Evolution of anisotropic flow of
produced particles from Au+Au
collisions at 𝒔𝑵𝑵 = 3-200 GeV in atransport models.
Arkadiy Taranenko, Petr Parfenov, Dim Idrisov, Vinh Luong (NRNU MEPhI)

TWENTIETH LOMONOSOV CONFERENCE ON
ELEMENTARY PARTICLE PHYSICS, August 19-25, 2021, Moscow
State University, Moscow,, Russia

This work is supported by: the RFBR according to the research project No. 18-02-40086 and by
Ministry of Science and Higher Education of the Russian Federation, No 0723-2020-0041.

OUTLINE

1. Why measure anisotropic flow?
2. Beam energy dependence of anisotropicflow. Models vs Data
3. What to expect for flow at NICA energies

4. Summary and outlook

2R. Lacey, SUNY Stony Brook

Anisotropic Collective Flow at top RHIC / LHC

Vn (pT, centrality) - sensitive to the earlystages of collision.
Important constraint for transport
properties: EOS, η/s, ζ/s, etc.
vn of identified hadrons:
Mass ordering at pT < 2 GeV/c(hydrodynamic flow, hadron rescattering)
Baryon/meson grouping at pT > 2 GeV/c(recombination/coalescence),
Number of constituent quark (NCQ)
scalingGale, Jeon, et al., Phys. Rev. Lett. 110, 012302

STAR PRL118 (2017) 212301

ICNFP Crete 2020

No difference between particles
and04.09.2020
antiparticles

3R. Lacey, SUNY Stony Brook

Hybrid models for anisotropic flow at RHIC/LHC
1) UrQMD + 3D viscous hydro model vHLLE + UrQMD
Iurii Karpenko, Comput. Phys. Commun. 185 (2014), 3016
https://github.com/yukarpenko/vhlle
Parameters: from Iu. A. Karpenko, P. Huovinen, H. Petersen, M.
Bleicher, Phys. Rev. C91 (2015) no.6, 064901 – good description ofSTAR BES results for 𝐯𝟐 of inclusive charged hadrons (7.7 – 62.4Gev)

Initial conditions: model UrQMD
QGP phase: 3D viscous hydro (vHLLE) with crossover EOS (XPT)
Hadronic phase: model UrQMD2) A Multi-Phase Transport model (AMPT) for high-energy nuclear
collisions. The main source codes: Zi-Wei Lin(http://myweb.ecu.edu/linz/ampt/v1.26t9b/v2.26t9b)

Initial conditions: model HIJING
QGP phase: Zhang’s parton cascade for modeling partonic
scatterings
ICNFP Crete 2020
Hadronic phase: model ART
Z.W. Lin, C. M. Ko, B.A. Li, B. Zhang and S. Pal:
Physical Review C 72, 064901 (2005).

404.09.2020

R. Lacey, SUNY Stony Brook

vHLLE+UrQMD: Elliptic and triangular flow in Au + Au collisions at 200 GeV

3D hydro model vHHLE + UrQMD ( XPT EOS), η/s= 0.08 + param fromIu.A. Karpenko, P. Huovinen, H. Petersen, M. Bleicher , Phys.Rev. C91
ICNFP Crete 2020(2015) no.6, 064901

04.09.2020

Reasonable agreement between results of vHLLE+UrQMD model and published PHENIX
data
5

R. Lacey, SUNY Stony Brook

vHLLE+UrQMD: Scaling of elliptic and triangular flow at top RHIC energy

6Reasonable
04.09.2020
ICNFP agreement
Crete 2020 between results of vHLLE+UrQMD modeland published PHENIX data for 200 GeV including KET/nq scaling
R. Lacey, SUNY Stony Brook

𝑣2 of charged mesons in Au+Au collisions at 𝑠𝑁𝑁 = 27 GeVSTAR data: Phys. Rev. C 93 (2016) 14907

reasonable agreement between vHLLE+UrQMD and data for charged pions and kaons
7

R. Lacey, SUNY Stony Brook

𝑣2 of (anti)protons in Au+Au collisions at 𝑠𝑁𝑁 = 27 GeVSTAR data: Phys. Rev. C 93 (2016) 14907

