Download or read book Are We Close to the QGP Hadrochemical Vs Microscopic Analysis of Particle Production in Ultrarelativistic Heavy Ion Collisions written by Steffen A. Bass and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quasiparticle Anisotropic Hydrodynamics in Ultra relativistic Heavy ion Collisions written by Mubarak Aydh K. Alqahtani and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last century, matter was confirmed to be made up from molecules which consist of two atoms or more. The atom itself consists of a nucleus made of protons and neutrons, and electrons "circling'' around the nucleus. The number of electrons or protons distinguish different elements. Later on, protons and neutrons were found not to be elementary particles but rather composite particles. The question turned then to be what are protons and neutrons made of and this is the focus of elementary particle physics. According to the standard model, protons and neutrons are made up of quarks and gluons. The theory that describes quarks and gluons is called quantum chromodynamics (QCD). According to this theory, quarks and gluons can not be detected freely; they appear only inside hadrons but are never observed freely (confinement). However, at high temperatures and/or densities a transition may happen where quarks and gluons do not exist in bound states (hadrons) anymore but rather exist freely (the asymptotic freedom). This phase of the nuclear matter is known as the quark-gluon plasma (QGP).To learn more about the QCD phase diagram, mainly the confinement and de-confinement transition, many different experiments have been performed from fixed target experiments to high-energy heavy-ion collisions in almost three decades. The discovery of QGP came from ultrarelativistic heavy-ion collision (URHIC) experiments. By ultrarelativistic heavy-ion collisions, we mean heavy ions like gold or lead that have been accelerated to speeds which are close to the speed of light (the ion momentum is much larger than its rest mass). Nowadays, ultrarelativistic heavy-ion collision experiments at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) are being used to create and study the quark-gluon plasma. From the early days after confirming the existence of the QGP, relativistic hydrodynamics has been used to describe the hadron spectra and collective flow seen in these experiments and has been quite successful. Since then, different approaches have been developed to model the physics of the QGP. The first approach used was ideal hydrodynamics where the QGP is assumed to behave like a perfect fluid with no viscosity. However, improvements in both the experimental and theoretical sides demonstrated the importance of including dissipative (viscous) effects in QGP modeling. The resulting relativistic viscous hydrodynamics models have been quite successful in describing the data. Despite this success, studies found that the QGP generated in URHICs is a highly momentum-space anisotropic plasma which means that viscous hydrodynamics will break down in some situations. To take this into account, anisotropic hydrodynamics (aHydro) was developed. In aHydro, one includes the momentum-space anisotropies in the distribution function at leading-order, whereas viscous hydrodynamics is expanded around the isotropic distribution function as the leading term and the viscous effects are included as correction terms. In this study, we present a new method for imposing a realistic equation of state in anisotropic hydrodynamics which is called quasiparticle anisotropic hydrodynamics (aHydroQP). In this method, we introduce a single finite-temperature quasiparticle mass which is fit to QCD lattice data. By taking moments of the Boltzmann equation assuming an anisotropic distribution function, we obtain a set of coupled partial differential equations which can be used to describe the 3+1d spacetime evolution of the QGP. Due to the numerical difficulties and the need to understand this new method more, instead of considering the 3+1d case immediately, we begin by studying two simpler cases. First, we specialize to the case of a 0+1d system undergoing boost-invariant Bjorken expansion and compare with the standard method of imposing the equation of state in anisotropic hydrodynamics (aHydro). We find practically no differences between the two methods results for the temperature evolution and the scaled energy density. When we compare the pressure anisotropy, we see only small differences, however, we find significant differences in the evolution of the bulk pressure correction. Second, we present the results in azimuthally-symmetric boost-invariant (1+1d) systems and compare the quasiparticle model with the standard aHydro model and second order viscous hydrodynamics. We compare the three methods' predictions for the primordial particle spectra, total number of charged particles, and average transverse momentum for various values of the shear viscosity to entropy density ratio. We show that they agree well for small shear viscosity to entropy density ratio, but show clear differences at large values of shear viscosity to entropy density ratio. Third, and most importantly, we present the phenomenological predictions of 3+1d quasiparticle anisotropic hydrodynamics compared with LHC 2.76 TeV Pb-Pb collisions. We present comparisons of charged-hadron multiplicity, identified-particle spectra, identified-particle average transverse momentum, charged-particle elliptic flow, identified-particle elliptic flow, elliptic flow as a function of pseudorapidity, and HBT radii. We find good agreement when compared with ALICE data. Looking to the future, we plan to include next-leading-order anisotropic hydrodynamics corrections by including the off-diagonal terms of the anisotropy tensor in quasiparticle anisotropic hydrodynamics. However, since this will be very hard and numerically intense, we consider first next-leading-order anisotropic hydrodynamics using the standard method for imposing the equation of state. To do so, we Taylor-expand assuming small off-diagonal terms to make the formalism easier and numerically tractable. Then, by taking moments of the Boltzmann equation, we find the dynamical equations needed to model the full 3+1d system. In this part of the work, we present only the theory setup and leave the numerical analysis for a future work.

