Departmental Colloquium : Gang Wang
“Heavy Flavor Measurements at STAR”
Heavy quarks, charm and bottom, are believed to be produced mostly via initial gluon fusion in nuclear collisions at the Relativistic Heavy Ion Collider (RHIC), and their propagation through the medium created by the collisions is an excellent probe to study the medium properties. With much larger masses than light quarks, heavy quarks are expected to thermalize much more slowly than light partons. Thus by measuring the collective motion of heavy flavor particles like J/psi and D mesons, we can study the flow of charm quarks and the extent of thermalization reached by the medium.
Quarkonia like J/psi and Upsilon can be measured via di-lepton channels, while the measurements of open heavy flavor suffer from large combinatorial backgrounds from the hadronic channels. The STAR experiment is carrying out the detector upgrade of the Heavy Flavor Tracker (HFT), which will greatly improve the reconstruction of open heavy flavor by locating the displaced vertices. Furthermore, HFT can also help separate prompt J/psi from feed-down contributions, to deepen our understanding of J/psi production mechanism. In this talk, previous STAR heavy flavor measurements will be reviewed, and the outlook with HFT will also be discussed.