8R. Lacey, SUNY Stony Brook

𝑣2 of identified charged hadrons in Au+Au collisions at𝑠𝑁𝑁 = 27 GeV: AMPT vs Data
STAR data: Phys. Rev. C 93 (2016) 14907

9R. Lacey, SUNY Stony Brook

KET / nq scaling : hybrid models

UrQMD + 3D viscous hydro model vHLLE + UrQMD
Iurii Karpenko, Comput. Phys. Commun. 185 (2014),3016
https://github.com/yukarpenko/vhlle
Initial conditions: model UrQMD
QGP phase: 3D viscous hydro (vHLLE) EOS (XPT)
Hadronic phase: model UrQMD

A Multi-Phase Transport model (AMPT) for highenergy nuclear collisions. (v1.26t9b/v2.26t9b)
Initial conditions: model HIJING
QGP phase: Zhang’s parton cascade for modelingpartonic scatterings
Hadronic phase: model ART

Z.W. Lin, C. M. Ko, B.A. Li, B. Zhang and S. Pal:
Physical Review C 72, 064901 (2005).
10

Elliptic flow: protons vs. antiprotons

11

R. Lacey, SUNY Stony BrookElliptic flow: protons vs. antiprotons• The same trend is apparent in both UrQMD and AMPT• SMASH gives a different trend – close to the data

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R. Lacey, SUNY Stony BrookElliptic flow at NICA energies: Models vs Data comparison

3D hydro model vHHLE + UrQMD ( XPT EOS), η/s= 0.2 + param from
Iu.A. Karpenko, P. Huovinen, H. Petersen, M. Bleicher , Phys.Rev. C91 (2015) no.6, 064901
13

R. Lacey, SUNY Stony BrookElliptic flow at NICA energies: Models vs Data comparison

Pure String/Hadronic Cascade models give smaller v2 signal compared to STAR data for
Au+Au √sNN=7.7 GeV and above

14

R. Lacey, SUNY Stony Brook

KET / nq scaling : String/Hadronic Cascade models

15

STAR Collaboration, arxiv.org/abs/2007.14005

Pure String/Hadronic Cascade models give similar v2 signal
compared to STAR data for Au+Au √sNN=4.5 GeVElliptic Flow at 𝑠𝑁𝑁 = 3 GeV : interactions with spectators
Disappearance of partonic collectivity in𝑠𝑁𝑁 = 3 GeV Au+Au collisions at RHIC

STAR: https://arxiv.org/abs/2108.00908

Passage time: 2R/(βcmγcm)
Expansion time: R/cs , cs=c√dp/dε - speed of sounda delicate balance between (i) the ability of pressure developed early in thereaction zone and (ii) the passage time for removal of the shadowing by 16spectators

Elliptic Flow at 𝑠𝑁𝑁 = 3 GeV : interactions with spectators
Disappearance of partonic collectivity in𝑠𝑁𝑁 = 3 GeV Au+Au collisions at RHIC

STAR: https://arxiv.org/abs/2108.00908

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Summary
We performed a high statistics simulations with hybrid models (vHLLE+UrQMD
and AMPT) for several points in collision energy from RHIC BES program.
●The events were analysed in a similar way as the real experimental data andresults were compared with STAR published resuls of v2 for charged pions, kaonsand (anti)protons.
●The results from vHLLE+UrQMD model are in a better agreement withexperimental data than for AMPT ( tunning of the input parameters?)
Both models in the present configuration fails to reproduce the difference between
elliptic flow signal of particles and antiparticles: models predictthat 𝑣2 (protons) < 𝑣2 (antiprotons) , data show 𝑣2 (protons) > 𝑣2 (antiprotons)●Model/Data comparison for NICA energy range ( 4-11 GeV):
Pure String/Hadronic Cascade models (no QGP phase) give smaller v2 signal
compared to STAR data for Au+Au √sNN=7.7-11.5 GeV andmodels give similar v2 signal compared to STAR data for Au+Au √sNN=4.5 GeV.
v2 signal of produced particles from Au+Au at √sNN=3.0 GeV is negative – strong
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interactions of produced particles with spectators
Thank you for your attention!