Measurements of open charm production and flow in √sNN = 200GeV Au+Au collisions with the STAR experiment at RHIC

Spyridon Margetis

doi:10.1051/epjconf/201819200015

Abstract

We present an improved, higher statistics, measurement with respect to the previously published results of the D0 meson elliptic flow (v2) as a function of transverse momentum (pT) in Au+Au collisions at √sNN = 200 GeV with the STAR Heavy Flavor Tracker (HFT). The D0 v2 results are compared to those of light-flavor hadrons to test the number-of-constituent-quark (NCQ) scaling. They are also compared to recent hydrodynamic and transport model calculations. We also report on the updated measurements of D0 nuclear modification factors RAA and RCP using the 2014 data. The measured D0 RAAin central collisions is less than 1 across the entire pT region. The D0 yields show strong suppression at high pT (> 6 GeV/c) in central collisions, consistent with those of light flavor hadrons. We also report the measurements of collision centrality and pT dependences of the Λ±c production in Au+Au collisions at √sNN = 200 GeV, using the HFT. The Λ±c signal significance is greatly improved with the addition of the highstatistics data set collected in 2016 and the use of a supervised machine learning method for a more effcient topological reconstruction of the decay vertices. The measured Λ±c/D0 ratio in 10-80% Au+Au collisions shows a significant enhancement compared to the PYTHIA prediction for p + p collisions, across the measured pT range.

Highlights

Relativistic heavy-ion collisions at the RHIC and LHC create a hot dense medium consisting of deconfined quarks and gluons, usually referred to as the Quark Gluon Plasma (QGP) [1, 2]
The RAA values for pT > 5 GeV/c show significant suppression in central collisions, and the suppression decreases towards more peripheral collisions, as the system size decreases
The RCP values are consistent with unity for pT < 2 GeV/c, but decrease towards high pT (> 6 GeV)

Summary

Introduction

Relativistic heavy-ion collisions at the RHIC and LHC create a hot dense medium consisting of deconfined quarks and gluons, usually referred to as the Quark Gluon Plasma (QGP) [1, 2]. Enhancement of the ratio, relative to that in p + p collisions, is expected in the intermediate pT region (2 - 6 GeV/c) if charm quarks hadronize via the coalescence mechanism in the QGP [9, 10]. The magnitude of this enhancement is sensitive to the charm quark dynamics and the presence of diquarks in the medium [9]. RAA and RCP are presented for various centrality classes as a function of pT and compared to similar measurements for light flavor hadrons as well as model calculations

Experiment and Analysis

Results

Conclusion