subsequent chapters. Experimental facts on collisions of relativistic heavy ions are systematically presented in 15 consecutive chapters, starting from the simplest features like cross sections, multiplicities, and spectra of secondary particles and going to more involved characteristics like correlations, various relatively rare processes, and newly discovered features: collective flow, high pT suppression and jet quenching. Some entirely new topics are included, such as the difference between neutron and proton radii in nuclei, heavy hypernuclei, and electromagnetic effects on secondary particle spectra.Phenomenological approaches and related simple models are discussed in parallel with the presentation of experimental data. Near the end of the book, recent ideas about the new state of matter created in collisions of ultrarelativistic nuclei are discussed. In the final chapter, some predictions are given for nuclear collisions in the Large Hadron Collider (LHC), now in construction at the site of the European Organization for Nuclear Research (CERN), Geneva. Finally, the appendix gives us basic notions of relativistic kinematics, and lists the main international conferences related to this field. A concise reference book on physics of relativistic heavy ions, it shows the present status of this field.
Author: Tamas Csorgo
Publisher: World Scientific
ISBN: 9789810246556
Category : Science
Languages : en
Pages : 664
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Book Description
This book covers various experimental and theoretical aspects of multiparticle production in high energy interactions from lepton-lepton, lepton-hadron, hadron-hadron, hadron-nucleus and heavy ion collisons. This is the first time that data from CERN LEP, FNAL, DESY, BNL AGS, CERN SPS and BNL RHIC have been collected in a single volume. Not only accelerator-induced reactions but also cosmic ray interactions of very high energy are discussed, and the up-to-date theoretical interpretations are summarized.
![Transverse Momentum Evolution of Hardon-V0 Correlations in PP Collisions at [square Root] S PDF](https://books.google.com/books/content/images/frontcover/bZWytQEACAAJ?fife=w80-h100)
Author: Sandun Yasassri Jayarathna Pahula Hewage
Publisher:
ISBN:
Category : Heavy ions
Languages : en
Pages :
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Book Description
The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, is capable of accelerating beams of protons (pp) and heavy-ions (Pb+Pb) up to nearly the speed of light, which corresponds to center of mass energies of 7 TeV and 2.76 TeV, respectively. The goal of the pp program is to investigate physics of and beyond the standard model, while the heavy-ion program attempts to characterize the properties of a new state of matter, called the Quark Gluon Plasma. The main aim of this dissertation is to identify particle production mechanisms in pp collisions, also as a reference for possible modifications due to the plasma formation in heavy-ion collisions. Two-particle azimuthal correlation measurements were employed, which allow the study of high-pT parton fragmentation without full jet reconstruction. We present the results of correlations between charged trigger particles and associated strange baryons and mesons. Enhancements of the azimuthal correlations are seen at dphi= 0 and dphi= pi, resulting from back-to-back jet fragmentation in the parton center-of-mass system. Two model fit functions were introduced to characterize the properties of the jet peaks. Hard and soft yields were seperated using the ZYAM method and extracted yields were compared with pQCD inspired models and inclusive spectra. The analysis was performed in different multiplicity bins to detect possible enhancements of baryons or meson yields and the baryon/meson ratio. The latter was observed in high multiplicity Pb+Pb collisions and interpreted as a novel production mechanism in the deconfined medium produced at the LHC. A novel data-driven feeddown correction for Lambda is also introduced, which could allow a more accurate calculation of the primary Xi.