Download or read book Particle Correlations in Ultra Relativistic Heavy Ion Collisions written by Sudhir Bhardwaj and published by LAP Lambert Academic Publishing. This book was released on 2011-12 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum Chromodynamics calculations on the lattice predict that at extremely high energy densities, colliding nuclear matter would undergo a phase transition to deconfined matter of quarks and gluons. The nature of transition, the temperature and the energy density at which the transition occurs depend upon the details of calculations; these depend upon the number of quark flavors introduced in the calculation. This deconfined state of quark and gluons has been named Quark Gluon Plasma(QGP). This work purports to understand the azimuthal distribution of photons produced in Cu+Cu collisions at 200 GeV with Photon Multiplicity Detector (PMD). The PMD is part of the STAR (Solenoidal Tracker At RHIC) experiment.PMD covers a pseudorapidity range of -3.7 to -2.3 with full azimuthal coverage and measures the multiplicity and spatial distribution of photons on an event-by-event basis.The value of second order azimuthal coefficient has been determined for different centralities in different pseudorapidity windows and its pseudorapidity and centrality dependence has been obtained.

Download or read book Two particle Correlations of Identified Particles in Heavy Ion Collisions at STAR written by Prabhat Bhattarai and published by . This book was released on 2016 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of quarks and their interactions through gluons has been an active area of research since their discovery. For two decades the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been dedicated to studying the interactions between quarks by producing nuclear matter in an extremely dense and hot environment. It has been hypothesized that colliding beams of atomic nuclei near the speed of light creates the hot and dense environment in which all quarks in the nuclei de-confine to form a short-lived state of matter called a Quark Gluon Plasma (QGP). Because of the short lifetime of QGP, it is impossible to observe it directly and, the only way to study such matter is through the final state particles. Two-particle correlation, which is defined using Pearson's normalized covariance, is one of the techniques to study the early interactions via the final state particles. A broad survey has been made to study the two-particle correlations of identified-charged hadrons (pi, K and p) in various ranges of momentum for the hadrons produced in √sNN=200 GeV Au+Au collisions at the STAR experiment at RHIC. A total of 2123 two-dimensional independent structures made by correlation coefficients in relative angular space in (eta, phi) for different combinations of identified hadrons have been studied. Correlations between any two identified particles contrasts to all-particle correlations giving an opportunity to study the contribution of each particle species in the hadronization processes. As a new feature, same-side anti-correlations are observed in both like-sign and unlike-sign pairs in certain yT bins and in certain identified particles. A significant feature of the final state distribution of particles is an azimuthal anisotropy which is defined as the second Fourier component; the amplitude is proportional to parameter v2. We report the measure of azimuthal anisotropy of identified hadrons for the first time and test for the factorization used in conventional analysis. The data presented here constitute a comprehensive measurement of the light-flavor, di-hadron density as function of collision centrality, transverse momentum and 2D relative angles in longitudinal (beam direction) and azimuthal directions.

Download or read book Probing Quark Gluon Plasma and Chiral Effects in Heavy Ion Collisions Measurements of Strangeness Omega and phi Production and Identified Particle Correlation in Au Au Collisions at STAR RHIC written by Liwen Wen and published by . This book was released on 2019 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Analysis of Multiparticle Bose Einstein Correlations in Ultra relativistic Heavy Ion Collisions written by and published by . This book was released on 1990 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: We introduce the coalescence variables, a set of three boost-invariant kinematic quantities which may be used in analyzing n-particle correlations. These variables characterize the invariant mass of an n-particle and in three directions and separate the timelike and spacelike characteristics of the source. The analytic Kolehmanien-Gyulassy model is generalized to give two, three, and four-particle correlation functions, with coherence and Coulomb corrections applied to the basic formalism. We demonstrate the relation of the coalescence variables to be radius and duration of the source, and find that for sufficiently large transverse radii, Coulomb effects can suppress the structure of the Hanbury-Brown-Twiss correlations so that no significant information on source size can be obtained. 11 refs., 10 figs.

