scholarly journals Open heavy-flavour measurements with ALICE at the LHC

2018 ◽  
Vol 192 ◽  
pp. 00016
Author(s):  
Fabio Colamaria
Keyword(s):  
Collective Motion ◽  
D Meson ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Heavy Quarks ◽  
Particle Identification ◽  
Relativistic Heavy Ion Collisions ◽  
Ion Collisions ◽  
Central Rapidity ◽  
Wide Range

Heavy quarks are produced in the early stages of ultra-relativistic heavy-ion collisions, and their number is preserved throughout the subsequent evolution of the system. Therefore, they constitute ideal probes for characterising the Quark-Gluon Plasma (QGP) medium and for the study of its transport properties. In particular, heavy quarks interact with the partonic constituents of the plasma, losing energy, and are expected to be sensitive to the medium collective motion induced by its hydrodynamical evolution. In pp collisions, the measurement of heavy-flavour hadron production provides a reference for heavyion studies, and allows also testing perturbative QCD calculations in a wide range of collision energies. Similar studies in p-Pb collisions help in disentangling cold nuclear matter effects from modifications induced by the presence of a QGP medium, and are also useful to investigate the possible existence of collective phenomena also in this system. The ALICE detector provides excellent performances in terms of particle identification and vertexing capabilities. Hence, it is fully suited for the reconstruction of charmed mesons and baryons and of electrons from heavy-flavour hadron decays at central rapidity. Furthermore, the ALICE muon spectrometer allows reconstructing heavy-flavour decay muons at forward rapidity. A review of the main ALICE results on open heavy flavour production in pp, p-Pb and Pb-Pb collisions is presented. Recent, more differential measurements are also shown, including azimuthal correlations of heavy-flavour particles with charged hadrons in p-Pb collisions, and D-meson tagged-jet production in p-Pb and Pb-Pb collisions.

J/ψ PRODUCTION FROM CHARM COALESCENCE IN RELATIVISTIC HEAVY ION COLLISIONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2061-2065
Author(s):  
BIN ZHANG
Keyword(s):  
Heavy Ion Collisions ◽  
D Meson ◽  
Charm Quark ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Final State ◽  
Charm Quarks ◽  
Ion Collisions ◽  
Multi Phase

J/ψ production is closely related to the production of the strongly interacting Quark-Gluon Plasma (sQGP) in relativistic heavy ion collisions. To study the effects of charm quark dynamics on J/ψ production, the phase space distributions of charm and anti-charm quarks are generated using A Multi-Phase Transport (AMPT) model. These charm quarks then coalesce into J/ψ particles. The production and flow of J/ψ show strong sensitivity to final state charm interactions. The results are compared to charm quark and D meson results from the AMPT model and recent predictions from other models.

Study the early stage of heavy ion collisions with direct photons

2014 ◽  
Vol 29 ◽  
pp. 1460230 ◽  
Author(s):  
Fu-Ming Liu ◽  
Sheng-Xu Liu
Keyword(s):  
Collective Motion ◽  
Early Stage ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Transverse Momentum Spectrum ◽  
Direct Photons ◽  
Ion Collisions ◽  
Phenix Collaboration ◽  
Early Beginning ◽  
Hadronic Data

Based on the modelling of the collective motion in AuAu collisions at [Formula: see text] at centrality 0-20% and 20-40% and PbPb collisions at [Formula: see text] at centrality 0-40% with a 3+1D event-averaged ideal hydrodynamics constrained with hadronic data, we study the transverse momentum spectrum and elliptic flow of direct photons and find that the recent direct photon data from both PHENIX collaboration at RHIC and ALICE collaboration at LHC favour an early beginning of collective expansion (τ0 < 0.6 fm/c) and a late formation of quark gluon plasma (τ ~ 2 fm/c).

JET CONVERSIONS IN QGP AND SUPPRESSION OF IDENTIFIED HADRONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 1930-1936 ◽  
Author(s):  
WEI LIU ◽  
CHE MING KO ◽  
BEN-WEI ZHANG
Keyword(s):  
Transverse Momentum ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
High Transverse Momentum ◽  
Ion Collisions ◽  
Conversion Rates ◽  
Gluon Jets

A gluon or quark jet traversing through a quark-gluon plasma can be converted into a quark or gluon jet through scatterings with thermal partons. Their conversion rates due to two-body elastic and inelastic scattering as well as scatterings involving gluon radiation are evaluated in the lowest order in Quantum Chromodynamics (QCD). Including both energy loss and conversions of quark and gluon jets in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we find a net conversion of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the p/π+ and [Formula: see text] ratios at high transverse momentum. Using the larger QCD coupling constant from lattice QCD calculations than that given by the perturbative QCD further enhances the net quark to gluon jet conversion rate, leading to a closer similarity between these ratios at high transverse momentum in central Au + Au collisions at [Formula: see text] and in p + p collisions at same energy as observed in experiments.