Author: Rudolph C. Hwa
Publisher: CRC Press
ISBN: 9782881247347
Category : Science
Languages : en
Pages : 338
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Book Description
Papers of the June 1989 meeting in Beijing by the China Center of Advanced Science and Technology. This small book covers nucleus- nucleus collisions, states of the vacuum, and highly relativistic heavy ions in the experimental realm. Theoretical papers deal with quark-gluon plasma, and relativistic heavy ion collisions. Annotation copyrighted by Book News, Inc., Portland, OR
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 187
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Book Description
In August 2006, the CERN Theory Unit announced to restructure its visitor program and to create a 'CERN Theory Institute', where 1-3 month long specific programs can take place. The first such Institute was held from 14 May to 10 June 2007, focusing on 'Heavy Ion Collisions at the LHC - Last Call for Predictions'. It brought together close to 100 scientists working on the theory of ultra-relativistic heavy ion collisions. The aim of this workshop was to review and document the status of expectations and predictions for the heavy ion program at the Large Hadron Collider LHC before its start. LHC will explore heavy ion collisions at (almost equal to) 30 times higher center of mass energy than explored previously at the Relativistic Heavy Ion Collider RHIC. So, on the one hand, the charge of this workshop provided a natural forum for the exchange of the most recent ideas, and allowed to monitor how the understanding of heavy ion collisions has evolved in recent years with the data from RHIC, and with the preparation of the LHC experimental program. On the other hand, the workshop aimed at a documentation which helps to distinguish pre- from post-dictions. An analogous documentation of the 'Last Call for Predictions' [1] was prepared prior to the start of the heavy-ion program at the Relativistic Heavy Ion Collider RHIC, and it proved useful in the subsequent discussion and interpretation of RHIC data. The present write-up is the documentation of predictions for the LHC heavy ion program, received or presented during the CERN TH Institute. The set-up of the CERN TH Institute allowed us to aim for the wide-most coverage of predictions. There were more than 100 presentations and discussions during the workshop. Moreover, those unable to attend could still participate by submitting predictions in written form during the workshop. This followed the spirit that everybody interested in making a prediction had the right to be heard. To arrive at a concise document, we required that each prediction should be summarized on at most two pages, and that predictions should be presented, whenever possible, in figures which display measurable quantities. Full model descriptions were not accepted--the authors were encouraged to indicate the relevant references for the interested reader. Participants had the possibility to submit multiple contributions on different topics, but it was part of the subsequent editing process to ensure that predictions on neighboring topics were merged wherever possible. The contributions summarized here are organized in several sections, --though some of them contain material related with more than one section--roughly by going from low transverse momentum to high transverse momentum and from abundant to rare measurements. In the low transverse momentum regime, we start with predictions on multiplicity distributions, azimuthal asymmetries in particle production and hadronic flavor observables, followed by correlation and fluctuation measurements. The contributions on hard probes at the LHC start with predictions for single inclusive high transverse momentum spectra, and jets, followed by heavy quark and quarkonium measurements, leptonic probes and photons. A final section 'Others' encompasses those predictions which do not fall naturally within one of the above-mentioned categories, or discuss the more speculative phenomena that may be explored at the LHC.
Author: Aaron Angerami
Publisher: Springer
ISBN: 9783319347509
Category : Science
Languages : en
Pages : 0
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Book Description
This thesis presents the first measurements of jets in relativistic heavy ion collisions as reported by the ATLAS Collaboration. These include the first direct observation of jet quenching through the observation of a centrality-dependent dijet asymmetry. Also, a series of jet suppression measurements are presented, which provide quantitative constraints on theoretical models of jet quenching. These results follow a detailed introduction to heavy ion physics with emphasis on the phenomenon of jet quenching and a comprehensive description of the ATLAS detector and its capabilities with regard to performing these measurements.
Author: Simone Marzani
Publisher: Springer
ISBN: 3030157091
Category : Science
Languages : en
Pages : 205
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Book Description
This concise primer reviews the latest developments in the field of jets. Jets are collinear sprays of hadrons produced in very high-energy collisions, e.g. at the LHC or at a future hadron collider. They are essential to and ubiquitous in experimental analyses, making their study crucial. At present LHC energies and beyond, massive particles around the electroweak scale are frequently produced with transverse momenta that are much larger than their mass, i.e., boosted. The decay products of such boosted massive objects tend to occupy only a relatively small and confined area of the detector and are observed as a single jet. Jets hence arise from many different sources and it is important to be able to distinguish the rare events with boosted resonances from the large backgrounds originating from Quantum Chromodynamics (QCD). This requires familiarity with the internal properties of jets, such as their different radiation patterns, a field broadly known as jet substructure. This set of notes begins by providing a phenomenological motivation, explaining why the study of jets and their substructure is of particular importance for the current and future program of the LHC, followed by a brief but insightful introduction to QCD and to hadron-collider phenomenology. The next section introduces jets as complex objects constructed from a sequential recombination algorithm. In this context some experimental aspects are also reviewed. Since jet substructure calculations are multi-scale problems that call for all-order treatments (resummations), the bases of such calculations are discussed for simple jet quantities. With these QCD and jet physics ingredients in hand, readers can then dig into jet substructure itself. Accordingly, these notes first highlight the main concepts behind substructure techniques and introduce a list of the main jet substructure tools that have been used over the past decade. Analytic calculations are then provided for several families of tools, the goal being to identify their key characteristics. In closing, the book provides an overview of LHC searches and measurements where jet substructure techniques are used, reviews the main take-home messages, and outlines future perspectives.
