Speaker
Description
In heavy-ion collision experiments, the study of event-by-event fluctuations provides a powerful tool to characterize and understand the thermodynamic
properties of the hot and dense QCD matter.
The fluctuations of conserved quantities in a finite phase space rapidity window ($\Delta\eta$), like the net-charge, are predicted to be one of the most sensitive signals of the QGP formation and phase transition [1].
D-measure which is defined by second order cumulant per unit entropy was obtained as a function of $\Delta\eta$ in LHC-ALICE experiment at $\sqrt{s_{NN}}=2.76~$TeV Pb+Pb collisions, and it is observed to decrease with $\Delta\eta$ [2].
D-measure is considered to become $3$-$4$ in an equilibrated hadronic medium and $1$-$1.5$ in an equilibrated QGP medium [3]. Thus the ALICE results don't conflict with the theoretical prediction.
$\Delta\eta$ dependence of the higher order cumulant ratios are also important and predicted to decrease
as the $\Delta\eta$ become larger [4].
In this study, D-measure and 1st to 4th order cumulant ratios are calculated in Au+Au collisions at $\sqrt{s_{NN}}=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4,$ and $200~$GeV during Beam Energy Scan in 2010, 2011 and 2014.
We will report $\Delta\eta$, centrality and energy dependence of the net-charge fluctuation and compare STAR Beam Energy Scan results to ALICE results ($\sqrt{s_{NN}}$=2.76TeV).
Then, we will discuss an energy dependence of the fluctuation as a function of $\Delta\eta$ and possible information from the QGP phase transition.
[1] M.A.Stephanov, Phys. Rev. Lett. 102, 032301 (2009)
[2] B. Abelev et al.(ALICE Collaboration), Phys. Rev. Lett 110, 152301 (2013)
[3] S. Jeon and V. Koch, Phys. Rev. Lett. 85, 2076 (2000)
[4] Masayuki Asakawa and Masakiyo Kitazawa, Progress in Particle and Nuclear PhysicsiVolume 90, September 2016, Pages 299-342
| Preferred Track | Baryon-Rich QCD Matter and Astrophysics |
|---|---|
| Collaboration | STAR |