scholarly journals Strangeness production in Pb-Pb collisions at LHC energies with ALICE

2018 ◽  
Vol 171 ◽  
pp. 13007 ◽  
Author(s):  
Michal Šefčík
Keyword(s):  
Heavy Ion ◽  
Hadronic Decay ◽  
Particle Identification ◽  
Strangeness Production ◽  
Ion Collisions ◽  
Decay Products ◽  
Central Rapidity ◽  
Momentum Spectra ◽  
Strangeness Enhancement ◽  
Transverse Momentum Spectra

The results on the production of strange and multi-strange hadrons (K0S, Λ, Ξ and Ω) measured with ALICE in Pb-Pb collisions at the top LHC energy of [see formula in PDF] = 5.02 TeV are reported. Thanks to its excellent tracking and particle identification capabilities, ALICE is able to measure weakly decaying particles through the topological reconstruction of the identified hadronic decay products. Results are presented as a function of centrality and include transverse momentum spectra measured at central rapidity, pT-dependent Λ/K0S ratios and integrated yields. A systematic study of strangeness production is of fundamental importance for determining the thermal properties of the system created in ultrarelativistic heavy ion collisions. In order to study strangeness enhancement, the yields of studied particles are normalised to the corresponding measurement of pion production in the various centrality classes. The results are compared to measurements performed at lower energies, as well as to different systems and to predictions from statistical hadronization models.

STRONGLY INTERACTING QGP AND QUARKONIUM SUPPRESSION AT RHIC AND LHC ENERGIES

2012 ◽  
Vol 27 (02) ◽  
pp. 1250009 ◽  
Author(s):  
VINEET AGOTIYA ◽  
LATA DEVI ◽  
UTTAM KAKADE ◽  
BINOY KRISHNA PATRA
Keyword(s):  
Equation Of State ◽  
Degrees Of Freedom ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Strongly Coupled ◽  
Cornell Potential ◽  
Ion Collisions ◽  
Strongly Interacting ◽  
Strongly Coupled Plasma

We have developed an equation of state for strongly interacting quark–gluon plasma (QGP) in the framework of strongly coupled plasma with appropriate modifications to take account of color and flavor degrees of freedom and the interactions among themselves. For this purpose we used the effective potential to improve the plasma parameter (Γ) by correcting the full Cornell potential with a dielectric function embodying the effects of the deconfined medium and not its Coulomb part alone and obtain the equation of state in terms of Γ. Our results on thermodynamic observables viz. pressure, energy density, speed of sound etc. nicely fit to the results of lattice equation of state for gluon, massless as well massive flavored plasma. We have then employed our equation of state to estimate the quarkonium suppression in an expanding QGP produced in the relativistic heavy-ion collisions. We have found that our predictions matches with the recent PHENIX data on the centrality dependence of J/ψ suppression in Au+Au collisions at BNL RHIC within the limit of other uncertainties. We have also predicted for the ϒ suppression in Pb+Pb collisions at LHC energy which could be tested in the ALICE experiments at CERN LHC.

Resonance-like QGP signals displayed in general charge balance functions

2014 ◽  
Vol 23 (08) ◽  
pp. 1450036 ◽  
Author(s):  
Ying-Hua Pan ◽  
Wei-Ning Zhang
Keyword(s):  
Bound States ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Balance Function ◽  
Lattice Simulation ◽  
Charge Balance ◽  
Ion Collisions ◽  
Quark Production ◽  
Balance Functions

Experiment and lattice simulation show that the quark–gluon plasma (QGP) system displays strong interaction between constituents at temperature a few times the critical temperature Tc. This QGP picture can be explained by assuming that the QGP matter above Tc is rich in different kinds of bound states, namely resonance-like QGP (RQGP). The chemical composition of the QGP system produced in ultra-relativistic heavy-ion collisions can be investigated through a general charge balance function which describes two-wave quark production during expansion afterward. In this paper, we investigate the signals of this RQGP through general charge balance functions. We find that the quasiparticles in QGP contribute a little to the balance functions because of their heavy masses. The balance functions reduce to the situation discussed before where only one-wave charge production is involved if only the quasiparticles in QGP are considered. However, the baryonic bound states in QGP have a significant effect on the balance function [Formula: see text], causing a dip in the [Formula: see text] balance function at small Δy. The existence of the binary and baryonic bound states amplify the negative dip of the balance function BpK-(Δy) at Δy ∽ 1.

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