Article
Soft open charm production in HeavyIon Collisions.
McGill University, Montreal, Canada, H3A 2T8.
Physical Review Letters (Impact Factor: 7.73). 07/2009; 102(23):232302. DOI: 10.1103/PHYSREVLETT.102.232302 Source: PubMed

Article: Heavyquark production in ultrarelativistic heavyion collisions within a partonic transport model
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ABSTRACT: The production and spacetime evolution of charm and bottom quarks in nucleusnucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are investigated with the partonic transport model BAMPS (Boltzmann approach of multiparton scatterings). Heavy quarks, produced in primary hard parton scatterings during nucleonnucleon collisions, are sampled using the Monte Carlo event generator pythia or the leadingorder minijet model in conjunction with the Glauber model, revealing a strong sensitivity on the parton distribution functions, scales, and heavyquark mass. In a comprehensive study exploring different charm masses, K factors, and possible initial gluon conditions, secondary production and the evolution of heavy quarks are examined within a fully dynamic BAMPS simulation for central heavyion collisions at RHIC and LHC. Although charm production in the quarkgluon plasma can be neglected at RHIC, it is significant at LHC but very sensitive to the initial conditions and the charm mass. Bottom production in the quarkgluon plasma, however, is negligible both at RHIC and LHC.Physical Review C 10/2010; 82(4). · 3.88 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A brief introduction of the relationship of string percolation to the Quantum Chromo Dynamics (QCD) phase diagram is presented. The behavior of the Polyakov loop close to the critical temperature is studied in terms of the color fields inside the clusters of overlapping strings, which are produced in high energy hadronic collisions. The nonAbelian nature of the color fields implies an enhancement of the transverse momentum and a suppression of the multiplicities relative to the non overlapping case. The prediction of this framework are compared with experimental results from the SPS, RHIC and LHC for $pp$ and AA collisions. Rapidity distributions, probability distributions of transverse momentum and multiplicities, BoseEinstein correlations, elliptic flow and ridge structures are used to evaluate these comparison. The thermodynamical quantities, the temperature, and energy density derived from RHIC and LHC data and Color String Percolation Model (CSPM) are used to obtain the shear viscosity to entropy density ratio ($\eta/s$). It was observed that the inverse of ($\eta/s$) represents the trace anomaly $\Delta =(\varepsilon3P)/T^{4}$. Thus the percolation approach within CSPM can be successfully used to describe the initial stages in high energy heavy ion collisions in the soft region in high energy heavy ion collisions. The thermodynamical quantities, temperature and the equation of state are in agreement with the lattice QCD calculations. Thus the clustering of color sources has a clear physical basis although it cannot be deduced directly from QCD.01/2015;  [Show abstract] [Hide abstract]
ABSTRACT: Nonperturbative charm and bottom quarkpair production is investigated in the early stage of heavy ion collisions. Following our earlier works, the timedependent study is based on a kinetic description of fermionpair production in strong nonAbelian fields. We introduce timedependent chromoelectric external field with a pulselike time evolution, which simulates the overlap of two colliding heavy ions. The calculations is performed in a SU(2) color model with finite current quark masses. Yields of heavy quarkpairs are compared to the ones of light and strange quarkpairs. We show that the small inverse duration time of the field pulse determines the efficiency of the quarkpair production. Thus we do not see the expected suppression for heavy quark production, as follows from the Schwinger formula for constant field, but rather an enhanced heavy quark production at ultrarelativistic energies. We convert pulse duration timedependent results into collisional energy dependence and introduce flavourdependent energy string tensions, which can be used in string based model calculations at RHIC and LHC energies. Comment: 11 pages, 9 figuresPhysical review D: Particles and fields 10/2010; D82:074014.
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