Speaker
Description
One of main goals of the STAR experiment is to study the Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions. Charm quarks are an ideal probe of the QGP, as they are created primarily in hard partonic scatterings at early stage of Au+Au collisions. In this talk, we present the measurements of $D^{\pm}$ meson production in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV by STAR using the data collected in 2014 and 2016. D$^\pm$ mesons are reconstructed via a topological reconstruction of the three body hadronic decay $D^{\pm}\rightarrow K^{\mp}\pi^{\pm}\pi^{\pm}$, enabled by the exceptional track pointing resolution of the Heavy-Flavor Tracker. Supervised machine-learning techniques are used to improve the signal significance. The $D^{\pm}$ transverse momentum ($p_\mathrm{T}$) spectra are then obtained in 0-10\%, 10-40\%, and 40-80\% central Au+Au collisions. The spectra are used to calculate the nuclear modification factor as a function of $p_T$ which reveals a significant suppression of high-$p_T$ $D^{\pm}$ meson production in central and mid-central Au+Au collisions with respect to p+p collisions. The $D^{+}/D^0$ yield ratios as a function of $p_\mathrm{T}$ and centrality have also been extracted and compared to that from PYTHIA calculations. For the first time, STAR has measured the total charm quark production cross section per nucleon-nucleon collision, combining the main open charm hadron ground states (D$^0$, D$^\pm$, D$_\mathrm{s}$, and $\Lambda_\mathrm{c}$), at midrapidity in 10-40\% central Au+Au collisions at 200 GeV, which provides insight into the charm quark production in heavy-ion collisions.
