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Recent results from heavy ion collisions  [PDF]
Nu Xu
Physics , 2001,
Abstract: Systematic trends of baryon transport, chemical freeze-out, and kinetic freeze-out in high energy nuclear collisions are presented. Further measurements of particles with heavy flavors are proposed in order to shed light on collision dynamics at parton level.
Recent results on heavy quark quenching in ultrarelativistic heavy ion collisions  [PDF]
Pol Bernard Gossiaux,Joerg Aichelin,Marcus Bluhm,Thierry Gousset,Marlene Nahrgang,Sascha Vogel,Klaus Werner
Physics , 2012,
Abstract: In this contribution, we present some predictions for the production of D and B mesons in ultrarelativistic heavy ion collisions at RHIC and LHC energies and confront them with experimental results obtained so far by the STAR, PHENIX, ALICE and CMS collaborations. We next discuss some preliminary results obtained with an improved description of the medium based on EPOS initial conditions, and its possible implications on the nuclear modification factor and on the elliptic flow of heavy quarks.
Recent results from the UrQMD hybrid model for heavy ion collisions  [PDF]
Marcus Bleicher,Stephan Endres,Jan Steinheimer,Hendrik van Hees
Physics , 2015,
Abstract: These proceedings present recent results from transport-hydrodynamics-hybrid models for heavy ion collisions at relativistic energies. The main focus is on the absorption of (anti-)protons in the hadronic afterburner stage of the reaction, di-lepton production at SPS and heavy quark dynamics.
Recent developments in the theory of electromagnetic probes in relativistic heavy-ion collisions  [PDF]
Chun Shen
Physics , 2015,
Abstract: The theoretical developments in the study of electromagnetic radiation in relativistic heavy-ion collisions are reviewed. The recent progress in the rates for photon and lepton pair production is discussed. Together with the improvements in the hydrodynamic descriptions of the bulk medium, the combined effort is discussed to resolve the "direct photon flow puzzle" in the RHIC and the LHC experiments. Further prediction of the direct photon production in high multiplicity proton-nucleus collisions at the LHC energy can serve as a signature of the quark gluon plasma formation in these small systems. Phenomenological study of dilepton production at finite net baryon density is highlighted at the collision energies available for the RHIC beam energy scan program.
P odd fluctuations and Long Range Order in Heavy Ion Collisions. Deformed QCD as a Toy Model  [PDF]
Ariel R. Zhitnitsky
Physics , 2012, DOI: 10.1016/j.nuclphysa.2012.10.004
Abstract: We study the local violation of P and CP invariance in heavy ion collisions as observed at RHIC and LHC using a simple "deformed QCD" model. This model is a weakly coupled gauge theory, which however has all the relevant crucial elements allowing us to study difficult and nontrivial questions which are known to be present in real strongly coupled QCD. Essentially, we want to understand the physics of long range order in form of coherent low dimensional vacuum configurations observed in Monte Carlo lattice simulations. Apparently precisely such kind of configurations are responsible for sufficiently strong intensity of asymmetries observed in heavy ion collisions.
Recent experimental results from the relativistic heavy-ion collisions at LHC and RHIC  [PDF]
Ilya Selyuzhenkov
Physics , 2011,
Abstract: A new era has started in the field of relativistic heavy-ion physics with lead beams delivered by the Large Hadron Collider (LHC) in November 2010. In this proceedings I highlight the main results from experimental measurements with Pb-Pb collisions at the incident energy of 2.76 TeV/nucleon recorded by the LHC experiments. Recent experimental developments from the Relativistic Heavy Ion Collider (RHIC) at the GeV incident energy scale are also discussed. All together LHC and RHIC measurements provide new insights on the properties and features of the new hot and dense form of matter created in the course of the relativistic heavy-ion collision.
Recent results from HADES on electron pair production in relativistic heavy-ion collisions  [PDF]
The HADES Collaboration,T. Galatyuk,G. Agakishiev,A. Balanda,D. Belver,A. V. Belyaev,A. Blanco,M. B?hmer,J. L. Boyard,P. Braun-Munzinger,P. Cabanelas,E. Castro,S. Chernenko,T. Christ,M. Destefanis,J. Díaz,F. Dohrmann,A. Dybczak,L. Fabbietti,O. V. Fateev,P. Finocchiaro,P. Fonte,J. Friese,I. Fr?hlich,J. A. Garzón,R. Gernh?user,A. Gil,C. Gilardi,M. Golubeva,D. González-Díaz,F. Guber,T. Hennino,R. Holzmann,I. Iori,A. Ivashkin,M. Jurkovic,B. K?mpfer,T. Karavicheva,D. Kirschner,I. Koenig,W. Koenig,B. W. Kolb,R. Kotte,F. Krizek,R. Krücken,W. Kühn,A. Kugler,A. Kurepin,S. Lang,J. S. Lange,K. Lapidus,T. Liu,L. Lopes,M. Lorenz,L. Maier,A. Mangiarotti,J. Markert,V. Metag,B. Michalska,J. Michel,E. Morinière,J. Mousa,C. Müntz,L. Naumann,J. Otwinowski,Y. C. Pachmayer,M. Palka,Y. Parpottas,V. Pechenov,O. Pechenova,J. Pietraszko,W. Przygoda,B. Ramstein,A. Reshetin,A. Rustamov,A. Sadovsky,P. Salabura,A. Schmah,E. Schwab,Yu. G. Sobolev,S. Spataro,B. Spruck,H. Str?bele,J. Stroth,C. Sturm,M. Sudol,A. Tarantola,K. Teilab,P. Tlusty,M. Traxler,R. Trebacz,H. Tsertos,V. Wagner,M. Weber,M. Wisniowski,T. Wojcik,J. Wüstenfeld,S. Yurevich,Y. V. Zanevsky,P. Zhou
Physics , 2009,
Abstract: Systematic investigations of dilepton production are performed at the SIS accelerator of GSI with the HADES spectrometer. The goal of this program is a detailed understanding of di-electron emission from hadronic systems at moderate temperatures and densities. New results obtained in HADES experiments focussing on electron pair production in elementary collisions are reported here. They pave the way to a better understanding of the origin of the so-called excess pairs earlier on observed in heavy-ion collisions by the DLS collaboration and lately confirmed in two measurements of the HADES collaboration using C+C and Ar+KCl collisions. Results of these studies are discussed.