Download or read book Physics Perspectives of Heavy ion Collisions at Very High Energy written by and published by . This book was released on 2016 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: We expect heavy-ion collisions at very high colliding energies to produce a quark-gluon plasma (QGP) at the highest temperature obtainable in a laboratory setting. Experimental studies of these reactions can provide an unprecedented range of information on properties of the QGP at high temperatures. We also report theoretical investigations of the physics perspectives of heavy-ion collisions at a future high-energy collider. These include initial parton production, collective expansion of the dense medium, jet quenching, heavy-quark transport, dissociation and regeneration of quarkonia, photon and dilepton production. Here, we illustrate the potential of future experimental studies of the initial particle production and formation of QGP at the highest temperature to provide constraints on properties of strongly interaction matter.

Download or read book Properties of the Quark gluon Plasma Created in Heavy ion Collisions written by Pierre Moreau and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We review the properties of the strongly interacting quark-gluon plasma (QGP) at finite temperature T and baryon chemical potential μB as created in heavy-ion collisions at ultrarelativistic energies. The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature Tc from lattice QCD. Based on a microscopic transport description of heavy-ion collisions, we discuss which observables are sensitive to the QGP creation and its properties.

Download or read book A Short Course on Relativistic Heavy Ion Collisions written by Asis Kumar Chaudhuri and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the subject of high-energy, heavy-ion collisions, in particular, the subject of quark-gluon plasma (QGP) to graduate students and young researchers, in both experimental and theoretical physics.

Download or read book Hadron Production in Heavy Ion Collisions written by and published by . This book was released on 2009 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy ion collisions are an ideal tool to explore the QCD phase diagram. The goal is to study the equation of state (EOS) and to search for possible in-medium modifications of hadrons. By varying the collision energy a variety of regimes with their specific physics interest can be studied. At energies of a few GeV per nucleon, the regime where experiments were performed first at the Berkeley Bevalac and later at the Schwer-Ionen-Synchrotron (SIS) at GSI in Darmstadt, we study the equation of state of dense nuclear matter and try to identify in-medium modifications of hadrons. Towards higher energies, the regime of the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory (BNL), the Super-Proton Synchrotron (SPS) at CERN, and the Relativistic Heavy Ion Collider (RHIC) at BNL, we expect to produce a new state of matter, the Quark-Gluon Plasma (QGP). The physics goal is to identify the QGP and to study its properties. By varying the energy, different forms of matter are produced. At low energies we study dense nuclear matter, similar to the type of matter neutron stars are made of. As the energy is increased the main constituents of the matter will change. Baryon excitations will become more prevalent (resonance matter). Eventually we produce deconfined partonic matter that is thought to be in the core of neutron stars and that existed in the early universe. At low energies a great variety of collective effects is observed and a rather good understanding of the particle production has been achieved, especially that of the most abundantly produced pions and kaons. Many observations can be interpreted as time-ordered emission of various particle species. It is possible to determine, albeit model dependent, the equation of state of nuclear matter. We also have seen indications, that the kaon mass, especially the mass of the K, might be modified by the medium created in heavy ion collisions. At AGS energies and above, emphasis shifts towards different aspects. Lattice QCD calculations predict the transition between a Quark-Gluon Plasma and a hadronic state at a critical temperature, T{sub c}, of about 150 to 190 MeV at vanishing baryon density. The energy density at the transition point is about 1:0 GeV/fm3. It is generally assumed that chiral symmetry restoration happens simultaneously. In the high-energy regime, especially at RHIC, a rich field of phenomena [3] has revealed itself. Hot and dense matter with very strong collectivity has been created. There are indications that collectivity develops at the parton level, i.e. at a very early stage of the collision, when the constituents are partons rather than hadrons. Signs of pressure driven collective effects are our main tool for the study of the EOS. There are also strong indications that in the presence of a medium hadronization occurs through the process of quark coalescence and not through quark fragmentation, the process dominant for high-energy p+p reactions. We limit this report to the study of hadrons emitted in heavy ion reactions. The report is divided into two parts. The first part describes the phenomena observed from hadrons produced at low energies, whereas the second part concentrates on the search for signs of a partonic state at high energies.

