Open-Charm Hadron Measurements in Au+Au Collisions at √sNN = 200 GeV by the STAR Experiment

Jan Vanek

doi:10.3390/universe5090196

Abstract

Study of the open-charm hadron production in heavy-ion collisions is crucial for understanding the properties of the Quark-Gluon Plasma. In these papers, we report on a selection of recent STAR measurements of open-charm hadrons in Au+Au collisions at s NN = 200 GeV , using the Heavy-Flavor Tracker. In particular, the nuclear modification factors of D 0 and D ± mesons, elliptic and directed flow of D 0 mesons, D s /D 0 and Λ c / D 0 yield ratios are discussed. The observed suppression of D 0 and D ± mesons suggests strong interactions of the charm quarks with the QGP. The measured elliptic flow of D 0 mesons is large and follows the NCQ scaling, suggesting that charm quarks may be close to thermal equilibrium with the QGP medium. Both D s /D 0 and Λ c / D 0 yield ratios are found to be enhanced in Au+Au collisions. The enhancement can be explained by models incorporating coalescence hadronization of charm quarks. In addition, the directed flow of the D 0 mesons is measured to be negative and larger than that of light-flavor mesons which is in a qualitative agreement with hydrodynamic model predictions with a tilted QGP bulk.

Highlights

One of the main goals of the STAR experiment is to study the properties of the Quark-GluonPlasma (QGP), which can be produced in ultra-relativistic heavy-ion collisions
The results clearly shows that charm quarks gain significant elliptic flow as they transverse through the medium
STAR experiment has extensively studied the open-charm hadron production using the excellent vertex position resolution provided by the Heavy-Flavor Tracker (HFT)

Summary

Introduction

One of the main goals of the STAR experiment is to study the properties of the Quark-Gluon. Plasma (QGP), which can be produced in ultra-relativistic heavy-ion collisions. The most common way to access the energy loss is by studying the modification of open-charm hadron yields in heavy-ion collisions with respect to those in p+p collisions using the nuclear modification factor: RAA ( pT ) =. RAA < 1 for high-pT open-charm hadrons is considered a signature connected with the presence of the QGP and the level of the suppression gives access to the strength of the interaction between the charm quark and the medium [2,3] Another way to obtain information about the charm quark interaction with the QGP is to measure the azimuthal anisotropy of the produced charm hadrons (v2 ). The following section summarizes recent STAR measurements of open-charm hadrons in the context of the observables and phenomena described above

Open-Charm Measurements with the HFT

Results

Summary