Heavy flavor in relativistic heavy-ion collisions  [PDF]
E. L. Bratkovskaya,T. Song,H. Berrehrah,D. Cabrera,J. M. Torres-Rincon,L. Tolos,W. Cassing
Physics , 2015,
Abstract: We study charm production in ultra-relativistic heavy-ion collisions by using the Parton-Hadron-String Dynamics (PHSD) transport approach. The initial charm quarks are produced by the PYTHIA event generator tuned to fit the transverse momentum spectrum and rapidity distribution of charm quarks from Fixed-Order Next-to-Leading Logarithm (FONLL) calculations. The produced charm quarks scatter in the quark-gluon plasma (QGP) with the off-shell partons whose masses and widths are given by the Dynamical Quasi-Particle Model (DQPM), which reproduces the lattice QCD equation-of-state in thermal equilibrium. The relevant cross sections are calculated in a consistent way by employing the effective propagators and couplings from the DQPM. Close to the critical energy density of the phase transition, the charm quarks are hadronized into $D$ mesons through coalescence and/or fragmentation. The hadronized $D$ mesons then interact with the various hadrons in the hadronic phase with cross sections calculated in an effective lagrangian approach with heavy-quark spin symmetry. The nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$ of $D^0$ mesons from PHSD are compared with the experimental data from the STAR Collaboration for Au+Au collisions at $\sqrt{s_{NN}}$ =200 GeV and to the ALICE data for Pb+Pb collisions at $\sqrt{s_{NN}}$ =2.76 TeV. We find that in the PHSD the energy loss of $D$ mesons at high $p_T$ can be dominantly attributed to partonic scattering while the actual shape of $R_{AA}$ versus $p_T$ reflects the heavy-quark hadronization scenario, i.e. coalescence versus fragmentation. Also the hadronic rescattering is important for the $R_{AA}$ at low $p_T$ and enhances the $D$-meson elliptic flow $v_2$.
A Role of the Axial Vector Mesons on the Photon Production in Heavy Ion Collisions and Their Relevant Decays  [PDF]
Yun Chang Shin,Myung Ki Cheoun,K. S. Kim,T. K. Choi
Physics , 2001,
Abstract: A role of the axial vector mesons, such as $K_1$ and $a_1$, on the emitted photon spectrum in hot hadronic matter is studied through the channels $\pi \rho \to a_1 \to \pi \gamma$ and $K \rho \to K_1 \to K \gamma$. They are shown to be dominant channels in this spectrum. This study is carried out with an effective chiral lagrangian which includes vector and axial-vector mesons and explains well their relevant decays simultaneously.
Recent results in relativistic heavy ion collisions: from ``a new state of matter'' to "the perfect fluid"  [PDF]
M. J. Tannenbaum
Physics , 2006, DOI: 10.1088/0034-4885/69/7/R01
Abstract: Experimental Physics with Relativistic Heavy Ions dates from 1992 when a beam of 197Au of energy greater than 10A GeV/c first became available at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL) soon followed in 1994 by a 208Pb beam of 158A GeV/c at the Super Proton Synchrotron (SPS) at CERN (European Center for Nuclear Research). Previous pioneering measurements at the Berkeley Bevalac in the late 1970's and early 1980's were at much lower bombarding energies (~ 1 A GeV/c) where nuclear breakup rather than particle production is the dominant inelastic process in A+A collisions. More recently, starting in 2000, the Relativistic Heavy Ion Collider (RHIC) at BNL has produced head-on collisions of two 100A GeV beams of fully stripped Au ions, corresponding to nucleon-nucleon center-of-mass energy, sqrt(sNN)=200 GeV, total c.m. energy 200A GeV. The objective of this research program is to produce nuclear matter with extreme density and temperature, possibly resulting in a state of matter where the quarks and gluons normally confined inside individual nucleons (r < 1 fm) are free to act over distances an order of magnitude larger. Progress from the period 1992 to the present will be reviewed, with reference to previous results from light ion and proton-proton collisions where appropriate. Emphasis will be placed on the measurements which formed the basis for the announcements by the two major laboratories: "A new state of matter", by CERN on Feb 10, 2000 and "The perfect fluid", by BNL on April 19, 2005.
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