Productions Of Heavy Flavored Mesons In High Energy Heavy Ion Collisions In The Recombination Model

Quantum Chromo-dynamics (QCD) theory predicts a phase transition from hadronic matter to deconfined, locally thermalized Quark-Gluon Plasma (QGP) at very high temperature or high energy. QGP is believed to exist at the early stage of the formation of the universe before free quarks and gluons combined into hadrons. In general conditions, quarks are confined in the hadrons so that people can not detect a free quark in the laboratory. Heavy ion collisions provide a high temperature or a high energy density environment to create and search for the QGP matter. In recent years the Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Laboratory has achieved great processes through Au+Au and Cu+Cu collisions at center-of-mass energy (?)= 200 GeV. Lots of experimental phenomena detected in the lab such as the suppression of the particle yield in the region of high transverse momentum, the collective flow effect, etc. have preliminarily proved the production of the deconfined QGP phase transition. Now Pb+Pb collisions with higher energy of (?)= 5.5 TeV at the Large Hadron Collider (LHC) are also dedicated to study the character of QGP and the evolution process of the colliding system. Since heavy quarks are produced in the initial hard scattering processes before the formation of QGP phase transition, they are sensitive to probe the medium formed in the collisions as they may lose energy by gluon radiation during propagating through the medium and then carry abundant information of QGP. Heavy flavored hadron production at the final state at RHIC and LHC is a subject of current interest for understanding the.quark-gluon interaction. In this thesis we study the production of all kinds of heavy flavored hadrons and the elliptic flow parameter of these hadrons.Study of the particle production scheme is an important tool to understand the character of QGP and the evolution of the parton system created by the heavy ion collisions. There are two classical models to describe the hadronization scheme:the string model which is appropriate for hadrons with low pT and the parton individual fragmentation model which is successful to describe the hadron production at high pT.While these tow models are failed to be applied to explain many experimental facts at intermediate pT at RHIC energy. Recently the developed recombination model has achieved great progress in describing the particle production at any pT at RHIC and explaining the new experimental phenomena such as the Cronin effect, the ratio of p/π～1 at 3< pT< 4 GeV/c, the scaling law of elliptic flow in the number of constituents, etc..It's the first time for us to apply the recombination model to study the heavy flavored meson productions and their elliptic flow at RHIC and LHC. The process of a parton i fragmentation into a hadron h can be divided into two steps:(1) a hard parton i is produced by the hard scattering at the initial stage of the heavy ion collisions. And there are shower partons with all kinds of flavors distributed in the parton shower. (2) Two or three partons recombine together to form a hadron. The most important step in the model is to get the shower parton distributions (SPD) through describing the well-known fragmentation functions as the recombination of the shower partons. In this thesis we calculate the SPDs related with the heavy flavored meson productions by reproducing their fragmentation functions. We find that the distribution of light quarks initiated from hard parton c is higher than that of c quark in the region of small momentum fraction x< 0.35, and lower when x is large. In other words, there are more light quarks than charm quarks at low momentum fraction. The distribution of c quark created in a c jet is much higher than that of c quark in almost the whole region. A gluon jet has a density of produced light or strange quarks higher than that of charm or beauty quarks.The detected hadron at the final stage are all formed by the recombination of partons. Since there are two sources of the partons:thermal partons and shower partons, the hadron produc-tion can be expressed as the sum of contributions of thermal-thermal, thermal-shower and shower-shower recombinations. The energy loss effect of the parton propagating through the dense medium is considered in the hard parton distributions. We discuss the transverse momentum spectra of J/φin Au+Au collisions with different centralities at (?)= 200 GeV at RHIC, and the cal-culated results can fit the experimental data from PHENIX collaboration well. We find that at low transverse momentum range the main contribution comes from thermal-thermal recombina-tion and at high pT shower-shower recombination equivalent with the process of fragmentation is dominant. While the recombination of thermal-shower partons plays a major role in the region of intermediate momentum, which demonstrates the advantage of the recombination model. Also, we predict the momentum spectra of other charmed mesons and B mesons which will be tested by further experiments.Considering the production ofπand J/φin the same jet, we discuss the di-hadron correlation ofπ-J/φ. The correlation of the particle J/φwith pa associated with the trigger particleπwith pt on the near side shows the near-side yield increases with pt for pa> 3.8 GeV/c, while this trend is reversed in the region of low pa, and the shape of the distribution is independent of the centrality. On the other hand, the away-side yield becomes higher as pt increases, and the trend becomes smoother and similar to that of the near-side in more peripheral collisions. The difference is mainly caused by the significantly different fragmentation functions for J/φandπ.We get another important parameter, the elliptic flow parameterυ2 which reflects the az-imuthal anisotropy of the particle if we get the azimuthal angle dependence of the hard parton distribution. The value ofυ2 for J/φcan fit the experimental data from PHENIX collaboration. Andυ2 for D meson is higher than that for J/φ, which is not consistent with the number of quark (NQ) scaling ofυ2.Because in the model the momentum of D0 or Ds comes mainly form charm quark due to the unequal constituent quark masses, we get differentυ2 for J/φand D0 or DsAt higher energy such as LHC, the contribution from the recombination of shower partons from two different jets must be taken into account. And this term depends on the overlap probability between the two neighboring jets. The values ofυ2 for J/φmaintain as constants if the overlap probability is small enough or becomes quite large. When the contributions to the flow from the recombination of shower partons from two different jets and the recombination of shower partons from the same jets are comparative, the results ofυ2 decease with increasing pT which is very similar to the theory predictions based on the jet energy loss in perturbative QCD.