Speaker
Jaroslav Bielcik
(Czech Technical University (CZ))
Description
The calculations of Quantum Chromodynamics on lattice showed that under conditions of high energy density or high temperature nuclear matter undergoes a phase transition from state of confined quarks and gluons to deconfined state, the Quark-Gluon Plasma (QGP).
Such conditions were present in first moments after the Big Bang
in the early universe and can be created in laboratory by colliding of heavy ions with sufficient energy. During the last decade, the STAR experiment at Relativistic Heavy Ion Collider has studied the properties of the Quark-gluon Plasma.
One of the most prominent signatures of QGP formation is the Debye
screening of the quark-antiquark potential resulting in quarkonium
suppression in central heavy ion collisions. However, cold nuclear
effects, heavy quark recombination and hot wind dissociation could
influence the measured quarkonium yields. Measurements of
different quarkonium states in different collision systems and
centralities are necessary to extract the color-screening effects .
Quarkonium measurements allow to extract the thermodynamic properties, since different quarkonium states have different binding energy and therefore disassociate at different temperature of QGP.
In this talk, we will report on the recent STAR measurements of $J/\psi$ and $\Upsilon$ production at mid-rapidity in $p+p$, $d$+Au and Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV.
We will also present the $J/\psi$ polarization measurement in p+p
collisions and the $J/\psi$ elliptic flow measurement in Au+Au collisions.
Author
Jaroslav Bielcik
(Czech Technical University (CZ))
