We present predictions of elliptic flow
(
v
2
)
of identified hadrons at mid-rapidity
(
|
y
|
<
1.0
)
in Au+Au collisions at
E
lab
=
35
A
GeV
using the Parton Hadron String Dynamics (PHSD) model. The ...transverse momentum (
p
T
) dependence of identified hadron
v
2
in minimum bias (0–80%) and three different centrality intervals (0–10%, 10–40%, and 40–80%) are presented. A clear centrality dependence of
v
2
(
p
T
)
is observed for particles and anti-particles. We also present the
p
T
dependence of
v
2
difference
(
Δ
v
2
)
between particles and corresponding anti-particles. A significant difference in
v
2
values for baryons and anti-baryons is observed. Constituent quark scaling (NCQ) of
v
2
is investigated in Au+Au collisions. We also present a
v
2
(
p
T
)
ratio between the HSD and PHSD modes to explore the effect of hadronic and partonic interactions in the medium. These predictions are useful for interpreting the data measured in the Beam Energy Scan (BES) program at RHIC. They will also be useful for the future Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) and Multi-Purpose Detector (MPD) at the Nuclotron-based Ion Collider facility (NICA).
The multiplicities of light (anti)nuclei were measured recently by the ALICE collaboration in Pb+Pb collisions at the center-of-mass collision energy sNN=2.76TeV. Surprisingly, the hadron resonance ...gas model is able to perfectly describe their multiplicities under various assumptions. For instance, one can consider the (anti)nuclei with a vanishing hard-core radius (as the point-like particles) or with the hard-core radius of proton, but the fit quality is the same for these assumptions. In this paper we assume the hard-core radius of nuclei consisting of A baryons or antibaryons to follow the simple law R(A)=Rb(A)13, where Rb is the hard-core radius of nucleon. To implement such a relation into the hadron resonance gas model we employ the induced surface tension concept and analyze the hadronic and (anti)nuclei multiplicities measured by the ALICE collaboration. The hadron resonance gas model with the induced surface tension allows us to verify different scenarios of chemical freeze-out of (anti)nuclei. It is shown that the most successful description of hadrons can be achieved at the chemical freeze-out temperature Th = 150 MeV, while the one for all (anti)nuclei is TA = 168.5 MeV. Possible explanations of this high temperature of (anti)nuclei chemical freeze-out are discussed.
We present a summary of the recent results obtained with the novel hadron resonance gas model with the multicomponent hard-core repulsion which is extended to describe the mixtures of hadrons and ...light (anti-, hyper-)nuclei. A very accurate description is obtained for the hadronic and the light nuclei data measured by STAR at the collision energy sNN=200GeV and by ALICE at sNN=2.76TeV. The most striking result discussed here is that for the most probable chemical freeze-out scenario for the STAR energy the found parameters allow us to reproduce the values of the experimental ratios S3 and S¯3 without fitting.
The chemical freeze-out irregularities found with the most advanced hadron resonance gas model and possible signals of two QCD phase transitions are discussed. We have found that the center-of-mass ...collision energy range of tricritical endpoint of QCD phase diagram is 9; 9.2 GeV which is consistent both with the QCD inspired exactly solvable model and experimental findings.
The strange border of the QCD phases Kabana, S.
The European physical journal. C, Particles and fields,
07/2001, Letnik:
21, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We address the flavour composition along the border between the hadronic and the quark–gluon plasma phases of QCD. The ratio of strange to up and down antiquarks (\(\lambda_s\)) produced in particle ...and nuclear collisions is found to increase in collisions with an initially reached energy density (\(\epsilon_i\)) up to \(\epsilon_{\mathrm{{crit}}} \sim 1\) GeV/fm\(^3\). Above this value it decreases approximately linearly and reaches its asymptotic value at zero baryon chemical potential (\(\mu_{\mathrm{B}}\)). We demonstrate that \(\lambda_s\) in nuclear collisions approaches its asymptotic value at \(\epsilon_i \sim 8\)–9 GeV/fm\(^3\), corresponding to \(s^{1/2} \sim 3\)–8 TeV per \({\mathrm{nucleon}} +{\mathrm{nucleon}}\) pair, which will be reached at the LHC. After correcting for the difference in the chemical potentials of various colliding systems, \(\lambda_s\) universally saturates across the QCD phase boundary, following the temperature. Recent experimental puzzles as the increase in the \(K^+/\pi^+\) ratio in \({\mathrm{Pb}} + {\mathrm{Pb}}\) collisions at 40 GeV per nucleon, its different behaviour at midrapidity, the decrease of the double ratio of \(K/\pi(A+A/p+p)\) in nucleus–nucleus over \(p + p\) collisions with increasing \(s^{1/2}\), and the increase of \(\lambda_s\) in \(p+A\) over \(p + p\) collisions at the same \(s^{1/2}\), are naturally explained. We study the approach of thermodynamic observables at \(\mu_{\mathrm{B}}=0\) to the transition point and extract an estimate of the critical temperature.
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