Download or read book Particle production Mechanism in Relativistic Heavy ion Collisions written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss the production of particles in relativistic heavy-ion collisions through the mechanism of massive bremsstrahlung, in which massive mesons are emitted during rapid nucleon acceleration. This mechanism is described within the framework of classical hadrodynamics for extended nucleons, corresponding to nucleons of finite size interacting with massive meson fields. This new theory provides a natural covariant microscopic approach to relativistic heavy-ion collisions that includes automatically spacetime nonlocality and retardation, nonequilibrium phenomena, interactions among all nucleons, and particle production. Inclusion of the finite nucleon size cures the difficulties with preacceleration and runaway solutions that have plagued the classical theory of self-interacting point particles. For the soft reactions that dominate nucleon-nucleon collisions, a significant fraction of the incident center-of-mass energy is radiated through massive bremsstrahlung. In the present version of the theory, this radiated energy is in the form of neutral scalar ([sigma]) and neutral vector ([omega]) mesons, which subsequently decay primarily into pions with some photons also. Additional meson fields that are known to be important from nucleon-nucleon scattering experiments should be incorporated in the future, in which case the radiated energy would also contain isovector pseudoscalar ([pi][sup +], [pi][sup [minus]], [pi][sup 0]), isovector scalar ([delta][sup +], [delta][sup [minus]], [delta][sup 0]), isovector vector ([rho][sup +], [rho][sup [minus]], [rho][sup 0]), and neutral pseudoscalar ([eta]) mesons.

Download or read book Production of Supersymmetric Particles and Higgs Bosons in Ultrarelativistic Heavy ion Collisions written by Gerhard Soff and published by . This book was released on 1989 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Production of Supersymmetric Particles in Ultrarelativistic Heavy ion Collisions written by J. Rau and published by . This book was released on 1989 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Multiparticle Production and Phase Transition in Ultra relativistic Heavy ion Collisions written by Jian Gui Wang and published by . This book was released on 2000 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two particle Correlations in Angular and Momentum Space in Heavy Ion Collisions at STAR written by Elizabeth Wingfield Oldag and published by . This book was released on 2013 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: For over a decade studies of the strong interaction in extremely dense nuclear environments have been done at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It is hypothesized that colliding two beams of Au nuclei at relativistic speeds creates an environment of hot dense nuclear matter where the quarks and gluons inside the nucleus, which are normally confined within the protons and neutrons, become deconfined into a soup called the quark-gluon plasma. Since direct observation of this short-lived phase is impossible, many sophisticated analysis techniques attempt to study the early interactions via the final state particles. What has emerged from analyses of the data are two, contradictory paradigms for understanding the results. On the one hand the colliding quarks and gluons are thought to strongly interact and reach thermal equilibrium. The other view is that primary parton-parton scattering leads directly to jet fragmentation with little effect from re-scattering. It is in principle possible to distinguish and perhaps falsify one or both of these models of relativistic heavy ion collisions via the analysis of two-particle correlations among all charged particles produced in [mathematical symbols] = 200 GeV Au+Au collisions at the STAR experiment at RHIC. This dissertation presents studies of two-particle correlations, whose derivation can be traced back to Pearson's correlation coefficient, in transverse momentum and angular space. In momentum space a broad peak is observed extending from 0.5-4.0 GeV/c which, as a function of nuclear overlap, remains at a fixed position while monotonically increasing in amplitude. Comparisons to theoretical models suggests this peak is from jet fragmentation. In a complementary study the momentum distribution of correlations in ([eta],[phi]) space is investigated. The momentum distribution of correlated pairs that contribute to the peak near the origin, commonly associated with jet fragmentation, is peaked around 1.5 GeV/c and does not soften with increased centrality. These measurements present important aspects of the available six dimensional correlation space and provide definitive tests for theoretical models. Preliminary findings do not appear to support the hypothesis of a strongly interacting QGP where back-to-back jets are expected to be significantly suppressed.

Download or read book Fluctuations in Ultra relativistic Heavy ion Collisions from Microscopic Descriptions written by Stéphane Haussler and published by . This book was released on 2007 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurements of Di jet 0 h Correlations in Light heavy Ion Collisions at RHIC PHENIX written by Abinash Pun and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The possible presence of Quark-Gluon Plasma (QGP), the new state of matter created at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) in Au+Au and Pb+Pb collisions, is currently under investigation for smaller collisions systems such as light-heavy ions and even p+p. Long range angular correlations of particles produced in p+Pb, p+Au, d+Au, and 3He+Au, show evidence of QGP collective flow, but another signature, QGP-induced jet energy loss effects has not been identified. To address this situation, in this dissertation, a recently introduced observable RI is employed in light-heavy ion collisions. RI is derived from two-particle correlation method commonly used to study jet modification from energy loss in Au+Au.